Subscribing to our award-winning Hub enables readers to receive regular emails with the top articles most likely to interest them

Do UK homes have to become more Mediterranean to cope with heat?

You may well be forgiven for thinking that Summer 2023 went by in the blink of the eye of yet another storm.

But the heat has been on again over the last few months in the UK, with temperatures rising and extreme hot weather warnings issued at various points.

As scientists predict the onset of “global boiling” and we see mounting evidence of major shifts in climate patterns, the UK is preparing for such significant changes.

Despite the Government seemingly blowing hot and cold over the environment and the drive to achieve Net Zero, the wider construction industry is taking major steps forward.

Indeed, a new survey suggests 9 in 10 architects are going above and beyond the minimum requirements for tackling overheating in new homes, as developers seek to protect residents against extreme heatwaves.

Rooms with external blinds reached a maximum of just 28°

Paul Groves Paul Groves Editor of Specification magazine

Part O is making a difference

The poll, 12 months on from the introduction of Part O building regulations which laid out stricter measures for new homes to minimise their risk of overheating, saw only nine per cent admitting to just meeting the new regulations’ minimum requirements.

The study suggested developer demand was among the factors motivating architects.

Almost a third (32%) of respondents said extreme heatwaves, prompting greater interest in overheating from developers for occupant wellbeing, would be the biggest factor to influence greater measures for combatting overheating in new homes over the next five years.

Meanwhile, two in five (40%) architects said Part O would be the top driver.

But the study, commissioned by glassmaker Pilkington UK, also found 7 in 10 (71%) architects agreed there is a missed opportunity in Part O limiting the strictest measures for combatting overheating only to London and central Manchester, with other areas at a similar risk of overheating.

Learning lessons from hotter climates

Meanwhile Alex Hill, MD of Whitecode Consulting, agrees that adapting customary British house designs can help mitigate heat gain, improve occupant comfort, improve energy efficiency and help occupants to save on energy bills. He asks whether British developers should be borrowing from developers who are skilled in designing homes for hotter climates?

“Look abroad to warmer countries and it’s typical to see homes that utilise features such as exposed concrete soffits and tiled floors,” he explained. “Likewise, their homes built from materials with high thermal mass, such as concrete, stone and clay. These materials are used to absorb and store heat during the day and release it slowly at night when temperatures are cooler. This helps maintain a more stable indoor temperature.

“Newer British homes, particularly those constructed with lightweight materials and modern construction methods tend to have lower thermal mass. British housebuilders should employ high thermal mass materials, such as concrete, stone, or clay, as they can absorb and store heat during periods of high temperature, helping to regulate indoor temperatures. They act as a thermal buffer, absorbing excess heat during the day and releasing it slowly at night or during cooler periods. This helps to stabilise temperature fluctuations and reduce the need for active cooling systems in hot weather.

“In the southern hemisphere, houses are typically designed to maximise shade and minimise direct exposure to the sun's intense rays. The orientation of the house is crucial, with the main living areas facing away from the sun's path during the hottest times of the day. Additionally, the layout of the house often includes courtyards or central open spaces to facilitate natural ventilation.”

Natural ventilation is crucial for cooling homes in hot climates, and it is something the UK should also consider in its house design, he maintains. In hotter climates, developers typically incorporate features such as large windows, operable vents, and high ceilings to promote airflow. This allows hot air to escape and cool air to enter, creating a cooler indoor environment.

Life in the shade

Dr Zoe De Grussa, Technical and Sustainability Consultant at the British Blind and Shutter Association (BBSA), has researched overheating in homes. While people located in suburban and rural locations may find it easier to stay cooler using ventilation from open windows and doors, the increasing popularity of large glazed areas such as bifold doors, large windows and conservatories, can still make overheating a real problem.

In urban and city locations, opening windows and doors is not always possible because of noise, pollution and security concerns. Dr Zoe De Grussa explained: “As housing becomes better insulated and air-tight to help conserve warmth in the cold winter months, overheating is becoming an unintended consequence during the summer.

“Shading has been used for centuries to help make buildings where we live and work more comfortable.”

Research commissioned by the BBSA on London flats, showed that internal operative temperatures reached a scorching 47.5°C in rooms without shading.

Rooms which had external blinds reached a maximum of just 28°C and those with internal blinds closed peaked at a manageable 32°C.

Extreme weather patterns, particularly the increased heat and humidity the UK has seen in recent years, are prompting the UK construction to consider ways to mitigate the impact and also methods to successfully adapt traditional building systems and utilise the knowledge and expertise of those in other parts of the world.

Paul Groves is editor of Specification magazine