Nature + Green  


A green city center - BAF - Biotope area factor

Calculating the BAF

The BAF expresses the ratio of the ecologically effective surface area to the total land area.

BAF = 
surface areas
 total land area 

In this calculation, the individual parts of a plot of land are weighted according to their "ecological value".

Types of surfaces and weighting factors:
(Surface types not mentioned can be calculated as long as they have a positive effect on the ecosystem)

Weighting factor /
per m² of surface type

Description of surface types
fltyp_a pfeil_re Sealed

pfeil_re Surface is impermeable to air and water and has no plant growth
(e.g., concrete, asphalt, slabs with a solid subbase)
fltyp_b pfeil_re Partially sealed

pfeil_re Surface is permeable to water and air;
as a rule, no plant growth
(e.g., clinker brick, mosaic paving, slabs with a sand or gravel subbase)
fltyp_c pfeil_re Semi-open

pfeil_re Surface is permeable to water and air;
infiltration; plant growth
(e.g., gravel with grass coverage, wood-block paving, honeycomb brick with grass)
fltyp_d pfeil_re Surfaces with vegetation,
unconnected to soil below

pfeil_re Surfaces with vegetation on cellar covers or underground garages with less than 80 cm of soil covering
fltyp_e pfeil_re Surfaces with vegetation,
unconnected to soil below

pfeil_re Surfaces with vegetation that have no connection to soil below but with more than 80 cm of soil covering
fltyp_f pfeil_re Surfaces with vegetation,
connected to soil below

pfeil_re Vegetation connected to soil below, available for development of flora and fauna
fltyp_g pfeil_re Rainwater infiltration per m² of roof area

pfeil_re Rainwater infiltration for replenishment of groundwater;
infiltration over surfaces with existing vegetation
fltyp_h pfeil_re Vertical greenery up to a maximum of 10 m in height

pfeil_re Greenery covering walls and outer walls with no windows;
the actual height, up to 10 m, is taken into account
fltyp_i pfeil_re Greenery on rooftop

pfeil_re Extensive and intensive coverage of rooftop with greenery