Much of it is antiquated, dating from a time when the priorities were protection from the cold and rain. However, most new-build properties are equally unprepared for experts’ predictions that, by mid-century, there will be temperatures at the level of the 2018 summer high every other year. The climate change panel warned in a report last year that more than 570,000 homes had been built since 2016 that were not heat-resistant – and another 1.5m was not to be built over the next five years. Government advisers accused ministers of failing to act to protect people from rising temperatures which “could even leave many existing and new homes uninhabitable”. The problem is deadly serious as vulnerable people struggle to keep their cool in their beds. The commission noted that the 2020 heatwave in England killed more than 2,500 people and warned that the number of heat-related deaths could triple by 2050. Heat is not only a threat to life but also to the structural integrity of buildings, causing cracks in the walls. 2018 – the UK’s joint hottest summer so far along with 1976, 2003 and 2006 – saw a sharp subsidence as the ground beneath buildings dried out and shrank, with more than 10,000 households subsequently making insurance claims worth £64 million in just three months. Critics blame builders, property developers and the government for being slow to respond. “The housing industry is quite traditional and old-fashioned in adaptation and there are many challenges to address around zero carbon and future proofing,” says James Knight, from design and engineering consultancy Arcadis. So how can industry and the country respond to the growing threat posed by high temperatures?
Conversion of old properties
The most obvious heat mitigation measure is air conditioning, but it is prohibitively expensive in terms of installation and operating costs, and works inefficiently in damp older homes. Electronic systems also increase emissions – fueling global warming and exacerbating the overall problem. Closing the shutters on older houses – like this blue house on Portobello Street, west London – is an effective way to keep the sun out. Photo: June Green/Alamy Experts suggest the UK can learn from countries where extreme heat is more common, where houses have shutters or motorized blinds to keep out the sun and white surfaces to reflect the heat. Knight points out that around the Mediterranean, “people leave their houses closed all day, with the windows open at the back. How many of us leave the curtains closed on south and west facing windows when we go to work on a sunny day?’ Similar “passive measures” that require minimal energy and fuel use to cool homes include improving natural ventilation and increasing insulation, which has the dual benefit of reducing winter energy bills.
Heat design
There are even more effective measures that builders can introduce at the design and construction stage: ensuring that the house and windows are oriented and positioned to limit exposure to direct sun. reduction of glazing; adding shade trees and plants. and installing an air source heat pump, which can be used to cool as well as heat a home. Other cooling features include windbreakers, ceiling devices inspired by Persian architecture that use wind to blow fresh air into a room and expel stale air, and solar chimneys – tall, dark-surfaced structures designed to absorb solar radiation, creating a rising column of heated air which in turn maintains the flow of a ventilation system. The most advanced example of this principle is the “passive house”, an airtight, highly insulated building that relies almost entirely on passive measures such as sunshine, shading and ventilation to ensure a constant temperature. They often have an attic ventilation unit with two air collectors: one for cool outdoor air and one for warm indoor air, which are circulated around the house to keep the temperature even. “A passive house is the best solution where you have a natural airflow through it,” says Bob Ward, deputy chairman of the London Climate Change Partnership. “It should become the guide for how you build for zero carbon and zero warming.” Barratt’s Zed House, on the University of Salford campus in Manchester, is a pilot project testing technologies and capabilities to achieve the zero carbon target of 2030. Photo: Barratt Developments Meanwhile, Barratt, Britain’s biggest housebuilder, is trialling the Zed House, a zero-carbon home built in collaboration with 40 industry partners and the University of Salford. It has an air source heat pump and 95 sensors to collect data around the house, including air quality. Barratt claims the pilot is the first step towards achieving its commitment that all its new homes will be zero carbon by 2030.
What about larger buildings?
Heat is not just a problem for residential buildings – too many offices still rely on energy-guzzling air conditioning and have large glass facades. “Huge glass buildings are not a good idea – this is a greenhouse,” says Ward. “You have to design the glass in a way that keeps the sun out.” Now there is a growing trend to install louvered windows in commercial buildings: parallel panes of glass in frames that can be opened or closed at an angle to improve ventilation. Again, the countries of Europe are leading the way. Edge, a state-of-the-art office building built in Amsterdam for Deloitte in 2014, has been created as an example of how workplaces can be redesigned. It deploys dynamic windows, automatic shades, solar panels on the south side to keep out direct sun, underground heat energy storage pumps to pump hot or cold water into or out of the building, and 28,000 sensors that monitor movement, light levels, humidity and temperature.
What is the government doing?
Until now, the UK’s focus on building efficiency has been on how to improve homes, especially in light of exploding energy bills – but last year, the government added a section on overheating to the building regulations for the first time, Part O. which came into effect last month. It urges housebuilders to provide reasonable measures to limit solar gain in summer and “provide appropriate means of removing heat from the indoor environment”. Subscribe to the Business Today daily email or follow Guardian Business on Twitter @BusinessDesk However, the construction industry is not happy with the new rules, complaining that they could force already approved projects back on the drawing board. Stewart Baseley, the executive chairman of the Federation of Builders, wrote to the government in early June to complain that “the new regulations are bogus and could require tens of thousands of licensed homes to go back through the planning process”. And what does Ward think of Part O? “It should help, although who knows how well it will be enforced,” he says.
