New research from Energy House 2.0 reveals that current UK regulations may not go far enough to protect homes from overheating during extreme heat events.
In collaboration with Barratt Redrow and Saint-Gobain UK & Ireland, we tested how new-build homes, like the eHome2, respond to rising temperatures in the UK’s largest environmental chamber. Even without direct sunlight, outside temperatures above 32°C were enough to cause dangerous overheating indoors.
Professor Lubo Jankovic, leading the project at Energy House Labs, said:
“Our findings show that Part O of the Building Regulations may not offer sufficient protection under high, sustained temperatures. A review is needed to better reflect future climate conditions.”
Currently, Part O focuses on reducing solar gain and removing excess heat. However, our research found:
- Requirement O1(a) is difficult to meet during heatwaves, even under cloudy skies.
- Requirement O1(b), which relies on cross-ventilation, can worsen overheating by bringing in hotter air.
Tests on eHome2, a standard three-bedroom home, revealed:
- With windows closed, up to 85% of heat was blocked, thanks to high insulation and airtight design.
- With windows open, only 40% of heat was blocked, suggesting common advice to open windows may be counterproductive.
At sustained outside temperatures of 35°C, the indoor temperature still reached 31°C with windows closed, highlighting the limits of current strategies.
To improve future home performance during heatwaves, we recommend:
- Advising occupants to keep windows closed when indoor temperatures exceed 22°C.
- Installing secure nighttime ventilation options on ground floors.
- Using higher insulation levels to reduce heat ingress.
- Installing heat pumps with both heating and cooling functions as a sustainable alternative to air conditioning.
As the UK faces more frequent and intense heatwaves, it’s vital regulations evolve to ensure homes remain safe and comfortable.