The Department of Energy Planning of the City of Vienna

In 2019, The Economist ranked the City of Vienna, in Austria, as the city with the highest quality of life worldwide. Indeed, the City’s administration believes in the value of innovation to cope with climate change and reach excellence in the delivery of public services.

The Department of Energy Planning of the City of Vienna is responsible for implementing sustainable policies in the energy sector, allocating funds and testing innovative solutions to produce energy out of renewables, increase the use of waste heat and promote energy-efficient and climate-friendly mobility.

Among other tasks, the Department issues a periodical Energy Report aimed at raising residents’ awareness on the status of energy and climate-related issues in Vienna.

The challenge

Urban areas are generally warmer than their surrounding areas. This phenomenon, known as “urban heat island effect” can cause health risks and higher energy consumption in cities.

In the past years, the urban heat island effect in Vienna has been exacerbated by a growing population and an increase in urban development, which led to the loss of permeable open green spaces and to higher temperatures.

In 2003, the city experienced 44 heat wave days, which were responsible for 180 deaths. Forecasts predict that between 2021 and 2050, there will be an average of 19 heat days in Vienna, while the population is expected to increase from 1.8 million to 2 million by 2029.

To prevent health risks to the residents of Vienna, the Energy Planning Department was hence looking for ways to identify urban “hot spots” and take measures to mitigate the consequences of increasing temperatures in the city.

The satellite solution

In 2019, the Department asked ECOTEN Urban Comfort, a company based in Prague and specialised in urban and environmental engineering, to map heat islands in Vienna to help them identify where action was the most needed.

After assessing the needs of the Department, the company defined the relevant indices to assess the city’s vulnerability to heat waves. Exposure, which is the prevalence of high temperatures across the city, was calculated by looking at images from the Landsat 8 satellite from 2015 to 2019.

Sensitivity was measured based on the density of vulnerable people (younger than 14 and older than 65) with data derived from Vienna’s Open Data portal.

Finally, adaptive capacity, which represents the ability of the urban ecosystem to cope with heat events thanks to the presence of greenery and waterbodies, was calculated by using imagery from the Sentinel 2A European satellite, which carries information to estimate both the enhanced vegetation index of the city (the density of urban vegetation) and its normalised difference water index (measuring water-bodies).

The indices were then combined to create a Heat Vulnerability Map of the City of Vienna.

The map shows which areas in Vienna are more affected to heat (in orange and red), providing information about temperatures and vulnerable people in the 250 districts of the city. In total, ten heat vulnerable areas have been identified in Vienna.

The results

The map created by ECOTEN Urban Comfort on the basis of satellite data and released by the City of Vienna is meant to serve as an operational tool by the Department of Urban Planning and other city authorities to implement mitigating measures in the neighbourhoods that are more vulnerable to heat events.

Indeed, the map contains information on high temperatures in Vienna and on areas with low vegetation and waterbodies and with a high number of vulnerable people. Furthermore, the analysis carried out by Ecoten Urban Comfort showed that, if no action was taken, temperatures in Vienna would increase of 8°C by 2050.

The Urban Heat Vulnerability Map initiated a series of public reactions via social media and mainstream media which ultimately led to a political debate over initiatives that the city can take to protect its citizens from extreme heat and provide comfortable eco-friendly urban districts for urban dwellers that are most vulnerable to extreme heat.

Based on the Urban Heat Vulnerability Map, in 2019 the City of Vienna launched the “Coole Straßen” (Cool Streets) project, aimed at lowering temperatures in the three districts identified as the most vulnerable to heat. In these areas, the City authorities created open spaces with trees and brighter surfaces, which reflect less heat, and installed mist showers to cool the asphalt and humidify the pavement. In addition, parking was banned in selected streets.

