In city areas that lack tree canopy cover, the sidewalks, streets, parking lots, and buildings absorb solar energy much more quickly. The lack of tree cover also significantly decreases the potential for evaporative cooling, thus leading to higher air temperatures. When waste heat from city buildings and vehicles is added to heat trapped between tall buildings, increased urban temperatures are the result.

Lawrence Berkeley Laboratory’s Urban Heat Island Group found that changing the heat absorption level of pavement can reduce overall temperatures. Cooler pavements also have longer lifetimes because they are not as stressed by the excessive heat.

Smog Benefit/Total Benefit

  • Smog generation in LA simulated with normal and reduced temperature due to cooler pavements:
    • 2.5% reduction in exceedance of 90 ppb AQ standard
    • Savings from reduced ozone pollution: $75 M/year when total cost was $3B/year (Hall et al., Science 1992)
  • Total savings due to cooler pavements:
    Energy $15 M/year
    Ozone $75 M/year
    Total $90 M/year
    • Annual savings per m2 pavement = $0.07
    • Present Value (5-year surface life) = $0.35 per m2
  • Surcost of a thin, reflective coating = $0.35 per m2