Vienna's heat islands: New solutions for cooling down are required!

Vienna's heat islands: New solutions for cooling down are required!

In its Imp-DroP project, a research team from BOKU University is examining the effects of longer heat waves in the greater Vienna area. The study particularly highlights the problem of urban heat islands, which lead to higher temperatures in densely built-up areas, especially at night. There are many reasons for this: dense development, sealed areas, the lack of vegetation and additional heat sources such as traffic, air conditioning and industry contribute to overheating. This limited night-time cooling represents a significant challenge for the human organism as it impairs the necessary recovery, as oekonews reports.

The environmental protection department of the City of Vienna has been dealing with urban climatic issues since 2001 in order to promote urban design that is adapted to climate change and increased summer comfort. A variety of measures to combat urban heat islands have been developed to improve the urban climate. This includes analyzing weather data and evaluating urban projects to better understand heat-related emissions and their impact on the micro- and urban climate, the City of Vienna says on its website.

Research approaches and tested measures

The research team examined various measures to reduce temperature. This includes targeted irrigation of green roofs, parks and agricultural areas to optimize evaporative cooling. The approach shows promising results: targeted irrigation in Marchfeld could reduce local temperatures by up to 3 °C, while the cooling in the urban area is only around 0.2 °C. But it also becomes clear that this would require a significant water requirement of 630,000 m³ per day, while the high spring pipelines can only provide 375,000 m³. It is recommended to develop sustainable irrigation concepts that use, for example, rainwater or Danube water to effectively support urban greening.

In addition, the use of photovoltaics on green roofs could not only reduce fossil electricity imports, but also reduce heat emissions. The maximum implementation of a solar strategy on roofs could promote cooling of up to 1.5 °C. Such measures are part of a necessary mix of urban planning, energy policy and resource conservation to make cities heat-proof.

Innovative greening concepts and their goals

Another innovative project to improve the urban climate in Vienna is edible balcony gardens, which include retrofittable balconies and integrated vertical gardens. These concepts aim to increase quality of life, biodiversity and adaptation to climate change. For example, biochar from sewage sludge is also used in the GreenChar project to give roofs a better microclimate and reduce urban heat islands. The STREETTREE project is also being investigated to plant urban trees in heavily built-up areas with many underground utilities. The aim of these measures is to expand the quality of stay and the biodiversity of the city, as explained in detail on the BOKU website.

Continuous efforts to make the urban infrastructure climate-resilient are also important for urban planning. The environmental protection department continuously examines the effects of urban development projects on the micro- and urban climate and formulates suggestions for improvements that are essential in the context of worsening climatic conditions. All of these initiatives show how cities can address the challenges of climate change with the help of research and planned environmental protection, as boku.ac.at and wien.gv.at also illustrate.