Tackling Overheating in Homes Executive summary
Contents
1. n SUSTAINABLE HOMES Appendices Appendix 1 Background 1 Which of the following best describes your organisation Select one only Private Housebuilder Developer Private Landlord Registered Social Landlord Housing Association Local Authority Architectural Practice Building Services Provides Energy Efficiency Retrofit services Other Please describe O 00000 00Q0 Q Answer If Private Housebuilder Developer Is Selected 2 What best describes your type of role Select one only Technical Manager Director In house Architect or Designer Climate Change Energy Efficiency Strategy Research and Development Site Manager Procurement Finance Customer Services Marketing Board Member Other Please describe O00000 0 00Q Overheating survey findings 8 January 2015 Page 17 SUSTAINABLE HOMES Answer If Private Landlord Is Selected 2 What best describes your type of role Select one only OCOOWOWOO0O Technical Manager Director Climate Change Energy Efficiency Strategy Research and Development Buildings Manager Procurement Finance Customer Services Board Member Other Please describe Answer If Registered Social Landlord Housing Association Is Selected 2 What best describes your type of role Select one only O0O00000000Q0Q0 Q Technical Manager Director New Build Technical Manager Director Existing Stock Technical Manager Director New Build and Existing Stock In2. y SUSTAINABLE HOMES Tackling Overheating in Homes Survey findings Executive summary A survey produced by Sustainable Homes for the Zero Carbon Hub aimed to assess the degree of anxiety and uncertainty about overheating in UK homes Respondents representing 208 047 homes shared their experience Based on the survey responses on average 20 of homes have experienced overheating in the last 5 years 43 of respondents are extremely or very confident that those properties that have NOT experienced overheating problem do not present a risk of overheating in the future In comparison 23 of respondents are not confident Overheating risk assessment is routinely carried out for 59 of new build and 59 for existing homes 65 of respondents believe that the level of concern about overheating in their residential properties is high or fairly high However over 34 of respondents stated that the level of concern is still relatively low Further detailed information is contained in the report Sustainable Homes Marina Place 17 Marina House Hampton Wick KT1 4BH Telephone 020 8973 0429 Email info sustainablehomes co uk Report prepared by Magda Bilinska Overheating survey findings 8 January 2015 Page 1 n SUSLAINABLE HOMES Contents MOG GTO eoe E E E E E E EAE 3 BACK OUIAO a S 4 Pevac O OVNE N e 5 PASSO SSI OVE NGANO TISK serren E E E 8 FS IS A EE A A A E A A A E T 12 ONN U Yee A E E E E E E 16 APOO NOICOS
3. temperature is defined as the outside air temperature at 0400hrs Prove that the home won t go above 25 C for 10 of the time PHPP definition We recognise that we need to ensure adequate ventilation The move to external wall Insulation is done because it reduced overheating The provision of Heat Recovery Ventilation The provision of Air to Water heat pumps to provide cooling as well as heating often utilising the same terminals such as fan coil units The provision of an integrated system utilising phase change materials phase change materials to absorb heat during the warmest part of the day and the ability to discharge the heat to atmosphere through a dry air cooler when required or discharging the heat via the air to water heat pump when required The provision of air conditioning equipment Overheating survey findings 8 January 2015 Page 35 a SUSLAINABLE HOMES Appendix 6 We insist that the PHPP targets form part of the requirement Must meet Passivhaus requirements At planning stage we discuss overheating risk with the client and architect We report on the predicted performance of the design and options to improve performance Employers Requirements specifically requires contractors to advise and address overheating We encourage responsibility to be clearly allocated within the design and delivery process We draw attention to the problem of overheating and ask designers and contracto
4. Page 32 oa SUSTAINABLE HOMES district heating solar gain little mitigation restrictors on windows Window design Noise Comunity Heating Lack of user accepatnce that new buidlings require windows to be left open over long periods at night and when unoccupied Too much glass Heavily restricted window openings because of acoustics MVHR units are attempting to provide a high enough flowrate to control temperatures this is not something they were intended to do They are only intended to meet background fresh air requirements Poorly insulated heating pipework heat interface units Flats with large glazed areas High glazing percentage Very low U values Lack of shading Very low thermal mass Too much glazing with no insufficient external shading Insufficient ventilation opening windows either due to external noise security concerns single aspect design capital cost or architectural preference or architect client not engaging with the risk Centralised heating and hot water supply lose 30 50 of heat generated as waste heat Much of this 60 is lost internally in corridors Heat interface units are also wasteful e High insulation required by legislation without a corresponding legislative requirement for adequate ventilation e Higher internal gains than modelled e g normally higher occupancy in social housing than SAP estimates climate is hotter than design year Residents no
5. and made reference to CIBSE and other guidance which is not too helpful as some properties meet this but residents complain and are very uncomfortable Either CIBSE Guide TM52 EN 15251 However neither of these cover corridor overheating from services usually centralised heating systems Too hot humid We do not have a definition rather we become aware of issues following resident complaints Data being gathered using sensors at 6 recent new build sites with Hub Overheating is the state whereby the occupants experience an uncomfortable environment which cannot be easily controlled without some form of MHRV system or opening windows to release the heat Heating to the point of losses and need for cooling action temperatures in excess of those traditionally found in the flats or common parts AND likely to cause discomfort to the average occupier Maintaining a temperature over 15 degree centigrade Overheating survey findings 8 January 2015 Page 25 oa SUSTAINABLE HOMES A condition found in a domestic property whereby the indoor temperature is too high and cannot be controlled to provide comfort to the occupants Prolonged exposure to temperatures above levels deemed as comfortable within the home This is a personal rather than organisational definition but would describe the problem of overheating as the inability to deliver a constant comfortable temperature as specified by the inhabitants within their control paramet
