Stuttgart: Cool city
    




    







    
    
    
    














  
  
  
        
    
Published on Sustainable Cities (http://sustainablecities.dk)

    

    

    

    
    

    
11-02-2010

    			

								
Stuttgart: Cool city

				
Stuttgart’s climate planning strategy is seen as one of the best examples of heat island management in the world. Stuttgart has been planned not only to respect and protect nature, but to exploit how natural wind patterns and dense vegetation can actively help the city to reduce its problems of overheating and air-pollution. At night, clean air sweeps down from the surrounding hills and runs through a series of ‘ventilation-corridors’ which have been kept open as wide, tree-flanked arteries within the city’s street infrastructure.

				

			


    
Stuttgart is a city well known for its industrial productivity and affluence, and is often referred to as Germany’s ‘cradle of the automobile’. With this profile, one might expect a city littered with glass office buildings, stark urban plazas and with heavy traffic clogging its arteries.
In reality, Stuttgart is defined as much by its dense, convivial city-centre as by its lush surrounding hillsides. Over 60% of the city is covered in green. Vineyards, forests and public parks both surround the city, and, in places, stretch down the hillside to touch centre. This unique landscape feature and the particular topography of the region are used to ensure an attractive and comfortable urban environment for Stuttgart’s residents.
Since the city lies in the valley basin, the city cannot easily get rid of its own heat and it stays trapped within the city. In Stuttgart’s case, this is overcome by the fact that the topographical profile - the surrounding hills are up to 300m above the valley basin - causes thermally induced winds to flow into the city. In order to take advantage of this effect, it became vital for Stuttgart to map out where the winds come from and how they can be directed through the city. This has lead to a series of designated green corridors or ‘ventilation lanes’ which are prohibited from being obstructed by local planning legislation.
Thermal map of Stuttgart city, morning situation. Courtesy of Stuttgart Municipality.
The primary objective of Stuttgart’s current urban framework plan is to preserve cohesive green corridors and partly built-up areas of open land on hillside sites. The plan distinguishes between cold-air ventilation lanes, climate-relevant open land, climate-relevant building land and climatic recovery zones. The demand for development sites is growing but it is necessary to reserve qualities now in order to avoid compromise later. No development is allowed to obstruct air-flow and tree felling of trees over a certain size is banned.
The correct application of ‘green infrastructure’ can be used to combat the urban heat island effect. In Stuttgart’s case, this is made part of urban policy in such a way that it compliments other macro layers which offer environmental benefit; increasing bio-diversity and air-quality.
"On both a citywide and human scale, the parks and working landscapes within and surrounding Stuttgart are among the most climatically functional, socially useful and aesthetically pleasing of any modern city in the Western World"
Michael Hough, Cities and Natural Process

    
Key Learning Points
Vegetation areas have a significant effect on the local climate as they incite the production of fresh and cold air at night and have a thermally balancing effect during the day due to a high percentage of trees. Vegetation areas on the edge of settlement areas stimulate the mixing of the air.
Larger, cohesive vegetation areas are of particular value because they can connect areas of higher air quality and thereby ensure an increased level of air hygiene.
The correct application of ‘green infrastructure’ can be used to combat the urban heat island effect and offer environmental benefit; increasing bio-diversity and air-quality. 
City Facts
Country: Germany
City: Stuttgart

Area: 207 km²
Population: 600,038 (December 2008)
Density: 3,000/ km²

GDP per capita: USD 82,000 (2009 estimate)
Sources: Wikipedia
 
Project Facts
Since 1938, Stuttgart’s planning legislation has prohibited the obstruction of air flow entering the city from its surrounding hillsides.
 
Planning legislation stipulates that 70% of overall plot should be green.
Spatial framework plans maintain cohesive green structure in the urban periphery in order to avoid fragmentation of green space.
Urban climate information is provided to Stuttgart’s residents over the internet.
Facts for Thought
In cities, heat (and summer heat, in particular) is stored in roads, and building surfaces. The radiant heat loss is lower in urban areas than rural areas due to the lower concentration of green spaces, forests, fields etc. which can emit heat faster. This is known as the urban heat island effect.
In large US cities, a 1% rise in temperature, due to the urban heat island effect, can cause a 3-5% increase in electricity consumption due to an increase in cooling load.
Related Facts
Japan is now introducing the famous ‘Stuttgart urban ventilation lane’ (Nemoto 1991, Ichinose 1999) to some of its major cities.
Tokyo Metropolitan Government aims to reduce the number of excessively hot summer evenings to 20 per year. This involves thermal mapping analysis.
The city of Nagoya, Japan, now requires tree planting for all plots for new development over 300 m2.

    

    

    

    
Source URL: http://sustainablecities.dk/en/city-projects/cases/stuttgart-cool-city

    
Links:
[1] http://en.wikipedia.org/wiki/Stuttgart