Risk of Overheating


The trend for carbon savings encourages more solar gain in winter, and higher levels of insulation which means more heat is trapped inside the building. Less heating equals less carbon, however, these measures tend to trap hot air in buildings in the summer, so carbon is prioritised over comfort and the need for lessened demand is paramount.

The protection of the green belt and the push to redevelop brownfield sites has resulted in vast amounts of new housing that are constructed near sources of significant environmental noise near major roads, busy rail tracks, airports or across factories.

When a room overheats, the occupant may choose not to open the window due to the external incident noise levels and thus exacerbate the issue and increase health risks.

Open windows are also related to security risks, especially in some inner-city areas. Occupants will take adaptive action to maintain thermal comfort. A common solution is to turn on a noisy room fan and try to sleep with this on.

It is true that we do not know a lot about the human response and the relation of acoustic and thermal comfort in dwellings. However, we do know that disturbance of sleep harms health and wellbeing. Overheating has health risks. King’s College London and the Met Office predicted the number of heat-related deaths will quadruple in cities such as London by 2080.

An adequate source of fresh air is required for dwellings and this is addressed in Approved Document F of the Building Regulations.

During the design of a new scheme, if incident noise levels are sufficiently high, the acoustic design will necessitate that windows need to remain closed to achieve a suitable internal sound environment, and a recommendation will be made on either mechanically assisted or passive alternative ventilation strategies into the design.

The issue of thermal comfort during hot weather in such situations, however, has only recently entered the agenda. As such, there are currently no statutory controls in force, and helpfully, the Association of Noise Consultants published a guidance document in 2020, to address specifically the issue of overheating and noise.

Largely to date the issue has and is, either ignored or addressed on a case by case basis depending on the attitude of the developer, the awareness of the Local Authority to the issue, and the guidance given by the design team. The Government has been warned by experts for a number of years that the awareness of the public needed to be raised about the increasing risks of heatwaves due to climate change.

An ever-increasing number of local authorities have caught on and impose relevant conditions during the planning stage in order to alleviate this health risk as far as possible.

For buildings that have “slipped through” the planning net, landlords or even the developers could be faced with complaints where tenants individually or as a group come together to demand comfort cooling in their dwellings, which will be expensive, especially when retrospectively fitted. If their demands are not met, and they may even follow a legal avenue, building and rental values will go down due to lack of cooling system and also word of mouth about the bad conditions.

We can see a future where conveyancing solicitors may demand that overheating standards ought to be met before the sale can proceed.

In the UK, temperature-related death is usually associated with cold weather. However, heat-related mortality will become increasingly important as the frequency of extreme heat events rises with climate change.

A Met Office report released on 29 July 2021 showed that climate change is already being felt across the UK, with all of the top ten warmest years have occurred since 2002. The greatest warming has been in the East Midlands and East Anglia. 2020 was the third-warmest year on record, with temperatures up to 37.8 degrees Celsius in London, and the Met Office reported that 40 degrees Celsius is likely to become a regular occurrence. The Met Office has also introduced a new ‘extreme heat warning’ based on the likely impacts of the extreme heat rather than just the temperature, to help the public, businesses and authorities prepare better for hot conditions.

The issue is a complex one and requires expertise and input from a number of specialists, including mechanical, noise, air quality, energy & sustainability experts. It is the responsibility of everyone involved to ensure that overheating in residential buildings is avoided, it is a problem that will only get worse if nothing is done.

If you would like any more information about the risk of overheating please contact [email protected] who will be happy to help.

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