Green roofs

Green roofs collect, evaporate and detain rainwater. In this way, large amounts of water are diverted away from sewer systems and wastewater treatment plants. Green roofs are heavy, in particular when they retain water. The structural design of the building therefore has to be tailored to a heavy roof. A green roof can be established on top of existing as well as new buildings. However, the roof must have a slope of less than 30 degrees.

Green roofs have also demonstrated beneficial effects on the climate in cities, because the increased evaporation reduces local temperature rises. Ultraviolet radiation has a destructive effect on traditional roofs and building materials, whereas green roofs protect the building against ultraviolet radiation. The durability of roofs that have been built and designed correctly is therefore longer than for most conventional roof structures.