Green roofs seem to be quite a well kept secret but they are simply vegetated layers that sit on top of the conventional waterproofed roof surfaces of buildings; they come in many different forms and types but usually a distinction is made between extensive, intensive and biodiverse or wildlife roofs. (For further details, please visit this page of the Green Roof Centre website.)
There are numerous benefits – including reduction of water run off volumes and improved air quality – associated with green roofs and researchers at Columbia University have recently shown that a green roof can cut the rate of heat absorption through the roof of a building in summer by 84%. (For further information about the research, please visit this environmentalresearchweb page.)
Green roofs experience less thermal expansion and contraction stress, leading to predictions of at least a doubling of lifespan compared to black roofs.