Question 1

What is MEER?

Accepted Answer

MEER is an independent nonprofit research organisation developing practical, science-based approaches to reducing extreme heat. We combine climate science, materials research and community-based deployments to help protect people, ecosystems and infrastructure from a warming world.

Question 2

What does MEER stand for?

Accepted Answer

MEER stands for Mirrors for Earth's Energy Rebalancing — a reference to the underlying idea that reflecting a small additional fraction of incoming sunlight can help offset part of the heat currently trapped by greenhouse gases.

Question 3

Why is extreme heat becoming such an important issue?

Accepted Answer

Global average temperatures are rising, but the more urgent problem is the increasing frequency, duration and intensity of extreme heat events. Heat is now the deadliest weather hazard in many regions and threatens health, food systems, water resources, labour and infrastructure.

Question 4

How is MEER different from other climate organisations?

Accepted Answer

MEER focuses specifically on surface-based cooling — the physics of how sunlight is reflected, absorbed and re-radiated at the Earth's surface — and translates that science into field deployments with local partners. We are not a substitute for reducing emissions; we are a complementary adaptation and mitigation effort.

Question 5

Where does MEER work?

Accepted Answer

MEER's field research and deployment sites are in Sierra Leone, India, China and The Gambia. Alongside these, MEER operates from administrative bases in the United Kingdom and Japan, and its registered nonprofit headquarters is in the United States. Every field site is co-designed with local scientific and community partners.

Question 6

How does sunlight heat the Earth?

Accepted Answer

Sunlight arrives as shortwave radiation across visible, ultraviolet and near-infrared wavelengths. When it strikes a surface, part is reflected back to space and part is absorbed. Absorbed sunlight is converted into heat, which then warms the surface, the air above it and eventually the wider environment.

Question 7

Why do surfaces become hotter than the surrounding air?

Accepted Answer

Air is largely transparent to sunlight, so it is not heated directly. Surfaces absorb sunlight and heat up first — often to 30–50 °C above air temperature for dark materials in direct sun — and then transfer that heat into the surrounding air by conduction, convection and infrared radiation.

Question 8

What is the Earth's Energy Imbalance?

Accepted Answer

Earth currently absorbs more energy from the Sun than it radiates back to space. This difference — the Earth's Energy Imbalance (EEI) — is the fundamental driver of global warming. Reducing the imbalance requires either less absorbed sunlight or more outgoing heat.

Question 9

What is the surface energy balance?

Accepted Answer

The surface energy balance describes how energy received by a surface is distributed through net radiation, sensible heat exchange with air, latent heat associated with evaporation and transpiration, and conduction and storage in the surface and underlying materials. Their relative contributions vary with conditions, and heat exchange can occur in either direction.

Question 10

What is albedo?

Accepted Answer

Albedo is the fraction of incoming sunlight that a surface reflects, measured from 0 (perfectly absorbing) to 1 (perfectly reflecting). Fresh snow has an albedo near 0.85, while black asphalt can be as low as 0.05.

Question 11

What is solar reflectance?

Accepted Answer

Solar reflectance is a more precise engineering term for albedo weighted across the solar spectrum. It measures how much of the Sun's actual energy — not just visible brightness — a surface reflects.

Question 12

Why isn't white paint always enough?

Accepted Answer

A surface can look white to human eyes yet still absorb large amounts of invisible near-infrared sunlight. True cooling surfaces are engineered to reflect across the full solar spectrum and to emit strongly in the thermal infrared, which ordinary white paints often do not.

Question 13

What is near-infrared radiation?

Accepted Answer

Near-infrared (NIR) is the portion of sunlight just beyond visible red light. It carries roughly half of the Sun's energy but is invisible, so a surface that looks bright can still absorb significant NIR and become hot.

Question 14

What is thermal infrared radiation?

Accepted Answer

Objects emit thermal radiation according to their temperature and emissivity. Surfaces near everyday Earth temperatures emit over a broad infrared spectrum, including wavelengths within the approximately 8–13 µm atmospheric window. This window is relatively transparent under suitable conditions, not a perfect opening in the atmosphere.

