Urban heat management: materials and design strategies for cooler cities

Across the world’s urban centres (including towns and cities in the UK) rising temperatures, expanding paved landscapes and denser development have made summers noticeably hotter for residents, workers and visitors alike. This phenomenon, known as the urban heat island effect, occurs when dark, impervious surfaces such as roads and rooftops absorb and re-emit heat, making city temperatures higher than in surrounding rural areas.

Reducing that heat is not just a comfort issue; it is a matter of public health, energy demand and environmental resilience. Effective urban heat management hinges on smart design and material choices (from reflective surfaces to green infrastructure) which keep cities cooler without relying solely on energy-intensive air conditioning.

Why cities get hotter and why it matters

Cities are hotter not just because of buildings and people, but because of the materials we use and the spaces we design. Dark surfaces such as asphalt and conventional roofs absorb a large fraction of solar energy and re-emit it as heat. This trapped energy contributes to causing a rise in ambient temperatures, especially during heatwaves, and increases stress on energy systems as people turn to cooling devices to stay comfortable. Conversely, reflecting or reducing heat at the surface level can make measurable differences in surface and air temperatures.

Material strategies which help cities stay cooler

Reflective and “cool” surfaces

Using materials with high albedo (the ability to reflect solar radiation rather than absorb it) is one of the most direct ways to reduce surface heat. Light-coloured paints on roofs and walls, “cool roof” timber claddings and reflective finishings can all reduce surface temperatures and even lower indoor cooling loads. These surface treatments not only mitigate heat gain in buildings but also help lower heat radiating into streets and public spaces.

Green roofs and green walls

Integrating vegetation into rooftops and façades is a powerful way to combat urban heat. Green roofs (covered with plants and soil) not only provide insulation for buildings but also cool surrounding air through evapotranspiration, where moisture evaporates from leaves and soil, drawing heat out of the environment. Green roofs can be significantly cooler than conventional roofs and reduce surface temperatures dramatically in summer months. Similarly, green walls bring vegetation vertically onto façades, helping shade buildings and lower immediate microclimate temperatures.

Cool and permeable pavements

Traditional asphalt retains heat which continues to radiate long after the sun sets. In contrast, cool pavements (using lighter colours, reflective coatings or permeable surfaces) can reduce surface and air temperatures while allowing rainfall to infiltrate, which also aids stormwater management. Permeable pavements which allow water to evaporate from the surface contribute to cooling through latent heat flux, helping streets feel cooler on hot days.

Water and blue infrastructure

Incorporating water features (ponds, fountains or engineered waterways) can create local “cool islands.” Water cools its surroundings through evaporation, and when combined with green spaces, these blue-green systems can lower temperatures at the pedestrian scale and improve comfort in parks, plazas and urban centres.

Design strategies that complement materials

Materials are only part of the picture. A holistic approach to cooler cities also involves design thinking which maximises shade, airflow and natural thermal regulation:

• Urban tree canopy and park networks: Trees provide shade and cool the air through transpiration. Urban forests and park corridors can significantly reduce neighbourhood temperatures and improve comfort for people on streets and in open spaces.
• Building orientation and shading: Thoughtful orientation of buildings and incorporation of shading devices (such as brise-soleil and awnings) help reduce solar gain on façades and outdoor spaces, reducing heat absorption in critical areas.
• Street geometry and ventilation: Designing streets which align with prevailing winds and incorporating generous spacing between blocks can enhance airflow, helping dissipate heat more effectively than tightly packed, canyon-like streets.

Human-centred outcomes of effective heat management

Urban heat management has real impacts on people’s lives. Reducing extreme surface and air temperatures improves outdoor comfort for pedestrians, cuts energy demand for cooling, reduces heat-related health risks and supports more equitable urban environments where vulnerable communities are not left to bear the brunt of heat stress. Strategic material and design choices can help cities adapt as heatwaves become more frequent and intense with climate change.

The role of policy and planning

Cities around the world are beginning to integrate heat management into planning policies and sustainability frameworks. By aligning public infrastructure investment with materials and design strategies which cool cities naturally, local authorities can make long-term, resilient improvements which benefit communities now and in the future.

Final thoughts

Urban heat management is a multidisciplinary effort which blends material innovation, design strategy and landscape thinking. From reflective surfaces and cool pavements to green roofs, trees and water-informed design, cities have a growing toolbox of effective, sustainable ways to keep temperatures down and urban life comfortable. As cities continue to grow and climates warm, integrating these strategies into everyday planning and construction will be central to creating healthier, more resilient places for everyone.