Heat resilience and sustainable cooling – Report Summary

This is a House of Commons Committee report, with recommendations to government. The Government has two months to respond.

Author: Environmental Audit Committee

Related inquiry: Heat resilience and sustainable cooling

Date Published: 31 January 2024

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In July 2022 the UK Health Security Agency (UKHSA) issued its first ever Level 4 heat-health alert as temperature records were broken and 40°C was recorded in the UK for the first time. As temperature trends continue to rise, heatwaves are predicted to become more frequent and severe. According to the Met Office, the chances of a summer matching the current hottest on record in this country could be greater than 50% by mid-century. This is against a backdrop of increasingly extreme heat being experienced across the world, with 2023 confirmed as the hottest year ever recorded globally by a significant margin.

This has serious consequences for health, wellbeing and productivity. Exposure to heat raises a human’s blood pressure and heart rate, impacting the circulatory, nervous, respiratory and renal systems. This can lead to a number of effects which increase the risk of illness or death, including dehydration, heat exhaustion and heatstroke. UK heat-related deaths are believed to have exceeded 4,500 in 2022, and this could rise to 10,000 annually without concerted action to adapt to the warming climate. Those most at risk include the over 65s and those with existing health conditions. Hot weather also impacts mental health by exacerbating the symptoms of psychiatric illnesses, worsening the side effects of medication and increasing suicide risk. It has broader wellbeing effects on the population at large, including sleep deprivation. The economic costs are believed to run into the billions.

Humidity is an important factor in how the body experiences heat, yet this does not currently feature prominently in weather-related communications. We therefore recommend that the Met Office and the UKHSA begin to incorporate explicit messaging and/or metrics regarding the effects of humidity levels as well as temperature into weather forecasts and heat health alerts. We also suggest the Met Office trial a naming system for heatwaves (as is currently the case with major storms) in order to help communicate the threat heat can pose, and reiterate the call from our predecessor committee’s report on Heatwaves: adapting to climate change, issued in 2018, for a Minister-led public information campaign on the dangers associated with heat.

As the climate warms, demand for cooling technologies will rise. The International Energy Agency says that record-breaking temperatures feed the demand for air conditioning which in turn results in surges in demand for electricity—risking a vicious cycle of increased greenhouse gas emissions that in turn make the world even hotter. Although the UK has not yet experienced blackouts due to peak energy demand related to cooling in the summer, such peaks have occurred and have led to coal-fired power stations being brought into service, thereby increasing the carbon content of the UK’s energy mix. It is essential, therefore, that as well as continuing action to decarbonise the grid, Ministers adopt an approach to heat resilience adaptation which prioritises passive cooling–that is, the use of measures which do not require energy consumption. Establishment of minimum energy performance standards (MEPS) and continuation of work to reduce the use of fluorinated gases (‘F-gases’) used in cooling equipment—some of which have global warming potentials thousands of times greater than carbon dioxide—are vital to achieving a sustainable approach to cooling.

One of the most important ways in which passive cooling can be achieved is through nature-based solutions, such as parks, trees, water bodies and green infrastructure such as green roofs. These measures have not only been shown to have significant cooling effects, but also a multitude of co-benefits—for example, for health, wellbeing, air quality, flood resilience and biodiversity. We therefore recommend that the Government adopt a range of measures to protect and expand green spaces, particularly in urban areas where the ‘urban heat island’ effect (a consequence of reduced natural landscapes, urban geometry, a prevalence of man-made materials, and heat generated from human activities) typically raises temperatures in cities beyond those in rural areas. Such measures must prioritise disadvantaged areas currently underserved by access to green space.

Another core issue is the heat resilience of homes. The population spends on average 90% of its time indoors, yet the UK housing stock is not designed to cope with excessive heat, and millions of UK homes experience summertime overheating. While the introduction of Part O of the building regulations, which covers the overheating mitigation requirements of new residential buildings, is a positive step, this does not currently apply widely enough. We therefore recommend that Part O be expanded to cover refurbishments of existing properties as well as material changes of use to residential. Post-occupancy evaluation should also be brought in to ascertain the real-world performance of mitigation measures taken under Part O, within the first year of installation.

Four out of five homes that will exist in 2050 are already built, meaning that the scale of retrofitting required for existing homes to protect them from overheating is vast. We consider that there are opportunities to combine existing initiatives on insulation and energy efficiency into a much more ambitious and comprehensive housing retrofit programme which also addresses the risks of overheating. Such an approach, if well designed and delivered, can minimise both cost and disruption while ensuring homes are energy efficient and remain comfortable to live in. We recommend a locally-led approach delivered via local authorities—which know their areas and communities best—backed with adequate long-term funding, and prioritising passive measures, and then fans, over ‘active’ cooling measures. Private finance will also be a key component in achieving retrofit on such a vast scale; we therefore call on the Government urgently to bring forward proposals to encourage access to low-cost finance for householders following the consultation it carried out three years ago.

The Government’s third National Adaptation Programme (NAP3), published in July 2023, details its response to the risks and opportunities identified in the latest statutory Climate Change Risk Assessment, dating from 2022. Whilst NAP3 is an improvement on previous iterations, and identifies the right areas where action is required, it is mainly a compilation of existing policy and initiatives and does not demonstrate sufficient urgency or ambition with regards to heat resilience measures.

Effective joint working is essential if the impacts of heat are to be tackled in a coordinated, holistic and cost-effective way. The Climate Resilience Board set out in NAP3 is potentially an important development, as long as it includes representation from all relevant Government departments, agencies and other organisations, and meets sufficiently frequently. We recommend that the Government appoint a lead Minister for heat resilience to act as a focal point and drive forward coordinated action in this area.

Ultimately, we consider that a comprehensive national heat resilience strategy is required to draw together all of the recommendations outlined in our report and ensure coordinated action on all fronts. We were pleased to see the UK sign up to the Global Cooling Pledge initiative at COP28 and, with it, the commitment to produce a national cooling action plan: if sufficiently ambitious, that plan could embody the heat resilience strategy which is clearly required. We stand ready to continue to work constructively with all relevant Government departments to make this a reality.