Question 15

What is the atmospheric window?

Accepted Answer

The atmospheric window is an approximately 8–13 µm range of longwave infrared wavelengths where the atmosphere can be relatively transparent. Some surface emission can reach space through this range, but transmission varies with wavelength, humidity and clouds. Net cooling depends on all energy gains and losses.

Question 16

What is sensible heat?

Accepted Answer

Sensible heat is thermal energy exchanged between surfaces and air through contact and air movement, including turbulence. It can flow in either direction, depending on temperature differences and conditions.

Question 17

What is latent heat?

Accepted Answer

Latent heat is energy absorbed or released when water changes phase. Evaporation absorbs energy and condensation releases it. Transpiration moves water from plants to the atmosphere and contributes to evapotranspiration.

Question 18

Why is measuring temperature alone insufficient?

Accepted Answer

Temperature describes the thermal state of a surface or environment, not the rates or pathways of energy transfer. Similar temperatures can occur with different radiative, sensible, latent and stored-energy exchanges. A temperature reduction alone does not quantify these changes.

Question 19

What is passive cooling?

Accepted Answer

Passive cooling reduces the temperature of a surface, building or space using the physical properties of materials rather than mechanical systems. It relies on reflection, emission, shading, insulation and airflow — not electricity or refrigerants.

Question 20

How is passive cooling different from air conditioning?

Accepted Answer

Air conditioning moves heat that has already entered a space, using energy and refrigerants and often venting heat outdoors. Passive cooling prevents heat from being absorbed in the first place, or helps release it back to the sky, without any active energy input.

Question 21

Why prevent heat rather than remove it later?

Accepted Answer

Preventing absorption is far more efficient than removing heat afterwards. Every unit of solar energy reflected before it is absorbed avoids the compounding costs of hotter indoor air, higher electricity demand, greater equipment wear and increased outdoor heat rejection.

Question 22

Does passive cooling use electricity?

Accepted Answer

No. Reflective and radiative cooling surfaces operate purely on the optical properties of the material. They require no power, moving parts or refrigerants and continue working during blackouts and in off-grid locations.

Question 23

What is radiative cooling?

Accepted Answer

Radiative cooling is the natural process by which any object loses heat by emitting thermal infrared radiation. When a surface can emit more energy than it receives, it cools — sometimes to below the surrounding air temperature.

Question 24

Can heat really escape directly into space?

Accepted Answer

Some longwave thermal radiation from the surface can reach space through relatively transparent atmospheric wavelengths. The atmosphere also absorbs and emits radiation, including within the window. Cooling depends on atmospheric conditions and the overall surface energy balance, not simply on the temperature of deep space.

Question 25

Does radiative cooling work during the day?

Accepted Answer

Surfaces emit thermal radiation during both day and night. Passive daytime radiative cooling combines high solar reflectivity with thermal emission to limit heat gains and support heat loss. Below-air-temperature cooling is possible under suitable conditions, but depends on weather, surroundings and material properties.

Question 26

How do reflective and radiative cooling work together?

Accepted Answer

Reflection reduces absorption of incoming shortwave sunlight. Thermal emission releases energy as longwave radiation. These are different mechanisms; a surface can combine them, but its net cooling also depends on atmospheric radiation, heat exchange with air, conduction and other energy transfers.

Question 27

What is Passive Daytime Radiative Cooling (PDRC)?

Accepted Answer

Passive Daytime Radiative Cooling (PDRC) is cooling through net longwave radiative heat loss during the day without powered refrigeration. High solar reflectivity limits absorbed sunlight, while thermal emission, including within the approximately 8–13 µm atmospheric window, supports radiative heat loss. Performance depends on the material and environmental conditions.

Question 28

Why are advanced cooling materials different from ordinary paint?

Accepted Answer

Ordinary white paints are optimised for visible whiteness, not full-spectrum solar reflectance or infrared emission. PDRC materials are engineered at the microscale to control how they interact with each part of the solar and thermal spectrum.

