1. Pre-Design
A. Appraisal
B. Design Brief
1.1. Obtain design brief
1.1.1. CIBSE guidance and tools
The building services engineer should be able to influence the design brief at an early stage in terms of energy efficiency, system options, sustainability, climate change, regulations etc. There are various ways to influence the brief and the following suggested guidance provides information relevant to some of the issues related to building design.
CIBSE Guide F “Energy Efficiency in Buildings” provides information on energy efficiency issues at various design stages, including information to be used at early design stages, such as the drivers for energy efficiency (chapter 1), setting energy objectives, criteria and targets, equipment and system selection (chapter 2) and developing a design strategy (chapter 3 and 4). Furthermore, Guide F provides general information on LZC technologies (chapter 5), control strategies (chapter 6) and cooling system design considerations (chapter 10). Part C of Guide F provides benchmarks of energy performance for various building applications and a series of CIBSE policy statements that reinforce the drivers for energy efficiency.
CIBSE Guide L “Sustainability” provides information on sustainability issues to help towards influencing the design brief (chapter 2), forming a sustainability strategy (chapter 3), including energy and low carbon strategy with reference to LZC technologies (§3.1), and adaptation to the impacts of climate change (§3.3).
CIBSE publications related to renewable technologies are the AM12 “Small-Scale Combined Heat and Power for Buildings”, TM25 “Understanding Building Integrated Photovoltaics and TM38 “Renewable Energy Sources for Buildings” with an accompanied simple tool to assist in initial identification of the most promising renewable sources for a given project.
CIBSE TM45 “Groundwater Cooling Systems” explains the principals and issues associated with the installation and operation of such systems.
CIBSE Knowledge Series KS11 “Green Roofs” explains the thermal properties of the green roofs improve the thermal performance of the building during hot periods reducing demand for cooling loads.
The CIBSE Knowledge Series publication KS8 ”Sustainable Low Energy Cooling: an Overview” explains the principles of designing sustainable cooling strategies and presents various sustainable cooling options.
CIBSE Guidance Note GN1 “CFCs, HCFCs and Halons: Professional and Practical Guidance on Substances that Deplete the Ozone Layer’ informs of the regulations and environmental impact related to the various substances used as refrigerants in cooling technologies.
CIBSE TM36 “Climate Change and the Indoor Environment: Impacts and Adaptation” provides information on the impacts of higher summer temperatures caused by climate change, on a variety of building applications (domestic and non-domestic, new and existing), and examines various adaptation options to avoid overheating and higher energy demand for cooling.
A more holistic approach of how to influence the design brief that combines energy efficiency, sustainability, cost, regulations, future performance; how certain design decisions could affect the above choices and their interrelations e.g. sustainability against capital, and whole life cost against building regulations requirements etc.
1.1.2. Weather data available for present climate conditions
At this pre-design stage of consulting with the client some general weather statistics based on location could be used towards influencing the design brief in terms of energy efficiency and system option.
CIBSE Guide A “Environmental Design” provides warm weather data for various UK locations (chapter 2, §2.4) as well as cooling degree hours (chapter 2, §2.5) to inform the cooling strategy. CIBSE Guide J “Weather, Solar and Illuminance Data” also provides summary statistics (§3.5), warm weather data (chapter 4, §4.2) and cooling degree hours (chapter 4, §4.3), for the same UK locations.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The user should be looking for present day statistics of occurrence of high temperatures, maximum solar radiation (direct and diffuse), coincidence of high temperatures and high solar radiation and coincidence of dry bulb and wet bulb temperatures, based on location.
The weather data available in the CIBSE guides are location specific but not site specific. The user should take under consideration that locality and microclimate can considerably affect design decisions. Local information could be acquired from city councils, local planning authorities, environment agency, met office etc.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than the ones currently occurring.
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
1.1.3. Weather data available for future climate conditions
At this pre-design stage of consulting with the client some general climate change statistics based on location could be used towards influencing the design brief in terms of climate change; possible impacts on building and building site and designing for future conditions.
CIBSE Guide A “Environmental Design” (chapter 2, §2.9) and CIBSE Guide J “Weather, Solar and Illuminance Data” (chapter 3, §3.2 and chapter 4, §4.4) provide climate change trends for various emissions scenarios, for three UK locations (London, Manchester and Edinburgh); changes are based on a 1961-1990 baseline
CIBSE Guide L “Sustainability” summarises climate changes for one emissions scenario and for the same three locations.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
The user should be looking for future statistics of occurrence of high temperatures, maximum solar radiation (direct and diffuse), coincidence of high temperatures and high solar radiation and coincidence of dry bulb and wet bulb temperatures, based on location.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
The CIBSE climate change data (Guides A, J, L and TM34) are available for three locations only (London, Manchester and Edinburgh).
TM34 presents trends of summer temperatures and coincident dry bulb and wet bulb temperatures but there are no wind data available due to the lack of suitable algorithm to produce hourly wind speed data from the available UKCIP02 daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty is higher than for example for the temperature and rainfall changes.
The data in Guides A and J are not at the moment consistent. Climate change data in Guide A is in accordance with UKCIP02 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291), while Guide J data is in accordance with the previous version of UKCIP98 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=255).
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
1.1.4. Other useful references
Environment Agency’s Flood Map resource at: http://www.environment-agency.gov.uk/subjects/flood/826674/829803
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
1.1.5. Input from members
1.2. Identify client and building user needs and requirements
1.2.1. CIBSE guidance and tools
The building services engineers should be able to identify and acquire client requirements to be used while putting together the brief, so as to optimise design in terms of sustainability, energy efficiency, regulations, future needs etc. Such requirements could include budget, required performance, attitude to risk, health and safety requirements etc.
An example of listing client and user needs and requirements is presented in CIBSE Knowledge Series publication KS8 “How to Design a Heating System”. A similar list could be developed and expanded to accommodate the design of cooling systems. Potentially such a list could be composed by designers by using a series of CIBSE publications such as Guide A “Environmental Design” for internal environment requirements, Guide F “Energy Efficiency in Buildings” for energy efficiency requirements, Guide L “Sustainability”, Guide H “Building Control Systems” for control requirements etc.
CIBSE could offer a checklist of all relevant needs and requirements that the engineer could advise towards reaching objectives described in task 1.1.
1.2.2. Other useful references
1.2.3. Input from members
1.3. Refer to feedback and lessons learned from previous projects
1.3.1. CIBSE guidance and tools
The building services engineers should be able to keep in touch with previous projects in order to learn from them and improve their design methods. Some guidance on energy audits and surveys is included in Guide F, chapter 18.
Facilities managers (FMs) are usually responsible for the management of the building services and energy use in a building and have access to performance and energy use data. Liaising with the FMs during design process could provide useful information about the future operation and maintenance needs of a building and its services. Limited information on facilities and energy management is provided in Guide F, chapter 15.
Further guidance could include advice on possible channels and actions through which the design team could revisit or keep in touch with previous projects. Perhaps some research could be done in current practices.
Could CIBSE influence client perception of the value of monitoring and feedback? For example in some current projects monitoring and feedback is used as an educational process.
Further guidance could concentrate on encouraging integration with Facilities Management (FM), e.g. FM participation during design stages.
1.3.2. Other useful references
1.3.3. Input from members
1.4. Gather information about site, including utilities provision and fuel options
1.4.1. CIBSE guidance and tools
The building services engineers should make sure that they acquire all site specific information that could influence the design decisions. A comprehensive list of all relevant site specific information could assist towards the above.
CIBSE Guide F “Energy Efficiency in Buildings” provides some general site considerations (chapter 4, §4.1).
CIBSE Guide L “Sustainability”, chapter 3, provides information on site analysis, in relation to energy use (§3.1), and on assessment of flood risk (§3.4), site accessibility (§3.6) and impacts on local environment and community (§3.11). Climate changes are summarised in Guide L for three locations in order to assist in forming adaptation solutions to climate change.
CIBSE TM36 “Climate Change and the Indoor Environment: Impacts and Adaptation” provides information on the impacts of higher summer temperatures caused by climate change, on a variety of building applications (domestic and non-domestic, new and existing), and examines various adaptation options to avoid overheating and higher energy demand for cooling.
Fuel choices (mostly presented for heating) are included in CIBSE Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapter 1, §1.6, and in Guide F, chapter 5, §5.2.
A comprehensive checklist of all relevant site specific information and their possible sources e.g. city councils, local planning authorities, environment agency, met office, site visits etc. could be useful.
1.4.2. Weather data available for present climate conditions
At this pre-design stage of gathering site information, statistics on summer events based on location could influence decisions on building form and orientation.
CIBSE Guide A “Environmental Design” provides warm weather data for various UK locations (chapter 2, §2.4) as well as cooling degree hours (chapter 2, §2.5) to inform the cooling strategy. CIBSE Guide J “Weather, Solar and Illuminance Data” also provides summary statistics (§3.5), warm weather data (chapter 4, §4.2) and cooling degree hours (chapter 4, §4.3), for the same UK locations.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The user should be looking for site specific climate/weather trends/extremes of occurrence of high temperatures, coincidence of high temperatures and high solar radiation (direct and diffuse) and coincidence of dry bulb and wet bulb temperatures. Furthermore, the user should be looking for site specific flooding/drought occurrences as they might affect the access to the building, e.g. for fuels, or the cooling strategies that are based on external plants.
The weather data available at the CIBSE guides are location specific but not site specific. The user should take under consideration that locality and microclimate can considerably affect design decisions. Local information could be acquired from city councils, local planning authorities, environment agency, met office etc.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than the ones currently occurring.
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
1.4.3. Weather data available for future climate conditions
At this pre-design stage of gathering site information, trends of future summer events based on location could assist in understanding the changes that the site might undergo over the lifetime of the building. Such information could help in forming a flexible cooling strategy that could inspire future low/zero energy use for cooling and be able to respond to future summer events.
CIBSE Guide A “Environmental Design” (chapter 2, §2.9) and CIBSE Guide J “Weather, Solar and Illuminance Data” (chapter 3, §3.2 and chapter 4, §4.4) provide climate change trends for various emissions scenarios, for three UK locations (London, Manchester and Edinburgh); changes are based on a 1961-1990 baseline
CIBSE Guide L “Sustainability” summarises climate changes for one emissions scenario and for the same three locations.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
The user should be looking for future site specific climate/weather trends/extremes of occurrence of high temperatures, coincidence of high temperatures and high solar radiation (direct and diffuse) and coincidence of dry bulb and wet bulb temperatures.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
The CIBSE climate change data are available for three locations only (London, Manchester and Edinburgh).
TM34 presents trends of summer temperatures and coincident dry bulb and wet bulb temperatures but there are no wind data available due to the lack of suitable algorithm to produce hourly wind speed data from the available UKCIP02 daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty is higher than for example for the temperature and rainfall changes.
The data in Guides A and J are not at the moment consistent. Climate change data in Guide A is in accordance with UKCIP02 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291), while Guide J data is in accordance with the previous version of UKCIP98 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=255).