“For the first time we have a map that shows us where cooling is urgent and allows us to take specific measures.” Birgit Hebein, Former Deputy Major, City of Vienna

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Copenhagen Solutions Lab

Copenhagen Solutions Lab is an internal consultancy of the Technical and Environmental Department of the Municipality of Copenhagen, in Denmark. With a staff of eight people, Copenhagen Solutions Lab works on issues of transversal interest among the City’s departments by using innovative technologies to promote green urban strategies and policies.

The challenge

Air quality is an issue that concerns several municipal departments, including those responsible for adaptation to climate change, environmental protection, transport, biodiversity, water, economic development, and, — especially — health.

Indeed, even in a clean city like Copenhagen, air pollution is identified as one of the main causes of premature deaths and it is suspected of exacerbating illnesses such as cancers, cardiovascular, respiratory and lung diseases, and even neuro-logical disorders like autism, dementia, Parkinson’s, depressions, and more

Traditionally, air quality is monitored through sensors at static stations located around the city. These provide a generic representation of air quality, and in particular its annual average, which reveals long-term trends. Nevertheless, traditional measurements are not able to deliver precise information on where and when pollutants are most present during the day and people are exposed to it.

Copenhagen Solutions Lab was looking for ways to localise air pollution at the street level and to understand when specific city spots are particularly vulnerable to this phenomenon.

The satellite solution

In 2017, Google offered to support the efforts of Copenhagen Solutions Lab by using the methodology developed within their Air View Project, with the help of the University of Utrecht and the University of Aarhus.

Google equipped its Street View cars with air quality sensors and collected data on air quality in every street of Copenhagen. The measurements targeted the pollutants that are emitted in the city, especially nitrogen dioxide, ultrafine particulate matter and black carbon.

The cars logged one measurement per second, collecting very granular spatial data on air quality, which could be geolocated thanks to the Satellite Navigation systems embedded in the cars. These passed on every street at least six times during one and a half year, in order to get the seasonal distribution of air pollution. This was done until March 2020, when the city lockdown caused by the COVID-19 crisis was declared in Copenhagen.

The spatial accuracy of the information collected in such a way allows for the identification of correlations between human activities, infrastructure and air pollution, according to the time of the day and the season.

The results

In October 2019, a preliminary map of air quality in Copenhagen was published and presented by the City’s Deputy Mayor at the meeting of the mayors of the C40 Cities Climate Leadership Group, that was taking place in Copenhagen.

In the same year, the project caught the attention of other local and international partners. Gehl Architects, a Copenhagen-based urban design agency, got interested in the map and decided to use it to understand how they could reduce the effects of air pollution on children by redesigning public spaces. This initiative, The Thrive Zone project, funded by the Bernard van Leer Foundation and the ICLEI Action Fund, aims at designing urban solutions to increase air quality and reduce exposure to pollution, and at involving citizens in data collection, design and in behavioural changes.

In particular, Gehl mapped childcare institutions and interviewed care workers and care givers on children’ movements in two neighbourhoods, and crossed such data with the information they had on air quality to understand how air pollution impacts on them. Afterwards, Gehl produced a “Cleaner Air Network” map, indicating the areas where air quality is better and where children could spend more time, suggesting urban design interventions.

The final map of Copenhagen’s air quality was released openly in the Spring 2021, accessible to anyone. The map allows for the identification of the most polluted areas (major inroads, airport and the city centre) for the different pollutants, i.e. nitrogen dioxide, ultrafine particulates and black carbon. The map aims at serving all departments of the City’s administration, by putting air quality at the core of city policies.

Copenhagen AirView NO2

The dataset and the model to use it are made available to support urban policies aimed at reducing the exposure to pollution, especially for the most vulnerable groups. Meanwhile, the Thrive Zone project continues to test how implementation can happen in existing urban areas and document effects in real life settings, e.g. by using bushes and trees to contrast fine particles, or by building spaces for children and the elderly where air quality is higher) and to make residents less exposed to pollution by changing their behaviour (i.e. by spending less time in polluted areas).

“By making scientific data available to citizens, we have the potential to make global challenges relevant at the local scale”, Rasmus Reeh, Copenhagen Solutions Lab

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