Designing urban environments for a hotter future

With infrastructure often designed for a climate that no longer exists, many cities now face a critical question: how can we adapt urban environments for long-term climate resilience? Sika believes that one answer is right above our heads: cool roofs. 

Cities around the world are feeling the heat. As global temperatures rise, urban areas are becoming more vulnerable, not just to extreme weather, but to a phenomenon known as the urban heat island (UHI) effect. In essence, cities are heating up faster and more intensely than their rural surroundings. The dense concentration of buildings, roads, vehicles and human activity generates and traps heat, creating microclimates that can be several degrees warmer than outlying areas. This temperature spike isn’t just uncomfortable, it’s a major public health concern, an energy efficiency challenge, and a growing threat to liveability.  

Temperature distribution in cities

 UHIs are driven by the materials that dominate cityscapes such as asphalt, concrete, and dark rooftops. These surfaces absorb and retain solar radiation during the day and slowly release it at night, creating persistently elevated temperatures. In major metropolitan areas, urban temperatures can rise by as much as 10°C compared to neighbouring rural zones. The consequences of UHIs are wide-ranging. More energy is used to cool buildings, increasing electricity demand and carbon emissions. Air quality worsens, heat-related illnesses become more common, and vulnerable populations face heightened risks. Add in the stress on water resources, urban infrastructure, and social services, and the need to respond urgently becomes clear. 

Cool roofs are one of the most impactful technologies available to address the UHI effect. They are engineered to reflect more sunlight and absorb less heat than traditional materials. Often featuring light-coloured, reflective coatings or membranes, cool roofs help maintain lower surface and indoor temperatures. They lower the temperature inside buildings, cutting the need for air conditioning and reducing energy bills. And, by reflecting more solar energy back into the atmosphere, they reduce ambient heat in the surrounding environment, helping to cool entire neighbourhoods. 

Where heatwaves are becoming more frequent and severe, this is a matter of public health. By decreasing indoor and outdoor temperatures, cool roofs can help reduce cases of heatstroke, respiratory issues, and other heat-related health concerns. 

The following illustration depicts the energy flow of sunlight hitting a conventional flat roof (left) and a cool roof covered with a white membrane or coating (right)

Building resilience from the top down 

The resilience benefits of cool roofs extend well beyond individual buildings. Cities that invest in cool roofing systems see measurable reductions in energy demand during peak times, leading to a more stable and efficient power grid. Water consumption is also positively affected as buildings require less irrigation and cooling support. The use of durable, reflective roofing materials can increase the lifespan of rooftops by reducing thermal expansion and UV degradation. When deployed at scale, cool roofs become a powerful tool in a city’s climate adaptation strategy. They align closely with net-zero goals, air quality and public health, making them a win-win for urban planners and policymakers. 

Among the industry leaders helping cities implement cool roofing technologies is Sika, a global provider of high-performance building solutions. Sika’s cool roof systems combine energy efficiency, durability, and long-term performance, making them suitable for residential and commercial buildings, industrial facilities and municipal infrastructure alike.  

The beauty of cool roofs lies in their scalability. They can be incorporated into new developments or retrofitted onto existing structures. With supportive policies and planning frameworks, cities can adopt cool roofs as standard, with the benefits being cumulative. Each cool roof adds to the collective impact, lowering local temperatures, easing demand on cooling systems, and improving quality of life for residents. It’s an opportunity to deliver climate action that is visible, measurable, and immediately effective. 

The future of our cities will be shaped by how we respond to rising temperatures and evolving climate risks. Cool roofs are not a silver bullet – but they are a smart, proven, and accessible solution. As part of a broader strategy to create climate-resilient urban environments, they tick multiple boxes: sustainability, affordability, public health, and performance. The question now is not whether we can afford to invest in cool roofs, but whether we can afford not to. 

www.sika.co.uk/roofing