Green ventilation corridors

The city’s location has a significant influence on its local climate includingimplications for solar radiation, air temperature, humidity, precipitation andwind. Stuttgart sits in the wide Neckar basin formed by two river valleys, shielded by steep hill slopes. Stuttgart’s centre is located at about 240m above sea level, while the surrounding hills rise to 500m a.s.l.

Stuttgart has a mild, temperate climate with warm summers. Wind speedsthroughout the city are generally low, which along with the urban heat island effect, contributes to poor air quality. The future climate projections for 2071-2100 suggest a 2ºC increase of mean annual temperature inStuttgart. The projections for heat waves (T>30°C) suggest that thenumber of days with heat stress (when people’s thermoregulation isimpaired) will increase significantly. By 2100, 57% of the Greater Stuttgartregion could have more than 30 days with heat stress (in the low lyingareas over 60 days). Therefore, a significantly higher percentage of peopleare likely to be exposed to the risks associated with heat waves than at present.

The Climate Atlas

The Climate Atlas for the region of Stuttgart was published in 2008, basedon the previous work in this area carried out by the City of Stuttgart sincethe 1980s and the in-house urban climatology department (in existence inthe City of Stuttgart since 1938). The Climate Atlas provides standardisedclimatic assessments for the 179 towns and municipalities in the Stuttgartregion. The Atlas comprises maps which show regional wind patterns,flows of cold air, air pollution concentrations, and other relevant informationrequired to inform planners on what to do for urban climatic optimizationthat could inform new projects and retrofits. A key element of the Atlas isan area classification based on the role that different locations play in airexchange and cool airflow in the Stuttgart region, based on topography, development density and character, and provision of green space. The Atlas distinguishes eight categories of areas in this manner, and for each of them different planning measures and recommendations are provided.

In addition to responding to local climate characteristics, the following principles form the basis for the planning recommendations included in the “Climate Booklet for Urban Development Online – Städtebauliche KlimafibelOnline”:

  • Vegetation should be placed to surround developments and larger,connected green spaces should be created or maintained throughoutdeveloped areas to facilitate air exchange;
  • Valleys serve as air delivery corridors and should not be developed;
  • Hillsides should remain undeveloped, especially when developmentexists in valleys, since intensive cold- and fresh-air transport occurshere;
  • Saddle-like topographies serve as air induction corridors and shouldnot be developed;
  • Urban sprawl is to be avoided;
  • All trees growing in the urban core with a trunk circumference of morethan 80 cm at height of 1m are protected with a tree preservationorder.