Green Roofs in Germany

Germany is widely regarded as the birthplace of the modern green roof industry. Lightweight green roof systems were developed there in the 1960s, and by the 1970s stormwater problems in growing cities encouraged their wider use. Germany was the first country to develop and market green roofs on a large scale, and its technical guidelines have influenced practice worldwide.

Technical guidelines

The FLL (Forschungsgesellschaft Landschaftsentwicklung Landschaftsbau, the Landscape Research, Development and Construction Society) was founded in 1975. Its green roof working group produced guidelines covering design, construction and maintenance; the current Green Roof Guideline was published in 2011, and an English edition exists. The FLL guidelines are used or adapted in many countries that lack their own standards.

Scale

Published estimates suggest that about 10 percent of German roofs have been greened and that about 10 million square metres (roughly 108 million square feet) of new green roofs are built each year, around three-quarters of them extensive and one-quarter roof gardens.

Policy approach

By the early 2000s, many German metropolitan areas had laws requiring green roofs, and nearly a third of German cities have regulations supporting green roofs and rainwater technology. Requirements are typically set locally rather than nationally, so rules differ from city to city.

Influence abroad

German manufacturers, research and guidelines shaped early green roof markets elsewhere in Europe and North America. Cities such as Basel in neighbouring Switzerland developed their own requirements, adding biodiversity criteria.

Stormwater emphasis

German green roof policy grew largely out of stormwater management. Green roofs can retain up to about 75 percent of rainfall and slow the remainder, reducing peak flows to sewers. This link to water management is one reason many German regulations treat green roofs together with other rainwater technologies.