Question 29

Are these materials still being developed?

Accepted Answer

Yes. PDRC is a rapidly advancing field. Researchers are improving durability, cost, colour options and manufacturability, and MEER's work contributes real-world data on how these materials perform under harsh field conditions.

Question 30

What is a reflective canopy?

Accepted Answer

A reflective canopy is an engineered overhead structure that reflects incoming sunlight while allowing air to circulate freely underneath. Unlike a simple shade cloth, it is designed to send solar energy back skyward rather than absorbing and re-radiating it downward.

Question 31

How is it different from ordinary shade?

Accepted Answer

Ordinary shade blocks direct sunlight but the shading material itself absorbs energy and heats up, then re-radiates warmth to whatever is beneath. A reflective canopy stays cooler and re-radiates far less heat downward.

Question 32

Why is reflecting sunlight better than simply blocking it?

Accepted Answer

Reflected sunlight leaves the local system entirely. Blocked sunlight becomes heat that must eventually be released — often into the same environment you were trying to cool.

Question 33

Where could canopy systems be used?

Accepted Answer

Potential applications include schoolyards, markets, transit stops, informal settlements, working yards, livestock shelters and agricultural fields — anywhere people, animals or crops are exposed to intense direct sun.

Question 34

What is an Urban Heat Island?

Accepted Answer

An Urban Heat Island (UHI) is the tendency of built-up areas to be warmer than surrounding rural land. Dark roofs and pavements absorb sunlight during the day, then release heat slowly through the night, keeping cities hot long after sunset.

Question 35

Why do cities stay hot after sunset?

Accepted Answer

Massive amounts of concrete, asphalt and masonry store heat during the day and release it gradually overnight. Combined with waste heat from vehicles and buildings and reduced sky exposure between tall structures, this keeps urban air significantly warmer than the surrounding countryside.

Question 36

How can reflective roofs help?

Accepted Answer

Increasing roof reflectance reduces the heat absorbed by buildings, lowers indoor temperatures, cuts cooling energy demand and, at scale, measurably reduces neighbourhood-level air temperatures.

Question 37

How can public spaces be cooled?

Accepted Answer

By combining reflective surfaces, engineered canopies, trees, water features and thoughtful materials selection, public spaces can be made dramatically cooler even without changing the underlying climate.

Question 38

What role do canopy systems play?

Accepted Answer

Canopies provide immediate, localised relief in places where planting mature trees or rebuilding infrastructure is not possible. They can be deployed quickly and adapted to schools, markets, health facilities and informal settlements.

Question 39

Why do crops suffer during extreme heat?

Accepted Answer

High temperatures disrupt photosynthesis, accelerate water loss, damage pollen and stress plants during critical growth stages. Even short heat events at the wrong moment can significantly reduce yields.

Question 40

Can cooler soils improve growing conditions?

Accepted Answer

Yes. Cooler soils retain more moisture, support healthier microbial communities and reduce heat stress on roots. Modifying the surface energy balance of farmland can meaningfully improve conditions for many crops.

Question 41

How can canopy systems help agriculture?

Accepted Answer

Reflective canopies can moderate temperature extremes over crops and livestock, reduce evaporation from soils and provide a controllable microclimate that improves resilience during heatwaves.

Question 42

Why do reservoirs lose water through evaporation?

Accepted Answer

Sunlight heats the water surface and drives evaporation, particularly in hot, dry and windy conditions. In arid regions, evaporation can remove a substantial fraction of stored water each year.

Question 43

Can reflective systems reduce evaporation?

Accepted Answer

Yes. Floating reflective covers reduce the sunlight reaching the water, lower surface temperature and cut evaporation dramatically — while also limiting algal growth in some conditions.

Question 44

Can water be cooled without mechanical systems?

Accepted Answer

Yes. By reducing solar gain at the surface and, in some designs, allowing radiative cooling to the sky, water bodies can be kept meaningfully cooler without pumps, chillers or electricity.

Question 45

Why can two places with the same air temperature feel completely different?

