How effective are adaptation measures in combating urban heat stress? - The "HRC-Hitzetool" was designed to evaluate them

Very sunny, hot days and warm nights compromise the well-being of city dwellers. To protect the population from heat stress urgently requires adaptation measures such as shading or the removal of impervious surfaces followed by the planting of vegetation in urban areas. When it comes to implementation, municipalities, the housing sector and individuals repeatedly face the issue of which measure will be most effective in countering overheating. Digital planning tools can offer support with this critical decision.

The Leibniz Institute of Ecological Urban and Regional Development (IOER), TU Dresden and the HTW Dresden - University of Applied Sciences joint forces with municipal partners to develop such a tool as part of the HeatResilientCity joint project (HRC). The “HRC-Hitzetool” (HRC heat tool) enables users to estimate how effective adaptation measures are outdoors as well as in and around residential buildings. The development of the tool was based on an extensive research of already existing tools. Based on the findings, the project team devised the "HRC-Hitzetool". The goal was to compensate for the shortcomings of existing applications while providing a simple and easily transferable tool for assessing small-scale heat adaption measures.

Adaptation measures in outdoor spaces
The outdoor indicator of the "HRC-Hitzetool" helps users estimate the impact of measures taken to combat heat stress in open spaces. This makes it possible to assess just how effective small-scale measures and roadside greenery are. Based on the given model surface areas, surfaces can be selected which best represent the initial condition of the space as well as the planned measure. The difference in human thermal load between the two areas is evaluated. Furthermore, the tool enables time-based diagnostics which take into account the different conditions of the summer months and times of day. Both aspects represent an innovation in comparison to other applications. A system similar to that of a traffic light visualizes simply how effectively a measure reduces heat stress.

Adaptation measures for residential buildings
The second part of the "HRC-Hitzetool" helps users estimate the impact of measures taken to combat heat stress in indoor spaces. First, the current heat stress level of a room is calculated.This requires entering the location of the given room within the building, the dimensions of the windows, the construction method used for the building and the ventilation system. The second step requires users to select the adaptation measure, for instance outside blinds or planting greenery on the roof, so that its effectiveness can be assessed. How effectively the selected measure reduces heat stress in the given room is also indicated via a tarffic light system.

Background
The HeatResilientCity project was funded by the Federal Ministry of Education and Research (BMBF) and the European Union. In addition to the Leibniz Institute of Ecological Urban and Regional Development in Dresden, the project network comprises: the Institute for Urban Research, Planning and Communication of the University of Applied Sciences Erfurt (ISP), the Chair of Meteorology of Technische Universität Dresden (TUD), the HTW Dresden - University of Applied Sciences, the Environmental Office of the City of Dresden, the Environmental and Nature Conservation Office of the City of Erfurt as well as the Railway Workers’ Housing Cooperative (Eisenbahner-Wohnungsbaugenossenschaft) Dresden (in Phase I) and the Office of Health and Prevention of the City of Dresden (in Phase II). The project was honored with the 2022 German Sustainability Award for Research.