The Solar Furnace Laboratory as a Low Energy Building

In addition to the optical based test facilities the laboratory building itself was designed as a test and research system in the field of low energy building system technology.
The building includes the laboratories, measurement rooms, workshop areas and the solar simulator room. This building with an effective area of 240 m² was designed in accordance with the rules of low energy architecture. The aim was to investigate the possibilities and limitations of lowering the energy demand of non-residential buildings.      
The reason to carry out this project was that the mass- and energy profiles of those buildings differ significantly in comparison to normal houses. Hence new ideas have to be worked out to reduce the energy demand of non-residential buildings.
The building and the earth-to-air heat exchanger (L-EWT) were measured over a five year period on behalf of the Ministry of Research of the federal state North Rhine-Westphalia.

The governmental support program named „Working-Group Solar North Rhine-Westphalia“ attended the project „Energetic Diagnosis of Buildings“, which contains a network of 13 non-residential buildings scattered all over North Rhine-Westphalia. Each of them were measured intensively and the collected data were examined and compared at the University of Siegen.


The Planning Guide Earth-to-Air Heat Exchanger (L-EWT)
L-EWT of the working-group Solar NOrth Rhine-Westphalia

Apart from the well known passive measures the earth-to-air heat exchanger (L-EWT) is the most important active element of the thermal adjustment of indoor air. Of very special interest is the effect of L-EWT to cool the working rooms in hot summer time periods, especially due to the high amount of inner thermal sources like persons, computers, running machines and thermal processes.

Earth-to-air heat exchanger (L-EWT)


An extensive, multi-faceted planning guide was compiled. All kind of possible methods of calculating L-EWT (numerical and analytical) were respected. Numerous running L-EWT all over Germany were investigated and compared. An extensive system of regulations to calculate L-EWT of all sizes can be provided now.


In the right column all parts of the planning guide are available for download.

Part 1 „Small Systems“ of the L-EWT planning guide earth-to-air heat exchanger (L-EWT) consists information and applicable corporate guidelines and rules for simple systems for residential homes (up to 1000m³/h volume flow).

Part 2  „Big Systems“ of the L-EWT planning guide earth-to-air heat exchanger (L-EWT) is focused on design and technical optimization of big L-EWT above a volume flow of 1000m³/h for non-residential houses.

Dr.-Ing. Hans-Gerd Dibowski
German Aerospace Center

Institute of Solar Research
, Facilities and Solar Materials
Tel: +49 2203 601-3211

Fax: +49 2203 601-4141

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Downloads zu diesem Artikel
L-EWT Teil 1 Systeme für Wohngebäude (
L-EWT Teil 2 Planungsleitfaden Lies Mich (
L-EWT Teil 2 Einleitung (
L-EWT Teil 2 Technische Planung (
L-EWT Teil 2 Testanlagen im Verbundprojekt (
L-EWT Teil 2 Bewertungskennzahlen (
L-EWT Teil 2 Benchmarking (
L-EWT Teil 2 Datenblätter (
L-EWT Teil 2 Anhang (
L-EWT - Simulationsprogr.- Dokumentation (Zip-Datei) (