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BBR-Online-Publikation 18/08, Eds.: BMVBS/BBR, December 2008
Editing:
Passive House Institute, Darmstadt (contractor)
Oliver Kah (project leader), Dr. Wolfgang Feist, Dr. Rainer Pfluger, Jürgen Schnieders, Dr. Berthold Kaufmann, Tanja Schulz, Zeno Bastian
Federal Office for Building and Regional Planning, Bonn
Andrea Vilz (project leader)
andrea.vilz@bbr.bund.de
Much of the total energy consumed in Germany is used for space heating, therefore a decrease in this energy demand is an essential prerequisite for meeting national CO2 emissions reduction goals. Reducing space heating demand therefore represents an important contribution towards climate protection. In order to realise these potential energy savings, the cost-effectiveness of the required measures is just as important as knowledge of the available potential.
This study includes recommendations for new efficiency requirements in residential and non-residential buildings, as well as retrofits of existing buildings based on the Energieeinsparungsgesetz (EnEG), taking recent changes in the economical boundary conditions into account. The results are to be used as a basis for decision-making for an updated version of the Energieeinsparverordnung.
The results of the study show that energy efficiency is one of today's most economically rewarding energy "sources". The energy saving measures that have been analysed here frequently incur considerably lower initial costs than the purchase of conventional fuels. Moreover, the creation of value using these measures occurs almost exclusively in medium-sized, domestic manufacturing businesses. These enterprises have a very high labour content, so the consistent mobilisation of the economic potentials described here has a considerable impact on national employment.
The renewal and renovation of building components takes place over relatively large time intervals (every 20 to 50 years), therefore these occasions should be used as comprehensively as possible for improving overall building efficiency. Saving one kilowatt hour of heat energy by investing in an energy saving measure is frequently significantly cheaper than the alternative of purchasing energy (this study has been based on a future purchase price for natural gas/oil of 6,6 Eurocents/kWh). The economically required heat transmission coefficients which have been identified for exterior building components are between 0,16 and 0,19 W/(m²K). The cost for saving one kilowatt hour with these components is between 1 and 4,6 Cent/kWh.
Against the background of these changed economic boundary conditions a new standard for residential buildings is determined. The calculations for this are based on the DIN V 18599. The proposed, new primary energy demand is 35% lower than in prior regulations. It must be pointed out that these tightened requirements will have a greater impact on buildings with a disadvantageous A/Ve ratio. For the verification of cost-effectiveness, which is required by existing German legislation, packages of measures have been defined which achieve the proposed new required standard, and at the same time cause a lower combined financial burden for the investor and the user. In addition to the primary energy savings, the annual overall burden (made up of capital, operational and energy costs) for the documented execution examples drops by an average of 1 €/(m² living area). The necessary extra expenditures of the execution variants are at an average of 52 €/(m² living area).
For non-residential buildings, the required primary energy demand is specified with the help of a reference building execution, and for this a new reference execution has been developed. For three model buildings (two office buildings and one school) the primary energy savings and the cost-effectiveness of the required standard which can be expected have been analysed. For buildings with supply/extract air ventilation systems, an average of 47% of primary energy can be saved compared to the Energieeinsparverordnung 2007 (EnEV). The overall lower annual burden has been proven, using case study examples. The average, annual return compared to an execution according to EnEV 2007 is 2,30 €/(m² net floor area). In this case the additional investment for the execution examples is at an average of 64 €/(m² net floor area).
In the second part of the study, the calculation rules for the evaluation of buildings with a particularly low energy demand are examined. Using four projects which have previously been subject to measurements, the question of whether the measured space heat demand can be reproduced with sufficient accuracy with the calculations according to DIN V 18599 has been analysed. For this analysis, the space heat demand, calculated according to DIN V 18599, is compared to the results of the measurements.
Moreover an additional parametric study regarding the energy demand with different insulation standards, buildings sizes, mechanical systems and boundary conditions has been carried out, using a model building. With the help of previously validated dynamic simulation software, a building model has been created which allows for a differentiated analysis of the different energy efficiency measures, as well as of the effects of the studied parameters. The results have been systematically evaluated and compared to the results of the DIN V 18599 calculation methods.
The DIN V 18599 calculation method leads to realistic results when calculating the energy demand of buildings. With a detailed data input, energy efficient buildings can be represented with sufficient accuracy as well. A list of proposed complements and modifications has been developed.
The abstract is part of the German publication "Bewertung energetischer Anforderungen im Lichte steigender Energiepreise für die EnEV und die KfW-Förderung", BBR-Online-Publikation 18/08, Hrsg.: BMVBS/BBR, Bonn December 2008
ISSN 1863-8732, urn:nbn:de:0093-ON1808R222
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