Participation in TASK 25 of the Implementing Agreements on Solar Heating and Cooling of the International Energy Agency (IEA)

Participation in TASK 25 "Solar Assited Air Conditioning of Buildings". Description and Analys of the state of the art, development of a simulation tool, build up and measurement of demonstration plants.

Content Description




Combining solar thermal energy and cooling of buildings is one "dream" of research in the filed of solar energy, because solar yield and heat demand highly correlates.

Task 25 "Solar Assisted Air Conditioning of Buildings" of the Implementing Agreement on Solar Heating and Cooling of the International Energy Agency (IEA) was started in June 1999 and deals with the possibilities of environmental benign cooling systems, which use solar energy solely or in combination with other energy carriers for the air conditioning of buildings. The goal of the task is the improvement of the conditions of the market introduction of solar assisted air conditioning systems in order to reduce primary energy demand and peak electricity demand of air conditioning systems. Besides the theoretical analysis of different technologies, existing plants were deeply measured and new plants were designed and build up. Operating Agent of Task 25 was Dr. Hans-Martin Henning from Fraunhofer Institut for Solar Energy Systems ISE in Freiburg/Germany. The four Subtasks of Task 25 had the following results:

Results of Task 25

Subtask A: Survey of solar assisted cooling technologies

  • Webpage with solar assisted cooling programs and projects

Subtask B: Design tools and simulation programs

  • User friendly software for architects and planners for the design of solar assisted air conditioning systems (SOLAC) with handbook.
  • Guideline for system selection

Subtask C: Technology, market aspects and environmental benefits

  • Handbook for planners of solar assisted air conditioning systems with a market analysis of available components, systems and control strategies
  • Technical report on new developments (systems, components)
  • Coloured brochure "Using the sun to create comfortable indoor conditions"
  • Poster series (10 bi-lingual English/German, 3 bi-lingual English/Italian, 3 bilingual, English/Portuguese, 3 bi-lingual English/Spanish)
  • Study about Market sectors

Subtask D: Solar assisted cooling demonstration projects

  • Report about built examples of solar assisted air conditioning systems

Results of work of IWT(Institut für Wärmetechnik)

  • Improvement of the solar/Storage/Boiler module of the simulation tool.
  • Delivery of parts of the handbook
  • Presentations at workshops for the market analysis and for the dissemination of results.
    • Workshop "Solares Kühlen - Markterhebung, Potentialabschätzung", 16. Dez. 2003, 9:00 bis 18:00 Uhr Arsenal Research, Atrium (Objekt 214), Faradaygasse 3, 1030 Wien
    • CLIMAMED, Congresso Mediterrânico di Climatização, Lissabon, 16.-17. April 2004
    • Conference, Solares Kühlen, 7. Mai 1994, Wirtschaftskammer, Wien, Organisation: AEE-Intec, Gleisdorf


  • Solar assisted air conditioning is technically feasible (about 70 plants in Europe)
  • Investment costs are higher than for conv. systems => high full load hours needed
  • Control and hydraulics can often be improved
  • Therefore these plants still have research and demonstration status
  • Current main effort in the development of small systems (< 20 kW cooling power) because the market in this sector is estimated big and nearly no product is available.

Project Partners

Project manager:
Prof. Wolfgang Streicher
Institute of Thermal Engineering, Graz, University of Technology

Hans-Martin Henning


Prof. Wolfgang Streicher
Institute of Thermal Engineering, Graz, University of Technology
Inffeldgasse 25b
A 8010 Graz
Tel.: +43 316 873-7306
Fax: +43 316 873-7305