Can Painting City Streets Reduce the Urban Heat Island Effect?

The impervious surfaces in a city such as streets, parking lots, and buildings absorb solar radiation during the day.  This absorption of heat from the sun creates higher temperatures than adjacent vegetative areas.  This phenomenon is known as the Urban Heat Island Effect.  During the summer months, urban heat islands can create higher temperature conditions that are 1-3°C (2-5°F) warmer than in nearby rural areas.  Higher temperatures result in higher energy costs from increased air conditioner use and high air pollution [1].

Cool Pavement Pilot Project in Los Angeles

The City of Los Angeles is experimenting with lowering the urban heat island effect by painting its streets a lighter color with a pilot project known as “Cool Pavement” [2].  A light gray reflective paint called CoolSeal will be applied to the majority of streets in Los Angeles in an effort to lower road temperatures across the city by up to ten degrees Fahrenheit.  The light gray paint boosts solar reflectively and reduces the overall temperature of road surfaces.  The CoolSeal coating costs $40,000 per mile and last seven years.  Painting the streets is part of a multi-pronged that includes cool roofs and more vegetation to reduce the overall summer temperature of Los Angeles by three degrees Fahrenheit [3].

References

[1] Akbari H, Menon S, Rosenfeld A. 2009. Global cooling: increasing world-wide urban albedos to offset CO₂. Climatic Change, 94 (3-4), 275-286.

[2] Los Angeles Tests Whether Lighter Color Streets Will Lower The Temperature.  NPR.org, August 23, 2017

[3] L.A.’s mayor wants to lower the city’s temperature. These scientists are figuring out how to do it. Los Angeles Times, February 9, 2017

See Also

• Vegetation Helps to Lessen the Effects of Urban Heat Islands
• The Urban Heat Island Effect is Triggering Larger and More Spiders
• Hot Cities Getting Hotter in the US