Urban Fabric Types and Microclimate Response – Assessment and Design Improvement (Urban Fabric + Microclimate)

ACRP 3rd Call, Thematic Area 4: Understanding the climate system and consequences of climate change
Climate and Energy Fund, The Austrian Federal Ministry of Agriculture, Forestry, Environment and Water Management (BMLFUW)

Project start and duration:
1.5.2011 – 20.1.2014 (33 months)

Coordination of project:
Vienna Technical University, Department of Landscape Architecture (Team: Prof. DI Richard Stiles, Dr. Katrin Hagen, DI Heidelinde Trimmel, DI Beatrix Gasienica-Wawrytko)

Project partners:
Austrian Institute of Technology GmbH; Energy Department (Team: Dr. Wolfgang Loibl, Dr. Tanja Tötzer, Mag. Mario Köstl)

TU München; Strategic Landscape Planning and Management (Team: Prof. Dr. Stephan Pauleit, DI Annike Schirmann)

Executive summary:

Urban areas are particularly vulnerable to the impact of climate change; they are also the living environment of choice for a significant majority of Europe‘s population. Global warming has an increasing influence on the urban climate and will consequently affect the future health and well-being of a large proportion of the people of Europe. The objective of the project was to develop a differentiated approach to climate change amelioration in urban areas. This was to respond to the fact that different parts of the urban fabric are likely to be differently affected by climate change, as a function of their characteristic combinations of built structures and open space patterns. Using the city of Vienna as a case study, the first step was to develop an ‘urban fabric typology’, and then to model the microclimate of typical samples of different fabric types. As a result of this, specially defined packages of measures for ameliorating the impacts of climate change were proposed in order to maximise the perceived microclimatic comfort of the urban population in response to expected future climate change.

To generate the typology, data sets were compiled describing those aspects of the urban structure likely to have an important influence on the microclimatic conditions. These included data representing the terrain, building density and height; the distribution of sealed and unsealed surfaces, and the characteristics of the urban vegetation,as well as key microclimatic parameters. A cluster analysis was then carried out, which resulted in the identification of nine main urban morphology types that provided a convincing reflection of the variation of Vienna’s urban landscape, on the basis of the above criteria. Three of these types were further analysed to generate three sub-types in order to further differentiate the larger and more heterogeneous classes.

These “urban fabric types” were then analysed and characterised after which a statistical random sample of each was taken. This was subjected to further analysis with the help of a range of geospatial data, in order to select one sample quadrant of each (sub-)type for more detailed investigation and simulation of the microclimatic conditions.. The analysis involved the identification of typical open space structures within each sample quadrant and the evaluation of their status quo climate conditions by means of simulations.

In parallel, meteorological field measurements were conducted over a period of several months at six sample locations within the Seibersdorf Research Campus of project partner AIT, representing different microclimatic open space characteristics. The results were used to parameterize and validate the microclimate simulation program used in the project, and to draw first microclimate conclusions.

With the help of literature research, the insights of the field study made it possible to interpret the status quo simulations and develop proposals for design interventions, the microclimatic effects of which were subsequently simulated.

The design measures proposed include different combinations of tree planting, de-sealing of ground surfaces and roof greening. The evaluation of the urban fabric types was structured according to the open space structures identified. This led to general recommendations being made with regard to planning and design measures together with the development of specific packages of measures tailored to the conditions prevailing in each sample quadrant and, by implication, to the different urban fabric types which they represent.