Heat precautions, i.e. preparing cities and their inhabitants for hot temperatures, is not only an issue for large cities, emphasises Jens Hasse of the German Institute of Urban Affairs (Difu), Environmental Research Division: "Bonn, like many other cities in the Rhine rift valley, is repeatedly in the situation where it is significantly warmer than in other cities, for example in the plains, due to its topographical location." The same applies to southern German cities such as Karlsruhe, Würzburg or Stuttgart.

The city of Bonn has been working on solutions in urban and environmental planning for many years and participates in research projects, says Hasse. In 2018, for example, the Zures project produced the climate analysis map (see graphic), which the city says will be updated at the end of 2023. Bonn is also participating in the Difu research project "Plan C", funded by the Federal Ministry for the Environment. According to Hasse, this involves the development and implementation of heat action plans in Düsseldorf and Karlsruhe and the transfer of experiences to other cities.

But what are heat action plans anyway? According to scientist Hasse, the idea is to extend precautions "beyond the administration to social institutions", such as old people's homes, hospitals, schools and kindergartens, "to help them adapt to heat early and trigger the acute measures on time".

On 10 March 2022, the Federal City's Main Committee mandated the administration to prepare a heat action plan. "Financial resources are available in the recently approved double budget of the Federal City of Bonn," was the statement on the status of the project from the city hall. The administration is coordinating the further procedure with the specialised departments. According to the press office, the aim of the heat action plan is to "prevent heat-related illnesses and possible deaths" through behavioural tips. These are aimed especially at vulnerable groups such as the elderly or people who are exposed to intense heat at work.

What concrete, acute heat protection measures, such as behavioural tips, misting systems and drinking fountains, has the city implemented so far, in addition to the heat action plan that is currently being planned? In response to this question, the press office mentions the heat warnings via the city website, social media and press releases. In addition, the health department distributes information on heat precautions to care facilities and doctors. And the administration is planning to train staff in heat-prone kindergartens on climate adaptation from 2024.

In order to also reach people who do not live in a care facility, there are heat telephones in some German cities. In Kassel and Saarbrücken, for example, elderly people or people in poor health can register and are then called in the event of heat and provided with tips on how to behave. In Kassel, this is organised by volunteers from the seniors' advisory council, who also check for health problems on the phone and inform the family doctor if necessary. In Cologne and Erfurt there is a heat telephone hotline that people can call themselves.

"The idea behind this is that neighbours, circles of friends or senior citizens' councils exist in neighbourhoods who then look out for each other a bit more than usual, especially for single older people or the chronically ill," says Difu researcher Hasse. Cities should initiate such actions, which then usually organise themselves independently.

However, heat action planning is not only about acute help, but also about urban planning measures. "Dense, stone or asphalted cities with little shade heat up and accordingly cool down very, very badly at night," says Hasse. In order for public space to remain attractive, new planning must pay attention to ventilation, greenery and materials that do not heat up.

According to the city of Bonn, a climate adaptation concept will be developed within two years starting this month, funded by the Federal Ministry for the Environment. In the process, for example, the need for spray fogging, as has already been tested in Cologne, is to be examined. So far, such a system is only planned in Bonn for the planned redesign of the theatre square in Bad Godesberg by 2026.

"However, some components of a climate adaptation concept in the field of heat have already been realised in Bonn," explains the press office. The urban climate analysis and planning reference maps are used in planning and approval procedures. The Municipal Building Management (SGB) has already built climate-adapted buildings, such as the new buildings of the Marie-Kahle School and the Elisabeth-Selbert Comprehensive School with green roofs and rainwater retention in the form of infiltration trenches, underground storage tanks.

In building projects, the SGB pays attention to space-saving construction methods, light-coloured surfaces, façade insulation and sun protection. "In the redesign of open spaces, water features and shaded recreational areas are implemented, especially in heat hotspots," says the city, citing Budafok Park as an example.

According to the city, the greening of roofs and facades is regularly prescribed and promoted in urban land use planning. In 2022, almost 60 subsidies were approved, most of them for green roofs. "On private land, a good 3,000 square metres of area could be newly greened and partially unsealed," the press office reports. With the 2023/24 double budget, 100,000 Euro per year are available for funding.

In addition to greening, Hasse says that options for urban climate adaptation include arcades, light-coloured façades and awnings. Up to now, solar sails have been rare in Germany: "But there are good experiences in other European countries, also in Austria. Last year, however, the administration rejected the Green Party's proposal for a sun sail on Ria-Maternus-Platz in Bad Godesberg because of the high costs and susceptibility to damage.

(Original text: Christine Ludewig / Translation: Mareike Graepel)