The London Assembly's Planning and Regeneration Committee met on 10 June 2026 to discuss whether London's homes are ready for heatwaves. The committee heard from experts that while passive cooling measures should be prioritised, active cooling solutions like air conditioning may be necessary for vulnerable populations and in certain building types, though their integration needs careful consideration to avoid exacerbating the urban heat island effect and increasing energy costs for residents. The committee also discussed the need for better data, stricter enforcement of existing regulations, and a more holistic approach to building design that considers both heating and cooling needs throughout the year.

Overheating Risks and Vulnerabilities

Experts agreed that London faces significant overheating risks, exacerbated by the urban heat island effect, an ageing population, and the concentration of vulnerable individuals in densely populated, less green areas. Antonietta Canta, Associate at Arup London, highlighted that while passive measures are crucial, active cooling might be necessary for the most vulnerable, but affordability and maintenance remain key concerns. Dr Anastasia Mylona, Technical Director at CIBSE, noted that current building regulations, such as Approved Document O (Part O), are not being consistently enforced, and there is a lack of data to assess their effectiveness. David Stronge, Design Director at Peabody, expressed concern that more recently built homes, particularly those with large, unshaded glazing, are overheating worse than older, more thermally massive Victorian buildings.

The Role of Passive and Active Cooling

The consensus among the panel was that passive cooling strategies, such as external shading, improved ventilation, and the use of materials with high thermal mass, should be prioritised. Dr Tom Dollard, Partner at Pollard Thomas Edwards, stressed that these measures are key to enforcing the cooling hierarchy and reducing reliance on air conditioning. However, the panel also acknowledged that in extreme heatwave conditions, active cooling might become necessary, particularly for vulnerable individuals. Antonietta Canta cautioned against widespread adoption of air conditioning, as it can worsen the urban heat island effect and increase energy bills, while Dr Mylona noted that reversible heat pumps could offer a more energy-efficient solution for both heating and cooling.

Policy and Design Considerations

The committee discussed the effectiveness of current policies, including the London Plan's cooling hierarchy and Approved Document O (Part O) of the Building Regulations. Dr Mylona and Tom Dollard agreed that while the cooling hierarchy is a robust methodology, its enforcement is lacking, leading to a tendency to bypass passive measures and jump directly to active cooling solutions. Joel Callow, Founding Director of Beyond Carbon, presented Passivhaus-certified apartments as a potential solution that integrates efficient heating, cooling, and hot water systems, significantly reducing running costs and carbon emissions. He also highlighted the conflict between planning requirements for daylight and acoustic regulations, which can hinder the effective use of openable windows, a key passive cooling strategy.

Data Gaps and Future Actions

A recurring theme was the lack of comprehensive data on overheating in existing homes and the effectiveness of current regulations. Dr Mylona and Matthew Scott, Policy Manager at the Chartered Institute of Housing, emphasised the need for more post-occupancy evaluation (POE) and consistent monitoring of temperatures in homes. They suggested that the GLA could play a role in collating data from social housing providers to create a richer dataset. The committee also heard about the upcoming London Heat Risk Action Plan, which aims to address heat risk across various sectors and identify funding gaps for retrofit measures. Dan Bicknell, Climate Adaptation Manager at the GLA, stated that the plan will focus on vulnerable communities and explore blended funding options for retrofit projects.

Recommendations for the London Plan and Government

The panel suggested several changes to improve London's heat resilience. Dr Mavrogianni advocated for better integration of energy and cooling policies within the London Plan and the use of updated weather files for building design. Joel Callow stressed the need for regulations to clearly reference the Passivhaus standard and for mandatory use of future climate data in design modelling. Matthew Scott highlighted the importance of applying Part O to homes created through material change of use processes, such as office-to-flat conversions. Jules Pipe CBE, Deputy Mayor for Planning, Regeneration and the Fire Service, acknowledged the need for the London Plan to deviate from national standards on overheating, particularly in dense urban areas, and to promote stricter passive cooling requirements. The committee also discussed the potential for naming heatwaves to raise public awareness, similar to storm naming conventions.

The meeting concluded with a discussion on the potential for an EPC-style assessment for heat risk, which was considered a sensible idea that could inform purchasers and renters about a property's vulnerability to overheating. However, it was noted that such assessments would ideally be integrated into building control processes rather than solely relying on the planning system.