CommentaryRapid transition to beat the heat
Can we respond to extreme heat to protect human health and shore up infrastructure in such a way that actually accelerates a rapid, low carbon transition to...
UK homes are not built to handle the heat. Most of them were designed and constructed for a much cooler climate where extreme heat events were rarer and milder. Houses and offices in the UK therefore tend to maximise the amount of sunlight they let in and often have poor ventilation, making them extremely ill-suited for the temperatures currently being experienced.
Air conditioning (AC) is also a rarity within British homes compared with warmer countries, as only 3% of homes own an AC unit. In fact, the US uses as much energy to power all the AC units in the country as the UK uses to power its entire economy.
Even without a heatwave, approximately 20% of homes in the UK overheat during an average summer. Homes overheating hits the most vulnerable hardest, with elderly citizens or those already living with underlying health conditions set to shoulder the most adverse impacts of heat. According to the CCC, by 2050 heat deaths in Britain could reach 7,000 a year when 80% of the UK’s housing stock will still be in use.
New homes must be built with both hot and cold temperatures in mind. Maximising ventilation and airflow within homes and buildings can prevent overheating, but there are some concerns that a rush to insulate homes to fend off the cold could exacerbate this issue. There are a wealth of low-carbon cooling techniques that can be drawn from the tropical regions, where buildings have had to deal with extreme heat and limited power generation to keep inhabitants cool. The new hospital and maternity ward in Tambacounda in Senegal boasts a wealth of low-carbon and low-tech cooling techniques, from its double-skinned roof to its porous brickwork.
The position of homes needs greater attention in our new climate. The adamancy of developers to create communal spaces that receive constant sunlight has led to a flurry of apartment developments that are orientated east to west, following the sun’s path and absorbing its energy in the process. As is the proliferation of single-aspect flats in urban centres, where windows on one side of the apartment make cross-ventilation an impossibility.
Roofs can also play their part – especially in dense urban expanses. Research suggests that by making roofs a lighter and more reflective colour could reduce peak daytime temperatures by around 3°C, which could cut heat-related deaths by up to a quarter. Such a policy can also be targeted at a select number of buildings with larger roofs, such as commercial or industrial units, and deliver palpable temperature reductions.
In this series, the Rapid Transition Alliance will explore how housing, infrastructure and community resilience can be improved in the face of extreme heat and become part of the process of urgent decarbonisation and reducing energy demand, drawing on evidence-based hope from around the world.Read more
Heat pumps, the technology in pole position to decarbonise heating within the built environment which are being installed at a rapid rate throughout Europe, can also help fight the heat. Most ground source heat pumps and air-source heat pumps can reverse-cycle in order to cool buildings during the summer months while also keeping them warm throughout the winter, without the use of fossil gas. Cooling from heat pumps also dehumidifies air better than standard air conditioning units, cutting energy and emissions. Despite the huge benefits heat pumps will bring for households and their health, the UK was bottom of the list among 20 other European nations for installations in 2021.
Outside of the home, residential streets could benefit from mass-tree planting programmes to reduce the urban heat island effect and provide shading to surrounding buildings. This so-called green infrastructure can cut surface temperatures by between 15°C and 20°C and, in some cases, half air conditioning costs. Another study exploring the impact of street trees in Manchester found that surface temperatures were slashed by an average of 12°C and that the permanent shade provided by trees cooled concrete by up to 20°C at the height of summer. However, the cooling potential of trees varies according to species, so urban planners must choose carefully according to the surrounding environment. These efforts could go alongside broader efforts that seek to take public spaces back from polluting cars and, instead, make space for people and nature.
The need to make homes more resilient in the face of extreme heat (and cold) is an opportunity to rethink building materials and delivery models. Modern methods of construction, where homes are built in a factory off-site and then craned in, have been shown to be far more energy efficient than traditionally built homes, meaning they keep the heat and cold at bay while cutting energy consumption. Researchers exploring the environmental credentials of factory-built homes also found that by building nearly 900 homes off-site in Vision Modular Systems’ factory, 28,000 tonnes of embodied carbon were cut across two schemes in London, the equivalent amount absorbed by 1.3 million trees in a year.
But modern methods may not work in every context and other materials should also be considered. Some architects are calling for a return to traditional building materials such as mud, which is used extensively today throughout West Africa and in Yemen in the Middle East. Mud has a high thermal mass which means it absorbs heat slowly during the day, stores it and then releases excess heat during the night, preventing homes from overheating. As a material, mud is also porous so moisture can enter the household and improve the air quality, without compromising on its robustness as a building material. Mud buildings are also incredibly adaptable and can be transformed over time to fit the shifting needs of the household.
Beyond the need for tighter regulation and investment to make UK homes resistant to extreme heat, there are also individual behaviour changes that can make homes cooler immediately. The easiest way to try and beat the heat is by closing your blinds or curtains to reflect some of the sun’s radiation, especially when your home is in direct sunlight. Windows should remain closed until temperatures drop in the evenings so the cooler air can circulate around your home. Also, turning off all electrical devices at the switch can cool rooms down slightly.
Addressing the shortcomings of our housing stock in the face of increasingly frequent and severe heat waves could stimulate rapid transitions in a variety of key transition areas, such as heat pump installations and reclaiming streetscapes from cars. All of these developments will intertwine resilience through communities so they can beat the heat.