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Passive solar-energy air-heating wall panels

By R. A. Hobday


The development of products which enable passive solar-energy air-heating to be integrated into the heating strategies of public, commercial and industrial buildings is described. These buildings are, in general, only occupied significantly during the day; consequently the bulk of heating demand coincides with the period of solar gain. In these circumstances collected solar heat should be delivered with the minimum of delay. The design and operation of units which are capable of supplying solar heated air in this manner is outlined. These are passive, naturalcirculation air-heating collectors, also known as natural-convection air-heaters, or thermosyphoning air panels. Four methods of retrofitting such solar collectors to non-domestic buildings have been identified, one of which, the overcladding collector, has not been proposed previously. Problems associated with the successful installation and operation of these units have also been considered. The relative merits of a number of methods of testing passive solarenergy air-heating collectors have been investigated. A method of determining instantaneous collector efficiency based on the measurement of glazing temperature, inlet and outlet air temperature, ambient temperature and insolation has been developed. Three novel design proposals have been presented: i) a collector constructed with the insulation fitted outside, rather than inside, so that the metal body of the collector may provide more symmetrical heating of the air flow than the conventional arrangement, ii) an absorber which consisted of parallel ducts to increase the rate of heat transfer to the air, heating it symmetrically, (iii) a hinged air-deflector for conversion from the heating to the ventilation mode

Publisher: Cranfield University
Year: 1987
OAI identifier:
Provided by: Cranfield CERES

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  1. (1) (1) A I-i doi
  2. 1 a) a) N go r-I t; doi
  3. a TTAp-Ta rl.
  4. (1983). Cladding of Buildings, doi
  5. Collector outlet* T11 180 cm. from floor of test cell.
  6. dv AT L dx vL (T i L+ATX) Integrating both sides gives ln(v) -
  7. f rom floor of test cell. T13 5 cm. from floor of test cell. T14 Collector inlet* TEST CELL 2 TIS Collector outlet* T16 60 cm, from floor of test cell.
  8. flow rate constant through collector.
  9. Greater privacy DISADVANTAGES o Increased energy consumption from artificial lighting needed to replace natural light excluded from the building o Reduced exterior views o Reduced heating from direct solar gains
  10. Less ultra violet degradation of internal materials o Greater potential for incidental heat gains and heat from passive solar-energy air-heating wall panels
  11. Linear temperature profile along collector.
  12. (1986). Passive Solar Handbook, Basic Principles and Concepts for Passive Solar Architecture, Commission of the European Communities, doi
  13. (1986). Sample Calculation Table for Calculation of tj via SLR/SSF Correlation 228 Calculation of Mass Flow Rate Taking into Account the Increasin Velocity with Temperature [Hobson
  14. (1985). Solar Energy Fundamentals and Design with Computer Applications, doi
  15. x 0.0471 x 1.5 doi
  16. x 19 - E3,100 The simple payback period for the cladding collector system was then:

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