News Opinion: The UK heatwave highlights the urgent need to address overheating risks

Opinion: The UK heatwave highlights the urgent need to address overheating risks

Features, News

June 26, 2024

As the UK experiences a heatwave with the hottest day of the year, the risks of overheating in our buildings are more apparent than ever. The government’s heatwave mortality statistics for 2023 show that there were 2,295 excessive deaths attributed to heatwaves that year. There were a significant number of excessive deaths in all regions of England apart from the North-East. We should therefore not think that summertime overheating in buildings – or its impacts – occurs only in London and the South-east of England.

The government predicts that the number of annual deaths associated with overheating will triple by the 2050s. The majority of these deaths are in the over-65 age group, with a higher proportion than average among the over-85s, but the data shows that excessive deaths occur in every age group, although the problem becomes greater from the over-45 age group upwards.

Overheating in residential buildings of all types is attributable to a whole host of factors. These include rising summer temperatures, dense urban developments, the urban heat island effect, single aspect apartments, enhanced insulation levels and lower air permeability rates, lower ceiling heights, lightweight construction systems, large glazed areas, external noise preventing windows being opened, communal heating systems (including distribution pipework), mechanical ventilation systems which are poorly installed or do not operate correctly as well as occupant behaviour.

A combination of some or all of these factors can lead to excessive heat gain in dwellings, especially contemporary flats, student housing and later living accommodation.

It seems that little attention has been paid by some developers and designers to overheating in recent years. There is a requirement in the London Plan for overheating analysis against the policy requirements at planning stage, but this is not regulated at later stages of the development process.

There has been no requirement to consider overheating within building regulations other than the very basic analysis in the building regulations regulated energy software (SAP),  which was easy to pass by entering unrealistic yet allowable window opening behaviour. There has been no incentive to consider mitigation of solar gain when buyers are typically unlikely to want external shading devices and they add costs to an already financially competitive development.

However, the incentive to seriously consider overheating has to be risk. I have foreseen for a number of years that overheating presents health risk to individuals and commercial risk in the form of excessive deaths happening in the residential buildings that the industry designs, develops, constructs and manages.

In the future, a death or deaths in a building which are attributable to overheating could mean legal action against the parties involved in the design, development and ownership of the building. Claiming that there was no statutory requirement to consider overheating mitigation may not be an adequate defence, given that the evidence data and impact predictions have been available for 20 years.

With the proposed 30-year retrospective changes to the Defective Premises Act, we could see dwellings deemed unfit for habitation due to excessive summer heat. Since 2022, there has been a statutory requirement to consider overheating in residential buildings. These regulations apply to residential dwellings, later living developments, and student accommodation. The goal of the regulations is to ensure that the design and construction of buildings limit solar gain during the summer months and provide occupants with adequate means of removing excess heat from indoor environments.

It's encouraging to see some progress in the industry. A recent poll by Pilkington UK showed that 9 in 10 architects are going above and beyond the minimum requirements for tackling overheating in new homes. However, more still needs to be done. The same study revealed that one in seven architects commonly incorporates air conditioning systems to help limit overheating, despite Part O instructing architects to exhaust all passive measures for mitigating overheating before considering mechanical cooling.

This requirement has seemingly crept up on the industry, with many organisations not being aware it was coming. Perhaps they were focused on managing the impacts of changing building safety legislation, but there is not much time to react. 

We should all be very wary of the impacts of overheating and the need to carefully consider how the buildings we design and develop respond to the risks it presents. As we experience the hottest day of the year during this UK heatwave, the urgency to address these issues becomes even more apparent. The reality of our changing climate demands immediate and effective responses to ensure the safety and comfort of residents in their homes.

By Andrew Mellor, Partner at PRP

If you would like to find out more about our services to address overheating, get in touch with our team (events@prp-co.uk