Cool Pavements

Like conventional dark roofs, dark pavements get hot in the sun because they absorb 80 – 95% of sunlight. Hot pavements aggravate urban heat islands by warming the local air and contribute to global warming by radiating heat into the atmosphere. When temperatures in Southern California rise above 100 degrees Fahrenheit, surface temperatures on its asphalt roads can climb to 150. Solar reflective “cool” pavements stay cooler in the sun than traditional pavements. Pavement reflectance can be enhanced by using reflective aggregate, a reflective or clear binder, or a reflective surface coating.

Why use this strategy?

Some of the benefits of cool pavements include energy savings and emissions reductions; improved comfort and health; increased driver safety; improved air quality; reduced street lighting costs; reduced power plant emissions; improved water quality; and slowed climate change. Cool pavements lower the outside air temperature, allowing air conditioners to cool buildings with less energy, while also reducing the need for electric street lighting at night. Cool pavements also reduce heat-related illnesses, while slowing the formation of smog – improving pedestrian comfort. Light-colored pavements reflect streetlights and vehicle headlights at night, which increases driving visibility and reduce the costs of street lighting at night.

Note that in some instances cool pavements may reflect more heat and light onto adjacent buildings making those buildings hotter. Also, the carbon footprint of the reflective paints used to make an originally low albedo pavement more reflective may be higher than the amount of carbon that would be saved by slightly lowering ambient temperatures for adjacent buildings. An important challenge is to create cool pavement materials that reduce life-cycle energy, carbon, and cost for the entire neighborhood where the pavement is located.

How to use it?

Consider using pervious concrete or porous asphalt to also provide a cool surface. Consider using a light-colored pavement surface, like concrete. Consider using specially formulated paints to increase the albedo of a darker pavement surface.

Where to learn more and who to contact?

Environmental Protection Agency cool pavement compendium:

Lawrence Berkeley National Laboratory:

City of Los Angeles Cool Pavement Pilot Project: