Urban Heat Island Strategy UHI STRAT Vienna

​The Vienna UHI-STRAT (Urban Heat Islands Strategic Plan), published in 2015, is a strategic document aimed at initiating initiatives at various city levels to counteract the Urban Heat Island (UHI) effect but also at providing a comprehensive framework for these various sub-initiatives and -projects. UHI STRAT Vienna was developed under the leadership of the Vienna Environmental Protection Department (MA 22) in collaboration with scientific experts and numerous specialized departments of the City of Vienna. Its development was part of the Central European Urban Heat Islands Project, a collaboration project between the European cities of Bologna, Budapest, Freiburg, Karlsruhe, Ljubljana, Modena, Padua, Prague, Stuttgart, Warsaw and Venice, as well as Vienna.

​The "UHI Strategic Plan Vienna" describes options for cooling urban heat islands and also contains information about the expected effectiveness of individual measures on the urban climate and at the neighbourhood level. Additionally, the strategic plan provides information on the benefits and potential challenges of implementing these measures, as well as the expected costs for their establishment and maintenance.

​Since actions to improve the urban climate take place at a range of levels (climate, nature conservation, landscape planning, urban planning, architecture, etc.), responsibility for implementation is shared by various departments and partners of the City of Vienna.

​The main contents of the UHI STRAT are:

​- The description of the UHI Effect in the Context of Vienna's Urban Climate. That information is based on the results of the research projects "FOCUS-I" and "Urban Fabric Types and Microclimate Response".

- ​Urban Heat Islands and Urban and Nature Conservation Planning: describing areas of action, control levels, and options for action as well as the legal and strategic integration of climate-sensitive urban planning

- ​Strategic Measures for Climate-Sensitive Urban Planning

- ​Measures in Planning and Project Development

​- Areas of action and examples

​- Climate Function Map of Vienna

​- Evaluation Map for Climate/Air in Vienna

https://www.digital.wienbibliothek.at/wbrup/download/pdf/3559581?originalFilename=true
https://keep.eu/projects/5531/Development-and-application--EN/

​What is particular about the UHI STRAT is its comprehensive approach to urban heat mitigation – meaning it not only describes singular measures but serves as a framework for individual (sub-)initiatives and projects by:

- ​Taking a strategic approach emphasises the importance of considering urban climate aspects at various levels of action and decision-making. It aims to implement measures that are relevant to the city as a whole, as well as to individual lots or buildings, promoting a strategic and integrated approach to urban planning

- ​It specifically highlights the importance of public awareness and collaboration: The strategy involves raising public awareness and making various municipal departments and agencies sensitive to the challenges of tackling the UHI effect. This collaborative approach ensures that different stakeholders are involved in the implementation of measures

- ​It also includes s description of detailed measures for cooling urban heat islands and provides detailed information on the potential effectiveness of these measures. It also outlines the advantages, potential hurdles, and expected efforts required for implementation and maintenance

- ​It includes descriptions of exemplary pilot actions and their implementation to verify the feasibility of measures within the urban planning and development framework of Vienna but also make the information more tangible for various stakeholders. This should help in identifying practical solutions and ensuring their sustainable implementation

​As stated above, the UHI STRAT is a strategic document. However, with regards to technical aspects, these are some of the most important features it foresees:

- ​at the strategic level of Climate-Sensitive Urban Planning: measures for maintaining urban ventilation and linking open spaces, the adaptation of city structure and settlement patterns, use of lighter building and surface materials and permeability or the protecting and expanding of green and open spaces or the conservation and expansion of the stock of (street) trees

​- at the level of urban master planning, at the level of land use and zoning planning as well at the building level: it describes measures for increasing the quantity of green in streets and open spaces, greening and cooling of buildings, retaining more water in the city, shading open spaces and paths or for cooling public transport including implementation possibilities

​While the direct involvement of general public representatives in the development process is not explicitly detailed in the available information, the strategy emphasized public awareness and engagement as crucial components for the actual roll-out of the strategy. This suggests that while experts and city administration representatives were primarily involved in the development, public participation was explicitly targeted in the implementation and awareness-building phases.

​According to the City’s Environmental Protection Department (MA 22), which has led the development of the UHI STRAT, no evaluation specifically looking at the impact of the UHI STRAT has been carried out so far. However, since its publication in 2015, a whole range of initiatives related to urban heat mitigation have been implemented both on policy- and program-level as well as in the form of actual implementation projects throughout the city. In general, the City of Vienna shows commitment to addressing urban heat island mitigation through a combination of strategic planning, public engagement, and the implementation of sustainable urban design principles and the UHI STRAT can be considered as a “starting shot” for systematically addressing the issue.

​Some of the major UHI-related initiatives launched since:

- ​Vienna Climate Roadmap (“Wiener Klimafahrplan“) and its regular monitoring

​- Vienna Smart City Strategy and with it, the INKA Programme (“Infrastructure Adaptation to Climate Change”), launched in 2018, the program focuses on implementing measures to adapt the city's infrastructure to better withstand the impacts of climate change, such as increased heatwaves, heavy rainfall, and droughts.

- ​Vienna Heat Action Plan: a living document focusing on preparing health facilities, care, and nursing institutions for heat-related emergencies and protecting the population from the negative health effects of heat.

​- Vienna Climate Law: expected to be officially enacted in spring 2025 and with it serves as a binding instrument not only for climate protection and circular economy but also climate adaptation in Vienna

​Looking at the implementation of measures foreseen in the UHI STRAT, among the most challenging realms are:

​- the more comprehensive roll-out of green roofing and facades especially for the existing building mass. Among others, structural limitations but also cost considerations (focusing on the initial investments only vs. taking into account potential savings in the long run), as well as the perceived maintenance needs, are among the inhibiting factors

​- the more comprehensive integration of sustainable water management as part of or in combination with urban heat mitigation. Here among the inhibiting factors is the required entanglement of public and private land or objects for implementation which is not foreseen (yet) in relevant technical norms and legal processes

​Both the development and implementation of the UHI STRAT were comprehensive and time-consuming processes and as stated above, encompassed a whole range of individual processes and initiatives at different levels. Therefore, it is challenging to distil the recommendations into a few essential points. Hence, the following are some overarching, very generally formulated recommendations:

- ​Early and Continuous Expert Involvement: engage scientific, administrative, practical, and political experts from the outset and throughout the process to ensure well-informed decision-making and effective strategy development.

- ​Stakeholder Inclusion for Greater Acceptance: Involve both public and private sector actors to enhance support and acceptance of measures, ensuring that different perspectives and needs are considered.

​- Interdepartmental and Interdisciplinary Collaboration: foster cooperation between government departments and encourage interdisciplinary teamwork across fields such as urban planning, architecture, climatology, building physics, and green infrastructure to create comprehensive and effective solutions.

​- Public Awareness and Engagement: educate citizens about the effects of climate change and urban densification on their quality of life to increase public support and participation in adaptation measures.

​- Coordinated and Adaptive Planning Process: Align the sequence of planning steps, decision-making levels, and implementation tools in a structured and flexible manner to ensure the smooth execution of heat mitigation measures.

- ​The provision/establishment of binding instruments (like the Climate Law in Vienna) is key to actually enforcing implementation.