Urban Heat Vulnerability Assessment of



Between 1961 and 1990, Vienna experienced on average 9.6 heat days per year. From 1981 to 2010, the number of heat days rose to 15. According to forecasts, there will be an average of 19 hot days between 2021 and 2050, and 41 between 2071 and 2100. Moreover, the population is expected to increase from 1.8 million to 2 million by 2029. To protect the population from the consequences of heat events, the Energy Planning department of Vienna decided to take action.


1. We study the urban needs.

2. We define relevant indices to take into consideration for heat assessment.

EXPOSURE is measured by studying and quantifying the occurence of high temperatures within the city between 2015 and 2019  

SENSITIVITY is measuring the population density for individual younger than 17 and older than 65.

ADAPTIVE CAPACITY highlights greeneries and water-bodies. It is the ability of the ecosystem to cope with heat events.

3. Based on our algorithm, we map the sub-indices and combine them to create the Urban Heat Vulnerability Map.

4. We customise environmental solutions to cool down critical hotspots.


Without any action, + 8°C by 2050

The top 10 districts have been ranked based on their average Urban Heat Vulnerability Index. These districts  present a very little vegetation. The map also shows that even in less urbanized areas, heat vulnerability points are likely to appear. Through the study, we found that by 2050, Vienna will heat up to 8 degrees if no action is taken. 

The Cool Streets project

Vienna is developing „Cool Streets“: places for people to stay outdoors, play games, and socialise. This program intends to provide additional seating, cooling systems such as mist showers and establish parking ban to allow citizens enjoy the city at its best. After interviewing 518 citizens results showed that „Cool Streets“ was a great success and should be continued next year. The municipality plans to extend this measure to all 23 Viennese districts.

For the first time we have a map that shows us where cooling is urgent and allows us to take specific measures.
Birgit Hebein
Vienna's deputy major