Both extensive and intensive rooftop greenery forms a microclimate, thereby improving urban and room climate.
Numerous national and international scientific studies exist on the subject of rooftop greenery, and they come to a shared conclusion: Green rooftops offer multiple benefits for humanity and nature. In addition to the ecological pluses of acoustic and thermal insulation, a green rooftop also filters dust and pollutants, thus ensuring a good urban climate.
Some 130 hectares of nature are sealed over in Germany every day, an area equivalent to around 200 football pitches, day after day.
Every day, an incredibly large expanse of nature is sealed over in Germany alone through asphalt surfacing on streets, concrete work on buildings and surfaces and metal on quite a lot of roofs.
After initial hesitation, our policy makers have also been dealing with this topic for some time now. All over Germany, conditions are being imposed on developers when their planning applications are approved. For example, with a provision that when a flat-roofed garage is built, it must be provided subsequently with a green rooftop. However, new construction or modification of flat roofs in industrial estates is also affected by this regulation. Some German federal states promote the implementation of green rooftops through a very wide range of incentive programmes. Owing to the fact that construction law falls within the purview of the respective local administration, an inquiry to the responsible office can indeed have a positive effect.
The primary task of a rooftop garden is to ease the burden on the sewerage system.
A rooftop garden insulates and naturally protects a roof against wind, hail and extreme temperatures. The primary task of a rooftop garden, however, is to ease the burden on the sewerage system. Under heavy rainfall conditions, the downpouring water is unable to seep away into surfaces that have been sealed over with asphalt, concrete or metal. The only solution is to channel it into the sewerage system. If the sewers and retaining basins are full, the effluent water causes flooding.
A green roof, on the other hand, collects the rain. Some of it is soaked up by the rooftop garden and some of it is slowed down or released into the sewerage system on a delayed basis. This eases the burden on the sewerage system. In an area with numerous rooftop gardens, a noticeable easing of the burden on the sewerage system can be observed.