As the days grow shorter and temperatures drop in the lead-up to the festive season, it may seem surprising to discuss heatwaves, urban heat islands, and their harmful impacts on Londoners, wildlife, and infrastructure. However, preparation and adaptation are long-term efforts that don’t begin or end with summer heatwaves.
This is precisely the message from Shade The UK, which this week released an insightful report titled Building Heat-Resilient Neighbourhoods, produced in collaboration with Love Design Studio and the Grantham Institute at LSE. Using the borough of Islington as a case study, the report highlights the risks associated with densely built urban areas, limited green spaces, and poorly adapted housing. It also proposes the development of a much-needed Overheating Index for buildings—timely as the Greater London Authority (GLA) launched Operation Helios (see post) last summer, a large-scale exercise to test emergency services’ response to heatwaves, and as the GLA works on drafting a heat strategy, as recommended in the London Climate Resilience Review (see article).
The context: Why London is at risk
The facts are stark: the climate is warming, and London is especially vulnerable. The city is among the fastest-warming areas in the UK and faces some of the highest future temperature increases. The 2022 heatwave, which brought temperatures above 40°C, caused nearly 3,000 deaths in England, with over a tenth of those deaths occurring in London alone. Without intervention, this figure could increase tenfold by 2070.
Nearly half of UK homes—designed to retain heat rather than keep cool—are at risk of overheating. If global temperatures rise by 2°C by the end of the century, that number could reach a shocking 90%. Existing tools to assess overheating risks are complex and inaccessible for individuals and businesses according to the authors, and retrofitting buildings to reduce risks would cost an estimated £500 billion over 20 years. The question of “who will pay for this” remains unanswered, but the cost of inaction will likely be far greater.
Heatwaves are often referred to as “silent killers.” Their dangers are invisible and, at times, go unnoticed until it’s too late. They disproportionately affect vulnerable populations, increase the risk of mental health issues and violence, and cost billions in healthcare, lost productivity, and infrastructure damage.
Why an Overheating Index is a great idea
The proposal for an Overheating Index is both innovative and timely. Metrics that enable comparisons of products, services, or systems based on their climate impact, biodiversity footprint, or contributions to health and well-being empower individuals to make informed choices while fostering accountability.
For instance, why shouldn’t tenants or homeowners know upfront whether a property is prone to overheating, even in moderate temperatures? Such an index, incorporated into existing tools like Energy Performance Certificates (EPCs), could help people make better decisions about where to live or what renovations to prioritise.
While the report recognises that an Overheating Index would support stakeholders in decision-making, it also acknowledges that it is not a standalone solution. Comprehensive adaptation policies for the built environment are still needed.
The Islington case study
Islington, one of London’s most densely populated boroughs, was chosen as the focus of the study due to its high vulnerability to urban heat islands. The study assessed various building types in Islington and engaged key stakeholders, including councils and residents, to incorporate their lived experiences and perceptions.
Key findings include:
– Vulnerable built environments: Schools, care homes, and hospitals in Islington are among the most exposed to heatwaves.
– Limited green spaces: Compared to other boroughs, Islington has fewer green spaces, exacerbating the urban heat island effect.
– Disproportionate impact on at-risk groups: Elderly residents and other vulnerable populations are most affected by extreme heat.
– High overheating risk in residential buildings: Many homes in the borough are poorly equipped to handle rising temperatures.
– Economic impact: Heatwaves lead to significant costs from lost productivity and infrastructure damage.
The study conducted overheating assessments for different building types (schools, residential blocks, hospitals) to identify their vulnerabilities. The conclusion? Islington is unprepared for sustained temperature increases, particularly in its residential sector. Alarmingly, few measures have been taken since the deadly 2022 heatwave to adapt buildings to rising heat risks.
What’s next?
The report calls for further research into the feasibility of a local overheating metric that could be scaled up across London. While innovative, such a tool would need to be part of broader efforts to ensure the built environment can withstand future climate challenges.
With London’s temperatures set to rise, the time to act is now. Investing in heat-resilient buildings, green spaces, and comprehensive adaptation strategies isn’t just about saving lives—it’s about creating a city that can thrive in the face of a changing climate. The report is now open for public consultation—your opportunity to contribute ideas and help shape how we address and communicate heat risks in buildings.