6. ara a E E E 17 Overheating survey findings 8 January 2015 Page 2 oa SUSTAINABLE HOMES Introduction This short survey produced by Sustainable Homes for the Zero Carbon Hub aimed to help gain a picture of how those who build new homes and those who manage or retrofit existing homes assess the risk of those properties potentially overheating Responses from the following types of organisations were sought Housebuilders Developers Private Landlords Registered Social Landlords Housing Associations e Local Authority Housing Architects Building Services Engineers Companies providing Energy Efficiency Retrofit services The answers to the survey were confidential to allow respondents to be candid in their response However aggregated findings are reported here Responses will help the Zero Carbon Hub to identify where there may be common issues with current processes and practises so that they may be improved The survey is part of wider project which will ultimately lead to a report to government and industry decision makers recommending actions that can make an impact in tackling future overheating problems The list of all questions can be found in the appendix 1 Overheating survey findings 8 January 2015 Page 3 n SUSTAINABLE HOMES Background Q1 Which of the following best describes your organisation 75 valid responses were received They came from a variety
7. insulation central heating plant pipework in corridor spaces lack of potential to disperse excess heat through natural ventilation Site location Landscaping Position of the main axis of the building The high level of insulation combined with down lighters Lack of heating on top floor of three story building keading to excess heat on lower floors Not enough shading to windows 1 High levels of glazing on southern facing elevations with little shadings 2 Top floor properties with low levels of insulation typically flats where we have dormer roofs 3 south facing solid wall properties 4 Unventilated internal corridors Single aspect no solar shading to large windows lack of insulation to heating pipes windows which cannot be opened etc Communal heating pipework in flats single aspect windows passive saloar gain MVHR postion of insulation Overheating in common parts caused by CH and HW distribution pipes from central plant rooms Overheating in flats from HIU and service pipes to CH and HW from central plant rooms large glazed areas to south facing single aspect flats inability to ventilate adequately either due to design of windows or because overlooking noisy or dirty roads railways or neighbours activities Low natural air changes and inadequate or unsuitable mechanical ventilation Well insulated properties that have poor ventilation in place Over insulation amp air tightness Lack of natural ve
8. monitoring in the building or other post occupancy work Through our Building Site Managers reporting problems Through un solicited customer feedback complaints Through customer surveys which specifically ask a question s about thermal comfort overheating Through customer surveys which do not specifically ask a question s about thermal comfort overheating don t know Other Please describe O WOOO OO Overheating survey findings 8 January 2015 Page 20 we SUSTAINABLE HOMES Assessing Overheating Risk 9 For your residential properties that have NOT experienced overheating problems how confident are you that they do not present a risk of overheating in the future Key 0 Not confident 5 Extremely confident know Level of confidence 10 Does your organisation have a method or process to assess the risk of your residential properties overheating 0 1 2 3 4 5 don t Q Yes QO No O I don t know Only appears if Yes is selected in question 10 11 For each of the following options rate how important they are in triggering your organisation to assess overheating risk Not at all Unimportant Neither Important Extremely important important nor important unimportant Because Regulation Building Control requires us to Because our Local Authority Local Plan requires us to Because our expert contractors frequently advise us to Because our competitors others assess overhe
9. of organisations but dominated by responses from registered social landlords followed by architectural practice There were a number of responses from other professions not specified in the survey but of high value see the table below The other professions included consultants energy assessors manufacturers academics and others There was a good combination of responses from those who build new homes 38 and those who manage or retrofit existing homes 37 Organisation type Other Please describe Registered Social Landlord Housing Association Architectural Practice Local Authority o o e Q3 Where does your organisation operate in the UK As shown in the graph below the responses came from organisations managing properties all over the UK 3 Where does your organisation operate in the Overheating survey findings 8 January 2015 Page 4 a SUSTAINABLE HOMES Respondents representing 208 047 homes shared experience Approximately 43 867 properties have been retrofitted to improve the energy efficiency in the last five years The total number of residential properties that have been built by the respondents in the last five year amounted to 44 718 Responses for about 32 727 homes relating to design or specification work The remainder were managed homes Prevalence of overheating 19 How would you rate the current level of concern in your organisation about overheating in residential properties in
10. out about the overheating problem in their properties through un solicited customer feedback or complain The remaining respondents identified that problem through a variety of ways which can be seen on the graph below 8 For those properties that have have had overheating problems how did your organisation find out there was a problem 0 Through our Building Site Managers reporting problems E Through customer surveys which specifically ask a question s about thermal comfort overheating don t know E Through monitoring in the building or other post occupancy work E Other Please describe E Through un solicited customer feedback complaints ld Through customer surveys which do not specifically ask a question s about thermal comfort overheating Other includes through research projects through a call to Environmental Health department visiting the property experiencing it and other The full list is in appendix 4 Overheating survey findings 8 January 2015 Page 7 ye SUSTAINABLE HOMES Assessing overheating risk 9 For your residential properties that have not experienced overheating problems how confident are you that they do not present a risk of overheating in the future In terms of properties that have NOT experienced overheating problem 43 of respondents are extremely or very confident they do not present a risk of overheating in the future In comparison 23 of respondents are not conf
11. perceptions Only defined for hot weather conditions When the environmental temperature is high enough to make occupants uncomfortable This is conditional on fans be available Our minimum criteria are Part L1A criterion 3 CIBSE A guide figures CIBSE Living room and kitchen requirements lt 280C for 99 of occupied hours CIBSE bedroom requirements lt 260C for 99 of occupied hours Although these are not especially comfortable so we try to achieve CIBSE Recommended for bedrooms lt 230C for 99 of occupied hours More recently we have been applying TM52 for non domestic properties It gives a finer view on comfort than the blunt targets set above TM52 could be applied to living spaces but it specifically does not address sleeping spaces We see this as a major omission and perhaps indicative of a lack of research amp useful guidelines on comfort conditions for sleep We would welcome some clear guidance on this very important topic use the SAP assessment Overheating survey findings 8 January 2015 Page 29 oa SUSTAINABLE HOMES Appendix 3 Improved airtightness remedy is to open windows often negating insulation benefits Lack of trickle vents due to changes in the CfSH or Building Regs Improved insulation to maintain the heat without some form of air changes to refresh the rooms MHRV is not mandatory under the Building Regs For a Code 6 house to be achieved then MHRV is a must High levels of
