Urban Heat Island
Also known as: UHI
Dark roofs, asphalt roads, tightly packed buildings and lack of vegetation cause cities to trap and store solar heat. The result is that an urban core can be 5–10 °C hotter than nearby rural areas, especially at night.
Scientific detail
The urban heat-island (UHI) effect is driven by low urban albedo, low sky-view factor, high thermal mass, reduced evapotranspiration, and anthropogenic heat release. UHI intensity is typically greatest at night when stored heat re-radiates. Mitigation via cool roofs, reflective pavements and canopies has been shown in modeling and field studies to reduce peak UHI intensity by 1–3 °C in exposed districts.
Related terms
Albedo
The fraction of sunlight a surface reflects — 0 is black, 1 is a perfect mirror.
Cool Roofs (Reflective Roofs)
Roofs coated or built with high-reflectance materials so buildings absorb far less heat.
Reflective Canopies
Overhead structures with a reflective upper surface that shade people and land beneath.
Heat Stress
The thermal load a human body experiences from its environment.
Climate Adaptation
Actions that reduce harm from a changing climate here and now.
Where this concept shows up on MEER
Related projects
- Pune, India
Rooftop reflective installations in dense urban housing.
- Beijing, China
Urban rooftop deployments.
- California, USA
Rooftop mirror arrays measuring cooling potential.
Related publications
Related stories
- Human stories
First-person accounts of life inside extreme heat.
- News & stories
Related resources
In HeatLens
- HeatLens
Interactive heat-risk assessment tool.
Explore in topic hubs
Curated collections of MEER research, projects, publications and stories that feature this term.
Urban Heat
The urban heat-island effect, its measurement, and how MEER's reflective roofs, canopies and pavements reduce peak city temperatures and protect vulnerable urban populations.
Climate Adaptation
MEER's approach to climate adaptation: adaptive mitigation, radiative forcing, resilience, and the policy context around passive surface cooling.