Regulations to stop overheating in homes fall short, new research shows

Regulations designed to tackle overheating in new homes could be improved to protect occupants against extreme heat conditions, new research suggests.

At the University of Salford’s Energy House 2.0, scientists are working with Barratt Redrow and Saint-Gobain UK & Ireland to test how homes can withstand hotter summers caused by climate change.

The research inside the world’s largest environmental chamber found that dangerous levels of overheating can occur inside a home even without the sun directly shining on the building, but rather from high outside air temperatures of over 32°C.

Professor Lubo Jankovic, who is leading the research at the University of Salford’s Energy House Labs, said: “The findings provide vital evidence to help strengthen future regulations and ensure buildings remain safe as heatwaves become more frequent.

“The results of the overheating tests suggest that Part O Building Regulations wouldn’t have the required effect under high and sustained external temperatures above 32°C. Therefore, we recommend that the Regulations are reviewed to take into account the consequences of climate change, which will result in more frequent heatwaves in the future.”

Under current UK Building Regulations, a set of guidelines known as Approved Document O stipulate that buildings need to:

1. be designed and constructed to limit unwanted solar gains in summer
2. provide an adequate means of removing excess heat from the indoor environment

The University of Salford’s research suggests that it could be challenging for some new buildings to comply with Requirement O1(a) in a heatwave, when skies are overcast.

Similarly, Requirement O1(b), which relies on cross-ventilation, risks making matters worse by drawing in even hotter outside air.

Overheating fears tested in home of the future

The scientists tested the eHome2, a typical three-bedroom family home, under tightly controlled conditions that firstly simulated a heatwave, (32°C daytime and 12°C night-time temperature), and then sustained temperatures of over 35°C, to understand how well new homes mitigate against high heat.

The UK has seen its hottest summer on record after the country sweltered under four heatwaves in a season, with temperatures in the Southeast hitting almost 36°C, according to the Met Office.

In a country where homes are primarily designed to keep in heat during cold winters, the research investigated whether the typical consumer approach of flinging open windows during hot weather could be making overheating worse.

The results showed that in heatwave conditions, the concept house blocked out up to 85% of the outdoor heat when the windows were closed. Stable indoor temperatures were maintained because of eHome2’s high thermal insulation and airtight construction, which minimised heat coming in from the outside.

However, when the windows were opened during the same conditions, the house’s ability to keep out the heat dropped significantly, with just 40% of the hot air being excluded.

In the test of the home at a sustained external temperature of 35°C, over a period of three days, the internal air temperature in the house reached 31°C with windows closed.

Oliver Novakovic, Head of Innovation at Barratt Redrow, said: “The country is seeing more frequent and intense weather extremes due to climate change. As part of this, there is an increasing risk of overheating, even during cooler summers, which has a detrimental effect on wellbeing.

“We’re working with the University of Salford to test new technologies and methods of reducing overheating and improving air quality, so the homes that are built in the next 10 or even 50 years can cope with rising temperatures.”

Recommendations to guard against rising temperatures

To future-proof new homes against overheating, the scientists at the University of Salford’s Energy House 2.0 identified ways that occupants could be made more comfortable during hot weather.

These include:

• Advising homeowners and tenants, via home user manuals, to close windows when internal temperatures rise above 22°C to limit overheating
• Installing windows with secure ventilation openings on the ground floor of homes to enable cool air to circulate at night, whilst still protecting the home from intruders
• Increasing thermal insulation levels, which reduces the amount of heat that enters the house from the outside during hot weather (known as a lower Heat Transfer Coefficient)
• Installing heat pumps with dual heating and cooling capability, which is more sustainable than air conditioning

Novakovic added: “We undertook this scientific research to learn valuable lessons as we move to zero carbon homes. Since the Energy House 2.0 project launched, we’ve taken learnings and put these into customers’ homes to reduce their energy consumption and ensure that homes have better air quality and are more comfortable to live in.

“This latest research has unearthed further important insight. Some of the lessons are already visible in our new homes, such as higher levels of insulation to both keep homes warmer in winter and absorb heat in summer. We know that across the Mediterranean, people close windows and use shutters and blinds to keep out heat during the day. The research reinforces this approach and demonstrates how Brits need to adjust to living in a country that is only getting hotter because of climate change.”