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
1.4.4. Other useful references
Environment Agency’s Flood Map resource at: http://www.environment-agency.gov.uk/subjects/flood/826674/829803/
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
BRE (1990) “Climate and Site Development. Part 2: Influence of Microclimate”
BRE (2000) “Environmental Site Layout Planning: Solar Access, Microclimate and Passive Cooling in Urban Areas”
1.4.5. Input from members
1.5. Obtain information on use of building, occupancy hours and on possible building form, fabric, etc.
1.5.1. CIBSE guidance and tools
The building services engineers should be able to acquire all building related information such as form and fabric details, building use and occupancy patterns, etc. An example of listing building specific information is presented in the CIBSE Knowledge Series publication KS8 “How to Design a Heating System” (§ 3.2).
CIBSE could further develop a checklist list and guidance on where/how to acquire the relevant information for the design of the cooling system e.g. client’s brief, by further questioning the client, design plans and details, etc.
1.5.2. Other useful references
1.5.3. Input from members
1.6. Establish and confirm design requirements from Regulations, Codes of Practice etc.
1.6.1. CIBSE guidance and tools
The building services engineers should be able to refer to all regulations, codes and standards that relate to the individual project. The most up-to-date references and links to specific regulations and codes are included in CIBSE Guide L “Sustainability”. Legislation regarding health issues associated with the building services could also be found in CIBSE TM40 “Health Issues in Building Services”.
CIBSE could further develop a comprehensive and dynamic list of all necessary documents and where to find them, download them etc, as well as possible future developments and updates.
1.6.2. Other useful references
1.6.3. Input from members
1.7. Establish requirements for use of on-site renewables
1.7.1. CIBSE guidance and tools
The building services engineers should be able to establish requirements for the use of LZC technologies e.g. check infrastructure, financing, environmental impact, planning requirements etc. CIBSE Guide L “Sustainability” provides guidance on LZC technologies options, environmental impact, current government targets and cost. Further guidance on the requirements for the installation and operation of LZC technologies could also be found in AM12 “Small-Scale Combined Heat and Power for Buildings”, TM45 “Groundwater Cooling Systems”, TM25 “Understanding Building Integrated Photovoltaics” and TM38 “Renewable Energy Sources for Buildings”.
Guidance on potential impacts of future developments of the surrounding area that could affect the effectiveness of the LZC technologies – e.g. future high buildings will affect solar & daylight availability, change in land use could improve performance, etc. CIBSE could further develop a comprehensive and dynamic list of all relevant documents and/or where to find them e.g. county councils, building regulations, application documents, etc.
1.7.2. Other useful references
Grants available for installing renewables: http://www.clear-skies.org/
‘Integrating renewable energy into new developments: Toolkit for planners, developers and consultants’: http://www.london.gov.uk/mayor/environment/energy/london_renew.jsp
Energy Saving Trust: http://www.energysavingtrust.org.uk/generate_your_own_energy
1.7.3. Input from members
2. Preliminary Design
C. Concept
D. Design development
2.1. Establish the key design data and parameters that relate to the design of the cooling system, including building air tightness data, and the potential use of renewables
2.1.1. CIBSE guidance and tools
The building services engineer should be looking for guidance on how to establish internal and external design conditions in order to inform the design and sizing of the cooling system e.g. comfort requirements, weather data etc.
CIBSE Guide A “Environmental Design” provides comfort criteria for design (chapter 1), surface condensation and mould growth design criteria (chapter 7, §7.6 and §7.7) and other health issues associated with building services (chapter 8).
CIBSE TM40 “Health Issues in Building Services “ also provides comprehensive guidance on health issues associated with the operation and maintenance of building services.
The CIBSE Knowledge Series publication KS6 “Comfort” explains internal comfort criteria.
CIBSE TM23 “Testing Buildings for Air Leakage” provides guidance on air leakage tests.
CIBSE Guide F “Energy Efficiency in Buildings” (chapter 5) and Guide L “Sustainability” (chapter 3, §3.1 and chapter 5, §5.1) provide general information on LZC technologies and design requirements.
Other CIBSE publications related to renewable technologies are the AM12 “Small-Scale Combined Heat and Power for Buildings”, TM25 “Understanding Building Integrated Photovoltaics” and TM38 “Renewable Energy Sources for Buildings” with an accompanied simple tool to assist in initial identification of the most promising renewable sources for a given project.
There is some concern that the existing overheating criteria suggested by CIBSE do not take under consideration people’s ability to adapt to extended periods of high temperatures and that encourages the use of mechanical cooling. The CIBSE Overheating Group is reviewing the existing overheating criteria with a view to create a new set that would take under consideration the adaptive comfort model.
Even though TM23 covers air leakage testing methods (post construction) further guidance on methods to minimise air leakage at design stage could also be beneficial.
2.1.2. Weather data available for present climate conditions
Weather data at this preliminary design stage should be used towards deciding on the external conditions for designing the cooling system. Data gathered at pre-design stage (task 1.4) could be analysed based on risk, building form and with client involvement in order to establish external design conditions.
CIBSE Guide A provides warm weather data for various UK locations (chapter 2, §2.4) as well as cooling degree hours (chapter 2, §2.5) to inform the cooling strategy. CIBSE Guide J “Weather, Solar and Illuminance Data” also provides summary statistics (chapter 3, §3.5), warm weather data (chapter 4, §4.2) and cooling degree days (chapter 4, §4.3) for the same UK locations.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
Solar and wind data in Guide A (chapter 2, §2.7 and §2.8) and Guide J (chapter 5 and chapter 6) as well as the maps of average wind speed in the UKCIP08 recent trends report could be used for assessing potential use of renewables.
The user should be looking for percentage of certain conditions exceeded, such as high temperatures, coincidence of high temperatures and solar radiation (direct and diffuse) and coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control), based on location.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than the ones currently occurring.
Site specific information should be acquired for assessing potential use of renewables e.g. local wind, sunshine availability and elements blocking the sun around the site etc. Local information could be acquired from city councils, local planning authorities, environment agency, met office etc. and by site visits and discussions with client.
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
2.1.3. Weather data available for future climate conditions
Climate change information at this preliminary design stage should be used towards deciding on the external design conditions, to help inform the cooling strategy over the lifetime of the building. Data gathered at pre-design stage (task 1.4) could be analysed based on risk, building form and with client involvement in order to establish external design conditions that would take under consideration climate change.
Climate change information could also be used here to inform future potential use of renewables; for example, examining the potential of LZC technologies for meeting future demand for cooling.
CIBSE Guide A “Environmental Design” (chapter 2, §2.9) and CIBSE Guide J “Weather, Solar and Illuminance Data” (chapter 3, §3.2 and chapter 4, §4.4) provide climate change trends for various emissions scenarios, for three UK locations (London, Manchester and Edinburgh); changes are based on a 1961-1990 baseline
CIBSE Guide L “Sustainability” summarises climate changes for one emissions scenario and for the same three locations.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
The user should be looking for probability of certain conditions exceeded in the future, such as high temperatures, coincidence of high temperatures and solar radiation (direct and diffuse) and coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control), based on location.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
CIBSE climate change data are available for three locations only (London, Manchester and Edinburgh).
The data available in TM34 can be used towards establishing future external design conditions, but there are no wind data available due to the lack of suitable algorithm to produce hourly wind speed data from the available daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty is higher than for example for the temperature and rainfall changes. Furthermore, the daily average wind speed and cloud cover changes in the scientific report could be used to assess potential use of renewables in the future.
The data in Guides A and J are not at the moment consistent. Climate change data in Guide A is in accordance with UKCIP02 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291), while Guide J data is in accordance with the previous version of UKCIP98 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=255).
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
2.1.4. Other useful references
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
The Building Regulations second tier document “Low or Zero Carbon Energy Sources: Strategic Guide” provides a simplified calculation tool for assessing the reduction in carbon emissions through the use of LZC technology: http://www.planningportal.gov.uk/uploads/br/BR_PDF_PTL_ZEROCARBONfinal.pdf
Geological surveys at the British Geological Survey: http://www.bgs.ac.uk/
Grants available for installing renewables: http://www.clear-skies.org/
‘Integrating renewable energy into new developments: Toolkit for planners, developers and consultants’: http://www.london.gov.uk/mayor/environment/energy/london_renew.jsp
Energy Saving Trust: http://www.energysavingtrust.org.uk/generate_your_own_energy
BRE (2001) “Cooling Buildings in London: Overcoming the Heat Island”
BRE (2006) “Achieving Airtightness”, three part set
BRE (1994) “Minimising Air Infiltration in Office Buildings”
2.1.5. Input from members
2.2. Develop room design data sheets
2.2.1. CIBSE guidance and tools
The use of room data sheets (RDS) to define detailed performance requirements during design and specification of new build or refurbishment of buildings is common practice.
Such room data sheets were developed for the Carbon Trust’s Low Carbon Design Initiative (LCDI) to provide support to clients of the construction industry and their consultants/advisers, in developing design specifications for new building designs that will achieve a low carbon impact. Copies of the existing peer reviewed room data sheets, overarching technical briefing and other LCDI documents could be acquired from http://www.carbontrust.co.uk/about/reports/lcdi.
It should be noted that the above documents were originally intended to deal with school buildings, and their application to other building types should be undertaken with caution and additional client input.
Furthermore, the building services aspects of the LCDI room data sheets were mainly composed using the information in CIBSE guidance, e.g. Guides A and B, and similarly the same guidance could be used to produce room data sheets for other building applications.
CIBSE could customise the above data sheets for use specifically by the building services engineers and for various types of buildings.
2.2.2. Other useful references
2.2.3. Input from members
2.3. Check that design parameters comply with legislation, energy targets etc.
2.3.1. CIBSE guidance and tools
Design parameters should be reviewed here to check that they comply with legislation and energy targets. A checklist of regulations, codes, standards etc, a sub category derived from the comprehensive list of task 1.6, could be used here that give specifications on design parameters and energy targets.
Guidance on ways to check the design is included in CIBSE Guide F “Energy Efficiency in Buildings”, chapter 13.
CIBSE could develop a dynamic list of possible documents to be used at this stage.
2.3.2. Other useful references
2.3.3. Input from members
2.4. Analyse building – establish fabric thermal performance and air tightness
2.4.1. CIBSE guidance and tools
The building services engineer should be looking for guidance, rules of thumb and tools to estimate factors that describe the thermal response of surfaces (U-values, dynamic admittance Y-value, decrement factor f, surface factor F), solar gain and shading factors and infiltration rates, and guidance on how to achieve an air tight building (material and construction). Site and building data gathered during pre-design stage as well as external and internal design conditions from task 2.1 should also be used here.
CIBSE Guide A “Environmental Design” provides guidance, rules of thumb and calculation tools for the estimation of U-values of construction elements (chapter 3), thermal response of surfaces factors (chapter 3, Appendix 3.A6 and chapter 5, §5.7.2), solar gain and shading factors (chapter 5, §5.7.3) and infiltration rates (chapter 4). Thermal properties for a variety of material and constructions are given in chapter 3, Appendix 3.A7. Furthermore, infiltration rates could be estimated by using the guidance and tools in CIBSE AM10 “Natural Ventilation in Non-Domestic Buildings”.
