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HFT meets IBA – Urban climate and green spaces

Climate-friendly urban planning: Concepts for Stuttgart from research and practice

The series HFT meets IBA presents innovative solutions for a sustainable city development in the region of Stuttgart

Hot spells in summer, heavy rainfall in winter - climate change will increasingly pose a challenge for cities and urban planning in the future. The first lecture in the series of "HFT meets IBA" therefore dealt with "Urban climate and green spaces". The Stuttgart University of Applied Sciences (HFT) and IBA'27 are jointly organising a series of lectures. Architects, planners from the municipalities, representatives of the Stuttgart Region Economic Development Corporation (WRS) and interested citizens informed themselves about new impulses from the field of urban planning and research. The event took place on 23 January 20 at Das Gutbrod, the meeting place of the Stuttgart Region.

Consequences of climate change for the region

"Climate protection was yesterday - we as a society have missed the train to take effective measures here. It is now a matter of climate adaptation measures that are becoming increasingly urgent," said Dr. Steffen Wurzbacher, Managing Director of the HFT research focus "Energy-efficient buildings and sustainable urban development", who initiated the series. The consequences: Longer periods of drought in the summer growing season and more heavy rainfall in the winter dormancy meant stress for the vegetation and stress for the maintenance of urban green spaces. The increase in rather small-scale flooding in the area of the tributaries of the Neckar is also expected. These have potentially destructive power, according to the prognosis in the climate adaptation concept of the city of Stuttgart.

What can urban planning do against the consequences of climate change?

Dr. Christoph Diepes, Head of Urban Planning of the City of Hagen, spoke about the framework conditions for climate-friendly urban planning. "Climate change is not fiction, climate change is fact." Records have been broken, particularly in the last two decades, in terms of rising temperatures, the potential for storms and drinking water shortages. A central problem is the warming of cities, as there is often a lack of ventilation corridors due to dense development.

However, the city planner emphasized that each municipality can decide for itself in the urban land use planning whether it wants to implement measures for climate protection and climate adaptation. However, many cities and municipalities would not have any concrete standards here. Diepes therefore recommended that they should set concrete standards for a healthy urban climate.

Standards for a healthy urban climate in Stuttgart

Such standards already exist in the city of Stuttgart, for example in the Stuttgart Interior Development Model (SIM) and the Stuttgart Framework Plan for Semi-Altitude Locations, explained Rainer Kapp, Head of Urban Climatology at the Stuttgart Office for Environmental Protection. In its urban land use planning, for example in the framework plan for semi-height sites, the city of Stuttgart has defined around 50 concrete measures to provide fresh air corridors and a cooling infrastructure. In the Neckarpark area, retention areas have also been created to allow water to drain away. In addition, car-free paths, water-permeable coverings, greening of roofs and facades as well as the planting of trees were defined in the planning. In order to alleviate the burden of traffic noise on the citizens, attempts are being made to optimise the structure of the building in such a way that quiet areas such as courtyards are created on the noise-reducing side.

In the framework plan for semi-height sites, importance is also attached to the ventilation of the area with cold air through undeveloped areas. For example, the city of Stuttgart has also imposed a corresponding building ban in certain areas. "If justified accordingly, the municipality or the local council may attach such value to the urban climate", says Kapp. This was also confirmed by the ruling of the Federal Administrative Court, which had dismissed the action of developers for the granting of building permits.

Kapp's conclusion: "In Stuttgart we have always had a need for action and a lot of practice in integrating urban climate issues into the planning process. However, due to the increasing problems caused by climate change, Stuttgart needs to become even more involved and better positioned. It is important to sensitise politicians and to get citizens on board at an early stage through citizen participation. Without the support of the population, who could then demand climate-friendly urban planning themselves, it would not work.

Innovative approach: water reuse

An innovative lecture on the subject of water reuse was given by engineer Prof. Dr. Sonja Bauer from the Department of Geodetic Land Management/Authority Surveying at the HFT Stuttgart. She referred primarily to the "Semizentral" project, which was developed at her former university, the TU Darmstadt, in cooperation with partners from China and Germany for rapidly growing urban areas. In parts of China, wastewater is already being recycled and used for special purposes such as irrigation of green areas, cooling water for industrial plants, toilet flushing or street cleaning.

One approach would be to provide separate pipe networks for grey water (domestic wastewater without faeces) and black water (wastewater from toilets). This is also suitable for special circuits within urban areas and industrial plants. In the Chinese city of Qingdao, for example, black water and grey water are conducted and treated in separate modules in a so-called "Resource and Recovery Centre (RRC)". The grey water is used for flushing toilets in the neighbouring settlements and for irrigating the green areas. The water saving potential is about 30%, Bauer calculated. In Qingdao the water consumption per inhabitant and per day is 109 litres - for comparison - in the USA it is 400 litres and in Germany 120 litres.

Although Germany is still a long way from such considerations, the examples from Asia could also provide an important impetus for the future of our cities, the HFT professor emphasised. However, she said that it could not be a solution to additionally water city trees with drinking water during periods of drought in Germany, especially as drinking water had also become scarce in some cities in Hesse during the hot summer.

Visionary concept: building botany

Oliver Storz from the Bureau Baubotanik Schwertfeger Storz presented visionary ideas on building botany. These are mixed constructions of living plants and conventional components: In his presentation Storz showed, among other things, buildings supported by willow trunks and plants that grow together to form a building structure. This enables them to take over the supporting properties of steel or concrete over time. The architects implement their projects throughout Germany, including the "Theater Of The Long Now" on a wasteland at Stuttgart's Nordbahnhof.

Susanne Rytina, Research and Science Communication, M4_LAB (susanne.rytina@hft-stuttgart.de)

Contact person

Steffen Wurzbacher
Steffen Wurzbacher steffen.wurzbacher@hft-stuttgart.de +49 711 8926 2957
Publish date: 31. January 2020 By Susanne Rytina ()