Passive solar agricultural greenhouses: A worldwide classification and evaluation of technologies and systems used for heating purposes

Results from a recently completed study of 95 solar greenhouses from around the world, representing the state-of-the-art in this field, are presented and are classified. Relevant technical information on the utilised heating systems using alternative energy sources are identified and the existing applications are grouped according to the characteristics of the implemented type of technology. Five categories of passive solar greenhouses are reviewed, according to the characteristics of the heat storage system, namely, water, latent heat material, rock bed, buried pipes, and some other type of systems. Available information on the performance of each system is also included. The suitability of the technologies for each climatic zone and type of cultivation is estimated and evaluated. This up-to-date information on the state of the art in this field can be of great importance to potential users for the successful development of future applications.