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Costs of energetically relevant construction- and system-components in the course of energetic refurbishment of residential buildings

BMVBS-Online-Publikation 07/12, Ed.: BMVBS, June 2012

Institut Wohnen und Umwelt, Darmstadt - institute for housing and environment -
Eberhard Hinz
Federal Ministry of Transport, Building and Urban Development (BMVBS), Berlin
André Hempel

Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBSR), Bonn
Andrea Vilz


Based on the decisions of the German Government the German Energy ordinance will be developed further in 2012. This study presents results (costs of energy saving measures) as a basis for the evaluation of economical efficiency of future standards for the energetic refurbishment of the building stock.

The results base on the analysis of costs of energy saving measures in 531 projects; among these 399 single family houses. Most of the projects (72%) have a living area between 100 to 300 m². the overall area of measures in the thermal envelope of the building (thermal insulation, windows) is 237.333 m², the invest is up to € 19.6 million. 509 heating and ventilation systems were evaluated with an invest up to € 9.7 million.

For the following measures the costs and the structure of the costs were investigated:

  • Outer wall
  • Step roof, flat roof
  • Upper ceiling, basement ceiling
  • Windows
  • Solar energy systems for space heating and/or hot water supply
  • Heating systems (gas, oil, Pellet)
  • Heat pumps
  • Exhaust ventilation systems

Function of full costs as well as for additional costs were developed by the method of regression analysis. The statistical significance of the results was tested by further statistical evaluations. With these functions "typical" costs of energy saving measures can be estimated. Two fundamental results of the project are:

  • In general the direct coherence between the costs of energy saving measures and the energetic quality is small.
  • In general the 95%-Confidence-Interval is large. That means, in a single project the costs of energy saving measures can be much higher than the "typical" costs or even much lower. This is in coherence with practical experience.

The aim of the project was to evaluate typical costs of those energy saving measures that are already state of the art. For this the database is eligible. One consequence is that the results can not be transformed to high-quality-standards in energetic refurbishment near to passive-house. Thence the study should be extended to measures of high-quality standards of energetic refurbishment.

The abstract is part of the German publication "Kosten energierelevanter Bau- und Anlagenteile bei der energetischen Modernisierung von Wohngebäuden" - BMVBS-Online-Publikation 07/12, Hrsg.: BMVBS, Juni 2012, Berlin