Fraunhofer Institute for Building Physics IBP
Fraunhofer Institute for Building Physics IBP

Pollutants in precipitation runoff from non-metal roofs

Precipitation runoff from non-metal roofs
© Peshkova/Shutterstock
How can precipitation runoff from non-metal roofs be used in water-sensitive cities?

In growing cities, more and more surfaces are being sealed. This increases the contact of rainwater with materials, e.g. roofs, resulting in the contamination of precipitation runoff with harmful substances. However, no clear or statistically relevant information on pollutant emissions is available for most roof materials, as hardly any studies have been carried out and these are usually based on one-off random samples. General conditions such as atmospheric influences or gutter material, are often not sufficiently described. There is therefore a considerable need for research in order to draw scientifically sound conclusions about pollutants in precipitation runoff from non-metal roofs.

Project goals

The aim is to obtain a comprehensive and reliable database on the release of substances from non-metal roofs through contact with rainwater under different conditions (heavy rainfall, long periods of dry weather, etc.). Laboratory and field tests are carried out based on research into relevant products. A standardized laboratory procedure is used to obtain building product eluates for estimating emissions. Outdoor tests are used to continuously study material emissions under real weather conditions. The resulting database allows material emissions to be reliably assessed and can be used to derive recommendations for regulations. It serves as a basis for developing decentralized treatment plants for precipitation runoff. Consequently, runoff water from potentially pollutant-emitting building products can be used sustainably in urban areas in response to the challenges of climate change.

Status of the project

Initially, based on a market analysis (AP1), roofing materials for the following practical tests were selected. A total of fifteen different roofing materials, including clay tiles, concrete roof tiles, fiber cement, bitumen and wooden shingles, as well as various plastic-based products, were subjected to laboratory testing according to DIN EN 16637-2, and the eluates were analyzed (AP2). Based on the results, six products were selected for outdoor weathering exposure the Fraunhofer IBP test site in Holzkirchen (AP3). The results obtained from these tests will be used for risk assessment and will support the development of practical recommendations (AP4).

Work packages 1 and 2 have already been completed. The test roofs for work package 3 have been installed and the start of the outdoor weathering exposure is imminent.

Project partners

  • Technical University of Munich, TUM School of Engineering and Design, Chair of Urban Water Management