Hot property: how planning can help Londoners beat the heat

Extreme heat is now a major and growing public health threat in London, causing hundreds of deaths annually, and exposing serious weaknesses in the capital's housing stock.

An estimated 75% of London's social housing stock is considered at high risk of overheating, which could place more than one million children at increased risk.

After an investigation by the London Assembly Planning and Regeneration Committee, the report: Hot property: how planning can help Londoners beat the heat has been published.

It sets out the changes that need to happen not just in the planning processes of new buildings, but in the need to retrofit as well, and calls on the Mayor and the Government to urgently do more to prevent heat-related deaths, improve public awareness of extreme heat and ensure both existing and future homes are fit for a warming climate.

The report also highlights new survey data from this summer, as many Londoners reported being unable to sleep during periods of extreme heat, particularly because bedrooms became excessively hot. Respondents described negative impacts on their mental and physical health, and general wellbeing.

The investigation found that overheating is a widespread problem across London's housing stock, with 86 per cent of Londoners surveyed reporting overheating in their homes in 2025.

To address these challenges, the Committee calls for a series of measures, including:

• The Mayor should set a target to reduce heat-related deaths below current levels and publish a roadmap for achieving it.
• The Mayor should also accelerate the retrofitting of existing homes with measures such as shutters, shading and improved ventilation to reduce overheating risk.
• The Government should protect London's ability to set higher overheating standards than national requirements through the planning system.
• The Greater London Authority (GLA) should review its ‘cooling hierarchy’ to ensure it reflects the increasing role that active cooling (e.g. air conditioning) will need to play as London's climate changes. Passive cooling should continue to be prioritised, but the hierarchy should also support the appropriate use of efficient active cooling technologies.
• The GLA should also explore new public awareness measures, including the potential naming of heatwaves, to improve public understanding of heat risks.