OVERALL HEAT-TRANSFER COEFFICIENT OF A GREENHOUSE COVER

Theoretical considerations concerning the greenhouse energy behaviour during the night, allow us to propose an evaluation method of the overall heat transfer coefficient through the greenhouse cover material as a function of easily accessible climatic parameters, the covering material's radiometric properties in thermal radiation, the adopted cultural technique and finally of the construction's geometry. The method which has been experimentally tested makes it possible to estimate separately the greenhouse heat transfer by radiation and convection and can be used: to classify covering materials from the point of view of thermal losses; to estimate the greenhouse energy losses; to appreciate the efficacy of the different energy saving equipment.