Overheating in Homes - the big picture
Zero Carbon Hub investigates why overheating in homes happens and how local and national government can help the housing sector prevent the issue getting worse
Report from – Rob Pannell
As temperatures soar across the country these questions are being considered by the Zero Carbon Hub in a project which is investigating what changes to government and industry policies and frameworks could be needed to tackle the issue. Our preliminary report “Overheating in Homes – the Big Picture” was published on 16 June 2015.
Overheating, in this context, is the term used to describe situations where the conditions in a building become uncomfortably warm or excessively hot, because the design of the building hampers the occupant’s ability to keep it sufficiently cool.
Why the concern about overheating?
With expected increases in the number of unusually hot summers as the climate changes, more frequent and intense heatwaves, and continuing construction in dense cities, it will be even more important to consider ways to ensure our homes remain at comfortable temperatures all year round, without automatically resorting to energy-using cooling systems.
Although action is being taken to tackle this issue, it is clear that overheating in homes is already happening – potentially in up to 20% of the housing stock in England.
Exposure to excess heat in homes can have serious consequences for the health of the people living there, especially if high temperatures persist over prolonged periods. In extreme cases, there can be a risk to life for vulnerable groups such as the elderly or sick. The elderly are usually less able to adapt to higher temperatures, and may also live alone and not seek help quickly enough if feeling unwell.
Fortunately, homes which are overheating – however mildly or severely – tend to have recognised combinations of risk factors. An obvious example is when a dwelling’s windows, intended to provide ventilation and to purge hot air, open onto a noisy main road, and so are rarely used by the occupants. By understanding the range of risk factors, designers, housing providers and retrofitters can use this knowledge to target overheating mitigation efforts to the homes and people which most need them.
Simple changes to the design of dwellings, measures to reduce heat gains, and advice for occupants can help to prevent the problem occurring. Certain measures and solutions can also create win-wins by simultaneously making homes more energy efficient and helping to keep them cool. For example, low energy lighting reduces energy use and should also lower the level of internal heat gains.
A key question is to what extent the housing sector is assessing the risk of their stock overheating and then treating the properties that need work?
For example, 59% of the 74 housing providers answering our survey reported having a form assessment process in place intended to identify properties at risk of overheating but 36% did not, and the remainder did not know.
A number of housing providers interviewed by the Zero Carbon Hub also described how their technical teams are using their experience and knowledge of overheating risk factors to identify properties or designs which have characteristics that make them more prone to overheating, before carrying out any formal risk assessment modeling exercises. A form of ‘first pass’.
These ‘higher risk’ properties are then subjected to detailed checks and, if found to fall short of the chosen overheating criteria, measures are installed or design changes made to reduce the potential for overheating.
Furthermore, the risk of overheating varies from building to building. Those which have a higher chance of overheating usually have recognisable risk factors, which mean the sector can be cautiously optimistic about being able to identify and treat them. The Zero Carbon Hub plans to take forward work this year with industry partners to pin down what these risk factors in simple guidance.
You can download the full report at www.zerocarbonhub.org. A second phase of the project to advise on the changes to frameworks will begin this summer. If you have any experiences you would like to share with them please contact firstname.lastname@example.org.
Rob Pannell, Managing Director of the Zero Carbon Hub, which will be speaking at Build4Quality, a one day conference about efficient construction of quality low carbon homes.