Measures for Minimisation of Rebound-Effects Concerning Residential Building Renovation (MARESI)
Redevelopment of buildings is seen as an effective measure to reach national and international agreements for climate protection. But energy savings of realized redevelopment projects often do not reach the expected calculated values. Under different side conditions there are no savings observable at all and in extreme situations, energy consumption for space heating increases after redevelopment.
This phenomenon has been discussed since 1980 in scientific literature, but a comprehensive study or a detailed quantitative investigation of these so called "Rebound-effects" is still missing. Essential obstacles for a systematic investigation are insufficient data on the one hand and a missing interdisciplinary approach considering technicalstructural and socioeconomic aspects on the other hand. This research project pursues two methodically different approaches for a comprehensive point of view. First, 12 case studies of representative Austrian buildings which have been redeveloped up to 10 years ago, are analysed in view of qualitative aspects of consumers behaviour and the influence on the success of redevelopment. Second, the micro data of about 500 Austrian households are analysed to allow a quantification of qualitative observed effects. Finally, internet based information platforms for the target groups of the research project (builders, contractors and energy policy makers) are installed and distributed offensively.
The results of the study emphasize the importance of rebound-effects in the area of building redevelopment and corroborate the findings of national and international literature. Rebound-effects can be subdivided into economical, structural and technical effects. Economic effects are caused by decreasing costs of thermal comfort, structural effects are based on heating system changes or an increasing living area, and technical effects are caused by a missing adjustment of the heating system to the new building parameters. The quantification of rebound-effects shows, that these effects rise, when the condition of building before redevelopment is worse and the redevelopment is more comprehensive. Therefore, small redevelopment actions on by and large good buildings (100 kWh/m2 a) lead to small rebound-effects about 5%. Redevelopments on average buildings (200 kWh/m2 a) cause rebound-effects up to 20% and redevelopment of buildings in bad condition (400 kWh/m2 a) show typical rebound effects up to 50% and more.
The investigation shows that possibilities for the reduction of rebound-effects are restricted, if increasing comfort of consumers is to be provided. But there is still the possibility to reduce e.g. technical rebound-effects by the optimisation of heating system and to restrict consumers' scope of comfort to a meaningful measure by intelligent regulation systerms. Furthermore energy policy measures like redevelopment subsidies can influence structural rebound-effects e.g. by a limitation of living area increase in the coherence with building redevelopment.