CIBSE TM35 “Environmental Performance Toolkit for Glazed Facades” and TM37 “Design for Improved Solar Shading Control” provide guidance and calculation tools for estimating the solar properties of various glazing and shading options including U-values, solar gain and shading factors, daylight factors etc.
Some guidance in relation to building air tightness could be found in CIBSE TM23 “Testing Buildings for Air-Tightness”.
The guidance and tools for estimating thermal properties of material and infiltration rates is comprehensive at this design stage. Guidance and examples on the practical application of the various surface factors could help to better understand their importance in building design. Further guidance could also concentrate on how to achieve air-tightness through material, construction and operation of buildings.
2.4.2. Weather data available for present climate conditions
External design conditions established at task 2.1 should be used here to analyse fabric thermal performance. Although a single number is often used in design (e.g. a single U-value etc) an analysis of fabric performance based on seasonal variability of the material properties could be beneficial. The values given for the thermal characteristics of the material are often measured under steady state conditions, which could mean that they significantly vary under variable weather conditions.
CIBSE Guide A “Environmental Design” provides warm weather data for various UK locations (chapter 2, §2.4) as well as solar data to inform the cooling strategy (§2.7). Wind data in chapter 2 (§2.8) could be used to assess infiltration rates and heat transfer by convection of external surface. CIBSE Guide J “Weather, Solar and Illuminance Data” also provides warm weather data (chapter 4, §4.2), solar data (chapter 5) and wind data (chapter 6), for the same UK locations.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends, including summer temperatures, cloud cover and wind speeds, based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The user should be looking for percentage of certain conditions exceeded, such as dry and wet bulb temperatures (for condensation analysis), wind speed and direction, solar radiation on a surface and other weather variables that might affect the performance of the building fabric, based on location.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than those currently occurring.
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
2.4.3. Weather data available for future climate conditions
Future external design conditions established at task 2.1 should be used here to analyse fabric thermal performance. Although a single number is often used in design (e.g. a single U-value etc) an analysis of fabric performance based on climate change projections could be beneficial. The values given for the thermal characteristics of the material are often measured under steady state conditions, which could mean that they significantly vary under variable weather conditions and extreme events (e.g. increased rainfall, increased sunshine and temperatures etc).
CIBSE Guide A “Environmental Design” (chapter 2, §2.9) and CIBSE Guide J “Weather, Solar and Illuminance Data” (chapter 3, §3.2 and chapter 4, §4.4) provide climate change trends for various emissions scenarios, for three UK locations (London, Manchester and Edinburgh); changes are based on a 1961-1990 baseline.
CIBSE Guide L “Sustainability” summarises climate changes for one emissions scenario and for the same three locations.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
The user should be looking for probability of certain conditions exceeded, such as dry and wet bulb temperatures (for condensation analysis), wind speed and direction, solar radiation on a surface and other weather variables that might affect the performance of the building fabric, based on location.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
The data available in the CIBSE Guides A, J and L are general climate change trends that can inform towards future conditions, but can not be used readily in calculations.
The data available in TM34 can be used towards assessing future fabric perfomance, but there are no wind data available for infiltration/ventilation calculations due to the lack of suitable algorithm to produce hourly wind speed data from the available daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty is higher than for example for the temperature and rainfall changes.
The data in Guides A and J are not at the moment consistent. Climate change data in Guide A is in accordance with UKCIP02 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291), while Guide J data is in accordance with the previous version of UKCIP98 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=255).
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
2.4.4. Other useful references
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
BRE (2005) “Summertime Solar Performance of Windows with Shading Devices”
BRE (2004) “Impact of Horizontal Shading Devices on Peak Solar Gains”
BRE (1999) “Solar Shading of Buildings”
BRE (2006) “Achieving Airtightness”, three part set
BRE (1994) “Minimising Air Infiltration in Office Buildings”
2.4.5. Input from members
2.5. Estimate approximate building total heat gains to inform system selection process
2.5.1. CIBSE guidance and tools
The building services engineer should be looking for guidance, rules of thumb and tools to assess heat gains of the building to inform the cooling strategy. Site and building data gathered during pre-design stage as well as external and internal design conditions from task 2.1 should also be used here.
CIBSE Guides A “Environmental Design” provides guidance, benchmark values and calculation tools for estimating the heat gains of a building. Chapter 5 (§5.8.1 – CIBSE Cyclic Model) provides a model for the calculation of the solar, fabric and internal heat gains, a calculation method for the solar gain factors is presented in appendix 5.A7, while chapter 6 provides benchmark values for internal heat gains for a variety of building applications.
CIBSE TM37 “Design for Improved Solar Shading Control” explains the thermal properties and performance of windows and glazing/shading combinations and provides a method for calculating their total solar energy transmittance (g-value). Basic equations for calculating heat gains (solar and internal) are also presented in this document.
CIBSE TM29 “HVAC Strategies for Well-Insulated Airtight Buildings” provides guidance on reducing solar heat gains through glazing by optimising window performance.
The guidance and tools for estimating heat gains are sufficient at this early design stage.
2.5.2. Weather data available for present climate conditions
In order to estimate the heat gains in a building a good knowledge of frequency and duration of summer conditions is important. Design external conditions established at task 2.1 should be used here taking also under consideration the outcomes of the thermal analysis of the fabric (task 2.4).
Guide A provides warm weather data for various UK locations (chapter 2, §2.4) as well as solar data (§2.7) and wind data (§2.8) to inform the cooling strategy. CIBSE Guide J “Weather, Solar and Illuminance Data” also provides warm weather data (chapter 4, §4.2), solar data (chapter 5) and wind data (chapter 6), for the same UK locations.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends, including summer temperatures and cloud cover, based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The user should be looking for frequency and duration of average and extreme events of high temperatures, coincidence of high temperatures and solar radiation (direct and diffuse) and frequencies of hourly wind speeds by direction and temperature, based on location.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
In both Guides A and J the summer temperatures and solar radiation data are presented separately. A good understanding of frequency and duration of coincident high temperatures and high solar radiation is essential for assessing solar gains, especially in highly glazed buildings. The use of joint probabilities of weather variables could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to include joint probabilities of weather variables, such as temperature and cloud cover, based on observed data (http://www.ukcip08.net).
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than the ones currently occurring.
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
2.5.3. Weather data available for future climate conditions
In order to estimate heat gains over the lifetime of the building, a good knowledge of frequency and duration of future summer events is important. Design external conditions established at task 2.1 should be used here taking also under consideration the outcomes of the thermal analysis of the fabric (task 2.4).
CIBSE Guide A “Environmental Design” (chapter 2, §2.9) and CIBSE Guide J “Weather, Solar and Illuminance Data” (chapter 3, §3.2 and chapter 4, §4.4) provide climate change trends for various emissions scenarios, for three UK locations (London, Manchester and Edinburgh); changes are based on a 1961-1990 baseline.
CIBSE Guide L “Sustainability” summarises climate changes for one emissions scenario and for the same three locations.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
The user should be looking for probability of occurrence of future events such as high temperatures, coincidence of high temperatures and solar radiation (direct and diffuse) and frequencies of hourly wind speeds by direction and temperature, based on location.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
The data available in the CIBSE Guides A, J and L are general climate change trends that can inform of future climate conditions, but can not be used readily in calculations.
The data available in TM34 can be used in manual calculations, but there are no data available for infiltration/ventilation calculations due to the lack of suitable algorithm to produce hourly wind speed data from the available daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty in higher than for example for the temperature and rainfall changes.
The data in Guides A and J are not at the moment consistent. Climate change data in Guide A is in accordance with UKCIP02 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291), while Guide J data is in accordance with the previous version of UKCIP98 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=255).
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
2.5.4. Other useful references
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
BRE (2005) “Summertime Solar Performance of Windows with Shading Devices”
BRE (2004) “Impact of Horizontal Shading Devices on Peak Solar Gains”
BRE (1999) “Solar Shading of Buildings”
2.6. Assess overheating risk and establish the need for a cooling strategy
2.6.1. CIBSE guidance and tools
The building services engineer should be looking for guidance related to overheating criteria based on building application and calculation tools to assess overheating risk of spaces, in order to inform the cooling strategy. Site and building data gathered during pre-design stage as well as external and internal design conditions from task 2.1 should also be used here.
CIBSE Knowledge Series publication KS3 ”Sustainable Low Energy Cooling: an Overview” summarises the ways to reduce building heat gains (table 2), explains the principles of designing sustainable cooling strategies and presents various sustainable cooling options.
CIBSE Guides A “Environmental Design” provides a calculation method for estimating the overheating risk of a building. Chapter 5 (§5.8.1) gives equations for the calculation of overheating risk and a numerical example (example 5.2) using the CIBSE Cyclic Model.
Overheating criteria and thermal comfort issues are analysed in Guide A (chapter 1) and in the CIBSE Knowledge Series publication KS6 “Comfort”.
CIBSE TM36 “Climate Change and the Indoor Environment: Impacts and Adaptation” presents the results of a study on the risk of overheating due to climate change on a variety of building applications (domestic and non-domestic, new and existing), and examines various adaptation options to deal with the overheating risk while keeping energy demand at low levels.
Even though this is an early design stage, an in depth analysis and understanding of building overheating risk is essential, especially when passive cooling measures are examined. This could be achieved by the use of computer based calculation tools that examine building thermal performance based on hourly weather data.
Computer based simulation tools, such as thermal models and CFD, could be used to assess space overheating risk based on hourly external data and corresponding building performance. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
There is some concern that the existing overheating criteria suggested by CIBSE do not take under consideration people’s ability to adapt to extended periods of high temperatures and that encourages the use of mechanical cooling. The CIBSE Overheating Group is reviewing the existing overheating criteria with a view to create a new set that would take under consideration the adaptive comfort model.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine space temperature variation (model output) by varying the natural ventilation rates (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
2.6.2. Weather data available for present climate conditions
In order to assess overheating risk in a building a good knowledge of frequency and duration of summer conditions and extreme events is important. Design external conditions established at task 2.1 should be used here taking also under consideration the outcomes of the thermal analysis of the fabric (task 2.4).
Guide A provides warm weather data for various UK locations (chapter 2, §2.4) as well as solar data (§2.7) and wind data (§2.8) to be used in the overheating calculations. CIBSE Guide J “Weather, Solar and Illuminance Data” also provides warm weather data (chapter 4, §4.2), solar data (chapter 5) and wind data (chapter 6), for the same UK locations.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends, including summer temperatures and cloud cover, based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for 14 different UK locations.
The user should be looking for frequency and duration of extreme events of summertime temperatures, coincidence of high temperatures and solar radiation (direct and diffuse), coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control) and frequencies of hourly wind speeds by direction and temperature, based on location.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
In both Guides A and J the summer temperatures and solar radiation data are presented separately. A good understanding of frequency and duration of coincident high temperatures and high solar radiation is essential for assessing solar gains, especially in highly glazed buildings. The use of joint probabilities of weather variables could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to include joint probabilities of weather variables, such as temperature and cloud cover, based on observed data (http://www.ukcip08.net).
