Planting the rooftops of urbanized areas brings many benefits to public, private, economic and social sectors, as well as to the local and global environments. While all green roofs have similar functions, each installation is unique, so technical performance will vary by region, climate, building and green roof type and design. The benefits described below can be achieved by virtually all green roof systems and designs.
Benefit: Green roofs reduce stormwater runoff
During heavy or continuous rain, runoff can overwhelm stormwater infrastructure and potentially damage waterways and fish habitat.
Benefit: Green roofs are energy efficient
Green roofs reduce the heat flux through the roof, and less energy for cooling or heating can lead to significant cost savings. Shading the outer surface of the building envelope has been shown to be more effective than internal insulation.
Plant leaves trap dust particles from the air, and evapotranspiration cools ambient temperatures.
Benefit: Green roofs can serve as habitat
As undisturbed areas, rooftops can serve as refuge for creatures that struggle for survival. Ground-nesting birds, such as Killdeer, use green roofs for nesting and raising their young.
Vegetated rooftop habitats can serve as stepping stones, to create corridors connecting other patches (roofscape or at grade) across an urban sea to natural habitats beyond the city.
Natural habitats can serve as templates for green roofs designed for biodiversity.
Low maintenance green roofs can be designed to serve as refuge for species such as ground-nesting birds.
Benefit: Green roofs last longer
Green roofs cover the waterproofing membrane, protecting it from UV rays and extreme daily temperature fluctuations. This protection extends the lifespan of the waterproofing twice as long as conventional roofing, meaning that membranes under green roofs last twice as long as those on traditional roofs.
Reduced material waste from re-roofing.
Less frequent re-roofing, less costs over time.
Courtesy: centre for architectural ecology