Providing a green space on a roof top is not a new idea, but modern technology has evolved to make green roofs an option on many projects that would not have previously considered them. In addition environmental concerns have helped to identify the greening of roof tops as an ideal way of reducing rainwater runoff, increase urban bio-diversity and reduce the urban heat island effect.
Why green roofs?
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.
benefits of Green Roofs:
Green roofs—sometimes referred to as ‘vegetated roofs’ or ‘eco-roofs’—consist of a waterproofing membrane, growing medium (soil) and vegetation (plants) overlying a traditional roof. Green roofs are used to achieve environmental benefits including reducing stormwater runoff, energy use, and the heat island effect.
By protecting the roof membrane, however, a green roof can extend the life of a roof by two or three times beyond its typical lifespan. In Europe, where they have been building with green roofs since the 1960s, green roofs have been known to last for from 30 to 50 years.
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. In summer, the green roof protects the building from direct solar heat.
A sedum roof is one type of living green roof. A green roof is a layer of vegetation (living plants) deliberately put on top of a conventional roof surface and bringing a whole host of benefits to the building and the environment.
On hot summer days, the surface temperature of a green roof can be cooler than the air temperature, whereas the surface of a conventional rooftop can be up to 90°F (50°C) warmer. Green roofs can be installed on a wide range of buildings, from industrial facilities to private residences.