IEA ES Annex 50: Prefab Systems for Low Energy/High Comfort Building Renewal

Development of integrated concepts for multi-storey buildings, which enable renovations of buildings with high energy efficiency at good user acceptance during the realisation phase as well as afterwards (comfort, affordability). Relevant components: integrated solutions of roof and façade with high rate of pre-fabrication, the possibility of integrating the energy façade/roofs and energy distribution and supply.

Short Description




Starting point / motivation

A really conservation of energy is only in existing buildings possible. The fraction of the total energy consumption for new buildings is in most of the industrial countries only about 10-20%. 80% is allotted to the existing buildings. The topic “sustainable retrofit for residential buildings” is for this reason also of high importance in a lot of EU-countries (Austria: for example the “impuls program” Sustainable Economise from BMVIT or the climate protection initiative “klima:aktiv” from the federal ministry for agriculture, forestry, environment and water management) and plays an important role in the R&D programs of IEA with relations to buildings.

Experiences with national and international research work in the “new building sector” show that holistic approaches in combination with innovative construction technology lead to the aimed results and that a primary energy reduction of a factor 5-10, in comparison to existing construction standard, is possible.

For the building retrofit, it is crucial that future standard retrofits are carried out with high energetically measures and that renewable energy sources are integrated in the energy supply. A fundamental technical success factor appears to be the implementation of approved techniques of new constructions of passive and low-energy buildings in combination with necessary adjustments of the actual building requirements.

Objectives and contents

The goal of the Annex is to break new ground for retrofit processes and to develop holistic concepts for typical multi-family houses. These concepts should allow large-volume-building retrofits of highly energy efficient standards (passive and lowest energy standards) with a simultaneous user acceptance in the implementing phase (“inhabited construction site”) and also afterwards (comfort, affordability). Important components to develop are holistic roof and façade solutions, which, through a high level of prefabrication, feature good integration possibilities of energy façades and roofs and also complete integration possibilities for energy distribution systems (plug-and-play concept).

Methods of treatment

Fife work programs where compiled by the applicant in cooperation with the operating agent (Mark Zimmermann, EMPA Dübendorf, Schweiz) and professionals from the Implementing Agreements (ECBCS, SHC, PV and HPP) to reach these goals. The emphasis are:

  • Specification of holistic and integral retrofit concepts
  • New development of prefabricated roof and façade solutions
  • Complete integration of the energy distribution system with prefabricated components
  • Integration of solar thermal systems in roof and façade elements
  • Implementation of prototypes in demonstration projects
  • Accompanying know-how transfer on national level

An increase in the efficiency of the national effort is anticipated through participation. This since the contents of this annex very well coincides with the goals of the Austrian research and dissemination strategy. Further is this a great chance to enlarge the Austrian leading position in the area of “sustainable building and retrofit”.


At the beginning the primary work was the extensive cataloguing of the different building types and the development of solution possibilities for prefabricated facade and roof elements. Also the finding of the demonstration project was part of the work.

By the concretisation of the demonstration project „Graz-Dieselweg“, through the housing cooperative GIWOG, it was possible for the AEE INTEC to support the project from the planning through the development to the assembly. Therefore planning tools for the development and planning of large size, prefabricated modules (e.g. 10-steps) were devised.

A module documentation shows vivid the procedure of the development and serves as an assistance for similar projects in the future.

By the co-development of a software called „Retrofit Advisor“, it is possible for owners, clients and policymakers to carry out an economic efficiency analysis in early stage of the high quality retrofit.

The elaboration and development of holistic integral renovation concepts for typical multi-family buildings – in cooperation with industry, building and housing industry and end consumers – are possible with these planning tools and documentations.

The monitoring enables important conclusions for future projects. Also the extensive dissemination (national and international) allows an important intercommunication and knowhow transfer.


Project Partners

Project management

DI Dr. Karl Höfler
AEE – Institut für Nachhaltige Technologien

Project collaborator

DI Ernst Blümel, DI Sonja Geier, DI Rene Hummer, DI David Venus
AEE – Institut für Nachhaltige Technologien

Project and cooperation partners

  • DI Johann Aschauer, DI Volker Taschil
  • gap solution GmbH
  • Ing. Alfred Willensdorfer


Österreich, Tschechische Republik, Frankreich, Niederlande, Portugal, Schweden, Schweiz

Contact Address

AEE Intec
Feldgasse 19
8200 Gleisdorf