Reduction of Urban Heat Island – Research in Tyndale Centre for climate change suggests we need a 10% increase in green space in our cities to combat climate change. This is particularly relevant to the reduction in the Urban Heat Island [UHIE]. Green roofs are recognized to have a positive effect on reducing the UHIE
Biodiversity – Green roofs can provide important refuges for wildlife in urban areas. Research in Switzerland and the UK has demonstrated that green roofs can provide important refuges for rare invertebrate populations.
Water – Green roofs can significantly reduce the surface run off volumes and rates of rainfall leaving roofs. As a source control mechanism in the Sustainable Urban Drainage System green roofs can help reduce flash floods as a consequence of intense rainfall events. This will become increasingly important as a consequence of climate change.
Green roofs also improve the quality of water and although the amount of water is reduced it is possible to rainfall harvest from roofs that have been greened.
Thermal Performance – Green roofs cannot be given a U-value at present. However they have been shown to significantly reduce the need for air conditioning in summer and can provide a degree of insulation in winter.
Sound Insulation – The combination of soil, plants and trapped layers of air within green roof systems can act as a sound insulation barrier. Sound waves are absorbed, reflected or deflected. The growing medium tends to block lower sound frequencies whilst the plants block higher frequencies.
Protection of Waterproofing – The original green roofs in Germany stem from covering wet bitumen with 6cm of sand, which became vegetated. This covering was to protect the wet bitumen from fire. Green roofs have now been shown to double if not triple the life of waterproofing membranes beneath the green roof.
Air Quality – airborne particles and pollutants are filtered from the atmosphere by the substrates and vegetation on a green roof.
Amenity Space – in dense urban environments there is often a lack of green space for residents. Roof Gardens and roof top parks provide important green spaces to improve the quality of life for urban residents.
Urban Agriculture – Urban Rooftop Food Growing – roofs, where strong enough provide a space for urban food growing. Although many large flat roofs may not have the loading capabilities to hold food growing some roofs will and the many balconies in are urban areas are ideal.