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Support of pilot projects for the exchange of electric off-peak storage heaters

BMVBS-Online-Publikation 01/13, Ed.: BMVBS, January 2013

ITG Institut für Technische Gebäudeausrüstung Dresden
Dr.-Ing. Thomas Hartmann, Prof. Dr.-Ing. Bert Oschatz, Matthias Ußner
Federal Ministry of Transport, Building and Urban Development, Berlin
Andreas Schüring

Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBSR), Bonn
Horst-Peter Schettler-Köhler (project leader)
Christian Ahrens


The pilot project for the exchange of electric off-peak storage heaters has been conducted by the Federal Ministry of Transport, Building and Urban Affairs (BMVBS) with academic support by ITG Institute for Building Systems Engineering Dresden GmbH during the period from November 2008 to the end of 2011.

Background of the pilot project

For electric off-peak storage heaters which will have been in use for over 30 years in 2020 (only in buildings with more than five dwellings) the Energy Conservation Act 2009 (EnEV 2009) officially requires a gradual phasing out of electric off-peak storage heaters. The amendment of the Energy Conservation Act 2009 (EnEV 2009) and the pilot project for the exchange of electric off-peak storage heaters are fulfilling an order of the Integrated Energy and Climate Program (IEKP) released by the Federal Government.

Pilot Project

All over Germany, the pilot project involved more than 70 owners of residential buildings with at least six dwellings. Best-practice examples of effective redevelopment strategies have been worked out and the results have been made available to potential investors.
During the project the following tasks have been examined:

  • Reduction of primary energy demand and CO2-emissions
  • Profitability of different technical solution in the context of the market and in the context of founding
  • Presentation and evaluation of energy consumption before and after redevelopment, also taking into account the behaviour of tenants.

For the involved property owners are also statements about the expected effects of a conversion of the heating system from the economic, energetic and practical implementation point of view of strong interest. Both the sole heating conversion as well as the combination of modernization of the heating system and energy refurbishment of buildings were considered.


  • A new lease of dwellings equipped with electric storage heating systems is difficult due to the public awareness that rising energy prices lead to rising heating costs. This is the issue facing owners and housing companies when exchanging electrical off-peak storage heaters. Therefore the exchange of electrical off-peak storage heaters is an essential part of redevelopment strategies. It can be inferred that the demand to exchange the heaters referring to EnEV 2009 is not the main aspect.
  • It is clear that the most economical solution is the ongoing usage of still existing electrical off-peak storage heaters, but the upcoming failures of the heaters mainly older than 20 years and the problems with new lease of such dwellings, make this not a real option. Simply replacing the electrical off-peak storage heaters against new ones is related with high investment costs and high operating costs. It is not profitable and not future-proof. Technical developments in regard to Smartgrid can bring back the need of additional storage possibilities; perhaps in collaboration with new interesting price models a reintroduction of a new type of electrical off-peak storage heaters could be energy-related, economically and ecologically reasonable. However this is not yet in sight.
  • The comparison of energy passes (primary energy demand vs. final energy consumption) gives a wrong impression as it looks like electric off-peak storage heaters are much better than their reputation. However for the most part the energy demand for hot water preparation and direct electric heating in the bathrooms is forgotten to be regarded with. When this is taken into account the difference between demand and consumption drops significantly.
  • By switching from decentralised electric off-peak storage heaters to a centralised hot water heating system aspects such as workable construction, pipe routing, centralised/decentralised heating systems, infrastructure for new energy carrier, economic aspects such as apportion of investment costs, founding, and administration aspects such as heat costs billing procedure have to be considered.
  • The pilot project is dominated by standard systems such as condensing gas boilers and district heating, followed by usage of renewable energy (heat pumps, solar thermal collectors). Despite slightly rising end energy consumption by using energy carriers such as gas or district heating, the amount of heating costs (due to different energy carrier specific prices) and primary energy demand declines. If the primary energy factor for electricity (not renewable) drops to 2.0, this statement still will be true.
  • In most instances, both at a total cost basis as well as from landlords and tenants perspectives referring to second calculation ordinance (in council housing stock) the exchange to condensing gas boilers or district heating is economical compared to a 1:1 replacement of electric off-peak storage heaters.
  • The building is more future-proof and has increased energy efficiency with a combination of exchange of electric off-peak storage heaters and improved heat insulation of the building. The operating conditions of use for a variety of modern heating systems (such as condensing boilers, heat pumps, renewable energy) are improved. The combination of exchange of electric off-peak storage heaters and broad heat insulation of the building envelope is more expensive compared to a 1:1 replacement.
  • The project finds that the founding for exchange of electric off-peak storage heaters (scrapping premium) is no more necessary, due to:

    • exchange already being an essential part of redevelopment strategies,
    • the removal of electric off-peak storage heaters not necessarily resulting in their disposal, with reinstallation seen in other buildings,
    • the removal of electric off-peak storage heaters already having been founded by other funding instruments such as founding's for installation of new energy efficient heating systems.

The abstract is part of the German publication "Begleitung von Modellvorhaben zum Austausch von Nachtstromspeicherheizungen" - BMVBS-Online-Publikation 01/13, Hrsg.: BMVBS, January 2013, Berlin