Evidence of the Climate Mitigation Effect of Green Roofs—A 20-Year Weather Study on an Extensive Green Roof (EGR) in Northeast Germany
by
Manfred Köhler 1,*
and Daniel Kaiser 1,2
and Daniel Kaiser 1,2
1
Department of Landscape Ecology, Faculty of Landscape Sciences and Geomatics (LG), University of Applied Sciences, Neubrandenburg, 17033 Neubrandenburg, Germany
2
Faculty of Geography, Humboldt University of Berlin, 12489 Berlin, Germany
*
Author to whom correspondence should be addressed.
Buildings 2019, 9(7), 157; https://doi.org/10.3390/buildings9070157
Received: 16 April 2019 / Revised: 3 June 2019 / Accepted: 5 June 2019 / Published: 28 June 2019
(This article belongs to the Special Issue Quantification of Green Roof Benefits and the Implementation into Urban Politics)
Approximately 10 km2 of new green roofs are built in Germany every year. About 85% of these are Extensive Green Roofs (EGR). An EGR with several research features was installed on new buildings belonging to the University of Applied Sciences Neubrandenburg in 1999. The results of the almost 20-year permanent survey of the climate effects of the green roof in contrast to gravel roofs are presented here. High-quality sensors, similar to those used by official weather stations, are in use, and data is collected every 10 s and aggregated to hourly values which enable comparisons to official measurements made by the DWD in Neubrandenburg and Berlin. The results show the typical urban heat island effect (UHI) and the mitigation effect of EGR. Whilst the temperature increased over the years due to the urban heat island effect, the temperature within the growing media in the green roof remained constant. The EGR has a stabilization effect of 1.5 K. This is good news for all those seeking a UHI mitigation solution for city centers. In a best-case scenario, the green roof potential of cities in Germany is between 3 and 8%. A value of 50% can be achieved for all buildings; roofs represent about ¼ of urban surfaces, and the cooling effect of 1.5 K in 20 years is a reasonable contribution to cooling cities and achieving environmental goals by greening urban surfaces.
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Keywords:
extensive green roofs; climate mitigation; surface temperatures; urban heat island effect; global warming
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
MDPI and ACS Style
Köhler, M.; Kaiser, D. Evidence of the Climate Mitigation Effect of Green Roofs—A 20-Year Weather Study on an Extensive Green Roof (EGR) in Northeast Germany. Buildings 2019, 9, 157.
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