Calculating the BAF

Types of surfaces and weighting factors per m²

• Sealed surfaces
  (Weighting factor 0.0 per m²)

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

• Partially sealed surfaces
  (Weighting factor 0.1 per m²)

  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).

• Semi-open surfaces
  (Weighting factor 0.2 per m²)

  Surface is permeable to water and air, water infiltration, but no plant growth (e.g., sand, gravel, clinker brick with high water infiltration).

• Greened surfaces
  (Weighting factor 0.4 per m²)

  Surface is permeable to water and air, water infiltration and plant growth (e.g., gravel with grass, wooden cobbles, grass paving blocks).

• Surfaces with vegetation, unconnected to the soil below, small substrate thickness
  (Weighting factor 0.5 per m²)

  Surfaces with vegetation that have no connection to the ground and 20 to 40 cm of soil covering.

• Surfaces with vegetation, unconnected to the soil below, medium substrate thickness
  (Weighting factor 0.6 per m²)

  Surfaces with vegetation that have no connection to the ground and 41 to 80 cm of soil covering.

• Surfaces with vegetation, unconnected to the soil below, large substrate thickness
  (Weighting factor 0.7 per m²)

  Surfaces with vegetation that have no connection to the ground and 81 to 150 cm of soil covering.

• Surfaces with vegetation, unconnected to the soil below, very large substrate thickness
  (Weighting factor 0.9 per m²)

  Surfaces with vegetation that have no connection to the ground but more than 150 cm of soil covering.

• Surfaces with vegetation, connected to the soil below
  (Weighting factor 1.0 per m²)

  Vegetation connected to soil below, available for development of flora and fauna.

• Rainwater infiltration per m² of roof area
  (Weighting factor 0.2 per m²)

  Rainwater infiltration for replenishment of groundwater; infiltration over surfaces with existing vegetation.

• Water surface
  (Weighting factor 0.5 per m²)

  Rainwater fed water surface. Through establishment of vegetation the BAF can increase to 0.6.

• Vertical greenery with connection to the ground
  (Weighting factor 0.5 per m²)

  Direct connection of the vertical greenery with the soil, supply with nutrients and water directly over the roots in the soil.

• Vertical greenery without connection to the ground
  (Weighting factor 0.7 per m²)

  Vertical or horizontal vegetation on a wall without direct connection to the soil on the ground, permanent planters supplying the vegetation, with artificial irrigation.

• Extensive roof greening
  (Weighting factor 0.5 per m²)
  since December 2019*

  Nature-like design of the roof surfaces with a substrate thickness under 20 cm without artificial irrigation. Through systems for water retentionthe BAF can increase to 0.6 (only for extensive roof greening).

• Semi-intensive roof greening
  (Weighting factor 0.7 per m²)

  Mixture of extensive and intensive roof greening with a substrate thickness of 15 to 50 cm (depending on the chosen plantings), usually in combination with artificial irrigation.

• Intensive roof greening
  (Weighting factor 0.8 per m²)

  Design of the roof similar to ground-based green areas with a substrate thickness more than 50 cm, usually in combination with artificial irrigation.