Planning for overheating in homes


    As our climate and hot summers become more probable, the Zero Carbon Hub asks if we should we make better use of the planning system to help prevent overheating in homes…

    For the last year the Zero Carbon Hub has been working with local authorities, central government departments and the housing and health sectors to understand how well prepared we are in England and Wales to tackle the issue of overheating in homes.

    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, especially during warmer weather.

    The project team has drawn together information and evidence on why overheating in homes happens and the extent to which the construction and energy efficiency sectors are gearing up to address the issue. A second phase of the project, beginning this summer, will make recommendations on what more local and national governments could do to support Housing Providers in reducing the incidence of overheating.

    A key question is what is the role of the planning system?

    Why the concern about overheating?

    As temperatures soar across the UK, Rob Pannell, Managing Director of the Zero Carbon Hub commented:

    “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. Getting building designs right is critical.”

    Although action is being taken by the government and by the industry, it is clear that overheating in homes is happening – potentially in up to 20% of the housing stock in England. And there is concern that overheating will become a much bigger problem in the coming decades.

    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.

    There are now estimated to be approximately 2,000 heat-related deaths per year in England and Wales. In the absence of adaptation of the population or mitigation measures, researchers estimate that this figure could rise to over 7,000 heat-related deaths per year by the 2050s as a result of climate change and a growing and ageing population – a tripling of current levels. London and the East Midlands are the regions that have been most affected by heat to date.

    Fortunately, homes which overheat – 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. Here, the ventilation strategy fails. Rob added:

    “The risk of overheating varies from building to building. Those which have a higher chance of overheating usually have known causes, which means 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 these risk factors in simple guidance.”

    It is also clear that the number of cases of overheating and the severity and impact of those cases will vary from area to area due to differences in local climate, geography, construction practices and the profile of the population.

    “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…”

    Policies such as the Heatwave Plan for England 2015 aim to reflect this variation by triggering action at different temperature thresholds across the country. The trigger in the North East of England for example, is lower than in the South East as is it expected that people in the South are generally more acclimatised to warmer weather.

    A spatial perspective will also be important when formulating policies to tackle overheating specifically. Local authorities may find there are certain ‘overheating hot spots’ in their area, meaning deliberate steps to manage the issue are needed. An apartment block in a deep urban area with little or no surrounding green spaces (known to have a cooling effect) is more likely to overheat than a larger detached house in the countryside. The important thing is to check the risk profile to be certain.

    For new dwellings, experts advise that Housing Providers and their design teams should give serious consideration to whether schemes are at risk of overheating at the concept stage of the project – before plans are submitted to local planning authorities.

    At this early stage, modifications to the design of the building are more likely to be possible. The range of options available to address overheating once a dwelling is built and there are people living there, are often more limited than if measures had been designed-in to begin with.

    In many cases, the risk of overheating may be low, and little or no action will be necessary. However, unless Housing Providers and planners consider the potential current and future levels of risk methodically, there is potential to be ‘caught out’ by changing external circumstances such as the climate.

    It is evident that certain local authorities are already tightening up the provisions on overheating in their Local Plans and Local Development Frameworks. However, it is unclear at present how widespread the inclusion of overheating requirements in Local Plans is. Guidance in England’s National Planning Policy Framework in England is vague. The Planning Policy Wales has more explicit coverage on overheating.

    The Zero Carbon Hub’s stakeholders certainly view the use of the planning system to help ‘design out’ overheating as integral to future policy responses.

    The Zero Carbon Hub’s preliminary report “Overheating in Homes – The Big Picture” can be found at . If you have experiences on overheating you would like to share with them, please contact . ■

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    Zero Carbon Hub

    Tel: 0845 888 7620


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