12. provide information about ventilation practices to aid understanding of systems and thereby hopefully operation Takes a whole system approach SO includes discussion of thermal mass etc How to use heating controls and ventilation systems provided Keeping curtains closed during the day Open windows at night where possible Thermometers guides on keeping at a comfortable temperature guides on insulation dynamics and how this interacts with ventilation The houses should be fitted with a mechanical ventilation heat recovery system and the windows should be opened to the locked ventilation position in overheating conditions Overheating survey findings 8 January 2015 Page 37 oa SUSTAINABLE HOMES General advice on using heating controls How weather compensation works What to expect such as lower surface temperature on radiators while retaining overall heating comfort Once they understand how it works and what to expect there are no issues arising from ambiguity Open the windows vents Ventilate Home User Guide with measures for staying warm or cool Each property is different and so all the advice is different and will come in many different forms Tips provided in residents magazine Specific advice may be given directly complainants To keep their properties ventilated during the daylight hours whilst the external air is warmer and drier Regulate the heating appliances better and discuss with them th
13. MES Appendix 4 Existing familiarity with building behaviour in hot weather including thermal modelling thermal imaging Through our Technology Strategy Board research project into the affect of climate change Damage to fire smoke venting systems by residents who required additional ventilation for heat relief Via a call to our Environmental Health dept Through organisations such as yourselves By comparison with dynamic thermal modelling of equivalent Hemcrete insulated buildings Experiencing it Through discussion with the Client and or end users Expected levels of overheating only early stage planning reports highlight some problems but they don t always get dealt with We don t often receive comments regarding overheating post hand over This is usually flagged up and addressed at design stage Visiting the finished building being involved in schemes where user had complained Overheating survey findings 8 January 2015 Page 34 SUSLAINABLE HOMES Appendix 5 Includes requirement for 10ac h night time ventilation in hot weather automatically controlled with a noise level in sleeping areas that will not interfere with sleep and does not prejudice security Performance in use requirement is that internal fabric temperature 25mm in the fabric shall get within 3C of the night time minimum temperature each night provided that the internal temperature is not reduced to below 20C NB minimum
14. TAINABLE HOMES 17 Does your organisation currently specify overheating related requirements in your contracts with architects designers More than 50 of respondents stated that their organisation currently does not specify overheating related requirements in their contracts with architects designers 17 Does your organisation currently specify overheating related requirements in your contracts with architects designers E Yes E No E Do not know Those who do do it by amongst other methods Ensuring PHPP targets are included Requiring contractors to advice and address overheating through Employers Requirements Requiring contractors to assess passive shading measures Requiring contractors to do dynamic thermal modelling The full list can be found in appendix 6 Overheating survey findings 8 January 2015 Page 14 we SUSTAINABLE HOMES 18 Do you provide advice directly to occupants of your residential properties on how they can help Keep their properties at comfortable temperatures Over a half of respondents 62 stated that they provide advice directly to occupants of their residential properties on how they can keep their properties at comfortable temperatures The advice is included in the Home User Guide and occupant handbook as well as face to face briefing sessions and or informal discussions Type of advice given relates to Using the MVHR system heating controls correctly Using li
15. al extraction to increase air changes within the affected dwelling s Also planning approved schemes incorporating large amounts of glazing which are oriented in such a way as to incur undue overheating This is by far the most common reason which is why we are looking to address this pre application stage However it s worth noting that quite often developers will come to use with schemes having already been granted planning approval which have been designed by others There is obviously no way to avoid overheating issues which have been inherited from another s designed scheme that has otherwise not addresses this issue These have to be dealt with retrospectively which has achieved varying degrees of SUCCESS Omission of cooling shading devices by client Normally overheating in houses built using our system is due to lack of ventilation or large glazed facades facing to the south or south west Poorly thought out windows and ventilation routes are the most common issues which also has an impact on the homeowner as there is limited they can do in mitigation However it is also accepted that over insulation of the thermal fabric and high airtightness are contributing to overheating issues Finally other instances have occurred in common areas due to heating pipework being uninsulated or highly glazed spaces such as stairs which in turn leads to overheating in residential spaces Overheating survey findings 8 January 2015
16. ating risk so we do too Because we have had overheating Overheating survey findings 8 January 2015 Page 21 a SUSLAINABLE HOMES problems in the past and want to avoid it in the future We have a general policy to ensure our properties are suitable for a changing climate We want to ensure our customers are happy Because we think it makes financial sense Other Please describe Other Please describe Other Please describe Only appears if Yes is selected in question 10 12 Which of the following best describes your usual approach to assessing the level of overheating risk in your residential properties Chose one option only We usually use SAP Appendix P We usually use PHPP We usually use dynamic simulation modelling We usually rely on our technical experience longstanding knowledge We usually rely on the findings of our own research to inform us We usually rely on industry guidance We usually use dynamic simulation modelling when other methods identify a medium or high risk of overheating We usually use SAP Appendix P alongside other qualitative methods don t know Not applicable Other Please describe OCOO0O000 O O 13 Approximately on what percentage of your residential properties do you use dynamic simulation modelling to assess overheating risk If you do not use this approach please leave the slider at 0 Overheating surv
