The Federal Office for Building and Regional Planning

Publication Monitoring of calculation-methods used for non-residential buildings within the scope of the German Energy Saving Ordinance 2007 (EnEV 2007)

BBR-Online-Publikation 17/08, Eds.: BMVBS/BBR, December 2008

Series: BBSR-Online-Publikation Published: 2008

Editing:
Institut für Erhaltung und Modernisierung von Bauwerken e.V. an der Technischen Universität Berlin (contractor)
D. Markfort (project leader), K. Prior
in co-operation with
Ingenieurbüro Prof. Dr. Hauser GmbH, Kassel
Univ.-Prof. Dr. A. Maas

Federal Office for Building and Regional Planning, Bonn
Horst Peter Schettler-Köhler (project leader) horst.schettler@bbr.bund.de , Andrea Vilz andrea.vilz@bbr.bund.de

Abstract

This research project aimed on checking the verification-methods of the German energy saving ordinance 2007 (EnEV 2007) within the scope of a monitoring on specific buildings using the calculation methods of DIN V 18599 (German standard). The examinations were executed both for the so-called detailed proceedings and for the simplified proceedings on the basis of a single-zone-model.

The monitoring of the detailed proceedings was carried out by using the simplifications for the zoning rules of buildings which are available and accounted in the DIN V 18599 and an announcement of the Federal Ministry of Transport, Building and Urban Affairs (BMVBS). The monitoring of the simplified proceedings was executed based on the stage of development published in the EnEV 2007. In the research project the present simplifications concerning the zoning-rules of buildings within the verification methods should be evaluated as well as further possibilities for simplification should be investigated. Both, the work time expenditure should be reduced and simultaneously the compliance with the requirements from the ordinance should be guaranteed.

According to the requirements of the project a suggestion for suitable example buildings for carrying out the monitoring was to work out as well as an ascertainment of the documents required for the plan (building data, furnished proofs etc.) had to be done. Despite intensive efforts merely three calculations of energy performance could be found, therefore it is recommended for future research projects to provide ready example calculations or pattern buildings.

All in all the monitoring was executed with seventeen buildings. In terms of making statistically proofed statements, the number of examined buildings is too small. It is therefore recommended to expand the examinations on a larger scale.

The monitoring of the detailed proceedings was executed under use of simplifications which are available and accounted in the DIN V 18599 and an announcement of the BMVBS. Nine simplifications were examined at a total of seventeen example buildings. Key findings from the examination are:

  • The calculation method of DIN V 18599 permits that the so-called profile No. 19 and 20 can be merged according to DIN V 18599-10 with the profile No. 18. Because of the strong effects on the annual primary energy demand for lighting it is suggested to modify the simplification by regarding the user-specific ventilation flow-rate and to summarize these areas to a profile No. 19.
  • The calculation methodology of DIN V 18599 allows the ascertainment of conduit lengths based on characteristic measurements of a building or a zone. The formulas for the simplified calculation of the conduit lengths within the DIN V 18599 are incorrect. Therefore, considerable need for action is seen with regard to a correction of this simplification.
  • According to an announcement of the contracting authority concerning the simplified data-recording for non-residential buildings, U-values of building’s components can be estimated by knowing the age of the component. Significant need for action is seen with regard to the revision of this simplification. In particular possibilities should be found for further differentiation of the indicated U-values.

In the monitoring of the simplified proceedings the applicability, the boundary conditions to be complied with and the possibility for the extension of the application field were determined.

  • As a result of this investigation it is noticed that the single zone model can provide plausible calculation results even beyond the defined field of application. For the verification methods it is recommended to uncouple the requirement concerning the lighting from the reference building system.
  • Wanting to expand the scope of the single zone model, example calculations were executed. It is recommended to enlarge the application field on the building types "gym" and "library".
  • When using the single zone model in the scope of a public law verification it is recommended to give up the general charge of 10% for the calculation of the thermal-heat-transmission-transfer-value.
  • Before calculating the annual primary energy demand of a non-residential building the components of the heat transferring envelope as well as their U-values and area quotas have to be determined individually for every building zone. With regard to a reduction of the work time expenditure it is recommended to allow the calculation of an average U-value for outside air contacting opaque building components prior to the zoning.
  • The zone-wise regulation of the specific transmission-heat-transfer coefficient for the reference building leads to a significant work time expenditure within the verification procedure. A substantial simplification accompanied with a reduction of the amount of work is achieved when a component based procedure is being introduced to describe the building envelope.

With regard to the simplification of the zoning procedure analyses in direction of a double-zone-model were realized. However, only three of the seventeen example buildings match with the field of application. Reasons for the small number of suitable buildings are either:

  • the buildings are too complex for a simplified consideration,
  • they fall in the scope of the single zone model or
  • they were already calculated in the "detailed calculation" with merely two zones.

The sample in this examination is therefore too small to derive meaningful results. Because of the low application in the context of this research project it is suspected that a double-zone-model does not have any relevance in practice. Rather seem comprehensive, but easily understandable, supports for the zoning of buildings in the form of a practical guide to be necessary.


The abstract is part of the German publication "Monitoring der Verfahren für die Bewertung von Nichtwohngebäuden nach EnEV 2007", BBR-Online-Publikation 17/08, Hrsg.: BMVBS/BBR, Bonn December 2008
ISSN 1863-8732, urn:nbn:de:0093-ON1708R220
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