Studies show that different plants cool off landscapes in different ways. The classic example is trees, because of course shade is cooler than sun. Beyond that, though, plants go through a process called evapotranspiration. Simply speaking, plants release water into the air, cooling things off.
In theory, different plants cause different amounts of cooling. Studies, such as the one below from Cooling Cities, Natural Areas Conservancy, 2003, show that even switching from lawn to a grassland can cause a temperature drop of 4°F!
With the expertise of Dr. Natalie Love of the Chicago Botanic Garden, we are collecting temperature and humidity data at city parks all over Chicago to see what kind of landscape helps cool off our city.
Rethinking Lawns 