How can we keep buildings (and ourselves) cool on a heating planet?

2022 has been a record-breaking summer, with UK temperatures exceeding 40°C for the first time. Around the world, the heat wave has brought disruption ranging from wildfires, transport meltdown and increased mortality.

With temperatures in cities sometimes up to 10-15°C higher than in rural areas, the built environment has to be central to our response to climate change. We need to work out how to design cities to be comfortable in higher temperatures, while also ensuring infrastructure can cope.

Coping strategies

But how can we learn to cope with extreme heat while also cutting our carbon emissions? Strategies to address heatwaves need to be sustainable, so that we don’t either bulldoze buildings to rebuild cooler ones with vast embedded carbon costs or look to energy-guzzling air conditioning to solve the problem.

Making cities heat resistant while still hitting net zero targets will require a change to how we live and how we build, and standards will play an important role.

Why is extreme heat so damaging?

From wildfires to the exacerbation of drought conditions, the impact of extreme heat on the natural environment is often easy to spot. However, extreme heat can also have severe and unpredictable consequences for people and infrastructure in the built environment.

The potentially catastrophic effect of extreme heat on vulnerable people was brought into stark relief earlier this year. The three-day heatwave experienced between the 17th and 19th of July 2022 is estimated to have killed 1,000 people in England and Wales, with half of these deaths expected to have been in people 85 or older.

Safeguarding issue

As extreme heat is particularly dangerous for the elderly and for infants (whose bodies can’t cool themselves as efficiently), counteracting its effects will increasingly need to become a safeguarding issue affecting education and care policy. Heat could exacerbate health problems for those who are being cared for at home, such as older people or those with disabilities, who may also be less able to afford air conditioning or well-insulated properties that would mitigate the heat.

While there is no law for maximum working temperatures in the UK, employers will also need to think carefully about the measures they adopt to keep workers comfortable in the summer. Health and safety law requires the temperature to be a comfortable level, with fresh clean air. Requiring employees to work in excessive heat could result in additional accidents and injuries, resulting in the risk of litigation.

Overheating infrastructure

Extreme heat can also put infrastructure under severe strain, crippling key services and inflicting a significant economic toll.

Earlier this year, one of the UK’s largest hospital trusts suffered a major IT failure after both its datacentres stopped working in the extreme heat. This meant operations were cancelled, examination notes had to be written by hand, and the results of diagnostics tests like X-rays and CT and MRI scans couldn’t be accessed remotely.

Elsewhere, the July 2022 heatwaves led to major disruption and delay on the trains as steel rails expanded and threatened to buckle. In the UK, steel rails are ‘pre-stressed’ to just 27°C, much lower than the temperatures now becoming the norm.

With summer temperatures only likely to increase, what’s the solution?

Changes to how we build

Many countries experience hotter conditions than the UK, and there are many examples of low-carbon natural cooling that the construction industry can draw inspiration from in the UK, Australia, and USA. These include:

• Improved ventilation and airflow so that hot air can rise and escape
• Minimising the impact of direct sun heat by, for example, shading windows
• Ensuring doors and windows are well-insulated and tinted or shaded
• Creating cool spaces by introducing more tree shade
• Reducing the use of dark, dense building materials like asphalt, concrete and tarmac, all of which absorb heat
• Painting buildings (particularly roofs) a lighter colour or using light coloured building materials to help reflect heat

Solutions can often be retrofitted into existing buildings, which has the added benefit of avoiding the embodied carbon of a new build. As global temperatures rise, practical solutions to mitigate the ‘heat island’ effect in cities are becoming a focus for researchers, and organisations will benefit from taking note.

A change to how we live

While changes to the built environment will be key to building resilience against the effects of extreme heat, changes to the way we live may also be necessary. As with building design, it is possible to take inspiration from hotter parts of the world.

During the hottest parts of the year, a change of lifestyles and habits may be required to mitigate the human toll of extreme heat. For example, some people may find it necessary to alter daily routines to incorporate rest during the hottest part of the day.

This is particularly true for home workers who don’t have access to air conditioning, or for people who work outside, for example. Employers that haven’t yet rolled out flexible working may find it’s necessary to look again as temperatures continue to rise.

How can standards help create cooler buildings?

Whether designing and constructing new buildings, or retrofitting old ones, there are a number of standards that can be used to help organisations adapt to rising temperatures, without compromising carbon reduction efforts:

• PAS 2035/2030 provides businesses with a framework of new and existing standards on how to conduct effective energy retrofits of existing buildings. The PAS covers a range of energy efficiency measures intended to improve, among other things, insulation of building fabric elements and airtightness.
• PAS 2038:2021 sets out requirements on retrofitting non-domestic buildings for improved energy efficiency. The PAS defines technically robust and responsible “whole building” retrofit processes that support, among other things, enabling buildings to use low- or zero-carbon energy supplies
• BS EN ISO 14091:2021 provides guidelines for assessing risks related to the potential impacts of climate change – helping organisations to improve the planning of adaption to climate change.
• BS 8631 gives organisations a systematic guide for creating or improving a plan for climate change adaption, using adaption pathways.
• BS EN ISO 14090:2019 specifies principles, requirements, and guidelines for adaptation to climate change.

If you want to learn more about which other standards can help you mitigate the impact of extreme heat in the built environment, BSI members can get in touch with the Knowledge Centre’s information experts.