ISHS Acta Horticulturae 115: Symposium on More Profitable Use of Energy in Protected Cultivation
HEATING LOAD OF A GLASSHOUSE FROM THE PHYSICAL POINT OF VIEW |
| Author: | G.P.A. Bot |
| Abstract:
The heating load of a greenhouse depends considerable on a number of environmental conditions. Regarding the energy balance over the entire greenhouse, the heat consumption represents the net energy flow from the greenhouse to the environment under steady state condition. Due to the inherent fluctuations in the magnitude of the various environmental factors, the heat consumption will also vary. When the heat consumption is related to the temperature difference between the in-and the outdoors air respectively, a functional dependence exhibiting fluctuations within the broad margins ascribed to the anple and continuous environmental changes has been found. Analysis of each particular situation indicates that the majority of the environmental factors produce an offset to the heat consumption (thus for each temperature difference between the in- and outdoors the in- or decrease in heat consumption is the same). Moreover it is solely the wind velocity that affects the slope of the line representing the heat consumption plotted versus the temperature difference. This is of particular importance in current efforts aimed to have "more profitable use of energy in protected cultivation". Since just these slope variations are relevant in predicting the amount of energy that could be saved by a one degree temperature reduction in the greenhouse. Like wise the slope can be interpreted as the amount of energy required to increase the greenhouse temperature by one degree. Such figure is of crucial importance in the optimization studies. | |
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