Neighborhoods with more trees and green space stay cooler, while those coated with layers of asphalt swelter. Lower-income neighborhoods tend to be hottest, a city report found, and they have the least tree canopy.
The same is true in cities across the country, where poor and minority neighborhoods disproportionately suffer the consequences of rising temperatures. Research shows the temperatures in a single city, from Portland, Oregon, to Baltimore, can vary by up to 20 degrees. For a resident in a leafy suburb, a steamy summer day may feel uncomfortable. But for their friend a few neighborhoods over, it’s more than uncomfortable — it’s dangerous.
An increase in the number of solar cells in an area can be useful, but shade cover from trees would have a greater cooling effect on most areas. Trees both shade and provide transpiration cooling. The water evaporating from leaves cools the surrounding air as the water goes from a liquid to gas phase.
And just like solar panels, trees harvest a part of the energy in sunlight, giving additional cooling to just a shade. And trees are cheaper to set up, even if they may not provide a return on electricity.
Ideally you would have trees on the ground and solar panels on the roofs, to further increase cooling.