Description: Temperatures in urban areas are rising as a result of climate change. In Los Angeles, the Bureau of Street Services conducted a pilot study in 2017 to investigate the cooling effect of light-colored pavement coating. The project involved applying a light gray, water-based coating onto the pavement that absorbs less heat than its darker asphalt counterpart. Results from the study showed a cooling effect of greater than 10 degrees F. The goals include reducing the risk of heat-related deaths and reducing energy use for air conditioning.
After seeing a difference of 11-13 degrees Fahrenheit on the coated streets, Los Angeles and other cities plan on implementing more reflective roofs and pavements to reduce the impacts of “heat islands.”
The reduced urban temperatures resulting from the “Cool Streets LA” program, launched in 2019, will enable the City to meet a number of additional goals set forth in Mayor Garcetti’s Green New Deal, such as: reducing urban/rural temperature differential by at least 1.7 degrees by 2025 and 3 degrees by 2035; increasing tree canopy in areas of greatest need by at least 50% by 2028; and installing cool pavement material on 250 lane miles of the City’s streets.
Goal: Reduce heat island effect and thereby reduce energy use for air conditioning
Measurement: Reduced air temperature and reduced heat island effect
Time to Implement: LA’s 2015 “Sustainable City Plan” calls for a reduction of urban-rural temperature differentials of 3 degrees by 2035
Links:
Los Angeles Painting the Streets White…Again
https://www.archdaily.com/893171/los-angeles-is-painting-the-streets-white-again-and-your-city-might-be-next
Cool pavement in Los Angeles
https://gizmodo.com/the-radical-plan-to-cool-down-la-as-the-world-heats-up-1797711611
Mayor Kicks Off Second Phase of “Cool Streets LA” Program
https://www.lamayor.org/mayor-garcetti-kicks-second-phase-cool-streets-la-program
Additional Information:
The Environmental Protection Agency defines a “heat island” as a place where open land and vegetation are replaced with infrastructure, buildings and roads. Development patterns that replace naturally occurring, more moist and permeable environments with buildings, roads, and other infrastructure causes dense urban regions to become much warmer than the surrounding areas. Conventional road and roof surfaces can often be more than 50-90 degrees Fahrenheit warmer than the air temperature. The net result is that daytime temperatures in urban areas are about 1–7°F higher than temperatures in outlying areas and nighttime temperatures are about 2-5°F higher.
Reduction of urban-rural temperature differential relies on requiring lighter-colored roofs on new & renovated buildings and increasing tree canopy, in addition to cool pavements.
Learn About Heat Islands – EPA website
https://www.epa.gov/heatislands/learn-about-heat-islands
Contact Info:
Department of Public Works
City of Los Angeles
Email: Bureau of Street Services
1149 South Broadway, 4th floor
Los Angeles, CA 90015