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than the ones currently occurring.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
2.6.3. Weather data available for future climate conditions
In order to future proof the building against overheating over its lifetime, a good knowledge of frequency and duration of future summer and extreme events is important. Design external conditions established at task 2.1 should be used here taking also under consideration the outcomes of the thermal analysis of the fabric (task 2.4).
CIBSE Guide A “Environmental Design” (chapter 2, §2.9) and CIBSE Guide J “Weather, Solar and Illuminance Data” (chapter 3, §3.2 and chapter 4, §4.4) provide climate change trends for various emissions scenarios, for three UK locations (London, Manchester and Edinburgh); changes are based on a 1961-1990 baseline.
CIBSE Guide L “Sustainability” summarises climate changes for one emissions scenario and for the same three locations.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
The user should be looking for frequency and duration of extreme events of high temperatures, coincidence of high temperatures and solar radiation (direct and diffuse) and coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control), based on location.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326. The next generation of UKCIP scenarios is expected to present changes in a probabilistic way (http://www.ukcip08.net).
The data available in the CIBSE Guides A, J and L are general climate change trends that can inform of future climate conditions, but can not be used readily in calculations.
The data available in TM34 can be readily used in manual calculations, but there are no wind data available for calculating infiltration/ventilation heat gains due to the lack of suitable algorithm to produce hourly wind speed data from the available daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty in higher than for example for the temperature and rainfall changes.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
2.6.4. Other useful references
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
BRE (2001) “Cooling Buildings in London: Overcoming the Heat Island”
2.6.5. Input from members
2.7. Consider zoning requirements
2.7.1. CIBSE guidance and tools
Appropriate zoning of spaces based on temperature variation, hours of operation, glazing levels and other material, etc. could help in maximising the efficiency of the cooling system. The building services engineers should be able to identify zoning requirements and integrate them into the design of the systems.
CIBSE Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, §2.4 refers to zoning requirements for the design of systems, e.g. mixed mode ventilation systems (§2.4.5), comfort cooling and air-conditioning systems (§2.4.6) etc.
More in-depth guidance is needed to inform effective zoning that could optimize the efficiency of the cooling strategy.
2.7.2. Other useful references
2.7.3. Input from members
2.8. Consider alternative cooling source and cooling system options
2.8.1. CIBSE guidance and tools
The building services engineers should investigate the various cooling options available based on environmental impact, cost, efficiency etc. A combination of systems that cover base and peak cooling load could improve efficiency of the cooling strategy and minimise environmental impact.
Comprehensive guidance could be found in CIBSE Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapters 2 and 4, the Knowledge Series publications KS3 “Sustainable Low Energy Cooling: an Overview” and KS13 “Refrigeration”, TM45 “Groundwater Cooling Systems”, Guide F “Energy Efficiency of Buildings”, chapter 7 and 8 and some guidance on the use of CHP for both heating and cooling in AM12 “Small-Scale Combined Heat and Power for Buildings”.
Existing CIBSE guidance seems sufficient at this design stage.
2.8.2. Other useful references
2.8.3. Input from members
2.9. Establish contribution from renewable sources
2.9.1. CIBSE guidance and tools
The building services engineer should be looking for guidance and calculation tools to assess the potential use of renewable energy sources based on the building form, application and location. Cost and benefit analysis is essential at this point as well as assessing potential sources of financing the technologies, environmental impact and alternatives. Site and building data gathered during pre-design stage as well as key design parameters, such as external design conditions, from task 2.1 should also be used here.
CIBSE Guide F “Energy Efficiency in Buildings” (chapter 5) and Guide L “Sustainability” (chapter 3, §3.1 and chapter 5, §5.1) provide general information on LZC technologies and design requirements.
CIBSE TM45 “Groundwater Cooling Systems” explains the principals and issues associated with the installation and operation of such systems.
Other CIBSE publications related to renewable technologies are the AM12 “Small-Scale Combined Heat and Power for Buildings”, TM25 “Understanding Building Integrated Photovoltaics and TM38 “Renewable Energy Sources for Buildings” with an accompanied simple tool to assist in initial identification of the most promising renewable sources for a given project.
CIBSE is not offering at the moment a calculation tool for the analysis of contribution from renewable energy sources and LZC technologies. It is an opportunity for CIBSE to develop a calculation tool that would provide a quantitative analysis of the potential use of such technologies as well as a cost and benefit analysis, for specific projects.
2.9.2. Weather data available for present climate conditions
At this preliminary design stage a good knowledge of the site and the microclimate is essential towards analysing the potential of various renewable resources and LZC technologies.
CIBSE Guide A “Environmental Design” (chapter 2, §2.7 and §2.8) and CIBSE Guide J “Weather, Solar and Illuminance Data” (chapters 5 and 6) provide solar and wind data, for various UK locations, that could be used for assessing potential use of renewables.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides wind speed trends based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The user should be looking for site specific weather data and local elements that could potentially affect the microclimate and/or the performance of renewable technologies.
The data in Guides A and J are not at the moment consistent. Wind data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of unlike external design conditions than those currently occurring.
The CIBSE weather data are location specific but not site specific. Site specific information should be acquired for assessing potential use of renewables e.g. local wind, sunshine availability and elements blocking the sun around the site etc. Local information could be acquired from city councils, local planning authorities, environment agency, Met office etc. and by site visits and discussions with client.
Guidance is required on the type of weather information needed for assessing potential of renewables and how to obtain such site specific information, e.g. Met Office, local weather station, city council archives etc.
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
2.9.3. Weather data available for future climate conditions
At this preliminary design stage a good understanding of the future weather trends and the microclimate of the site could help towards forming a strategy for improving the building’s carbon emissions by improving or incorporating LZC technologies and renewables.
CIBSE Guide A “Environmental Design” (chapter 2, §2.9) and CIBSE Guide J “Weather, Solar and Illuminance Data” (chapter 3, §3.2 and chapter 4, §4.4) provide climate change trends for various emissions scenarios, for three UK locations (London, Manchester and Edinburgh); changes are based on a 1961-1990 baseline.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
The user should be looking for probability of certain weather variables changing in the future that could potentially affect the performance of renewable technologies. For example increase sunshine hours will increase the use of solar renewable technologies.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Changes in sunshine hours included in TM34 could be used towards assessing future use of renewables, but there are no wind data available for wind technologies due to the lack of suitable algorithm to produce hourly wind speed data from the available daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed and cloud cover changes, but extra caution should be taken when using these data since the associated uncertainty in higher than for example for the temperature and rainfall changes.
The data in Guides A and J are not at the moment consistent. Climate change data in Guide A is in accordance with UKCIP02 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291), while Guide J data is in accordance with the previous version of UKCIP98 climate change scenarios (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=255).
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
2.9.4. Other useful references
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
The Building Regulations second tier document “Low or Zero Carbon Energy Sources: Strategic Guide” provides a simplified calculation tool for assessing the reduction in carbon emissions through the use of LZC technology: http://www.planningportal.gov.uk/uploads/br/BR_PDF_PTL_ZEROCARBONfinal.pdf
Geological surveys at the British Geological Survey: http://www.bgs.ac.uk/
Grants available for installing renewables: http://www.clear-skies.org/
“Integrating renewable energy into new developments: Toolkit for planners, developers and consultants”:
http://www.london.gov.uk/mayor/environment/energy/london_renew.jsp
Energy Saving Trust: http://www.energysavingtrust.org.uk/generate_your_own_energy
2.9.5. Input from members
2.10. Consider operating and control strategies, and building usage and layout data
2.10.1. CIBSE guidance and tools
The building services engineers should investigate the various control and operation strategy options based on the cooling systems under consideration. A checklist of information required, e.g. building plans, space usage, comfort requirements etc, could be used here to inform the process.
CIBSE guidance on controls exists in Guide H “Building Control Systems”, Knowledge Series KS4 “Understanding Controls”, Guide F “Energy Efficiency in Buildings” (chapter 6).
Guidance on system maintenance and operation exists in CIBSE “Guide to Ownership, Operation and Maintenance of Building Services. Guide M “Maintenance Engineering and Management” also provides comprehensive guidance in the management, operation, maintenance and control of building services. Guide F, Part B, refers to management (chapter 15) and maintenance of building services (chapter 17), while the principles of building services management are analysed in the Knowledge Series publication KS5 “Making Buildings Work”.
Furthermore, CIBSE Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapters 2 and 4 , and Guide F “Energy Efficiency of Buildings”, chapters 7 and 8, contain considerations on control, maintenance and operation options for a variety of cooling systems. Guidance on noise and vibration controls for HVAC can also be found in Guide B, chapter 5.
CIBSE could provide a checklist of all requirements necessary for designing the control and operation strategy of the cooling system.
2.10.2. Other useful references
2.10.3. Input from members
2.11. Assess options against client requirements, performance, risk, energy use etc.
2.11.1. CIBSE guidance and tools
The building services engineers should be able to follow a methodology for assessing the various options against a series of criteria set by the client, building regulations, standards etc. The assessment methods could include a series of consultations with the design team and the client, a prioritising strategy based on client’s brief etc. Assessing the various options identified could become critical when choosing between similar options.
CIBSE could provide a methodology for assessing options.
2.11.2. Other useful references
2.11.3. Input from members
2.12. Select proposed system
2.12.1. CIBSE guidance and tools
Based on the assessment of various options during task 2.11 the building services engineers should be able to identify the optimum solution based on client brief.
See task 2.11
2.12.2. Other useful references
2.12.3. Input from members
3. Design Development
E. Technical design
3.1. Calculate space heat gains
3.1.1. CIBSE guidance and tools
The building services engineer should be looking for calculation tools to assess space heat gains, in order to inform the cooling strategy.
CIBSE Guides A “Environmental Design” provides guidance, benchmark values and calculation tools for estimating the heat gains of a building. Chapter 5 (§5.8.1 – CIBSE Cyclic Model) provides a model for the calculation of the solar, fabric and internal heat gains, a calculation method for the solar gain factors is presented in appendix 5.A7, while chapter 6 provides benchmark values for internal heat gains for a variety of building applications.
CIBSE TM37 “Design for Improved Solar Shading Control” explains the thermal properties and performance of windows and glazing/shading combinations and provides a method for calculating their total solar energy transmittance (g-value). Basic equations for calculating heat gains (solar and internal) are also presented in this document.
CIBSE TM29 “HVAC Strategies for Well-Insulated Airtight Buildings” provides guidance on reducing solar heat gains through glazing by optimising window performance.
Computer based simulation tools, such as thermal models and CFD, could be used to assess space heat gains based on hourly external data and corresponding building performance. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
CIBSE TM35 “Environmental Performance Toolkit for Glazed Facades” includes information on the thermal modelling of glazed facades along with a basic tool (Façade Selector) to assist in the choice of façade based on location, building orientation and application, heating and cooling needs etc.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine space temperature variation (model output) by varying the window specifications (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.1.2. Weather data available for present climate conditions
Detailed calculations should be part of this design stage using either manual or computer based calculation tools. Depending on the approach, mean and maximum figures or hourly weather data that would best describe the average and extreme summer conditions should be used to assess space heat gains.
