Green Roofs 2016
In Berlin, 18,368 (3.0 %) out of a total of 604,865 buildings, including underground car parks without overlying buildings, have a greened roof area or greened partial roof areas of > 10 m2. In total, 400 ha of the roof areas are greened (3.9 %) (Table 1). A look at the map reveals a concentration of greened roof areas in Berlin’s inner city.
The categorisation per building as “intensively” or “extensively greened” is carried out based on the predominant component. If a building exhibits a greened roof area of > 50 % “extensive”, the entire greened roof area enters into the calculations as “extensive”.
Analyses on three spatial levels will be shown in the following – building, block and block segment of the ISU and borough.
The buildings were classified into six categories of building use based on the ALKIS and NOT-ALK use. Table 2 and Figure 3 show the order of magnitude and percentages of the building uses covered with green roofs.
The greened roof areas [m2] are relatively evenly distributed across the different building uses “Residential” (including weekend cottages), “Non-residential buildings” (e.g. schools, town halls, retirement homes, administrative buildings), “Office buildings, commercial” and “Underground car parks without overlying buildings” with percentages between 20 and 25 % (Fig. 3).
In addition, Table 2 indicates possible potentials for future green roofs. The building use “Office buildings, commercial”, which presumably has a high proportion of flat roofs, only has greened roof areas on 2.7 % of the buildings to date. A high potential for green roofs can be assumed here. By contrast, this potential is much more intensely utilised at 80 % in the case of underground car parks, as expected, albeit with different proportions of greening on the individual roof areas of greened underground car parks.
Block and block segment
The assignment of the buildings to the block and block segment areas of the ISU also allows analyses to be carried out based on the area types available there (Table 3).
With a total of more than 30 ha each, the area types “Settlement from the 90s or later (73)”, “Commercial and industrial area, large-scale retail with sparse development (30)”, “Closed block development, rear courtyard, 5-storey (2)”, “Core area (29)” and “Closed and semi-open, de-cored block development, post-war gap closure (7)” exhibit the largest greened roof areas in absolute terms. Relative to the building floor area, the two area types “City square / promenade (54)” and “Settlement from the 90s or later (73)” stand out with a greened roof proportion of 31 and 22 % of the building floor area, respectively. However, as a further area type with a large building stock, the type “Detached single-family homes with yards (23)” merely exhibits a share of 1 % greened roof areas in the building floor area. This implies that there are principally greater potentials for green roofs in the private settlement area, which are, however, limited to the limited proportion of greenable roof constructions (flat or barely inclined roofs).
Figure 4 shows the greened roof area in square meters per borough disaggregated according to the greened proportion of roof area in percent classes. Mitte and Charlottenburg-Wilmersdorf have by far the largest stock of greened roof areas. However, with respect to the share of greened roof area in the available building floor space, Friedrichshain-Kreuzberg exhibits the highest value in comparison (Figure 5). This diagram, too, underscores yet again the concentration of greened roof areas in the inner city, which is also due to the large number of flat and Berlin-style roofs that predominate there (Betz 2010). Figure 6 illustrates the overall low proportions of intensively green roofs. However, the proportions of intensively and extensively greened roof areas fluctuate across the boroughs.