One in five building services engineers unfamiliar with overheating regulations

A new survey commissioned by climate solutions specialist Zehnder Group UK in collaboration with CIBSE Journal has uncovered concerning gaps in knowledge among building service engineers regarding overheating regulations in the UK. The study found that a significant 20% of respondents were completely unfamiliar with Approved Document O, the Building Regulation that addresses the risk of overheating in new buildings.

An additional 46% of engineers claimed to understand the theory behind Part O, but were unsure how to properly implement its requirements in practice. While a third (33%) of respondents said they knew Part O well, the majority demonstrated only limited understanding, with 19% admitting they don’t comprehend the regulation at all.

These findings are particularly worrying given the mounting evidence that overheating is an increasingly serious problem in the UK. According to the government’s Climate Change Committee, nearly a fifth (19%) of homes in the country already experience overheating, and this figure is projected to reach 90% by 2050 if global warming trends continue unchecked.

Overheating is a real problem in residential buildings. When properties exceed a temperature threshold of 26°C for extended periods, it can seriously affect occupant thermal comfort, health and wellbeing as well as productivity. When asked what kept them up at night when planning a new building project, the top three concerns for engineers were design, cost and quality, with overheating being cited as only the sixth biggest worry.

The survey also revealed that high-rise apartments were identified by 65% of respondents as the most at-risk buildings for overheating. However, a significant proportion also raised concerns about schools (40%), care homes (39%), and hospitals (30%) – all building types that cater to children and the elderly, who are among the most vulnerable in society.

Despite these risks, passive cooling solutions like solar shading and openable windows were preferred over mechanical cooling by 78% of respondents. Some engineers cited limitations in relying solely on passive measures, advocating for a more integrated, whole-building approach.

While the level of understanding about Part O is concerning, knowledge of the causes of overheating in buildings was higher. The majority of respondents (78%) pointed to solar gain through increasing glazing as a primary cause, followed by unsuitable ventilation (45%), global warming (40%), inability to open windows (40%), and excessive insulation (39%).

Jason Bennett, an indoor air quality expert at Zehnder Group UK, comments: “Overheating needs to be designed out and thought about almost at the pre-planning stages. We have to look at the dynamics of the building and we need to be coordinating our efforts along the way – and not just us, as an indoor climate solutions manufacturer – we should be networking and coordinating with the others responsible for mitigating overheating risks.

“Mechanical cooling can be achieved with air conditioning, but this method is costly to run and recirculates air rather than replaces it with filtered air – and you would still need to ventilate the property. A better solution is to incorporate air temperation into an effective ventilation strategy, which is also required in line with Part F. The difference is fresh, clean air supply all year round with heat recovery in the winter and cooling in the hotter months – promoting better, healthy indoor air quality (IAQ).”

Read the full report here: https://www.cibsejournal.com/uncategorized/hot-and-bothered-zehnder-overheating-survey/

For more information on how to mitigate overheating in buildings visit: https://www.zehnder.co.uk/en/sectors-knowledge/topics/overheating