CIBSE Guides A “Environmental Design” provides warm weather data for various UK locations (chapter 2, §2.4) as well as solar data (§2.7) and wind data (§2.8) to inform the cooling strategy. CIBSE Guide J “Weather, Solar and Illuminance Data” also provides warm weather data (chapter 4, §4.2), solar data (chapter 5) and wind data (chapter 6), for the same UK locations.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends, including summer temperatures and cloud cover, based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for 14 different UK locations.
For manual calculations the user should be looking for frequency and duration of average and extreme events of high temperatures, coincidence of high temperatures and solar radiation (global and diffuse) and coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control), based on location. Frequency distributions of wind speed by direction and external temperature could be used to assess infiltration rates for humidity control.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
In both Guides A and J the summer temperatures and solar radiation data are presented separately. A good understanding of frequency and duration of coincident high temperatures and high solar radiation is essential for assessing solar gains, especially in highly glazed buildings. The use of joint probabilities of weather variables could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to include joint probabilities of weather variables, such as temperature and cloud cover, based on observed data (http://www.ukcip08.net).
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than the ones currently occurring.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
3.1.3. Weather data available for future climate conditions
In order to increase resilience of the building to the impacts of climate change, over its lifetime, a good knowledge of frequency and duration of future summer and extreme events is important. Detailed calculations should be part of this design stage using either manual or computer based calculation tools. Depending on the approach, trends of mean and maximum figures or hourly weather data that would best describe the average and extreme future summer conditions should be used to assess space heat gains.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For manual calculations the user should be looking for probability of occurrence of future events such as frequency and duration of high temperatures, coincidence of high temperatures and solar radiation (global and diffuse) and coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control), based on location. Frequency distributions with attached probability of wind speed by direction and external temperature could be used to assess infiltration rates for humidity control.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Furthermore, the data available in TM34 can be readily used in manual calculations, but there are no wind data available for calculating infiltration/ventilation heat losses due to the lack of suitable algorithm to produce hourly wind speed data from the available daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty in higher than for example for the temperature and rainfall changes.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.1.4. Other useful references
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
BRE (2001) “ Cooling Buildings in London: Overcoming the Heat Island”
BRE (2005) “Summertime Solar Performance of Windows with Shading Devices”
BRE (2004) “Impact of Horizontal Shading Devices on Peak Solar Gains”
BRE (1999) “Solar Shading of Buildings”
3.1.5. Input from members
3.2. Check whether unnecessary heat gains could be reduced
3.2.1. CIBSE guidance and tools
The building services engineers should be able to identify ways to reduce heat gains in order to minimise demand for cooling.
Guidance exists in CIBSE Knowledge Series KS3 “Sustainable Low Energy Cooling: an Overview”, TM36 “Climate Change and the Indoor Environment”, TM37 “Design for Improved Solar Shading Control”, concentrating on ways to reduce heat gains through glazing.
Further guidance and case studies of implementing design solutions in order to minimise heat gains (e.g. study in TM36) could be helpful.
3.2.2. Other useful references
3.2.3. Input from members
3.3. Assess ventilation requirements and provision
3.3.1. CIBSE guidance and tools
At this stage the building services engineer should be looking for guidance and calculation tools to assess ventilation and infiltration rates in order to:
1. ensure that ventilation is adequate to meet occupancy and other ventilation requirements;
2. determine the thermal gains caused by ventilation/infiltration in order to inform cooling load calculations;
3. assess the potential for using ventilation to assist in the passive cooling of the building.
The Ventilation Framework provides a detailed analysis of the stages towards designing the overall ventilation strategy.
CIBSE Guide B “Heating, Ventilating, Air Conditioning and Refrigerating” provides guidance on the issues related to the choice of ventilation strategy (chapter 2, §2.2), detailed analysis of the indoor air quality requirements for various applications (chapter 2, §2.3) and detailed analysis for the design of natural (chapter 2, §2.4.3) and mechanical (chapter 2, §2.4.4) ventilation systems. Furthermore, Appendix 2.A1 summarises the various techniques for assessing ventilation rates including the use of CFD and physical models.
CIBSE Guide A “Environmental Design” provides guidance and calculation methods for assessing room and building ventilation options including natural, mechanical and mixed-mode ventilation (chapter 4) and infiltration rates. Furthermore, paragraph 4.6.3.6 provides an equation for assessing the cooling potential of ventilation.
CIBSE AM10 “Natural Ventilation in Non-Domestic Buildings” provides extensive guidance and calculation methods to assist in the design of the natural ventilation strategy.
CIBSE AM13 “Mixed Mode Ventilation” provides extensive guidance on the design of a mixed mode ventilation strategy, including rules of thumb to assess whether mixed mode ventilation is a possibility and the various options available.
CIBSE TM29 “HVAC Strategies for Well-Insulated Airtight Buildings” provide guidance on mechanical ventilation options in heated/cooled spaced.
Computer based simulation tools, such as thermal models and Computer Fluid Dynamics (CFD), could be used to assess building ventilation strategy based on hourly external data and corresponding building performance.
CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
AM10 (chapter 4) provides guidance on the use of CFD (§4.2.5), combination of thermal models and CFD (§4.2.6) and physical models (§4.3.7) for the analysis of the natural ventilation performance in a building. AM13 (chapter 10) suggests the combination of thermal modelling and CFD in order to better understand the performance of a mixed mode approach, while TM29 provides case studies where dynamic simulations were used in order to analyse the performance of a mechanical HVAC approach.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine space temperature variation (model output) by varying the ventilation rates (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.3.2. Weather data available for present climate conditions
Detailed calculations should be part of this design stage using either manual or computer based calculation tools. Depending on the approach, mean and maximum figures or hourly weather data that would best describe the average and extreme summer conditions should be used to assess ventilation rates.
CIBSE Guide A “Environmental Design” (chapter 2, §2.4) and CIBSE Guide J ‘Weather, Solar and Illuminance Data’ (chapter 4, §4.2) provide warm weather data for various UK locations. The frequency distributions of wind by direction and by external temperature in Guide A (§2,8) and Guide J (chapter 6, §6.6) aim to assist in ventilation design.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends, including temperatures and cloud cover, based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for 14 different UK locations.
For manual calculations the user should be looking for frequency and duration of average and extreme events of high temperatures, coincidence of high temperatures and solar radiation (global and diffuse) and coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control), based on location. Frequency distributions of wind speed by direction and external temperature could be used to assess infiltration rates for humidity control.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
In both Guides A and J the summer temperatures and solar radiation data are presented separately. A good understanding of frequency and duration of coincident high temperatures and high solar radiation is essential for assessing solar gains, especially in highly glazed buildings. The use of joint probabilities of weather variables could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to include joint probabilities of weather variables, such as temperature and cloud cover, based on observed data (http://www.ukcip08.net).
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than the ones currently occurring.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
3.3.3. Weather data available for future climate conditions
A better understanding of the ventilation potential could increase resilience of the building to the impacts of climate change, over its lifetime. Detailed calculations should be part of this design stage using either manual or computer based calculation tools. Depending on the approach, trends of mean and maximum figures or hourly weather data that would best describe the average and extreme summer conditions in the future should be used to assess ventilation rates.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For manual calculations the user should be looking for frequency distributions of average and extreme wind speeds by both direction and external temperature, based on location.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x years event of wind speed and direction.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Furthermore, the data available in TM34 can be readily used in manual calculations, but there are no wind data available for calculating infiltration/ventilation heat losses due to the lack of suitable algorithm to produce hourly wind speed data from the available daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty in higher than for example for the temperature and rainfall changes.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.3.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
BRE (2000) “Environmental Site Layout Planning: Solar Access, Microclimate and Passive Cooling in Urban Areas”
3.3.5. Input from members
3.4. Check cooling strategy provision still appropriate
3.4.1. CIBSE guidance and tools
The building services engineers should be using assessment methods to evaluate the option selected at task 2.12. The evaluation should be based on results from detailed calculations performed in the previous tasks of stage 3.
CIBSE could provide a checklist of criteria for the evaluation of selected systems.
3.4.2. Other useful references
3.4.3. Input from members
3.5. Consider suitable position of cooling delivery systems and connections
3.5.1. CIBSE guidance and tools
The building services engineers should be using guidance on cooling delivery systems and optimum positioning for the various choices available.
Guidance exists in CIBSE Guide F “Energy Efficiency in Buildings”, chapters 7 and 8 and Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapters 2 and 4.
Extensive guidance on fans and fan coil units could be found in TM42 “Fan Application Guide” and TM43 “Fan Coil Units”.
CIBSE guidance on designing distribution networks is mostly in the form of general recommendations but there is not much practical advice. For example guidance in the form of schematics could be useful.
3.5.2. Other useful references
3.5.3. Input from members
3.6. Check distribution layout considering balancing and regulating requirements
3.6.1. CIBSE guidance and tools
The building services engineers should be using guidance on cooling distribution system layout requirements.
Guidance exists CIBSE Guide F “Energy Efficiency in Buildings”, chapters 7 and 8, and Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapter 3, and the Knowledge Series publications KS7 “Variable Flow Pipework Systems” and KS9 “Commissioning Variable Flow Pipework Systems”. Guidance on fans could be found in TM42 “Fan Application Guide”. Reference data on heat transfer and flow of fluids in pipes and ducts could be found in CIBSE Guide C “Reference Data”, chapters 3 and 4.
CIBSE guidance seems sufficient.
3.6.2. Other useful references
3.6.3. Input from members
3.7. Consider circuit layouts and connections, fans and pumping choices - variable or constant volume
3.7.1. CIBSE guidance and tools
The building services engineers should be using guidance on circuit design and various fun and duct choices.
Guidance exists in CIBSE Guide F “Energy Efficiency in Buildings”, chapters 7 and 8, and Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapter 3, and the Knowledge Series publications KS7 “Variable Flow Pipework Systems” and KS9 “Commissioning Variable Flow Pipework Systems”.
Extensive guidance on fans could be found in TM42 “Fan Application Guide”.
CIBSE guidance seems sufficient.
3.7.2. Other useful references
3.7.3. Input from members
3.8. Develop control requirements
3.8.1. CIBSE guidance and tools
The building services engineers should be using guidance on controls and control strategies for the cooling systems selected.
Guidance exists in CIBSE Guide H “Building Control Systems”, Knowledge Series KS4 “Understanding Controls” and Guide F “Energy Efficiency in Buildings”, chapter 6). Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapters 2 and 4, and Guide F, chapters 7 and 8, also present control requirements relative to the system options presented. Guidance on noise and vibration controls for HVAC can be found in Guide B, chapter 5.
CIBSE guidance seems sufficient.
3.8.2. Other useful references
3.8.3. Input from members
3.9. Size and select cooling delivery systems and distribution network and determine any distribution losses
3.9.1. CIBSE guidance and tools
The building services engineers should be using guidance and tools for selecting and sizing cooling delivery systems and distribution network.
Guidance on system selection is included in CIBSE Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapters 2 and 4, and Guide F “Energy Efficiency in Buildings”, chapters 7 and 8.
Some guidance on sizing and designing distribution network is included in Guide B, chapter 3.
For the estimation of distribution losses guidance and calculation tools could be found in Guide B, chapter 3, and Guide C “Reference Data”, chapter 3.