17. ccupants and their abilities to adapt their circumstances when conscious of overheating In an HMO occupants may not be able to flexibly move room while in a domestic house they may When temperatures or internal conditions exceed those which the occupier is able to tolerate for sustained periods of time At the bare minimum compliance will be examined against SAP calculations however increasingly we complete complex thermal modelling studies to demonstrate sound practical ventilation strategies to limit overheating prior to building commencing Uncomfortable conditions affects concentration Our role is in retrofitting properties which are not energy efficient Our brief is to make them more efficient and reduce the cost of heating for residents who are predominantly living with fuel poverty We recognise that overheating is a potential outcome of the retrofitting process but it is only one of a number of consequential issues that are less important than Overheating survey findings 8 January 2015 Page 26 oa SUSTAINABLE HOMES the fundamental problem for our clients ie they are paying or are unable to pay high costs to heat their cold homes Most of the properties we deal were not designed to reduce heat loss As such there are significant health problem for residents arising from the cold eg worry and depression due to heat or eat choices constant fuel poverty colds respiratory diseases illnesses arising from mould a
18. d with traffic noise reducing night time open windows in a 1900 s terrace house Solar gains and limited heat loss thermal elements For example large amounts of glazing on small flats that have large areas of party wall relative to the heat loss elements For existing properties the uptake of thermal improvement measures eg double glazing insulation etc For new build or houses built within the last 5 10 years solar gain has not always been properly considered when design has incorporated large expanses of glazing Lack of any infiltration due to airtight construction designs to minimise and landlock communal corridors build up of heat from domestic hot water services routed through communal area ceilings increased levels of insulation excessive glazing and poor ventilation Over glazing incorrect specification usage of blinds and shading devices lack of understanding of how to cool building by occupants room thermostat set too high large areas of unshaded glazing communal heating pipes in corridors with no adequate way to remove heat single sided properties no cross vent restricted window openings Lack of responsiveness of underfloor heating systems Due to their large heating mass they are slow to react to changes in weather including sunshine Existing buildings being converted can have limited scope for designing out overheating This is usually resolved through external shading features or via mechanic
19. definitions respondents estimated that on average 20 of properties have experienced overheating problems in the last 5 years The graph below show how the percentage differs between various types of organisations New build properties seem to experience overheating more frequently than existing ones on average 22 new build and 18 existing homes 6 What percentage of your residential properties have have had overheating problems in the last five years Private Provides Building Private RSL HA Other Architectural Local Housebuilder Energy Services Landlord Please Practice Authority Efficiency describe Retrofit services 7 For those properties that have have had overheating problems briefly summarise any common features which you believe contributed to problem A common feature that contributed to overheating problems in residential properties was poor or lack of insulation to communal heating pipes Other frequently mentioned reasons of overheating were high levels of wall and roof insulation improved airtighteness with poor natural ventilation Lack of windows shading with excessive glazing was also considered as a main contributor to overheating All responses can be found in the appendix 3 Overheating survey findings 8 January 2015 Page 6 we SUSTAINABLE HOMES 8 For those properties that have have had overheating problems how did your organisation find out there was a problem The majority of respondents found
20. e heating costs involved with the controls Use positive air vents in the properties to dry the moist damp air Mainly relating to keeping warm Advise them to read and use the electric heating units storage heaters with care There has to be some fore thought on their part about their chosen activities for the following day overnight charge not to overcharge their units at night They need to keep output at minimum to sustain the output for the day ahead and for the tenant to be aware of the forecast outside temperatures and wind chill If it s hot outside open the windows and doors when and where possible but it can be cooler to keep the dwelling sealed from very hot outside temperatures Most of our dwellings are of a heavy traditional construction with large heat capacities in floor and walls which help to stabilise daily temperature variation In the last 20 years the general population seems to want to be able to wander about their dwelling only wearing light summer clothing all year around and still feel comfortable in every part of their home Such a self indulgent attitude even in winter is bizarre and unsustainable in our view It will simply serve to speed global warming Our advice dress for the season and be in touch with the local weather save money and feel comfortable Open windows and turn heating down also use fans to cool Information on use of thermostats etc Advice on using heating amp ventilating homes More l
21. ers with occasional or regular over achievement of temperature settings which causes discomfort Excessive internal room temperatures experienced over prolonged periods of time Intermittent or prolonged exposure to internal temperatures higher than seasonal comfort levels Usually caused by excessive solar gain high levels of insulation or poor ventilation or any combination thereot Having temperatures in excess of 5 deg centigrade above ambient in summer time where heat is trapped inside a building that cannot be removed via passive or mechanical means The inability to maintain thermal comfort for the occupants or users of a building without the use of mechanical plant or air cooling Very similar to BB101 conditions for schools percentage of habitable time at over 26degrees lt does not recognize it as an issue It is something am currently working on amp think it will be based on levels of comfort for the resident Spaces which are uncomfortably warm and there is no effective way of mitigating or removing the heat Temp over 25 C in common spaces in a block of flats staircase shaft etc Temp over 2 C in living or bedroom spaces within a dwelling Improvement or Prohibition Notice served under Housing Act 2004 by local authority for excessive heat in a flat CIBSE define above 28 deg C with more specific criteria for different types of occupied Spaces but WHO for the vulnerable define above 24 deg C so it depends on the o
22. ey findings 8 January 2015 Page 22 eo SUSTAINABLE HOMES of properties 14 Approximately on what percentage of your residential properties do you use Appendix P of SAP to assess overheating risk If you do not use this approach please leave the slider at 0 of properties Only appears if Yes is selected in question 10 15 How confident are you that the methodology you usually use to assess overheating risk in your residential properties is an accurate representation of the likely future risk over the next 20 years Key 0 Not confident 5 Extremely confident I don t know Level of confidence Future risk 16 How do you ensure that any building or system designs and technical measures intended to mitigate the risk of overheating in your properties are implemented as specified Select all that apply Q We have a specific person responsible for ensuring that overheating mitigation measures are properly implemented We rely on our general quality control process Our quality control process specifically covers overheating We rely on building control inspections We don t have a process don t know Not applicable Other Please describe DOOOOUWOUL Question only appears for Existing Homes roles 17 Does your organisation currently specify overheating related requirements in your energy efficiency retrofit supply contracts QO Yes OQ No O don t know O Not applicable O
