MIT News reports on a study done on Boston and Phoenix that found that changing our traditional dark asphalt road surfaces to something lighter could reduce the urban "heat island" effect and in turn reduce local greenhouse emissions.
The researchers reported that, at least in Boston, switching to lighter, stiffer and smoother surfaces, such as concrete made with light-colored binders, could reduce overall temperatures by as much as 3 degrees and mean less greenhouse-gas emissions both by reducing the energy vehicles need to traverse the road and by reducing the need for cooling in neighboring buildings. Such savings are possible in part based on how much of our land surface is covered by asphalt.
The researchers emphasized, though, that it's not as easy as just replacing all the asphalt with concrete because in some spots, that could increase air-conditioning costs in buildings that have a lot of that sunlight reflected from the roads onto them. Also, unlike in Phoenix, cooling in the winter is not what we want to see in Boston, so the right pavement would have to be selected on a block by block basis, they say.
Achieving these savings, however, requires that cool pavement strategies be selected according to the climate, traffic, and building configurations of each neighborhood.
They add that the cladding on buildings could also be part of the strategy to reflect the sun's energy back into space rather than along the ground.