CIBSE guidance on designing distribution networks is mostly in the form of general recommendations but there is not much practical advice. For example guidance in the form of schematics could be useful.
3.9.2. Other useful references
3.9.3. Input from members
3.10. Calculate main cooling loads
3.10.1. CIBSE guidance and tools
The building services engineer should be looking for guidance and calculation tools for the calculation of cooling loads of the spaces, after reducing any unnecessary heat gains. Guidance on the calculation of peak loads and on how to avoid oversizing is also required here. Outputs from tasks 3.1, 3.2, 3.3 and 3.5 to be used here.
The guidance and tools in CIBSE Guide A “Environmental Design” (chapter 5, §5.8.2 and §5.10.4) could be used for the calculation of the cooling loads of spaces in a building, under steady-state conditions. The tables in paragraph 5.11 provide solar cooling loads for fast and slow response buildings for a variety of glazing options and orientations. The calculation method used to produce the tabulated values is described in Appendix 5.A6.
Computer based simulation tools, such as thermal models could be used to analyse the building cooling demand based on thermal response and assess cooling loads, based on hourly external data. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
Further guidance could concentrate on how to avoid oversizing when sizing the cooling plant.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine peak load (model output) by varying the window thermal properties (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.10.2. Weather data available for present climate conditions
In order to calculate the cooling loads of a building either manual or computer tools can be used. Hourly weather series often used by computer tools provide knowledge of the dynamic performance of a building in response to external conditions. Such an approach could help in avoiding oversizing of the cooling system. Average and extreme summer conditions should be used to calculate the cooling loads of the building and inform the sizing of the cooling system.
CIBSE Guide A “Environmental Design” provides warm weather data for various UK locations (chapter 2, §2.4) as well as solar data to inform the cooling strategy. CIBSE Guide J “Weather, Solar and Illuminance Data” also provides warm weather data (chapter 4, §4.2) and solar data (chapter 5), for the same UK locations.
The UKCIP08 publication “The Climate of the United Kingdom and Recent Trends” provides climate trends, including temperatures and cloud cover, based on observed data (two baselines 1961-1990 and 1971-2000) presented at a 5km x 5km resolution, in a form of graphs and maps. The publication is freely available by UKCIP (http://www.ukcip.org.uk/).
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for 14 different UK locations.
For manual calculations the user should be looking for frequency and duration of average and extreme events of high temperatures, coincidence of high temperatures and solar radiation (global and diffuse) and coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control), based on location. Frequency distributions of wind speed by direction and external temperature could be used to assess infiltration rates for humidity control.
The data in Guides A and J are not at the moment consistent. Weather data in Guide A have been updated to a more recent baseline (1983-2002), while data in Guide J are based on an earlier baseline (1976-1995). The most up-to-date weather data currently available by CIBSE is located in Guide A, chapter 2. Although the weather data in Guide A have been recently updated, Guide J provides the background information on their production and selection processes that could enhance the understanding of the uncertainty associated with their use and as a result lead to more robust design decisions.
In both Guides A and J the summer temperatures and solar radiation data are presented separately. A good understanding of frequency and duration of coincident high temperatures and high solar radiation is essential for assessing solar gains, especially in highly glazed buildings. The use of joint probabilities of weather variables could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to include joint probabilities of weather variables, such as temperature and cloud cover, based on observed data (http://www.ukcip08.net).
The baselines used for the production of weather data in Guides A and J do not include current manifestations of climate change, which could arguably lead to the choice of lower external design temperatures than the ones currently occurring.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
Depending on the outputs of the above activities decisions will be made upon revising and further updating the data in Guides A and J.
3.10.3. Weather data available for future climate conditions
In order to increase resilience of the building to the impacts of climate change, over its lifetime, a good knowledge of frequency and duration of future summer and extreme events is important. Detailed calculations should be part of this design stage using either manual or computer based calculation tools. Depending on the approach, trends of mean and maximum figures or hourly weather data that would best describe the average and extreme future summer conditions should be used to assess space cooling loads.
CIBSE TM34 “Weather Data with Climate Change Scenarios” provide climate change data in the same format as in Guide J for use in manual calculations to assess future system and building performance.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal ((http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For manual calculations the user should be looking for probability of occurrence of future events such as frequency and duration of high temperatures, coincidence of high temperatures and solar radiation (global and diffuse) and coincidence of dry bulb and wet bulb temperatures (for air conditioning design and humidity control), based on location. Frequency distributions with attached probability of wind speed by direction and external temperature could be used to assess infiltration rates for humidity control.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Furthermore, the data available in TM34 can be readily used in manual calculations, but there are no wind data available for calculating infiltration/ventilation heat losses due to the lack of suitable algorithm to produce hourly wind speed data from the available daily averages (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291).
The UKCIP02 scientific report (http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=353&Itemid=408) provides daily average wind speed changes, but extra caution should be taken when using these data since the associated uncertainty in higher than for example for the temperature and rainfall changes.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.10.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
3.10.5. Input from members
3.11. Analyse load diversity and intermittent operation and determine the total cooling load
3.11.1. CIBSE guidance and tools
The building services engineer should be looking for guidance in the use of dynamic simulation tools in order to analyse load diversity based on external conditions, building fabric and application. The load diversity analysis could identify integrated solutions for cooling for example covering base load, peak load and contingency load with a combination of LZC technologies and AC units.
Outputs from task 3.1could also be used here.
Computer based simulation tools, such as thermal models could be used to analyse load diversity in a building, based on hourly external data. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine load diversity (model output) by varying the window and shading thermal properties (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.11.2. Weather data available for present climate conditions
At this advanced design stage a detailed knowledge of the thermal performance of the building is essential in order to finalise the cooling system selection and sizing. This is possible by the use of computer based tools that use hourly weather series to provide a dynamic performance of the building in response to external conditions. Extreme summer conditions should be used to examine the cooling capacity of the plant and inform its sizing.
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for 14 different UK locations.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
3.11.3. Weather data available for future climate conditions
At this advanced design stage a detailed knowledge of the thermal performance of the building over its lifetime is essential in order to finalise the cooling strategy. Hourly weather series often used by computer tools provide knowledge of the dynamic performance of a building in response to external conditions. Future extreme events should be used to examine the cooling capacity of the plant over the lifetime of the building.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal (http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.11.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
3.11.5. Input from members
3.12. Consider any standby and future requirement
3.12.1. CIBSE guidance and tools
The building services engineers should be using guidance on issues related to assessing standby capacity, e.g. risk assessment, risk of oversizing etc.
Some guidance on space allowance for a variety of cooling systems is included in Guide B “Heating, Ventilation, Air Conditioning and Refrigeration”, chapters 2, while chapter 4 (§4.2.13) explains the issue of including future needs in the design of the cooling systems.
Further guidance is needed on including standby capacity when sizing the cooling system, while avoiding oversizing.
3.12.2. Other useful references
3.12.3. Input from members
3.13. Determine number of cooling delivery systems required and size and select main plant
3.13.1. CIBSE guidance and tools
The building services engineer should be looking for guidance on the various cooling system options based on the cooling load analysis previously undertaken. Guidance should inform of all possible options from free cooling to mechanical cooling and air-conditioning and energy efficiency issues related to their operation. Dynamic simulation tools could be used for module/plant sizing based on hourly building thermal performance. Outcomes from tasks 3.10, 3.11 and 3.12 could be used here. Alternatively, in case dynamic simulations were used to complete tasks 3.10 and 3.11, the results (based on the computer model used) could also incorporate output from plant sizing calculation.
CIBSE Guide B “Heating, Ventilating, Air Conditioning and Refrigerating” provides guidance on cooling system options. Chapter 2 gives information on ventilation and cooling system integration, such as night cooling and thermal mass §2.4.7, chilled surfaces §2.4.8 etc. while chapter 4 gives information on the various cooling systems available, such as free cooling §4.4.3, absorption cooling §4.4.5, evaporative cooling §4.4.8 etc.
The CIBSE Knowledge Series publication KS8 ”Sustainable Low Energy Cooling: an Overview” explains the main features of various sustainable cooling options.
CIBSE Guide F “Energy Efficiency in Buildings” provides guidance on the energy efficiency issues related to the selection of cooling sources and plant sizing (chapter 7 and 8). Guide F, chapter 5, also provides guidance on renewable and LZC cooling sources such as ground and water cooling (§5.1.13). The CIBSE AM12 “Small-Scale Combined Heat and Power for Buildings” provides some guidance on CHP (CHPC) operation for cooling. Information gathered in task 2.9 could also be used here.
Computer based simulation tools, such as thermal models could be used to size central plants, based on hourly external data. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
Further guidance on integrated solutions could be useful, for example covering base load, peak load and contingency load with a combination of LZC technologies and AC units.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine internal temperature variation, during long periods of hot and sunny weather, (model output) for variable occupancy (model input); is the cooling capacity still sufficient. Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.13.2. Weather data available for present climate conditions
Computer tools are normally used at this design stage to size the cooling plant and/or the cooling delivery systems of the building. Hourly weather series often used by the computer tools provide knowledge of the dynamic performance of a building in response to external conditions. Extreme events should be used to examine the capacity of the plant to cover peak load and provide thermal comfort conditions.
The CIBSE Design Summer Years (DSY) can be used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for 14 different UK locations.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects examine the use of UKCIP08 climate change information in building design.
3.13.3. Weather data available for future climate conditions
Computer tools are normally used at this design stage to size the cooling plant and/or the cooling delivery systems of the building. Hourly weather series often used by the computer tools provide knowledge of the dynamic performance of a building in response to external conditions. The capacity of the cooling strategy could be examined under future events, average and extreme, in order to inform adaptation options to improve the resilience of the building to future higher temperatures over its lifetime.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal (http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance.
3.13.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
3.13.5. Input from members
3.14. Finalise controls
3.14.1. CIBSE guidance and tools
Guidance and outcomes from tasks 2.10 and 3.8 could be used here in order to finalise the control strategy of the building. Dynamic simulation tools could also be used for more complex building form and cooling strategy design in order to finalise control requirements, for example when base load and peak load are covered by different cooling sources.
CIBSE Knowledge Series KS4 “Understanding Controls” provides an introduction and overview of control systems and related issues. Chapter 6 of CIBSE Guide F “Energy Efficiency in Buildings” and CIBSE Guide H “Building Control Systems” provide comprehensive guidance on control selection and operation.
CIBSE Guide B “Heating, Ventilating, Air Conditioning and Refrigerating” provides guidance on controls for various cooling systems (chapters 2 and 4), while Guide F provides guidance on controls for improving the energy efficiency of various cooling options (chapters 7 and 8).
Computer based simulation tools, such as thermal models could assist in finalising the control strategy of a building, based on hourly external data. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine internal humidity levels (model output) for variable occupancy (model input); are the controls responding sufficiently. Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.14.2. Weather data available for present climate conditions
Based on the complexity of building form and services the control strategy could be fine tuned with the use of computer tools. Hourly weather series often used by the computer tools provide knowledge of the dynamic performance of a building in response to external conditions. Control requirements for temperature and humidity to avoid condensation (e.g. for chilled beams and ceilings) could be established based on simulation outcomes.
