Energy efficient, resource conserving and differentiated renovation of historic European building stocks (ReCoRe)
This project is funded within the international research network Eracobuild.
The goal of this research project was to objectify and deepen the knowledge base on building stocks and then to develop integral, long term modernization scenarios which are also based on life cycle analysis. International project partners used similar methods and tools for research on their specific national building stocks.
In Austria research has focused on the social housing of the modern era (built between 1918 and 1934) - the architecture of Vienna, consisting of council housing (Gemeindebau) and housing estates (Siedlungen).
Contents and Objectives
The building stock of Red Vienna remains an essential part of the Viennese cultural and material capital. In addition to their significance in architectural (and social) history they still pro-vide valuable and inexpensive social housing. The initial story on the emergence of social housing in pre-war Vienna, on the housing policy and even on the original inhabitants is well researched and documented. Further research on how the building stock developed between 1934 and 2012 has not yet been carried out. Our building stock research focused both on the material substance as well as data of the buildings. In compliance with the long-term perspective of value preservation and refurbishment, we also investigated external factors (ie. policy) and socio-political trends which will influence the future development of the building stock. The two main objectives of the research project were: firstly, to compile a detailed description of the material substance of the stock and secondly, to define integral, long-term and resource-conserving scenarios. Case study research and an overall evaluation of the portfolio within its urban neighbourhood were techniques used to examine the chosen Austrian building stock. The impact of external factors on the building stock (such as subsidy policy for refurbishment, social housing policy, societal conditions, monumental protection as well as current renovation practices and maintenance) was analysed. We also defined and identified original features of the stock, which comply with contemporary criteria for sustainability and resilience. In line with the long term perspective, the potential for flexibility and adaptability was evaluated. There are a variety of different requirements (energy efficiency, contemporary housing facilities and also inexpensiveness and tenure mix) which the building portfolio will have to fulfil in the future. These sometimes conflicting requirements are all integrated into refurbishment planning.
Based on the preliminary research work from academic partners and the experience of the associated stakeholders, specific methods were developed to deal with specific parts of the stock. These methods were then compared and evaluated using predominantly "building stock research" and life cycle analysis. Building stock research investigates a larger number of buildings of the same age and use class. Thus it is possible to identify the specific portfolio potential of the stock. We used specific criteria to evaluate the sustainable and resilient qualities of the existing buildings.
Along with building stock research, a case study approach was also used. Developing a long-term perspective requires the integration of contingency and uncertainty. Building stock research and analysis of external factors such as demographic change, sociopolitical developments, policy and the availability of different forms of energy were used in scenario development in order to describe unforeseen changes to the building stock.
Scenario-based planning, an established method in management and spatial planning was evaluated and adapted for building stock application. To our knowledge, scenario-based planning has not yet been used in facility management and long term modernization of building stocks.
Building stock research revealed that a large part of the original material substance has been preserved. The buildings maintained their authentic aesthetic qualities, which are based on workmanship and valuable materials.
However, we were faced with a lack of statistical data on the building stock (level of renovation, energy efficiency, energy consumption, use of communal facilities etc.) and a lack of information about the dwellers (occupancy rate, social factors). These facts are either non-existent or not available. Originally, there were 61.175 dwellings in 348 housing units.
The condition of the buildings ranges from non-refurbished to partly-refurbished. There are also council houses with urgent refurbishment need. Renovation measures mostly comply with the subsidized programs offered by Vienna’s local government. Refurbishment and particularly energy-efficient renovation is considerably limited by monumental protection status and the strict rules enforced by the Bundesdenkmalamt (Federal Monuments Office).
Council houses of red Vienna have resilient and sustainable qualities, which originate from the original historic planning. For explicit economic reasons, the buildings were located next to existing material infrastructures and in the vicinity of public transport. Modest dwelling units are well suited for today's single households and contemporary urban and individual life styles. The original units were easily adaptable and were later equipped with modern facilities according to current standards. Communal facilities and spaces for local supply and social facilities, originally intended for joint use with adjoining neighbourhoods, have to some extent lost some of their designated uses. Currently there is a lack of pro-active policy, both concerning new uses for communal areas as well as the re-programming of local supply and social infrastructure spaces.
Council housing is spread almost evenly throughout the city with clusters in some city districts. The proximity of council housing estates to each other and the fact that they are interwoven into the existing fabric of the neighbourhoods shows that a portfolio based approach for refurbishment can be applied successfully. Building clusters allow strategic tenant allocation, which can prevent unwanted urban phenomena such as segregation and residualisation. Existing space can be used for local supply and social services in order to upgrade city quarters as part of urban renewal strategy. Long-term strategic modernisation of the building stock must also preserve the resilient and sustainable features of the buildings. Due to monumental protection status of the building stock, renovation measures on the façades of the buildings are very limited.
Prospects / Suggestions for future research
Parts of publicly owned building portfolios such as social housing, educational facilities, ad-ministration buildings, hospitals and care facilities will remain in the hands of large stake-holders. These building stocks will retain their not-for-profit characteristics. The existence of such large portfolios makes future research on building stocks even more important. Planning policies such as the Swiss SIA "Effizienzpfad Energie" (energy efficiency path for gradual lowering of energy consumption) and the Swiss "2000 Watt Society Strategy" which are both based on incremental optimization and a portfolio-based approach, allow highly differential strategies for non-homogenous building stocks. In larger portfolios owned or maintained by single stakeholders, such diversified strategies allow for further reduction of emissions.
This detailed and combined data comes from different sources such as GIS databases, material and spatial inventories, statistics, social area analysis and energy consumption data. In the future the availability of such aggregated and combined data resources will increase.
Vienna University of Technology; Department of Housing and Design
Project or cooperation partners
- Vienna University of Technology; Department for Industrial Building and interdisciplinary Planning
- European project leader: ETH Zürich, IDB - Institute for monument protection and historical building research
- Swedish partner: Chalmers University of Technology, Gothenburg