Passive Cooling
Passive cooling lowers temperatures without any moving parts, refrigerants or power supply. It relies on physical properties — how surfaces reflect sunlight, how heat radiates to the sky, how air moves, how water evaporates.
Scientific detail
Passive cooling technologies exploit the natural thermodynamics of solar reflection (high albedo), radiative emission through the atmospheric window (8–13 μm), evaporative and convective transfer, and shading to reduce sensible and radiant heat gain on surfaces and in indoor environments. Because no electricity is required, passive strategies are resilient, low-maintenance and effective in energy-poor communities where active air-conditioning is unaffordable or unreliable.
Related terms
Passive Daytime Radiative Cooling
A material that stays cooler than the air even under direct sunlight by radiating heat to the cold sky.
Reflective Cooling
Cooling by bouncing sunlight away from a surface before it can be absorbed as heat.
Radiative Cooling
Heat loss from any object by emitting thermal infrared radiation.
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.
Reflective Reservoir Systems
Covering water reservoirs with reflective floating panels to cut evaporation and cool the surroundings.
Where this concept shows up on MEER
Related projects
- Freetown, Sierra Leone
Reflective rooftops across informal settlements.
- Pune, India
Rooftop reflective installations in dense urban housing.
- California, USA
Rooftop mirror arrays measuring cooling potential.
- Tanzania
Community-scale reflective interventions.
- Beijing, China
Urban rooftop deployments.
Related publications
Related stories
- News & stories
- Human stories
First-person accounts of life inside extreme heat.
Related MEERTalks
- MEERTalks
Recorded conversations with scientists and partners.
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.
Passive Cooling
Everything MEER publishes on passive cooling — reflective roofs, PDRC materials, canopies, reservoir systems, projects, publications and stories, gathered in one place.
Radiative Cooling & PDRC
PDRC materials, the atmospheric window, thermal emittance and the practical engineering of surfaces that radiate heat directly to deep space.
Water & Cooling
How passive cooling and reflective materials protect water resources: reservoir systems, evaporation reduction, and the hydrological co-benefits of surface cooling.
Agriculture & Cooling
How reflective materials, canopies and passive cooling protect agricultural yields, livestock and rural livelihoods under extreme heat.
Climate Adaptation
MEER's approach to climate adaptation: adaptive mitigation, radiative forcing, resilience, and the policy context around passive surface cooling.
Communities & Stories
Human stories, community reporting and field partnerships that ground MEER's science in the lives of the people most exposed to extreme heat.