CAD Divider

Rising to the challenge of overheating

Oct 26, 2022

By Mark Dawes, Managing Director, CAD Architects

The heatwaves this summer have been a powerful reminder that property in the UK is often unsuited to heat. Climate change means that heatwaves are likely to be a more common phenomenon in future, throwing up a new challenge for architects and the government alike.

Many of the features exhibited in historic property (pre 19C) which were the result of the limitations of the technology of the time i.e thick stone walls and small windows assisted in keeping heat in but also prevented solar gain, keeping the heat out and the subsequent over-heating, but the dwellings that followed in later centuries enjoyed larger openings and more glass, culminating in more recent times with vast areas of glazing to take advantage of views and to bring light into contemporary dwellings. It seems we have reached the limit of this technology and have to look again and be creative to overcome this latest challenge.

In 2021, the climate change committee warned in a report that more than 570,000 residences had been constructed since 2016 that were not resilient to high temperatures – and nor were a further 1.5m due to be built over the following five years. The government advisers accused ministers of failing to act to protect people from rising temperatures that “could even leave many existing and new homes uninhabitable”.

In 2021, the government added a section on overheating to building regulations for the first time, Part O. This came into effect on 15th June 2022.

Any development that is subject to a building notice, has made a full plans application, or submitted an initial notice before this date will not have to comply with the overheating regulations, provided that the work is started on site before the 15th June 2023.

Part O urges housebuilders to make reasonable provision to limit solar gains in summer and “provide an adequate means to remove heat from the indoor environment”. The regulations will also address causes of overheating due to uninsulated heating pipes, cylinders or a lack of heating controls. It is also worth noting that mechanical cooling may also only be used where insufficient heat is capable of being removed from the indoor environment without it.

You can find more information about the new Part O building regulation at:

Meanwhile, industry momentum is gathering behind finding intelligent solutions to the urgent challenge of rising temperatures and lessons are being learnt from other countries which are more used to dealing with intense heat than the UK.

Air conditioning is not the ideal solution it may first appear as it is expensive to install and run, as well as inefficient in draughty homes. Of course, it also increases carbon emissions, thus compounding the overall global problem.

There is therefore increasing interest in what are called ‘passive measures’ – that is measures that need minimal or no use of energy and fuel.

For example, shutters are common in Southern France, Spain and Italy. White surfaces are also used in Southern Europe to reflect the heat. Shutters or automatic blinds could also be used more commonly in the UK in future.

Other solutions that could be introduced include:

· Positioning the house and windows in a way that minimises direct sun exposure (rather than being south-facing)

· Reducing the use of glass

· Planting trees around the building to create shade

· Installing solar panels on the south side to keep direct sun out

· Installing an air source heat pump (which can be used to cool a home as well as heat it.)

· Use of cooling features such as windcatchers. These are roof-mounted devices (used in the Middle East) that use the wind to drive fresh breezes into a room and expel stale air

· Solar chimneys – tall structures with a dark surface designed to absorb solar radiation. This creates a rising column of heated air that in turn keeps a ventilation system flowing

· Installing louvre windows – parallel glass slides in frames that can be tilted open or shut to improve ventilation.

· Installing sensors to track humidity and temperature

· A ventilation unit in the loft with two air collectors, one for cool outside air and one for warm indoor air, which are circulated around the property to keep an even temperature.

As a RIBA Chartered Architecture practice, CAD Architects is focussed on creating beautiful buildings that are environmentally-friendly and future-proof. In order to continue to allow our architects to design freely we are investing in “Dynamic Thermal Modelling” software to assist in the assessment of building designs for the purposes of attenuating heating and cooling.

To find out more about how we could help with your project, contact