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for 14 different UK locations.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
3.14.3. Weather data available for future climate conditions
Based on the complexity of building form and services the control strategy could be fine tuned with the used of computer tools. Hourly weather series often used by the computer tools provide knowledge of the dynamic performance of a building in response to external conditions. Future summer events could be used to develop a flexible control strategy that could respond to future increased overheating risk.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal (http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.14.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
BRE (2002) “Control of Solar Shading”
3.14.5. Input from members
3.15. Check layouts and services co-ordination for clashes and ease of commissioning and maintenance
3.15.1. CIBSE guidance and tools
Guidance and outcomes from tasks 3.5 – 3.9 could be used here in order to check systems layout. Dynamic simulation tools could also be used for more complex building form and cooling strategy design in order to check coordination of systems and avoid conflict of services e.g. AC and open windows at the same time, heating and cooling at the same time etc.
Comprehensive guidance on commissioning and maintenance can be found in CIBSE “Guide to Ownership, Operation and maintenance of Building Services” and Guide M “Maintenance Engineering and Management”. CIBSE Commissioning Codes R “Refrigerating Systems” and C “Automatic Controls”, A “Air Distribution Systems” and W “Water Distribution Systems”, as well as the Knowledge Series KS9 “Commissioning Variable Flow Pipework Systems” concentrate on comissioning issues relative to the respective systems.
CIBSE Guide F “Energy Efficiency in Buildings” provides guidance on the commissioning process (chapter 14) and maintenance issues (chapter 17) in order to achieve expected efficiency.
Computer based simulation tools, such as thermal models should be used to check co-ordination and clashes of services, based on hourly external data. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine whether heating and cooling are operating at the same time (model output) for variable ventilation rates (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.15.2. Weather data available for present climate conditions
Co-ordination of building services is important for energy efficiency and cutting carbon emissions, and for cost effectiveness of systems operation. A detailed analysis of the systems’ operation based on the thermal performance of the building can point out the areas where possible clashes of services could exist. Computer tools could be used at this design stage to explore possible clashes of systems. Hourly weather series often used by computer tools provide knowledge of the dynamic performance of a building in response to external conditions. Systems’ clashes could be examined under certain weather events e.g. temperature difference between south and north facing facades could encourage heating and cooling at the same time.
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for 14 different UK locations.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip.org.uk/scenarios/ukcip08/).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip.org.uk/scenarios/ukcip08/).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
3.15.3. Weather data available for future climate conditions
Future climate change conditions could differentiate the relationships between services and the maintenance strategy of the systems. A detailed analysis of the future operation of the systems could help identifying changes in operation and maintenance and incorporate solutions in the long term operational strategy of the building.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal (http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.15.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
3.15.5. Input from members
3.16. Review system design and check predicted system performance
3.16.1. CIBSE guidance and tools
At this advanced design stage a review of the overall system design against targets and client requirements could concentrate on various aspects of the design intent such as achieving required performance, energy efficiency at part load and control performance. This task will concentrate on confirming that the energy targets and the thermal comfort requirements are met.
Computer based simulation tools, such as thermal models, should be used to review and check design intent, based on hourly external data. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example confirm that the expected energy use meets targets (model output) for variable system efficiency (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.16.2. Weather data available for present climate conditions
At this advanced design stage a detailed analysis of system performance and building thermal response is essential for the fine tuning of the design. This is possible by the use of computer based tools that use hourly weather series to provide a dynamic performance of the building in response to external conditions. Extreme and average summer conditions should be used to examine the system performance and associated energy use.
The CIBSE Test Reference Years (TRY) are often used for building simulation and energy assessments. These are hourly weather series over a year and for 14 different UK locations.
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for the same 14 UK locations.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The currently available TRYs were specifically composed for the calculation of energy use in buildings over a year and express average conditions, while they exclude any extreme events. Furthermore, the TRYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
3.16.3. Weather data available for future climate conditions
At this advanced design stage the designer should make sure that the systems would be able to cope with future conditions and extreme events and that there is scope for their further development towards lower energy use and carbon emissions. A detailed analysis of system future performance is possible by the use of computer based tools that use hourly weather series to provide a dynamic performance of the building in response to external conditions. Extreme and average summer conditions should be used to examine the system performance and associated energy use.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal (http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.16.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
3.16.5. Input from members
3.17. Check part load performance
3.17.1. CIBSE guidance and tools
At this advanced design stage a review of the overall system design against targets and client requirements could concentrate on various aspects of the design intent such as achieving required performance, energy efficiency at part load and performance of controls. This task will concentrate on confirming that the system efficiency targets and system performance requirements are met at part load.
Often systems operate at high efficiency at peak load and low efficiency at part load. The load diversity analysis in task 3.11 could identify integrated solutions for cooling for example covering base load, peak load and contingency load with a combination of LZC technologies and AC units.
Computer based simulation tools, such as thermal models, could be used to check integrated system performance at variable cooling load, based on hourly external data. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine cooling load variation (model output) for variable solar gain (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.17.2. Weather data available for present climate conditions
The systems’ performance will be often directly associated with external conditions. It is important that the designer is able to check that the cooling strategy will cover low and high demand without compromising its efficiency. This is possible by the use of computer based tools that use hourly weather series to provide a dynamic performance of the building in response to external conditions. Certain summer events (e.g. cool summer period) could be identified in order to check the integrated system performance and associated energy use.
The CIBSE Test Reference Years (TRY) are often used for building simulation and energy assessments. These are hourly weather series over a year and for 14 different UK locations.
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for the same 14 UK locations.
For the dynamic computer simulations the user should be looking for hourly data of certain summer events, e.g. days of variable solar gains. Attached probability to the occurrence of certain summer events could assist in better understand the overall efficiency of the systems.
The currently available TRYs were specifically composed for the calculation of energy use in buildings over a year and express average conditions, while they exclude any extreme events. Furthermore, the TRYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
3.17.3. Weather data available for future climate conditions
Conclusions on the variable load performance of the system based on future conditions could help identify the potential of improving energy use for cooling. It is increasingly part of the client’s brief to present options for a future zero or neutral carbon building, so it is important that the designer is able to examine further options. This is possible by the use of computer based tools that use hourly weather series to provide a dynamic performance of the building in response to external conditions. The system variable load performance could be examined for future summer events in order to identify future options e.g. cover cooling load (both base and peak) with a combination of LZC technologies.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal (http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.17.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
3.17.5. Input from members
3.18. Check that the selected controls are capable of achieving the required level of control, response and energy efficiency, particularly at part load
3.18.1. CIBSE guidance and tools
At this advanced design stage a review of the overall system design against targets and client requirements could concentrate on various aspects of the design intent such as achieving required performance, energy efficiency at part load and performance of controls. This task will concentrate on confirming that the controls are able to respond effectively to the changes in the internal environment without compromising energy efficiency.
Often systems operate at variable efficiency based on demand. The load diversity analysis in task 3.11 could identify integrated solutions for cooling for example covering base load, peak load and contingency load with a combination of LZC technologies and AC units. Integrated solutions will require the fine tuning of their controls to make sure that variable load is covered without compromising the systems’ efficiency.
Computer based simulation tools, such as thermal models, should be used to check performance of controls, based on hourly external data. Results from simulations completed during tasks 3.14-3.17 could also be used here to extract information for the analysis of control performance. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
In relation to computer based tools further guidance could explore the input and output stages of the simulation process by providing directions on sensitivity analysis of model output, based on model input. For example examine energy use (model output) for variable occupancy and solar gains (model input). Suggested sensitivity analysis could vary based on building/space application and construction/fabric, e.g. different for lightweight and heavyweight buildings, naturally and mechanically ventilated etc.
3.18.2. Weather data available for present climate conditions
The ability of the controls to respond effectively to variable load is essential for the efficient operation of the system. It is important that the designer is able to check that the system will respond effectively to variable load without compromising its efficiency. This is possible by the use of computer based tools that use hourly weather series to provide a dynamic performance of the building in response to external conditions. Certain summer events (e.g. hot and sunny periods) could be identified in order to examine the system performance and associated energy use.
The CIBSE Test Reference Years (TRY) are often used for building simulation and energy assessments. These are hourly weather series over a year and for 14 different UK locations.
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for the same 14 UK locations.
For the dynamic computer simulations the user should be looking for hourly data of certain summer events, e.g. days of variable solar gains. Attached probability to the occurrence of certain summer events could assist in better understand the overall efficiency of the systems.
The currently available TRYs were specifically composed for the calculation of energy use in buildings over a year and express average conditions, while they exclude any extreme events. Furthermore, the TRYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examininge the use of UKCIP08 climate change information in building design.
3.18.3. Weather data available for future climate conditions
Conclusions on the ability of the controls to respond effectively to variable load, based on future conditions, could help identify future requirements for the fine tuning of controls. This is possible by the use of computer based tools that use hourly weather series to provide a dynamic performance of the building in response to external conditions. The response of the controls to the system’s variable performance could be examined for future summer events (e.g. more sunny days will potentially increase the need to control the direct sunlight) in order to identify future control requirements.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal (http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of future summer events, e.g. probability of x consecutive days of highly varied external temperature.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
The Met Office’s Hadley Centre is currently producing the new climate change projections UKCIP08. UKCIP08 will be presented in a probabilistic way in order to include uncertainty related to the production of climate change projections. The various sources of uncertainty are explained in http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
A UKCIP08 users interface will be able to provide information at a resolution of 25km x 25km, for three emissions scenarios. For more information on UKCIP08 and differences with UKCIP02 look at http://www.ukcip08.net.
CIBSE is part of the consultation group (UKCIP08 Users’ Panel) that discusses outcome and presentation of the forthcoming UKCIP08 information.
Furthermore, a group of EPSRC funded projects are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects.
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.18.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
3.18.5. Input from members
3.19. Check that final system and components meet client requirements for performance, quality, reliability, etc at acceptable cost; and also meet required energy targets and comply with regulations, such as meeting the seasonal efficiency requirements
3.19.1. CIBSE guidance and tools
This task confirms that the final solution does meet original design objectives. Actions could include value engineering and confirming compliance with the building regulations.
Building services engineers should be looking for guidance on value engineering and building regulations compliance tools. They should also make sure that there are no major alterations in the building’s envelope that have been done by the design team to effect building performance.
Computer based simulation tools, such as thermal models, should be used to check overall building performance and compliance with the building regulations, based on hourly external data. Results from simulations completed during previous tasks could also be used here. CIBSE TM33 “Tests for Software Accreditation and Verification”, provides ways to check the validity of dynamic models. CIBSE AM11 “Building Energy and Environmental Modelling” provides comprehensive guidance on the use of computer models, including the various options available and associated uncertainty and risk.
CIBSE could provide guidance on how to complete a value engineering assessment and issues associated. Guidance on SBEM and the other accredited compliance tools could inform the designers of the ‘problem areas’ related to the use of each of the tools. Finally, checklists of possible areas where last minute changes e.g. by completing a value engineering assessment, could affect the building performance could be beneficial towards maintaining performance of design intent.
