Topic hub·Cooling the city

Urban Heat

Cities absorb heat, store it and release it back at night. Reflective infrastructure is the fastest lever to bring urban temperatures down.

Typical urban heat-island uplift: +4-7°C
Global surface that is urban: ~2%
Of humanity lives in cities: >55%

Topics

Passive Cooling Heat Resilience Urban Heat Radiative Cooling & PDRC Albedo & Reflectivity Climate Science Water & Cooling Agriculture & Cooling Measurement & Data Climate Adaptation Communities & Stories

01

Understand the phenomenon

02

See it deployed

03

Measure & model

Key terms in this topic

Urban Heat IslandUHI
The phenomenon where cities are noticeably hotter than the surrounding countryside.
Cool Roofs (Reflective 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.
Albedo
The fraction of sunlight a surface reflects — 0 is black, 1 is a perfect mirror.
Mean Radiant TemperatureMRT
The average temperature of every surface radiating heat toward a person.
Wet Bulb Globe TemperatureWBGT
A composite heat index widely used to set safe limits for outdoor work, sport and military training.
Surface Energy Balance
The bookkeeping of energy flowing into and out of a surface at every moment.
Heat Stress
The thermal load a human body experiences from its environment.

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