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Overheating risk in new homes needs careful management

NHBC Foundation report highlights risk and impact of emerging issue

As we progress towards the zero carbon homes standard, with homes built to higher levels of air tightness, the issue of homes that suffer from overheating is one that is easily forgotten when outdoor temperatures are plummeting.

While overheating in dwellings is generally only experienced during summer months, NHBC Foundation has recently published its second research report on the subject, Overheating in New Homes: a review of the evidence to provide the industry with further guidance ahead of next year’s warmer seasons.

Report findings

A companion report to Understanding Overheating: where to start published earlier this year, the new report builds on the guidance provided to house builders and designers, documenting a wide-ranging review of existing information and evidence on overheating, approaching the issue from the perspectives of housing and health issues.

From a health perspective, the medical evidence finds that vulnerable groups such as the elderly may be particularly at risk, and although the health effects of exposure to heat can be mild, if left untreated symptoms have the potential to develop quickly into severe, often fatal heat-related illnesses. These problems are likely to worsen with an ageing population and as changes in the climate lead to warmer summers.

Overheating in new homes concludes that both newly-built and refurbished homes with high standards of energy efficiency and airtightness are most at risk of overheating, especially small dwellings and flats, and predominantly single-sided properties where cross-ventilation is not possible. Yet heat gain may be preventable in the design phase – designing buildings less susceptible to heat gains from outside and inside and through making sure that there is adequate ventilation to purge the hot air .

Neil Smith, Group Research and Innovation Manager, NHBC, said: “This report raises some key points about the causes and, most importantly, impact of overheating. It is clear that the health risks alone indicate there is an urgent need across the industry to develop a universally accepted definition of overheating in dwellings, as well as thresholds for intervention.

“We hope that the two reports published by NHBC Foundation on the subject of overheating will stimulate thought and provoke further debate and research on the topic, so that overheating can be mitigated or even designed out of new homes in the future.”

For more information and to download the report, please visit