Accepted Answer

Human thermal comfort depends on much more than air temperature. Radiant heat from surfaces, humidity, wind and direct sunlight all combine to determine what a body actually experiences.

Question 46

What is radiant heat?

Accepted Answer

Radiant heat is infrared energy emitted by warm surfaces — walls, pavement, roofs, vehicles. On a hot day, standing next to sunlit asphalt can feel dramatically hotter than standing under a reflective canopy at the same air temperature.

Question 47

Why is shade so effective?

Accepted Answer

Shade removes direct solar radiation from the body, which is often the single largest heat load a person experiences outdoors. A reflective shade also reduces the radiant heat coming from the shading structure itself.

Question 48

What is heat stress?

Accepted Answer

Heat stress occurs when the body cannot shed heat fast enough to maintain a safe internal temperature. It ranges from discomfort and reduced performance to heat exhaustion, heatstroke and death.

Question 49

What is Wet Bulb Globe Temperature (WBGT)?

Accepted Answer

WBGT is a heat-stress index that combines air temperature, humidity, wind and radiant heat into a single number. It is widely used in occupational health, sports and military settings to guide safe activity limits.

Question 50

What is Mean Radiant Temperature (MRT)?

Accepted Answer

MRT is the average temperature of all the surfaces radiating heat to a person. In sunlit urban environments MRT can be far higher than air temperature and is often the dominant driver of outdoor thermal discomfort.

Question 51

How are MEER technologies tested?

Accepted Answer

Materials are characterised in the lab for solar reflectance, thermal emissivity and durability, then deployed in real-world conditions with instrumentation that tracks surface and air temperatures, humidity and long-term weathering.

Question 52

Are projects monitored over time?

Accepted Answer

Yes. Field sites are monitored across seasons and years, in collaboration with local scientific partners, to understand real-world performance and how materials age under UV, humidity, salt and pollution.

Question 53

Does MEER publish research?

Accepted Answer

Yes. MEER and its partners publish in peer-reviewed journals, share technical notes and release open datasets so that methods and results can be independently reviewed and reused.

Question 54

Why is MEER researching heat and energy exchanges?

Accepted Answer

Understanding how heat and energy move through the environment supports scientific evaluation of passive cooling technologies and research into climate adaptation and environmental resilience. It helps assess why an intervention works, the conditions in which it may be effective and its limitations.

Question 55

Who funds MEER?

Accepted Answer

MEER is supported by individuals, charitable foundations, research institutions and grant-making organisations that share our mission to reduce the impacts of extreme heat.

Question 56

Is MEER independent?

Accepted Answer

Yes. MEER's research, scientific conclusions, operational priorities and public communications are entirely independent of any funder.

Question 57

Can companies influence MEER's research?

Accepted Answer

No. All support is accepted on the condition that it does not influence our science or decision-making, and we reserve the right to decline funding that could compromise — or appear to compromise — our independence.

Question 58

How does MEER maintain scientific independence?

Accepted Answer

Through transparent funding practices, open publication of methods and data, ethical funding review and collaboration with independent research institutions.

Question 59

What technologies is MEER currently developing?

Accepted Answer

MEER's active work includes reflective roof and pavement systems, engineered canopies for people and crops, floating systems for water bodies, and next-generation passive daytime radiative cooling materials.

Question 60

Where is MEER working?

Accepted Answer

MEER's field research and deployment sites are in Sierra Leone, India, China and The Gambia, with additional partnerships being explored in regions facing severe heat exposure. The United Kingdom and Japan host administrative bases, and MEER's registered nonprofit headquarters is in the United States.

Question 61

How can I support MEER's work?

Accepted Answer

You can support MEER by donating, partnering on a research or deployment project, or helping spread accurate information about heat and surface cooling. Individuals, foundations and institutions are all welcome.

Answers to the questions
we hear most often.

General

The Science

Passive Cooling

Radiative Cooling

PDRC Materials

Reflective Canopies

Urban Cooling

Agriculture

Water Cooling

Human Heat & Health

Research

Funding & Independence

Future