GREENHOUSE COOLING: PRESENT TECHNIQUES AND PROSPECTS

When a completely closed greenhouse is subjected to solar radiation during summer, its internal temperature reaches values between 60 and 75°C.

To avoid such temperatures, which are incompatible with plant growth, it is necessary either to reduce the solar heat supply or to increase exchanges of the greenhouse with the outside air or, finally, to eliminate the excess heat by means of a cooling system.

We shall review the different processes that characterise these three groups of techniques, with special reference to forced convection systems with or without supplementary cooling by water evaporation.

Although cooling of greenhouses is technically possible and permits an improvement of plant production due to the increase of carbon dioxide and water in the environment, the process is much too expensive at present.

However one can ask whether, with the evolution of industrial techniques, it is not impossible in the fairly distant future to find an application of refrigerating units applicable to the production of greenhouse plants of high commercial value.

Symposium on Cultivation of Vegetables under Protection in the Mediterranean Regions

A. Gac

https://doi.org/10.17660/ActaHortic.1974.42.6