23. general As shown in the graph below the majority of respondents believe that the level of concern about overheating in residential properties is high or fairly high However over 30 of respondents stated that the level of concern is still relatively low On average on a scale of 0 5 0 not concerned 5 extremely concerned the current level of concern about overheating in residential properties is 3 19 How would you rate the current level of concern in your organisation about overheating in residential properties in general E Extremely or very concerned E Fairly concerned E Not concerned E Do not know 5 How does your organisation define overheating in residential properties Almost all respondents 95 provided some sort of definition of overheating Most of them were defined in terms of occupant thermal comfort The most common definition was that occupants experience overheating when they are exposed to excessive temperatures gt 25 C or more over prolonged periods of time 10 of occupied hours Many definitions were based on CIBSE Guide criteria and a few on SAP assessments All the reported definitions can be found in the appendix 2 Overheating survey findings 8 January 2015 Page 5 we SUSTAINABLE HOMES 6 Using the definition you gave in question 5 approximately what percentage of your residential properties have have had overheating problems in the last five years Based on these
24. ghting heating and hot water systems properly Using energy efficient appliances to avoid internal gains Using windows and shading The full list can be found in appendix 7 18 Do you provide advice directly to occupants of your residential properties on how they can help keep their properties at comfortable temperatures E Yes E No E Do not know Overheating survey findings 8 January 2015 Page 15 oa SUSLAINABLE HOMES Summary 75 responses were received to the survey produced by Sustainable Homes for the Zero Carbon Hub The aim was to assess the degree of anxiety and uncertainty about overheating in UK homes Respondents representing 208 047 homes shared their experience Overheating risk assessment is routinely carried out for 59 of new build and existing homes The results show that on average 20 of homes have experienced overheating in the last 5 years In terms of properties that have NOT experienced overheating problem 43 of respondents are extremely or very confident they do not present a risk of overheating in the future In comparison 23 of respondents are not confident 14 do NOT know what the risk might be When asked about the level of concern about overheating in their residential properties 65 of respondents stated that it is high or fairly high However over 34 of respondents stated that the level of concern is still relatively low Overheating survey findings 8 January 2015 Page 16
25. here is currently no other means or procedure we use for identifying overheating risks although this is something we are aware of As we are now predominantly working on schemes using BIM software we are looking into what bolt on s are available to assess a number of factors including overheating This will allow us to identify any issues at the pre application stage and so design out potential problems by amending glazing orientation or incorporating features such as Brise Soleil Asin PHPP As per CIBSE and SAP guidance but also with reference to householder preferences Sustained room air temperatures of 25 Celsius or more for a period or periods of 1 hour or more in any one 24 hour period Where energy generation is in excess of that which is needed to meet useful heat demand leading to wastage Caused by uncontrolled systems or legacy building design Caused when Hanover s Planned Works Programme does not consider the building as a holistic whole and invests in high performance heating hot water generation that is installed without necessary upgrades to the distribution system Excessive temperature in built product following comments complaints from occupants Actual temperature varies dependant on room claimed as overheating in the build Too warm for thermal comfort Criterion 3 compliance Not in compliance with CIBSE Guide A criteria Uncomfortable heat due to miss use of heating appliance i e Open Fire Wood burn
26. house Architect or Designer Climate Change Energy Efficiency Strategy Research and Development Buildings Manager Procurement Finance Customer Services Board Member Other Please describe Answer If Local Authority Housing Provider Is Selected 2 What best describes your type of role Select one only O 00000 Q00Q0 Q Technical Building Manager Climate Change Energy Efficiency Strategy Research Planner Procurement Finance Customer Services Other Please describe Overheating survey findings 8 January 2015 Page 18 SUSTAINABLE HOMES Answer If Provides Energy Efficiency Retrofit services Is Selected 2 What best describes your type of role Select one only Technical Manager Director Climate Change Energy Efficiency Strategy Research and Development Procurement Finance Customer Services Board Member Other Please describe OCOOQO0O000 3 Where does your organisation operate in the UK Select all that apply London South East South West East of England East Midlands West Midlands Yorkshire and Humber North West North East Scotland Wales Northern IrelandQuestion only appears for Existing Homes roles DOOUOOWOWUDOUOOWOUOUL 4a Approximately how many residential properties does your organisation currently have management responsibility for OQ Number of properties Q don t know Question only appears for Existing Homes roles 4b Approximately how man
27. ident and 20 and fairly confident that non overheating properties may experience this risk in the future 14 do NOT know what the risk might be see the graph below On average on a scale of 0 5 0 not confident 5 extremely confident the current level of confidence is 3 3 9 For your residential properties that have not experienced overheating problems how confident are you that they do not present a risk of overheating in the future E Extremely or very confident E Fairly confident E Not confident E Do not know Overheating survey findings 8 January 2015 Page 8 we SUSTAINABLE HOMES 11 For each of the following options rate how important they are in triggering your organisation to assess overheating risk Ensuring that customers are happy is deemed to be the main trigger to assess overheating A general policy to ensure properties are suitable for a changing climate is the second most effective trigger The other prompts to conduct an overheating assessment can be seen in the graph below 11 For each of the following options rate how important they are in triggering your organisation to assess overheating risk 0 2 4 6 8 10 12 14 16 18 a aS NS LAS eS A general policy to ensure properties are suitable for a ss changing climate P et It makes financial sense Sf Overheating problems in the past and want to avoid it in eee the future ee Local Authority Local Plan requires us