3.19.2. Weather data available for present climate conditions
Building Regulations require the use of certified computer tools in order to prove compliance. The above requirement is also part of the European Energy Performance of Buildings Directive. Such tools use hourly weather data to provide information on the energy use and associated carbon emissions of the building and as a result provide evidence of the building’s design intent compliance with the building regulations.
The CIBSE Test Reference Years (TRY) are often used for building simulation and energy assessments. These are hourly weather series over a year and for 14 different UK locations.
The CIBSE Design Summer Years (DSY) are often used for the simulation of the summer thermal performance and overheating risk assessment of buildings. These are hourly weather series over a year and for the same 14 UK locations.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of summer events, e.g. once in x observed years event of high temperature and solar radiation.
The currently available TRYs were specifically composed for the calculation of energy use in buildings over a year and express average conditions, while they exclude any extreme events. Furthermore, the TRYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The DSYs are selected based on summer (April – September) means of dry-bulb temperatures (Guide J, §8.4). Based on the above selection criterion the third hottest year was selected of the 1983-2002 baseline. The above selection process raises concerns on whether the DSYs are able to express extreme events and allow the calculation of peak solar gains. Furthermore, the DSYs are based on the 1983-2002 baseline, which almost certainly will not represent the external conditions through the lifetime of the building.
The use of probabilities in weather data used for simulations could help in better understand the risk associated with the design of the building and its services. The next generation of UKCIP climate change scenarios (UKCIP08) is expected to present past events based on observed data in a probabilistic way (http://www.ukcip08.net).
The next generation of UKCIP climate change scenarios (UKCIP08), produced by the Met Office’s Hadley Centre, is expected to include weather information based on observed data as well as climate change model output. A variety of weather information based on observed data will be freely available through the UKCIP08 user interface (http://www.ukcip08.net).
There are currently discussions that explore the ways to use future weather data, rather than present data based on past baselines, in building design. CIBSE’s Climate Task Force is examining the short and long term options (including the use of the forthcoming UKCIP08 information) of providing the industry with the best available weather information. Furthermore, a group of EPSRC funded projects are examining the use of UKCIP08 climate change information in building design.
3.19.3. Weather data available for future climate conditions
Even though not formally required by the Building Regulations it is increasingly the client’s brief requirement to show that the building will be able to maintain predicted energy performance over its lifetime. This is possible by the use of computer based tools that use hourly weather series to provide a dynamic energy performance of the building in response to external conditions. Such tools use hourly weather data to provide information on the energy use and associated carbon emissions of the building and as a result provide evidence of the building’s long term energy performance based on design intent.
CIBSE in collaboration with UK Climate Impacts Programme (UKCIP) and ARUP has produced future hourly weather years, based on the existing Design Summer Years (DSYs) and Test Reference Years (TRYs), which incorporate the UKCIP02 climate change scenarios. The above future weather years are available for the same 14 sites, for three timeslices (‘2020s’ 2011-2040, ‘2040s’ 2041-2070 and ‘2080s’ 2071-2100) and for four emissions scenarios (Low, Medium-Low, Medium- High and High) (the future weather years could be ordered from http://www.cibse.org/index.cfm?go=page.view&item=1300). The data may also be provided ready-formatted for certain simulation packages (contact Ken Butcher on 020 8772 3628 or email kbutcher@cibse.org for details). Purchasers of any of the above packages will also receive CIBSE’s TM48: “Climate Change Data for Building Simulation”. TM48 serves as a valuable companion to the future DSYs and TRYs with information and guidance on their production and use.
CCWeatherGen – A Climate Change Weather File Generator: A climate change weather file generator (CCWeatherGen) has been developed by the Sustainable Urban Environment (SUE) programme at the School of Civil Engineering and the Environment, University of Southampton. The tool is Microsoft® Excel-based and uses the UKCIP02 climate change scenarios to transform CIBSE / Met Office TRY/DSY weather files into climate change TMY2 or EPW weather files which are compatible with the majority of building performance simulation programs. The CCWeatherGen and the accompanying documentation are available without charge from http://www.energy.soton.ac.uk/ccweathergen. This tool can be used to generate morphed versions of the DSY and TRY files similar to those provided by CIBSE. However, use of this tool does require some specialist expertise. Consequently, CIBSE is not responsible for any errors associated with its use or any other software to reproduce the morphed files provided by CIBSE. The objective of providing the ready made files is to provide a standardised data set for the industry providing a common platform for climate change impact assessments.
All current climate change data in CIBSE guidance originate from the Met Office’s Hadley Centre model outputs. Four UKCIP02 climate change scenarios are presented at a 50km x 50km resolution based on outputs from the Hadley Centre’s global and regional climate models (Had CM3 and HadRM3, respectively). For each of the four UKCIP02 climate change scenarios (H, M-H, M-L, L), changes are described for three future thirty-year time-slices: 2011 to 2040 (the 2020s), 2041 to 2070 (the 2050s) and 2071 to 2100 (the 2080s). All changes in climate are given relative to the baseline period of 1961 to 1990. For more information on emissions scenarios and the products freely available look at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=161&Itemid=291.
The next generation of climate change information (UKCP09) is currently available and presented in a probabilistic way ( http://ukclimateprojections.defra.gov.uk/). The UKCP09 provide information in various formats such as maps, graphs, plots, etc, available in printed reports and in customisable outputs. Changes in weather variables such as temperatures, rainfall, cloud cover etc are presented in a probabilistic way and are available for 25km grid squares, three emissions scenarios (Low, Medium and High) and seven future overlapping 30 year time periods. The provision of probabilistic projections is the major change from the previous UKCIP02 projections. Probabilistic projections assign a probability to different possible climate change outcomes, recognising the uncertainty involved in their production and inherent of our global climate, and as such help with making more robust adaptation decisions. A User Interface portal (http://ukclimateprojections.defra.gov.uk) has been specifically designed to guide the user to the information more appropriate to them and to explain the underlying science and outputs along the way. One of the resources provided through the User Interface is a Weather Generator which is a type of statistical model that uses relationships between climate variables to generate daily and hourly time series. The produced time series are comprised of set of climate variables at a 5 km resolution that are consistent with the underlying 25 km resolution climate projections. Customisable outputs, including the Weather Generator, are accessible after registration.
For the dynamic computer simulations the user should be looking for hourly data with attached probability of occurrence of summer events, e.g. probability of certain coincidence of high temperature and solar radiation happening in the next x years.
All currently available climate change data and weather series for building design are based on UKCIP02 scenarios and are presented in a deterministic way which means that a single number is used to express future changes in weather variables. A good understanding of the uncertainty related to the development of climate change data is essential in order to assist in robust design decisions. Information on the uncertainty associated with climate change information could be found at http://www.ukcip.org.uk/index.php?option=com_content&task=view&id=232&Itemid=326.
Although the new climate projections UKCP09 offer an opportunity for the building professionals to better understand and apply climate change information in the future proofing of buildings, their complexity and existing format can hinder their immediate implementation in building design. One of the issues associated with the data is the lack of correlation between weather variables presented as maps and graphs (Cumulative Distribution Function – CDF and Probability Density Function – PDF). For example for overheating calculations there is no correlation between the temperature and solar radiation figures for a given probability. Other issues include the weakness of the Weather Generator to represent extreme events, as well as the lack of projections on wind speed and direction.
The climate change trends (in both UKCIP and CIBSE guidance) are based on a different baseline (1961-1990) than the present day statistics (Guide A 1983-2002, Guide J 1976-1995, TRYs and DSYs 1983-2004) and so they are not directly comparable.
A group of EPSRC funded projects “Adaptation and Resilience in a Changing Climate” – ARCC are examining the use of probabilistic data and climate change information in building design. CIBSE is representing its members as a key stakeholder, technically co-ordinating the outputs of the projects. For more information and to get involved visit: http://www.ukcip-arcc.org.uk/
The outcomes from the above EPSRC funded projects will be integrated into the “Design Compass” as they emerge.
CIBSE’s suggestion of suitable external design conditions based on climate change data for use towards future proofing of buildings and their services should be made available and be incorporated in the weather related CIBSE guidance. Furthermore, CIBSE could further develop guidance on possible design options for adapting buildings to climate change, for both new built and refurbishments.
3.19.4. Other useful references
South East Climate Change Partnership “Adapting to Climate Change: a checklist for Developers”, November 2005
European Climate Assessment & Dataset (ECA&D) project for indices of extremes and daily information based on observations, for various European locations including UK: http://eca.knmi.nl/
The British Wind Energy Association gives access to wind speeds in the UK: http://www.bwea.com/
3.19.5. Input from members
4. Pre-Construction
F. Production information
G. Tender documentation
H. Tender action
4.1. Information from Design Development to be used here
[NO CONTENT]
This is a placeholder node that will require content to display "child" nodes
This also a content placeholder "end-point". This is due to the "parent" placeholder node also being empty.
4.2. CIBSE members’ involvement at this stage depends on the individual contract with the client
[NO CONTENT]
This is a placeholder node that will require content to display "child" nodes
This also a content placeholder "end-point". This is due to the "parent" placeholder node also being empty.
5. Construction
J. Mobilisation
K. Construction to practical completion
5.1. CIBSE members’ involvement at this stage depends on the individual contract with the client
[NO CONTENT]
This is a placeholder node that will require content to display "child" nodes
This also a content placeholder "end-point". This is due to the "parent" placeholder node also being empty.
6. Post Completion
L. Post practical completion
6.1. Commissioning, management and maintenance of the heating system
6.1.1. CIBSE guidance and tools
Guidance on the commissioning, management and maintenance of the building services, after the completion of the project, could be used here by facilities and energy managers in order to meet the design specifications.
The CIBSE Commissioning Codes such as Code A “Air Distribution Systems”, Code C “Automatic Controls” and Code R “Refrigeration Systems” could be used here to inform the commissioning process of the cooling system. CIBSE Guide M “Maintenance Engineering and Management” provide guidance on the management and maintenance of the building services.
CIBSE guidance seems sufficient.
6.1.2. Other useful references
6.1.3. Input from members
6.2. Design review – Refer to feedback and lessons learned
6.2.1. CIBSE guidance and tools
The building services engineers should be able to keep in touch with previous projects in order to learn from them and improve their design methods.
For post occupancy reviews see energy audits and surveys in Guide F “Energy Efficiency in Buildings”, chapter 18.
CIBSE could offer guidance on reviews at design stage (project team meetings, reviews with other design teams etc) and reviewing system performance at post occupancy.
Further guidance could include advice on possible channels and actions through which the design team could revisit or keep in touch with previous projects. Perhaps some research could be done in current practices.
Could CIBSE influence client perception of the value of monitoring and feedback? In some current projects monitoring and feedback is used as educational process.
Encourage integration with Facilities Management (FM), e.g. develop processes of reporting to the design team.
6.2.2. Other useful references
6.2.3. Input from members
6.3. End of life
6.3.1. CIBSE guidance and tools
Guidance on the building demolition and the recycling of materials is relevant here.
CIBSE Guide L “Sustainability”, chapter 8, provides some guidance on this last stage of the building’s life.
Further guidance is needed on end of life stage.
6.3.2. Other useful references
6.3.3. Input from members