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June 2, 2004
In Malmö, Sweden, a city program ensures foliage and water features are included in the design of new developments, such as the Western Harbor apartment complex.
Cities are made of hard surfaces, which prevent nature from doing its job of refreshing and renewing the environment.
A high degree of soil sealing causes rapid runoff of rainfall into the sewage system, which prevents replenishment of groundwater, and destroys plant and animal habitat. It also causes excessive warming. Ever get blisters by running barefoot across a parking lot on a hot summer day?
Requirements that property owners retain or add as much foliage as possible can be become part of the building permit process.
In Malmö Sweden, a contract between the city and real estate developers with property in Western Harbor specified a variety of green factors, from which the developers could choose. The a la carte menu included plant beds, foliage on walls (creepers and climbing plants), green roofs (mostly moss-stonecrop sedum carpets), bodies of water, large trees and bushes, and smaller items such as bat boxes. Developers chose from the list to earn enough points to meet the standard.
In developing its green space program, the city of Malmo relied extensively on Berlin, which had a successful and comprehensive green factor program in place called the Biotope Area Factor.
Like the Quality Program developed by Malmö, Berlin's program explicitly states what the ecological minimum standards are for structural changes and new development. It pertains to all forms of urban use: residential, commercial and infrastructure.
All potential green areas, including courtyards, roofs and walls, are included in the program. Berlin's BAF gives real estate developers, architects and landscape architects clear but flexible guidelines on the portion of land that must be planted or provide other ecological functions.
|Surface Type Description||Weighing Factor|
|Sealed - Surface is impermeable to air and water and has no plant growth (concrete, asphalt, slabs with a solid sub-base)||0.0|
|Partially Sealed - Surface is permeable to water and air and has no plant gro wth (clinker brick, mosaic paving, slabs with a sand or gravel sub-base||0.3|
|Semi-open - Surface is permeable to water and air andhas no plant growth (clinker brick, mosaic paving, slabs with a sand or gravel sub-base||0.5|
|Surfaces with vegetation, unconnected to soil below, such as underground garages with less than 80 cm of soil covering||0.5|
|Surfaces with vegetation, that have no connection to soil below but with more than 80 cm of coil covering||0.7|
|Surfaces with vegetation, connected to soil below available for development of flora and fauna||1.0|
|Rainwater infiltration per m2 of roof area over surfaces with existing vegetation||0.2|
|Greenery covering wall and outer walls with no windows; actual height up to 10 m||0.5|
The BAF formula is: BAF = Ecologically Effective Surface Areas/Total Land Area. Individual parts of a plot of land are weighted according to their "ecological value." The target BAF ranges from .30 to .60 depending on the type and size of property to be developed, and whether it is a new development or an addition.
The beauty of the BAF concept is that it specifies a target that developers must reach but doesn't prescribe how they must reach it. Developers know what the possibilities are and how many points each choice provides. This gives them and the professionals who work for them a myriad of options, which they can use however they want.
Patricia Chase is with International Sustainable Solutions (www.i-sustain.com). ISS encourages sustainability practices and products. Sponsorship of ISS education materials is provided by Catapult Community Developers, CH2M Hill, Gregory Broderick Smith Real Estate, Magnusson Klemencic Associates, Nitze Stagen, ZGF Partners and Vulcan Inc. Much of the information for this article was provided by the Senate Department of Urban Development in Berlin, and can be found at: www.stadtentwicklung.berlin.de/umwelt/landschaftsplanung/bff/index_en.shtml