28. ing stove Central heating radiators on full drying tenants clothes producing moisture in the room thus condensation and black spot mould starts Very difficult to educate our tenants on their use and the problems they create Ventilation is so important for the tenant as well as the property structure Uncomfortable and unable to reasonably control temperature We don t currently have an agreed organisational definition of overheating but we have gathered some anecdotal evidence and have noted overheating as a risk on our risk register This work has just begun Usually according to the Passivhaus principles gt 10 of the year over 25 degrees celcius This is an acceptable limit according to research conducted by the PHI in Germany Usually we look at the CIBSE criteria for overheating that will be the percentage of hours over 28 or 26 degrees in the indoor spaces depending on its use Weare particularly interested in overheating in communal areas of multi occupancy residences It is difficult to define overheating in these spaces due to their transientry Overheating survey findings 8 January 2015 Page 28 SUSTAINABLE HOMES nature Often CIBSE Guide A 1 hours over 28 degrees Is used but we prefer to use CIBSE TM52 criteria QObjectively we use of occupied hours over 250C but started to adopt CIBSE TM52 Adaptive thermal comfort criteria Subjectively on existing buildings this is driven by user feedback and
29. inked to staying arm amp reducing damp rather than heating We have a pamphlet providing advice on condensation mitigation and comfortable heating We provide a User Manual covering all the control processes they can operate Verbal advice based on my extensive experience in this sector and my understanding of climate change adaptation leaflet and visit from energy expert Advise them to keep windows doors closed and to draw curtains during the day to keep out hot air and cross ventilate where poss at night to allow the property to cool We discuss the need for insulation ventilation and air exchanges One to one discussion at the completion stage and a general advice note in the context of the change to the property following completion of the retrofit Direct contact with advise being for their specific building Overheating survey findings 8 January 2015 Page 38
30. nagement Systems BEMS Although in some cases high specification BEMS have been installed in most cases they have not been commissioned correctly and are not managed properly Location of Temperature Sensors External temperature sensors are often located in a shaded area where readings taken do not reflect the average external air temperature Larger than necessary windows no brie soleil no window blinds windows not opened enough due to safety catches in 1st 3rd floor windows New build No ability to cross ventilate Buildings where a combination of unventilated corridors centralised services unprotected glazed facades or windows and poorly realised ventilation for apartments A contributory factor is often poorly controlled value engineering and a lack of tools to highlight the risk The SAP tool is so poor that it is counterproductive Overheating needs the use of dynamic simulation to pinpoint the problem Heating system is set up to deliver a constant temperature CT on the heating water flow A high heating flow temperature will result in over shooting of the set temperature even after the boiler is turned off until the system loses its residual heat Room thermostats have a tolerance value of between 2 5 degrees C Coupling a thermostat with a CT boiler does not solve the issue Lack of thermostatic control linked to the CH boiler Lack of TRV s to radiators Lack of trickle ventilators to opening window units Ove
31. ntilation In new buildings less than 20 years old the lack of openable windows in the common spaces And the lack of shade to living rooms and bedrooms in single aspect flats nouses In new buildings less than ten years old i e since Part L required better ait tignhnesss in 2004 the lack of air renewal in common spaces which lack natural light or openable windows Single aspect south facing urban flats sometimes with unopenable windows Communal heating schemes with heat loss in communal corridors on new build schemes due to the requirement for 24 7 365 availability of heat and low heat demand from the system as the flats are so well insulated e g CSH level 3 4 This in turn heats up flats albeit slowly as corridor temperatures can easily exceed 30 degrees all year round Too much glazing to south facades Single aspect units Windows are not able to be opened due to security concerns i e entire door must be opened for ventilation instead of just a window area Poor insulation of communal heating pipe network Heat emitted from HIUs Miss use of heating appliances i e educating our tenants on using the heating appliances Black spot mould due to the exesive moisture in the air and lack of ventilation they don t want to lose the heat Overheating survey findings 8 January 2015 Page 30 oa SUSTAINABLE HOMES Lack of adequate through ventilation in apartments Windows in older persons accommodation do not
32. open sufficiently This is for safety and security reasons with which we must comply Solar glazing insulation poorly sized heating systems resident knowledge Poor installation of community heating Excessive glazing with poor G values Excessive internal insulation and reduction in the thermal mass of the building being accessible to residents Other environmental issues that limit opening wind Communal Gas Boilers Lack of ventilation High insulation levels Double glazing Extreme weather Lack of controlability of heating amp hot water systems Legacy Pipework Systems One pipe systems are not desirable because They can cause overheating if not controlled correctly They are very basic and don t allow for zone control of temperatures e g to account for solar gains Pipework Layout Buildings designed in the 1970s tended to have their heating and hot water pipework integrated into the building structure This means it is very hard to access and cannot be insulated easily The site surveys showed that pipework is not always insulated in the plant room communal areas and dwellings Pressurised Heating and Hot Water Systems Recent major plant room refurbishments have seen the installation of pressurised heating and hot water systems This has dramatically increased the efficiency at which heating and hot water is generated increasing the amount of heat energy going into the buildings Building Energy Ma
33. r insulating the walls floors roof space We have three properties one new build single aspect flat post 2010 and two very old The new build flat did need the air handling system and additional fans to be run for a few days last summer in th evening This was due to it being a highly insulated and air tight ground floor flat However it does benefit from extensive shading which the neighbouring flat does not Additional ventilation was only necessary during the day Completed building that DIDNT have Hemcrete in its timberframe external envelope All such lightweight structural solutions are subject to overheating risk because they do not Overheating survey findings 8 January 2015 Page 31 y SUSTAINABLE HOMES provide sufficient thermal mass inertia to deal with solar gain and ambient temperature rise Ventilation purge is not adequate in such conditions as prevailing external temperatures may not be much lower than internal The only way to future proof dwellings for nett temperature rise climatic conditions is to incorporate solar shading and build in thermal mass inertia inertia linked to mass to delay the build up cool down effects ie thermal buffering Advantage of Hemcrete natural material inclusion is also to provide a passive breathable envelope so the humidity effect always linked to temperature change is also modulated the recent addition of hi levels of roof at ceiling level insulation in the loft combine
