Green Roofs 2020

Map Description

In Berlin, there are 629,666 buildings, 20,446 (3.2%) of which are underground car parks without superstructures featuring green roofs or green roof areas larger than 10 m². In total, 656 ha of all roof areas are greened (5.4 %) (Tab. 1). Since 2016, the number of buildings with green roofs has therefore increased by 0.2 %. The ‘green roof’ area share even rose from 3.9 % to 5.4 %. Overall, the green roof area grew by 165 ha. A look at the map reveals that green roof areas are concentrated in the inner city of Berlin.

Tab. 1: Green roof areas in Berlin in 2016 and 2020

A building’s greenery is classified as either “intensive” or “extensive”, based on whichever share is larger. If a building has an “extensive” green roof area of >50 %, the entire green roof area is considered “extensive” in the calculation process.
In the following, analyses are presented for three spatial levels – building, ISU block (segment) area and borough.

Buildings

Buildings were classified into six “building use” categories based on the use information from ALKIS and NOT-ALKIS. Table 2 and Figure 3 illustrate the size and percentages of building uses that include green roofs.

With percentages ranging between 22 and 30 % (Fig. 3), green roofs [m²] are relatively evenly distributed across the building uses “Residential” (incl. weekend cottages), “Non-residential buildings” (e.g. schools, town halls, retirement homes, administrative buildings), “Office buildings, commercial” and “Underground car parks without superstructures”. Compared to rooftop greenery, that of underground car parks tends to be more comprehensive and denser (Fig. 3). The ratio of intensive to extensive greenery on underground car parks is about 80 % to 20 %, on building surfaces it is the reverse.

In addition, Table 2 identifies potential for future green roofs. So far, only 3.4 % of buildings in the “Office buildings, commercial” category, which are expected to have flat roofs for the most part, have green roofs. The green roof potential is therefore high. By contrast, and, as expected, this potential has been tapped into much more at 77 % in the category of underground car parks without superstructures. This is the case, although the proportion of greenery varies across the roof surfaces of underground car parks (Tab. 2).

One might also expect a larger proportion of green roofs on garages and sheds. This is complicated by the issue, however, that green roofs frequently remain undetected on these often rather small rooftops due to large tree canopies and are therefore not recorded during the mapping process. As a result of the TrueOrthophotos recorded in summer (August), this occurred more frequently in the course of the 2020 mapping compared to the 2016 mapping. The actual proportion of green roofs is therefore assumed to be higher in this building use category.

Tab. 2: Distribution of the green roof areas by building use, 2020

Fig. 3: Green roof area [m²] – share by building use class, 2020

Block (segment) areas

By linking the buildings to the block (segment) areas of the ISU, analyses may also be carried out based on the ISU area types (cf. Tab. 3).

With a total of more than 30 ha each, the area types “Settlement from the 1990s or later (73)”, “Commercial and industrial area, large-scale retail with sparse development (30)”, “Closed block development, rear courtyard, 5-storeys (2)”, “Core area (29)” and “Closed and semi-open, de-cored block development, post-war gap closure (7)” exhibit the largest green roof areas in absolute terms. The two area types “City square / promenade (54)” and “Settlement from the 1990s or later (73)” stand out with a green roof proportion of 26.2 and 27 %, respectively, in relation to the building floor area. The area type “Detached single-family homes with yards (23)” also has a large building inventory; however, it only has a green roof share of 1.1 % in relation to the building floor area. This suggests that private residential areas have a lot of untapped potential for green roofs in general, although it is limited to roofs that are suitable for greenery (flat or slightly sloping roofs).

Tab. 3: Distribution of green roof areas by ISU area type

Boroughs

For the 2020 mapping, Figure 4 shows the green roof area in square metres by borough with the green roof area shares divided into percentage classes. It also presents the total green roof area for the year 2016. Mitte and Charlottenburg-Wilmersdorf clearly have the largest inventory of ‘green roof areas’. Friedrichshain-Kreuzberg, however, has the highest proportion of ‘green roof area’ in relation to its building floor area (cf. Fig. 5). This diagram underlines the concentration of green roof areas in the inner city yet again, which is also due to the large number of flat roofs and Berlin roofs (asymmetrical roof with large (almost) flat areas) (Betz 2010). Figure 6 illustrates the overall low proportions of ‘intensive’ green roofs. The proportions of ‘intensive’ and ‘extensive’ green roof areas, however, vary across boroughs.

Fig. 4: Green roof area [m²] by borough, categorised by green roof area share [%], 2020

Fig. 5: Ratio of green roof area to building floor area and ratio of buildings with green roof areas to the buildings in each borough, 2020

Fig. 6: Green roof area [m²] by borough, distinguishing between "intensive" and "extensive" greenery, 2020

Tab. 4: Distribution of green roof areas by borough (* Ratio of green roof area to building floor area [%])