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Measures to implement the objectives of the energy concept in buildings - achievement scenario

BMVBS-Online-Publikation 03/13, Ed.: BMVBS, March 2013

Institut Wohnen und Umwelt (IWU), Darmstadt
Dr. Nikolaus Diefenbach, Dr. Christian v. Malottki, Dr. Andreas Enseling, Tobias Loga, Dr. Holger Cischinsky, Britta Stein, Michael Hörner, Michael Grafe
Federal Ministry of Transport, Building and Urban Development, Berlin
Alexander Renner

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


In the course of the here presented study scenario analyses were carried out with regard to the energy concept of the German Government and the related aims for the residential building sector (heating and hot water supply). Besides, instruments to attain these targets were discussed.

The scenarios were based upon an energy balance model for the German residential building sector wich was developed by the Institut Wohnen und Umwelt. Relevant data about the current state and modernisation trends in the building stock were derived form the research project "Datenbasis Gebäudebestand", during which a representative survey of house owners had been carried out.

The analyses of the new building sector show that for attaining the "climate neutral" level intended by the energy concept the building standard "Effizienzhaus 40" from the KfW subsidy programmes must approximately be kept. The target achieving scenario for the new building sector assumes a step-by-step progress to this aim.

The scenario analyses for the whole building sector (new and existing buildings) show that a 40% reduction of the CO2 emissions for heat supply until 2020 (related to 1990) will be possible. In order to achieve this goal, some effort must be made because in the trend scenario the CO2 emissions end up well above the target. Therefore, a relevant increase of the annual building insulation refurbishment rate will be necessary. The aim of the energy concept to double this rate will be sufficient and it can be realised stepwise (according to a realistic and market oriented development) if at the same time progress can be made concerning the quality of thermal protection measures and if there is a development towards a new structure of heat supply. This means that in case of heat supply modernisation measures gas and oil boilers which are currently still dominating have to be replaced by alternative systems. Among those are heat pumps and cogeneration systems (local or district heating systems) as well as supplementary solar systems.

For considering the long-term perspective of the year 2050 different variants were examined. Those are no scenarios but snapshots of 2050, in other words plausible assumptions of a possible state of building insulation and heat supply in about forty years. Thereby it was considered that the available potential of biomass as a renewable fuel source will be restricted in the future.

The results show that significant progress in the areas of insulation and an improved heat supply will be necessary for attaining the target of an 80% reduction of primary energy demand which is defined in the German Government's energy concept. The heat demand for heating and hot water in today's building stock must be reduced by at least 50%. This can be attained by doubling the thermal refurbishment rate and keeping this level in the long term. As a result in 2050 75% of today's building stock (as an average of all buildings and building element areas) would have been modernised by insulation measures. In the sector of "old buildings" (erected until 1978 before the introduction of the first ordinance on thermal protection) this fraction would be about 95%.

At the same time a conversion of the heat supply structure of the whole residential building sector will be necessary until 2050. In the considered variants the main part of the heat supply is delivered by heat pumps and by cogeneration systems (partly run with biomass, partly with fossil fuels). Heating systems which base upon boilers fired with oil, gas or biomass are widely pushed back. The majority of the residential buildings will be equipped with additional solar thermal systems. A relevant part of the electric energy used by heat pumps can be produced in the cogeneration systems. Electric energy which is used alternatively or beyond that must be largely produced by renewable energy sources.

The conversion of heat supply can be attained without a large increase of the modernisation rate of heating systems which actually already amounts to a scale of about 3%/a. Thereby it is important that the future heat supply structure is reflected by basically all systems implemented after approximately 2020, because a large part of the heat generators which will be installed later will not be replaced again until 2050.

A comparison of the short-term (2020) and long-term (2050) targets of the German energy concept shows that there are no fundamental conflicts of aims. In fact the doubling of the refurbishment rate, the change towards a new heat supply structure and the introduction of climate neutral new buildings serve to attain the short-term as well as the long-term targets.

To realise the goals of the German energy concept appropriate instruments are necessary. The basics of this question were also discussed in the course of the study.

In the new building sector the step-by-step transition to a climate neutral standard in 2020 can be realised by regulative measures (especially the energy saving ordinance) and a supplementary financial promotion of more far-reaching levels (like in the current KfW programme "Energieeffizient Bauen").

Concerning the existing building stock there is also the option of regulative measures. But here the field of economic steering mechanisms appears to be the most promising approach for a climate protection strategy which has to meet the challenge of increasing the refurbishment rates against the background of a large variety of individual situations of existing buildings. In principle, positive (e.g. subsidy programmes) and negative (e.g. charging of energy costs) financial incentives can be applied. Some of those mechanisms are already implemented, e.g. by the programmes of KfW and BAFA or existing energy taxes. But the trend analysis of the development of thermal protection and heat supply show that the existing instruments are not sufficient for attaining the aims of the energy concept.

The development of economic steering instruments was examined assuming a balance of positive and negative incentives. In other words it was assumed the energy saving promotion programmes could be financed by a fee on energy consumption over a longer period of time. This has to be seen as an exemplary approach because also other weighting of positive and negative incentives would be possible but could not be examined here.

A principle problem of designing economic steering mechanisms is the setting of the magnitude of incentives to attain the targets. Because a proper predicition of the effects of financial promotion programmes and increased energy prices on the frequency and quality of energy saving measures is not possible, model assumptions have to be made. Thus systematic monitoring of the implementation will be necessary to validate if the objectives will be met and to enable a readjustment of measures. But for this economic instruments appear especially suited.

In addition to the "hard" measures of regulatory law and economic incentives, which will probably be necessary for attaining the targets, also the "soft" measures of information, qualification and market transparency have to be considered. The report gives an overview of approaches in the fields of education, planning and quality control as well as information and energy consulting. Also the relation of investor and occupants in the rented building sector and solution approaches for low-income households are discussed. In the appendix of the report estimations for the sector of non-residential buildings are given.

The abstract is part of the German publication "Maßnahmen zur Umsetzung der Ziele des Energiekonzepts im Gebäudebereich - Zielerreichungsszenario" - BMVBS-Online-Publikation 03/13, Hrsg.: BMVBS, March 2013, Berlin