BONSEI! Optimal use of existing buildings – energy efficient implementation of renovation!

The project BONSEI! would like to support an energy efficient and socially acceptable densification of privately owned residential buildings in urban space and to develop a methodological basis for resource efficient urban areas. The results are used for the conception of an innovative service in order to provide a neutral consulting regarding private densification plans.

Short Description

Starting point/Motivation

Due to the extraordinarily high land consumption in Austria and the thereby induced pressure of population especially in urban regions, there is a need for developing innovative and sustainable solutions to cover the demand of housing requirements and increase energy efficiency simultaneously. An integrative observation of the interactions between different factors such as densification, resource efficiency and energy supply and the pursuit of a systematic, spatially transferable solution is often missing. Great potential of densification as well as a large refurbishment backlog have been identified particularly in single and double family houses. Almost the same applies to small apartment houses. To effectively activate the potentials the predominant private owners need to be contacted and convinced of taking further actions.

Contents and Objectives

The main objective of BONSEI! is the development of criteria and planning principles for an energy efficient densification as an important basis for the modernisation and sustainable development of urban regions. On the one hand the factors energy, location quality and mobility should be better integrated into the domain of densification and on the other hand interactions between densification, energy efficiency and energy supply should be taken more into consideration for the prioritisation of densification areas. The innovative criteria, which are developed within the project, will serve as basis for an exemplary innovative consulting service for the mobilisation of densification and renovation potentials for single and double family houses.


At first, a methodology is designed that automatically identifies potential densification areas. Subsequently, a criteria catalogue is worked out that provides indications on energy efficient densification concepts on both parcel and settlement level. Based on this, a prioritisation method for densification areas is developed and tested in selected areas. In the process the defined criteria (refurbishment backlog, legal restrictions, location quality) are integrated in a standardized format.
Building on this, the innovative concept of a service offer is supplied, which illustrates the urgent need and densification options to authorities and may serve as first contact point for citizens who are interested in objective advice regarding refurbishment and densification issues.


The project BONSEI! uses a cross-system approach and aims at an energy efficient and socially acceptable densification, which supports the resilience of cities and keeps quality of life at a constant level.

Important expected results are:

  • Transferable methodology for the automatized identification of densification potentials on parcel level
  • Criteria catalogue for energy efficient and socially acceptable densification concepts
  • Exemplary examination of interactions between densification and energy
  • Prioritisation matrix for energy efficient densification measures
  • Exemplary innovative consulting service offer for the mobilisation of densification potentials

Within the scope of the BONSEI! project a data base for densification potentials and a criteria catalogue for energy efficient densification were developed, which might serve as important planning basis for further densification measures and provides essential preliminary information for an efficient and target-oriented consulting service for the mobilisation of densification and renovation potentials in existing buildings. This new and innovative service aims at demonstrating the owners the densification potential of their buildings or parcels and exploring all the possibilities. Especially during the first steps the consulting service offers assistance to owners to facilitate a first fundamental decision concerning the further development of their building or parcel.

Prospects/Suggestions for future research

As the feedback for the BONSEI! project given by the involved cities was very good, the initiation of a follow-up project has already been scheduled. In the current structure, the consulting service is on the one hand useful for detailed individual consultation, but on the other hand also expensive and time-consuming. Therefore, it is considered to further develop and modify the whole consultation process to promote a more frequent use of the consulting service and to improve the implementation of the data basis and basic information. Concerning the development of the data basis, the integration of the topics greening and mobility might be interesting.

Project Partners

Project management

Research Studios Austria Forschungsgesellschaft mbH, Research
Studio iSPACE

Project or cooperation partners

  • Energieinstitut Vorarlberg
  • Architekt Paul Schweizer
  • Stadt Salzburg

Contact Address

Research Studios Austria Forschungsgesellschaft mbH,
Research Studio iSPACE
Dr. Thomas Prinz
Mag. Sabine Gadocha
Schillerstrasse 25
A-5020 Salzburg
Tel.: +43 (662) 908 585 213