Insight Into Germany’s Green Roof and Wall Market, Trends, and Policy
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Urbanization is still one of the most relevant challenges of our time. More and more people are moving into ever-growing cities – so living space is becoming increasingly rare and expensive. As a consequence, building greening is becoming more important as this trend progresses. The average increase of settlement and transport land area in Germany is about 60 hectares (148 acres) per day (BfN, 2020). However, ground is not a renewable resource. Thus, land should be used more sustainably in the future. By 2050, no new land should be used at all - in Germany and throughout the EU (BMU,2016:67f.).
Performance of one square metre of extensive green roof in Germany. Source: BuGG, Mann et al. 2021:3
Paving over natural surfaces has a particularly negative effect on water balance. Rainwater can no longer seep away unimpededly, which means that less groundwater is formed. In addition, the risk of flooding increases, because many sewers can no longer cope with water that accumulates during heavy rainfall. This can lead to local urban flash floods (UBA, 12.02.2020). Green roofs cannot replace depaving, but they can be a major contribution to decentralized rainwater management in cities. Green roofs store water during rain events, evaporate part of the stored water and release the excess water slowly into the sewer system. This eases the pressure on the sewage system and may prevent or at least reduces the impacts floods.
In addition to water retention, green roofs offer many other advantages such as increased biodiversity, temperature reduction, evaporation, noise reduction and amongst others. For the first time in Germany, the Bundesverband GebäudeGrün e.V. (BuGG) published with the “BuGG-Marktreport GebäudeGrün 2020“, an overview of the latest figures on roof, façade, and interior greening.
A survey of the total market of annually newly greened roofs has been carried out. For this purpose, substrate manufacturers and suppliers were asked about the quantities of the following substrate types supplied in Germany: extensive substrate single-layer and multi-layer, intensive substrate single-layer and multi-layer. With the determined delivery quantities and via fixed assumptions on the installation heights of extensive and intensive green roofs in single- and multi-layer construction, the overall newly greened green roof areas can be estimated.
Figure 2 Green roofs added in 2019 in relation to the total newly created flat roof area in Germany. Source: BuGG, Mann et al. 2021:6
The most important results of the BuGG Green Roof Substrate Survey are, that in Germany, a total of 7,217,720 sq. m of green roofs were built in 2019. This divides into 6,024,421 sq. m (83.5 %) extensive green roofs and 1,193,299 sq. m (16.5 %) intensive green roofs. However even though 7,200,000 sq. m sounds impressive at first, this only represents 9 per cent of the estimated 80,000,000 sq. m of new flat roof area constructed. This means that in 2019, about 91 % of flat roof areas remained non-greened - an enormous potential market!
The German market for building greening is growing and very promising. On average, the German green roof market is growing by about 7 per cent each year. The building greening sector, including its related professions, already provides thousands of jobs - and this employment trend is increasing in line with the growth!
To promote the implementation of green roofs and to make cities more climate resilient, they are promoted through various instruments on a municipal level. The most common funding and incentive instruments are: Determinations in development plans, municipal bylaws, funding programmes with financial subsidies, eco-points and fee reduction for the split wastewater fee.
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To look at these instruments in more detail, the 2019 BuGG city survey serves as a basis and is completed by the results of a BuGG research carried out in 2019/2020 on municipal funding in all German cities with 50,000 or more inhabitants - that is a total of 191 cities. The survey demonstrated that 49 (26 %) of the cities provide direct grants by a grant program, 137 (72%) offer a fee reduction for the split wastewater fee, 140 (73%) cities have determinations in development plans and 45 (24%) work with Eco-points. This also applies to facade greening: 45 (24%) cities provide direct grants by a grant program and 78 (41%) have determinations in development plans.
Learn more about international green roof and wall markets at the International Market and Project Showcase during CitiesAlive Virtual on November 11, 2021
In summary, it can be stated that 26% and 24% of cities with more than 50,000 inhabitants promote roof and/or facade greening and provide financial subsidies. Additionally, 72% of these cities indirectly promote green roofs and reduce the precipitation water fee when green roofs are installed.
For the field of green roofs, certain trends can be observed, even though these are not substantiated by figures yet: to consider green roofs as an important component of decentralized rainwater management is not new. However, it gained a new dimension with the development of the “retention green roof” and its enormous additional possibilities for retaining stormwater. Another trend is the combination of solar photovoltaics and green roofs. When professionally planned and executed, these two can be combined in solar green roofs and function well and sustainably together. This has been demonstrated in various projects already. However, this knowledge has not reached those involved in planning and constructing yet. Even if politics strongly focuses on advancing solar roofs, green roofs should not be neglected. Instead green roofs should be promoted as well as green and solar roofs are not mutually exclusive.
Figure 3: A residence with intensively used greened roof, solar panels and climbing plants on the balconies. Below the lawn is the underground car park - so also a green roof. Photo: BuGG
For green roofs construction in Germany, reliable figures are available. However, the data collection methods for facade and interior greening are not fully developed yet – nevertheless, it is obvious that building greening is no longer a niche product. The total estimated amount of greened roof area in Germany is approximately in the range of 120,000,000 sq. m and if the trend is taken as an indicator, the number will increase even more. Awareness for the green market and its many possibilities is ever-increasing, which also translates into a large number of diverse building greening projects.
Fiona Wolff is Project Manager at Bundesverband GebäudeGrün e.V (BuGG), the German Association of Building Greening. BuGG operates both as professional organization and advocacy group for companies, communities, universities, organizations and all parties interested in building greening (green roofs, green walls and interior greening).
More Information
Read the publication BuGG-Market Report on Building Greening 2020, Green Roofs, Green Facades and Interior Greening in Germany
Learn more about international green roof and wall markets at the International Market and Project Showcase during CitiesAlive Virtual on November 11, 2021
BuGG is hosting the World Green Infrastructure Congress in Berlin, May 10-12, 2022.
