Daniel Bell Landskap AB
Artillerigatan 26
SE-11451 Stockholm
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info@danielbellandskap.com

Geen Factor calculation | GYF

The cities have an overall responsibility to create a good on-built environment both within the city’s public and private areas. The “areal green factor” (GYF: from the Swedish Grönytefaktor) for new residential blocks used in the Stockholm area is one of many tools that help to work on the city’s ecosystem services and the public greenery on streets, parks and squares.

The green surface factor is a tool for working with social values, biodiversity, climate and acoustic adaptation on a certain area. The tool has have long been used in Germany and South Sweden before start to be used in the Stockholm area.

A model adapted for Stockholm has been developed within the Norra Djurgårdsstad project (one of the biggest developing residential area in Stockholm) and now it is used as a general planning tool for all the new neighbourhoods. In the GYF is preferred greenery that fills several functions, ex. creates green rooms for stay, collect and cleans stormwater, provides shade, contributes to pollination and is beautiful to look at. GYF is measured as a point quota between the amount of “eco-efficient surface” and the neighbourhood’s total area. The eco-efficient surface is made up of all green and blue surfaces within one block designed according to certain requirements. Blue surfaces mean plants linked to open stormwater management such as ponds, ditches, rain gardens etc.

The GYF is a flexible and supportive planning tool intended to serve as evaluation for builders and architects. GYF sets requirements for design and measurement surfaces with different qualities. However, GYF does not replace regular planning and design work or demands in the city, such as stormwater management, conservation and protection of valuable trees, green compensation,

social values, relationships between the surfaces, spatial qualities or architecture. GYF should be seen as a complement and support for the city’s work with these issues.

In the GYF, ecologically effective surfaces are measured and features. The GYF does not handle

connection, spaciousness or architecture.

The GYF encourages eco-efficient construction surfaces that can supply several different ecosystem services despite a limited area. Greenery and water create one environment that delivers ecosystem services both to them who live in the neighbourhood and to the district as a whole.

In the GYF model are managed 5 ecosystem services:

  • Viable ecological infrastructure,
  • Day water regulation & cleaning,
  • Local climate / temperature control,
  • Sound quality,
  • Social & recreational values.

The GYF is used in various planning process types of development and reconstruction projects;

housing, office, commerce, school / preschool / sports, businesses and the small industry.

The requirement on which green area factor to achieve can vary between different projects depending on the proportion of the neighbourhood that is built.

The factor may need to be regulated in regard to the proportion of undeveloped land surface. That means a lower GYF factor for dense built areas and vice versa.

In the GYF, the average factor normally used is 0.6.

But the factor 1.0 can be used for low exploitation and 0.4 if there is a very large part of the block that is built.

How it works

The structure of the GYF is measured as a point ratio between the amount ”eco-efficient surface”and the total area of the block. With eco-efficient Surface refers to all green and blue surfaces that have positive importance to the site’s ecosystem, contributes to better microclimate, stormwater management and noise reduction and have social values linked to greenery and / or water.

In GYF for neighbourhoods in Stockholm, the area is measured on so-called sub-factors (different plant beds and vegetation surfaces). Various additional factors are connected to these surfaces.

Both sub-factors and additional factors are measured in square meters. To punctual objects like trees have been assigned a template surface as 25 m2 each.

The calculation is made by the area for different sub-factors and additional factors and multiplied by their respective weighting factors. These factors are summed up then and shared with the total area of the block. The quota X is the GYF for the entire plot.

(NOTE: each municipality can change the factors according to the peculiarity of each territory, so the factor list and points are different from Stockholm to Uppsala).

 

Following some examples of GYF calculation mede by Daniel Bell Landskap in the Stockholm area:

Slakthusområde | Stockholm

Rosendal | Uppsala