Overheating and why mitigate it?

Overheating occurs when the local indoor thermal environment presents conditions in excess of those acceptable for human thermal comfort or those that may adversely affect human health.

The main causes of a property overheating are:

Solar heat gain
Internal heat gains
Poor removal of excess heat

UK Health risk

Overheating in buildings has been highlighted as a key risk for the health and productivity of people and businesses in the UK. It is estimated that there are about 2,000 heat-related deaths each year in England and Wales. The government’s stated ambition is to build 300,000 homes per year. Most of these properties will be inhabited by 2080 when temperatures are projected to have risen by a range of 1.2 – 8.1 degrees in England under the medium emissions scenario and, if no action is taken, by 2050, an estimated 7,000 people will die prematurely from heat-related causes (though not all in homes) annually (CCC 2015).

According to the ONS, 24% of people working were using their home as part of a hybrid arrangement in May 2022 and any experiences of overheating are likely to have had an impact on productivity (Baglee et al 2012).

According to the UK met Office

We have already seen average global land temperatures increase over 1 °C since the Industrial Revolution. As a result of this baseline increase in temperature, we are seeing extreme heat events, such as heatwaves and record-breaking high temperatures, become more frequent, long-lasting, and intense.

Whilst a 1 °C background temperature increase may not seem significant, the resulting increase in the severity of extreme heat events is already evident in the observed record. This has widespread and significant impacts.

The top 10 warmest years for the UK since 1884 have occurred since 2002. In contrast, none of the coldest years have been recorded in this century.

Overheating in buildings has been highlighted as a key risk for the health and productivity of people and businesses in the UK

It is estimated that there are about 2,000 heat-related deaths each year in England and Wales.

This has led to new regulations to ensure occupants in new residential buildings do not suffer excessive temperatures.

Approved Document O England

Approved Document O (2021 edition – England) was released in December 2021 and came into force for all Building Regulations building notices, full plans applications and initial notices for residential buildings submitted in England from 15 June 2022.

Approved Document O Wales

Approved Document O (2022 edition – Wales) was released in May 2022 and came into force for all Building Regulations building notices, full plans applications and initial notices for residential buildings submitted in Wales from 23 November 2022.

Scottish Building Standard 3.28

Standard 3.28 of the Scottish Building Standards Domestic Technical Handbook (December 2022 edition) was released in June 2022 and came into force for all residential Building Warrant applications submitted in Scotland from 01 February 2023.