Extension of services for assessing green roofing structures in terms of water retention capacity and their effect on the urban climate

Green roofs in urban areas
© Shutterstock/swissdrone
Green roofs increase the proportion of unsealed land in urban areas. Rainwater can seep into them and is stored instead of running off mostly as surface water.

Green roofs have a number of different properties, such as the ability to store rainwater. Consequently, they actively contribute to mitigating the consequences of climate change in cities.

Surveys conducted by municipal planning experts have shown that although the overall potential of greening is widely known, data and planning parameters for a concrete interpretation and impact assessment are still lacking. The Fraunhofer Institute for Building Physics IBP wants to remedy this problem through its research on green roofing structures.

Project goals

In the project, the experts working in the Department of Hygrothermics want to supplement their existing range of test facilities and simulation options at Fraunhofer IBP in order to record the rainwater retention capacity of green roofing structures on a time-dependent basis. The results of the tests are then incorporated into simulation tools. This enables the scientists to assess the impact of green roofs on the urban climate for a wide range of scenarios, for example. Different urban planning options can thus be compared against each other at an early stage, so that a city can better adapt to climate change.

Current project status

Current testing facilities

At present, the necessary general conditions are being created so that green areas can be tested in a realistic set-up and on an appropriate scale. Among other things, the researchers are installing sensors that enable water retention and run-off to be recorded on a time-dependent basis. In the near future, it will be possible to conduct tests on four test areas so that different systems can be compared against each other, for example. 

Simulation tools

Once material parameters have been determined in the laboratory, hygrothermal simulations can then be used to transfer findings to any climatic conditions. This enables roofing structures to be optimized and also urban building physics studies to be conducted in order to evaluate the impact of green roofs on the urban climate.

As a result, the hygrothermal design, dimensioning and optimization of green roofing structures according to EN 15026 / DIN 4108 / ÖN 8110 (durability of the entire construction) can already be carried out today. 

Click here for more information.


We are currently looking for partner companies interested in having the rainwater retention capacity of their green roofing structures assessed within the scope of pilot projects.

Are you interested in a cooperation? We are looking forward to hearing from you!