34. roximately 32 of respondents use the dynamic simulation modelling to assess overheating risk in properties 35 of properties are assessed using this approach Overheating survey findings 8 January 2015 Page 10 we SUSTAINABLE HOMES 15 How confident are you that the methodology you usually use to assess overheating risk in your residential properties is an accurate representation of the likely future risk over the next 20 years lt can be seen in the graph below that almost 80 of respondents are confident or fairly confident that the methodology they use is accurate Less that 20 are not confident see the graph below On average on a scale of 0 5 0 not confident 5 extremely confident the current level of confidence is 3 3 15 How confident are you that the methodology you usually use to assess overheating risk in your residential properties is an accurate representation of the likely future risk over the next 20 years 2 E Extremely or very confident E Fairly confident E Not confident E Do not know Overheating survey findings 8 January 2015 Page 11 ye SUSTAINABLE HOMES Future risk 16 How do you ensure that any building or system designs and technical measures intended to mitigate the risk of overheating in your properties are implemented as specified When asked about the process to ensure that measures intended to mitigate the risk of overheating are implemented in propertie
35. rs to advise us of what measures they are taking to address them We seek to ensure internal temperatures are no higher then 5 deg C above external ambient in the summer Contractors are required to assess passive shading measures and do dynamic thermal modelling Overheating survey findings 8 January 2015 Page 36 oa SUSTAINABLE HOMES Appendix 7 The majority of schemes we work on are for housing associations As such they generally need to achieve a Code for Sustainable Homes award Therefore a home user guide is provided for each dwelling at hand over This includes a section on the correct use of heating and cooling methods Occupant handbook and briefing sessions Home user guides on window opening and using blinds curtains for shading Do not touch any controls Use the MVHR system correctly Use only A appliances no tumble dryers Provide additional shading to south facing windows in summer if necessary Use opening windows to provide additional passive stack ventilation at night User guides with general information on how to use the home O amp M Manuals Informal discussions Discuss life styles and possible impacts of this on the risk of overheating Explain and demonstrate the passive temperature and humidity buffering that comes with Hemcrete solutions and relate this to client s needs and expectations This can be described as a soft landing approach Thereafter assisting client occupier with any adju
36. s many respondents admitted they do not have a process in place Many respondents use more than one method Please see the summary on the graph below 16 How do you ensure that any building or system designs and technical measures intended to mitigate the risk of overheating in your properties are implemented as specified 0 5 10 15 20 rs a a General quality control process A specific person responsible for ensuring that overheating a es No process in place mitigation measures are properly implemented rs a Other Building control inspections Quality control process specifically covers overheating don t know Not applicable Overheating survey findings 8 January 2015 Page 12 we SUSTAINABLE HOMES 17 Does your organisation currently specify overheating related requirements in your energy efficiency retrofit supply contracts A vast majority of respondents reported that they do not specify overheating related requirements in their energy efficiency retrofit supply contracts 17 Does your organisation currently specify overheating related requirements in your energy efficiency retrofit supply contracts E Yes E No W Do not know Those who do do it by amongst other methods The provision of adequate ventilation The provision of air conditioning equipment The full list can be found in appendix 5 Overheating survey findings 8 January 2015 Page 13 we SUS
37. ssociated with high levels of condensation etc These problems are only partially solved by the retrofit Given these circumstances which we find house by house overheating would be regarded as an unachievable luxury It should not be disregarded but assuming adequate ventilation options exist neither should it add cost to the retrofit programme My concern would be the additional cost of design would lead to a reduction in the number of homes that can be helped Internal temperatures getting too high for comfort and requiring the opening of windows or the installation of air conditioning units CIBSE criteria 26 for long periods In a regulatory sense passing Criterion 3 for Part L1A For more sophisticated projects the CIBSE TM52 definition where overheating is defined in terms of occupant comfort We do not have a specific definition although we are aware of Environmental Health legislation relating to the number of nights that the night temperature exceeds 250C or thereabouts No set or formally adopted definition but probably a hybrid of the CIBSE guide A and TM52 guidance around exceeding 26 degrees celsius in a bedroom 28 degrees celsius in other habitable rooms for more than 6 hours in a day or 1 3 of total occupied hours in a year We do not have a formal definition but use the CIBSE TM52 standards in our new developments We do not generally have an issue with overheating in our existing stock We use accumulated e
38. stments to life style or dwelling operation to maximise comfort and minimise space heating energy bills Short Form User Guide Encourage the landlord to provide training Engage with private users Overnight cooling means want an air in and an air out pathway to exist Use of fans by windows to draw in cool outside air Emphasis that the previous days heat must be allowed to escape if they are to be comfortable the next day Having designed amp installed an MVHR System to maximise it respective features amp benefits we advise how to make the most of the Summer Bypass and if fitted the Geothermal Intake Duct Advice is based on experience and actual performance data gathered over 3 decades Not to leave lighting on when no required and to use LED lighting where ever possible We advise proper use of heating amp hot water systems also regarding ventilation Open upstairs windows wide in extreme heatwaves close up by day and use blinds etc Use energy efficient appliances to reduce internal gains Rely on the thermal capacity in the dwelling in many cases Explain about the importance of opening windows for purge ventilation even when an MVHR is installed Utilise your natural ventilation at night Close solar shading devices during the day if secure ventilation openings are provided these may be designed to be left open Turn MVHR to summer bypass Purge build up of heat at end of day when you In handover guidance and in person
39. t fully understanding how to best to their homes cool e Resistance to installing cooling for cost eco concerns We try to educate individual householders in relation to more effective use of existing heating ventilation etc in the context of the changes introduced by the retrofit Unfortunately we find a reluctance to change behaviours such as windows remain closed and are often sealed by the resident the practice of blocking vents eg UPVC window trickle vents and room air vents to reduce draughts continues Lack of natural ventilation and window shading combined with excessive glazing Poor artificial gas or electric powered heat sources no or unsophisticated timing and temperature controls fixed glazing units with limited openers Some excess heat from neighbouring residential units terraced houses or flats in a block released to the subject dwellings rather than to the outside Tenants under dressed for the season in the year leading to excess artificial heating wasting natural resources overheating their rooms and wasting their money Common features include thermally lightweight structure hot air trapped by windows that do not allow hot air that has risen to the ceiling to escape eg top hinged with the ceiling at least 300mm above the hinge and premises security insurance requirements impeding fabric cooling by opening windows Overheating survey findings 8 January 2015 Page 33 a SUSLAINABLE HO
