EVAPOTRANSPIRATION AND ENERGY CONSUMPTION IN GREENHOUSES

A careful evaluation of greenhouse crop energy requirement is becoming more and more important, as energy costs are rising.
Due to the large amount of energy which is involved in evaporation (3 mm/day correspond to about 85 W/m²), one of the first aims of a study aimed to energy saving in greenhouses, should be the evaluation of the amount of artificially supplied energy which is transformed into latent heat.

A model to evaluate hourly evapotranspiration of a greenhouse crop was described in a previous paper by Stanghellini (1980). The model is based on a combination equation for potential evapotranspiration; i.e. greenhouse evapotranspiration is related both to net available energy and to vapour pressure deficit, coupled with a function of air movement.
Results obtained show that it is possible to get a reliable description of E.T. in greenhouses by a combination equation, provided that greenhouse climate is well described by the parameters used.
Thus, it was decided to set up an experiment to measure in a more comprehensive way the parameters driving evapotranspiration in a greenhouse.
Detailed measurements on the peculiar radiation enviroment and the relevant energy input due to heating are being performed.
The set-up of this experiment is described in the Materials and Methods and the first results.

III International Symposium on Water supply and Irrigation in the open and under Protected Cultivation

C. Stanghellini

https://doi.org/10.17660/ActaHortic.1981.119.25