Tackling the risk of overheating in new homes

Could overheating become an issue for new homes?

Given the summer we’re having, few are going to be complaining about being too hot in their homes. Cast your mind back to 2003 though, when Europe last had a serious heat wave, and things were different. Not only were people complaining of being uncomfortable, there were real health implications due to increased risk of illness from respiratory and cardiovascular disease. The heat wave is reported to have resulted in 2,000 extra deaths.

Almost a decade on, what would be the results of a similar temperature spike? Traditionally, overheating has not been a problem in UK housing due low levels of insulation and poor airtightness. However, with ever tightening Building Regulations demanding higher standards of both airtightness and insulation, overheating could become a real risk, according to the NHBC Foundation. What’s more, the discomfort of living in an overheated house could lead to occupants to install cooling or use portable air conditioning units, offsetting any energy saving benefits from better performing building envelopes.

According to the NHBC Foundation, the extent of any existing problem in new houses is hard to gauge but it is likely that many instances of overheating, caused by hot summer weather, are tolerated for short spells and the discomfort and health effects are soon forgotten when cooler weather returns. It claims that evidence from occupant surveys suggests that occupants in well-insulated homes are experiencing uncomfortably high summer temperatures.

The BRE has investigated and reported on case studies that demonstrate how overheating can occur in modern dwellings as a result of a combination of factors.

Most recent changes to Part L of the Building Regulations which governs improvements to the external envelope and airtightness of homes came about in 2006 and 2010. The Foundation says it doesn’t really know how houses built to these standards will perform, either in the next hot summer or over time with the effects of climate change. However, to address concerns about overheating it has published a new guide, compiled by Richards Partington Architects and supported by the Zero Carbon Hub. Called Understanding overheating: where to start, an introduction for house builders and designers. It covers the principles of overheating as well as factors that increase or reduce the risk. Seven case studies are also provided to demonstrate a number of reasons for overheating, including location of the site, errors in design or the way in which the home is being used by its occupants.
Download a copy of the report here [registration required] or read about the implications for air quality in new homes with mechanical ventilation and heat recovery.