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Projektinfo – Detailed information on energy research

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The TEK-tool software utilises the concept of partial energy characteristic values to quickly identify the energy savings potential of complex buildings.
© panthermedia.net, Kasia Bialasiewicz
Energy analysis of non-residential buildings
Projektinfo 16/2013

With the aid of reference values, object-specific partial energy characteristics of the various levels of aggregation including zone, utilisation unit or building can be categorised in one of five energy expenditure classes.
© IWU

© IWU
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Energy performance analysis of complex existing buildings

Together with academic and professional experts, scientists at Institut für Wohnen und Umwelt GmbH (IWU) Darmstadt have developed a method for the energy performance analysis of non-residential buildings. It has been implemented in software and tested in a field test. TEK-Tool helps energy consultants understand actual consumption, evaluate partial energy consumptions, identify weak spots and calculate potential savings. The approach as per DIN V 18599 has been simplified for the calculation process. This allows for a complex building to be assessed in terms of its energy performance within three working days.

Weak spots in terms of energy efficiency in existing non-residential buildings are often difficult to identify. Although consumption certificates as per the energy saving regulations may identify outliers within a given building category, the causes remain uncertain. A computational building analysis in accordance with DIN V 18599, in turn, requires detailed information rarely available for existing buildings. Since it does not consider user-specific power consumption, a reconciliation of calculated requirement and measured consumption is hardly possible. In addition, it takes a lot of time: about 100 hours of work per building, for example, are specified for the calculation of the energy demand of existing government buildings in accordance with DIN V 18599, even if they are significantly smaller than 10,000 m2.

Scientists at Institut für Wohnen und Umwelt GmbH (IWU) Darmstadt have now developed the partial energy characteristic values method in order to achieve meaningful results for complex existing buildings with reasonable effort. This was implemented in the Excel-based TEK-Tool program. The calculation kernel is the multi-zone effective energy balance from EnerCalC, a program for simplified energy balances in accordance with DIN V 18599. On this basis, an analysis of the building with partial energy characteristics (German abbreviation is TEK) and differentiated by zones and systems takes place.

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Why partial energy characteristics?

In order to provide authoritative evaluations of calculated or measured quantities with reasonable effort, we compare characteristics with a fixed reference value, such as the average of a representative sample (benchmarking). For energy consulting services for non-residential buildings, however, the characteristic valuesfor electrical energy and fuel such as they are determined for the energy consumption certificate do not suffice. This is because the causes of high consumption and viable measures to reduce this consumption remain uncertain. The TEK method breaks down the energy requirements of a building according to the various systems, such as heating, ventilation and lighting as well as building zones. These object-specific partial energy characteristic values are compared with reference values for the same systems and user profiles — similar to the reference building method for energy requirement certificates. The reference partial energy characteristic values are calculated for five energy expenditure classes ranging from “very high” to “very low”. Object-specific partial energy characteristic values can then be classified and evaluated.

Object-specific versus simplified calculation

The multi-zone effective energy balance in TEK is calculated closely following the algorithms of DIN V 18599. The input data of the building envelope can be documented in an object-specific and detailed way or if required soon, in a simplified manner. The otherwise highly complex partitioning of the building envelope into segments corresponding to usage zones is automated. As documentation is often lacking for existing buildings, one usually falls back on information available within the building itself where possible, such as readable data on rating plates of the lighting or ventilation systems. Specialists are able to carry out the survey in roughly one working day given a good data situation. Usage parameters can be entered as defaults or as object-specific parameters for all zones. Together with further simplifications to the calculation algorithm, the amount of input data can be significantly reduced and the building analysis thus significantly accelerated.

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Addresses

Project management
IWU GmbH

Load profile analyses - guideline and Excel tool / building analyses
KIT-fbta

Short-term measurements - guideline and Excel tool / building analyses
Fraunhofer ISE

Building analyses
Techem GmbH

Building analyses
IPJ GmbH

Building analyses
ENERGIE 2000 e.V.

Service

BINE-Projektinfo 16/2013
(PDF, 4 pages, 1.3 MB)

Links

TEK-Tool and guidelines
Download from Institut für Wohnen und Umwelt (in German)

Software EnerCalC 2013
Download from research initiative EnOB

Further software and tools
Web link with overview and information about software from EnOB research

Further design tools
Web link with overview and information from eneff-stadt.info

There is further information about the projects of the research initiative EnOB at enob.info.