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How will we cool down homes, offices, hospitals and schools?
Our Overheating Risk Analysis report for the UK Green Building Council is published today
Supporting the UKGBC’s work on making buildings in the UK more resilient to climate change, we assessed the overheating risk of six different building types for three climate change scenarios, reflecting global warming projections of 2°C, 3°C and 4°C. We investigated how these global warming projections will impact six representative cities in the UK, and how effective different mitigation measures would be to reduce that overheating risk. We assessed houses, high-rise flats, care homes, healthcare buildings, offices and schools in Cardiff, Glasgow, Leeds, London, Nottingham and Swindon.
We assessed the impact different designs, window configurations, ventilation strategies and human behaviour changes have on overheating outcomes. Without more adaptation measures the findings showed that many building types will be at extreme risk of overheating in the near future. Investing in climate resilience will be essential for maintaining human health and wellbeing, and without improving resilience there will be significant social and economic implications, for example resulting from reduced productivity.
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Our overheating analysis showed that for all types of building the most effective passive adaptations actions that reduce risk are reducing solar heat gains, such as using external shading and solar control glass, and increasing ventilation rates with more openable windows.
Without adaptation measures our report shows that houses and flats in England will be at greater risk of overheating than Wales, Scotland and Northern Ireland, particularly in a high global warming scenario. Our research found that for houses, the size of windows, method of ventilation, size of home and density of occupation have more of an impact on overheating risk than the age of the home. We assessed high-rise residential buildings and found that flats with large areas of south and west facing glazing and insufficient ventilation are particularly at risk.
We found that all care homes in the UK are at generally at high and extreme risk of overheating if no measures are put in place, but passive measures can significantly reduce the risk of overheating. Healthcare buildings are at very high to extreme risk in most regions of the UK, and at highest risk in Southern England in all future warming scenarios. Healthcare buildings with high proportions of glazing, lightweight construction and fewer openable windows put them at higher risk of overheating, as does smaller rooms with higher numbers of occupants.
Non-air-conditioned offices are at extreme risk of overheating with no further mitigation measures in place due to solar heat gains, rising external temperatures and heat from office equipment and other sources. Schools are at medium to extreme risk of overheating if no mitigation measures are put in place, but risks depend on the design and site context. Overheating risk is made worse by the prevalence of restricted window openings, and lack of high level safely openable windows which limit the ability of teachers to purge classrooms of heat gains. Schools also often lack adequate solar shading or green landscaping features than can improve the microclimate and provide additional shading.
Our findings come with some recommendations for industry. Building developers and owners should prioritise implementing passive climate adaptations first, as simple retrofit measures can avoid additional operational carbon emissions and energy costs. If active measures are needed, the most effective strategies are nighttime ventilation and mechanical comfort cooling. Future building regulations should include clearer guidance on safe window openings for public buildings to improve ventilation without impacting people’s safety. Planning authorities and policy makers need to be more demanding on the need for developments to incorporate climate resilience from the outset so that future developments are better protected from climate risks.
This report forms part of the UK Green Building Councils evidence base for the UK Climate Resilience Roadmap, creating a pathway for UK built environment stakeholders to follow to achieve a climate resilient built environment by 2050.