Since german reunification, the demand for living space in Dresden has risen by a third. Accordingly, the Saxon state capital has built a lot – with negative consequences for brownfield sites and urban greenery. Increasing density and sealing as well as decreasing green and open spaces are creating new heat islands. For a few years now, however, Dresden has been relying on the help of AI in addition to conventional measures such as unsealing.

The city council of Dresden has been dealing with climate change and the necessary changes for many years. For example, similar to Frankfurt am Main, green facades are to become mandatory in future – but only for new buildings and for large, windowless facades with an area of over 25 square meters. However, this is not enough for the very hot summers, the extreme groundwater drought and the high fire risk in eastern Saxony, the Elbe Valley and Dresden. The heatwaves that now occur every year are already causing health problems for many people and damage to the green infrastructure.

Nevertheless, Dresden has made a name for itself as a city that courageously stands up to the heat: As a model city, it is in demand nationwide due to its expertise. This is due to major completed studies such as the “Regklam” on regional climate adaptation, the current research network “HeatResilientCity”, which received the German Sustainability Award in 2022, and awards such as the prize for “Dresden baut Grün” as a climate-active municipality in 2020.

According to Environment Mayor Eva Jähnigen, Dresden is technically well positioned when it comes to adapting to the heat. What is still missing is implementation in the city’s everyday life, as many measures do not receive sufficient resources to be put into practice across the board. “Climate adaptation tasks must become part of our public services and a mandatory task. Everything that is newly built must be designed according to these criteria,” said Jähnigen.

Dresden is becoming more water-permeable

One practical adaptation measure in Dresden is heat protection as part of the renaturation of river courses and streams in the city. According to Lord Mayor Dirk Hilbert (FDP), Dresden has invested several million euros in these projects in recent years. However, more detailed information is difficult to find – and the prolonged drought is causing problems even for renaturalized rivers. As a result, they cannot help to alleviate heat islands in the city during hot spells as desired.

Dresden also wants to position itself as a sponge city and reorganize rain runoff. The city should not only be prepared for heat, but also for heavy rainfall. Measures such as the unsealing of sealed surfaces, retention basins, ditches and cisterns will enable the city to absorb rainwater locally instead of draining it away. Furthermore, additional green spaces can help to cool the city. A pilot project at Dresden Südpark is already testing how rainwater can seep away optimally. For the city’s new Technical City Hall, built by Ed. Züblin and Dressler Bau, a cistern with a capacity of ten square meters is planned, which will be used to water green spaces and trees. And the city’s parking space regulations already stipulate that parking spaces must be built with grass pavers so that they are permeable to water. One tree must be planted in the parking area for every five parking spaces. In future, bus stops are also to be equipped with green roofs.

Data train AI algorithms on heat islands

An innovative urban and traffic planning project is also taking place in Dresden: KLIPS is an AI-based information platform for the localization and simulation of heat islands. This platform should make it possible to localize heat islands in real time using a local sensor network and artificial intelligence. It should also be possible to make forecasts in order to identify and avert the risk of heat islands in good time.

KLIPS draws largely on existing data, such as data from pilot cities and satellite data from the Sentinel fleet of the Copernicus earth observation program. New sensor networks in Dresden and Langenfeld are intended to increase the spatial resolution of this data so that locally reliable measurement data can be obtained. These permanently measure the temperatures at particularly temperature-sensitive locations in the city. The data from KLIPS will also be used to train the AI algorithms as part of machine learning. This makes it possible to assess the consequences of construction and traffic planning for heat islands as well as the effect of planned measures to reduce heat islands.

Green measures in heat-prone microclimates

KLIPS is due to start in spring 2023. By then, the city of Dresden plans to distribute 300 temperature sensors throughout the city. The system will run until at least 2026 and provide important information on heat islands in the city. The federal government is funding the project until 2024 with 2.3 million euros from the Ministry for Digital Affairs and Transport. The participating project partners are also making their own contributions.

The hope of KLIPS is to become an integral tool for construction and traffic planning. The project aims to create a data basis for forecasting the local heat situation. In addition to the 300 sensors, satellite, cadastral, weather and climate data will also supplement the data picture. Various applications can be derived from this digital modeling. These could include, for example, a heat warning system to provide the public with more targeted information in the event of extreme temperatures.

Based on the database, the city should also be able to estimate how watercourses, shading, façade greening, trees and surface design affect the local microclimate. Accordingly, KLIPS would inform the design of public streets, squares and parks as well as local public transport stops and the question of possible greening of railroad tracks.

Dresden as a pilot city in the EU

In addition to the city of Dresden, various other players are involved in KLIPS: Software AG, the ERGO Environmental Institute, the German Aerospace Center, the Fraunhofer Heinrich Hertz Institute, the Institute for Information Systems at Hof University of Applied Sciences, the Leibniz Institute of Ecological Urban and Regional Development and the companies Pikobytes, terrestris and meggsimum. The city of Langenfeld in the Rhineland is also a pilot municipality within the research project.

As a pilot city and leading German city in heat measures, Dresden is also participating in the EU’s MAtchUP program. This model program for sustainable urban development is investigating how smart city applications can provide intelligent solutions for urban transformation. Valencia and Antalya are also involved in this program.

From adaptation to mitigating the effects of climate change

The initial results of KLIPS are eagerly awaited. After all, the data in combination with artificial intelligence could make a significant contribution to adapting to the warmer temperatures of the future and, among other things, protect the health of Dresden’s residents as well as the city’s flora and fauna.

In addition, however, it is necessary to take measures to mitigate the consequences of climate change as quickly as possible. Projects with a broader vision for climate protection, such as significantly improved energy efficiency in the building sector or the consistent greening of roofs in the city, are still lacking in Dresden – as in almost all other major cities.

More on this topic in G+L 06/23

Published as part of the international Beat the Heat initiative.