Foto: Stuttgart Aeration Germany: Landeshauptstadt Stuttgart, Amt für Umweltschutz, Stadtklimatologie
Green Aeration Corridors
In South-west Germany, greenery now covers more than 60% of Stuttgart City. To tackle climate heat stress and low air quality, important green belts and green divides have been created between built-up settlement areas. This protects communities from the impacts of climate change, like rising temperatures and changes in rainfall patterns. The green areas also provide important health and recreation benefits to Stuttgart’s residents, supporting the conservation of local wildlife at the same time. 39% of Stuttgart’s surface area is now under nature conservation orders and features in the land use plan, which will help to ensure the climate adaptation measures are protected well into the future.
The Adaptation Journey
The positive impact
The location of Stuttgart, as well as its climate and the heat island effect, contributes to poor air quality and the frequent experience heat stress in its residents. Heat waves are likely to increase due to climate change which will continue to worsen the experience of heat stress in the city, impacting vulnerable communities such as the elderly.
By creating belts of vegetation like trees, a supply of fresh air is fed into the streets, improving air quality and having a cooling effect in the area. Other types of smaller vegetation, like grass and hedges, can create fresh air coridoors in built-up areas by inducing local wind systems.
The green belts also have a wide variety of co-benefits which include the provision of new recreational spaces for residents, a reduction of wind speed during storms, improvements to biodiversity loss by providing animals and plants with new protected habitat, and climate change mitigation by taking carbon dioxide out of the air.
How does it work?
Topographic structures such as meadow valleys provide natural green belts which at the same time represent preferred pathways for ventilation, while green spaces benefit urban climate and its protection:
• Vegetation exerts a significant stabilizing effect on the carbon dioxide balance, cools the area and improves air quality.
• Green spaces serve as place-keepers, eliminating other uses which could impact negatively on climate protection due to potential emissions of relevance for the climate, such as roads or buildings.
• Where lower-level and less dense vegetation exists, green spaces promote ventilation within built-up areas through generation of cold air through thermally induced local wind systems such as ground wind and downslope winds and so act as fresh air corridors. This reduces exposure to pollutants and dissipates the build-up of heat and thermal stress, in particular during periods of extreme heat.
• Where vegetation is higher and denser, high wind speeds during storms are buffered. Furthermore, woodland plays a major role in terms of protection against soil erosion as a result of heavy rainfall and storms.
These green areas are protected and/or created in Stuttgart through the land use plan.
To enable the implementation of effective green belts and divides, a number of pre-conditions were particularly helpful in this case.
Data and Maps
Climatic and air-hygiene maps supported communication with local residents about why the project was important, as well as enabling the planning of green coridoors. For example, the area benefited from the ‘Climate Atlas’ for the Stuttgart region. Published in 2008, this had a set of standardised climatic assessments for 179 towns and municipalities in the Stuttgart region, sharing important information to make sure that green coridoors were created in the right places and with the right types of vegetation. This included data and maps on regional wind patterns, air pollution concentrations, temperature, topography, development density, green space provision, and so on. The Atlas distinguished eight categories of areas using this information, and for each of them different planning measures and recommendations were provided.
Land use plan
In addition, a preparatory land use plan (PLUP) was undertaken, which organises land into its building and other types of uses, including green areas and corridors. This PLUP is not legally binding, but serves as a basis for planning and information. The land use plan developed in 2010 has critical information for sustainable urban development, using the slogan "urban─compact─green". Its guideline is for brownfield rather than greenfield development in a 4:1 ratio, aiming to protect green areas and develop a green network through brownfield areas.
Operation and maintenance
Green corridors and networks are more important for climate objectives than small isolated green spaces, which have only a minimal remote impact in respect of their environment due to the so-called "oasis effect". However, this consideration does not in any way detract from the temperature-sinking importance of all vegetation areas.
In the experience of the project, it was found that keeping natural green corridors free of encroachment by buildings did not require a great deal of persuasion, because aspects of landscape and nature conservation also support the urban climatology arguments. This joint argumentation was key in supporting the debate surrounding conservation of the Greutterwald orchard district (Stuttgart-Weilimdorf).
Zieleń miejska Heating Zelená střecha Stínění Biodiverzita Vlny horka a tepelný ostrov Povodně a přívalové srážky