Increasing the solar reflectance and vegetative cover in urban areas cools temperatures, while reducing air pollution and energy consumption.
Urban development – increased human activity with land paved and covered with buildings – generates a “heat island effect”, an area warmer than its rural surroundings. In large cities, the average temperature difference can be 1-3°C (1.8-5.4°F), and as much as 12°C (22°F) on a clear, calm night.
- Reduce solar absorption – replace dark surfaces, black roofs, and asphalt paving, with “cool” or light colored surfaces.
- Increase tree canopy – each 10% increase in canopy cover reduces maximum mid-day air temperature about 1°C (1.8°F).
- Increase vegetative cover – vegetative pavement, green roofs, and grass and shrubs.
Plant street trees 6-12 meters (20-40 feet) apart; require parking areas to be at least 50% shaded.
Note: “cool” surfaces have a high solar reflectance, and possibly high thermal emittance.