40. to Competitors others assess overheating risk so we do too To ensure customers are happy Regulation Building Control requires us to Expert contractors frequently advise us to Overheating survey findings 8 January 2015 Page 9 n SUSTAINABLE HOMES 10 Does your organisation have a method or process to assess the risk of your residential properties overheating Almost 60 of respondents reported that they have a process in place to assess the risk of overheating However it can be seen in the graph below that there is still a high percentage of organisations that do not have a process to identify overheating issue in their properties Overheating risk assessment is routinely carried out for 59 of new build and 59 for existing homes 10 Does your organisation have a method or process to assess the risk of your residential properties overheating li Yes E No E Do not know 12 Which of the following best describes your usual approach to assessing the level of overheating risk in your residential properties Organisations with a process in place use various approaches to assess the level of overheating in residential properties SAP Appendix P alongside other qualitative methods and dynamic simulation modelling seems to dominate over other methods Approximately 36 of respondents use Appendix P of SAP to assess overheating risk in properties 66 of properties are assessed using this approach App
41. urvey findings 8 January 2015 Page 24 y SUSTAINABLE HOMES Appendix 2 Definition of overheating 71 definitions 95 No formal definition as far as I m aware perhaps linked to heatwave plan for England temperatures In relation to Passivhaus PHPP threshold temperature of 25 C and duration of 10 of occupied hours We also use CIBSE EN 7730 and EN15251 criteria Persistently exceeding the upper limit of the WHO guidance on thermal comfort ie 24 degrees C Too hot in summer More than 25 degrees C for more than 10 of the time Not really defined in our organisation Based on our research work for the Technology Strategy Board we work to the following Temperature of 32 C 18 C 32 C day night day heat wave for 2 consecutive days Added to this is an assessment of the impact these temperatures would have on the performance of the property its coping capacity A building s coping capacity was rated as High Medium or Low Where Environmental Health have been called in and deemed the property as a category 1 risk The necessity for the occupant to open a door or window to cool the property Where the house property becomes uncomfortably warm even when the heating system is off 10 per annum over 25C We do not use the adaptive definition as per CIBSE Simply by SAP 2012 algorithm We do not have clear definition but having 25degrees plus is a good starting point if the temperature cannot be reduced easily We used
42. verheating survey findings 8 January 2015 Page 23 eo SUSTAINABLE HOMES Only appears if Yes is selected in question 17 17a Please describe the form of requirements in your energy efficiency retrofit supply contracts Question only appears for New Build roles 17 Does your organisation currently specify overheating related requirements in your contracts with architects designers O Yes OQ No O don t know O Not applicable Only appears if Yes is selected in question 17 17a Please describe the form of requirements in your contracts with architects designers 18 Do you provide advice directly to occupants of your residential properties on how they can help keep their properties at comfortable temperatures O Yes Q No O don t know Only appears if Yes is selected in question 18 18a Please describe the form of advice you provide to occupants of your residential properties on how they can help keep their properties at comfortable temperatures 19 How would you rate the current level of concern in your organisation about overheating in residential properties in general Key 0 Not concerned 5 Extremely concerned 0 1 2 3 4 5 I don t know Level of concern 20 Does your organisation have research survey or monitoring data relevant to this project which you are willing to share in confidence with the Zero Carbon Hub Q Yes Q No O don t know Overheating s
43. xperience to drive design advice to architects and developers We use the CIBSE Guidance as a design benchmark We try to include within the project best practice primarily bases on a fabric first approach Need to provide cooling of some sort either opening windows or increasing mechanical ventilation for purposes other than normal ventilation Temperature above 25C No actual definition other than calculations provided by the energy consultant as part of the csh report Using CIBSE Guide A temperature thresholds 25 degrees in bedrooms and 28degrees in all other main habitable rooms However in line with new GLA guidance we are about to start undertaking dynamic overheating assessments in line with CIBSE TM52 When the property exceeds 25 deg C We define Overheating as the result of thermal mass solar gains and fabric of the dwelling Quantify by the number of hours for which the internal temperature is above 250C over the course of a year Overheating survey findings 8 January 2015 Page 27 oa SUSTAINABLE HOMES Overheating occurs when residential properties struggle to expel built up heat from external and internal heat gains and their internal temperature rises above the standard thermal comfort levels During the design of new dwellings we currently recognize overheating when it is identified by the SAP assessor undertaking their design stage SAP appraisal This would typically happen after the planning stage T
44. y residential properties has your organisation retrofitted to improve the energy efficiency in the last five years OQ Number of properties Q don t know Question only appears for New Build roles Overheating survey findings 8 January 2015 Page 19 oa SUSTAINABLE HOMES 4 Approximately how many residential properties has your organisation built in the last five years O Number of properties Q don t know Question only appears for Architectural Practice and Building Services 4b Approximately how many residential properties has your organisation designed or provided specification for in the last five years O Number of properties Q don t know Prevalence of overheating 5 How does your organisation define overheating in residential properties Please describe 6 Using the definition you gave in question 5 approximately what percentage of your residential properties have have had overheating problems in the last five years of properties with overheating problems Only appears if answer to question 6 is gt 0 7 For those properties that have have had overheating problems briefly summarise any common features which you believe contributed to problem Please summarise Only appears if answer to question 6 is gt 0 8 For those properties that have have had overheating problems how did your organisation find out there was a problem please choose the most common route Through
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