Green ventilation corridors

The city’s location has a significant influence on its local climate, including implications for solar radiation, air temperature, humidity, precipitation and wind. 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 speeds throughout 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 the number of days with heat stress (when people’s thermoregulation is impaired) will increase significantly. By 2100, 57% of the Greater Stuttgart region could have more than 30 days with heat stress (in the low lying areas over 60 days). Therefore, a significantly higher percentage of people are likely to be exposed to the risks associated with heat waves than at present.

The Climate Atlas of the Region of Stuttgart

The Climate Atlas for the region of Stuttgart was published in 2008, based on the previous work in this area carried out by the City of Stuttgart since the 1980s and the in-house urban climatology department (in existence in the City of Stuttgart since 1938).

The Climate Atlas provides standardised climatic assessments for the 179 towns and municipalities in the Stuttgart region. The Atlas comprises maps which show regional wind patterns, flows of cold air, air pollution concentrations, and other relevant information required to inform planners on what to do for urban climatic optimization that could inform new projects and retrofits.

A key element of the Atlas is an area classification based on the role that different locations play in air exchange and cool air flow 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 Klimafibel Online”:

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