Plants have the ability to reduce the overall heat absorption of a roofs surface, which results in less energy consumption. Plant surfaces do not rise more than four to five degrees Celsius above the ambient. By cooling the surface area the plants also affect the temperature of the air. The plants cool the air by evaporating water in a process known as evapotranspiration.
The Bioscience magazine, which conducted years of studies, reported that roof gardens can cut heat loss from a building as much as 50%, and reduce air conditioning cost by as much as 25%. Roof gardens provide excellent resistance to thermal radiation, and the top layer of plants can shield as much as 88% of solar radiation. The benefits of a roof garden have been backed by the US Green Building Council's endorsements of the systems though the LEED (Leadership in Energy and Environmental Design) certification program.
Energy efficiency year round
Adds valuable useful space, while providing economic benefits