HOW CALCULATE GREENHOUSE HEAT LOSSES ACCORDING TO THE PLANT COMFORT AND THE TYPE OF GREENHOUSE HEAT EXCHANGER
- the air heater consumes one quarter less energy than pipes,
- the duct consumes one quarter more.
The thermal gradients differ mostadly according to the heating system used (graph 1a). However, these variations occur mainly in the first and the last fifty centimeters of greenhouse height, the remaining two meters being quite homogeneous, and for vertically growing plants (tomatoes, cucumbers), the effect of the thermal gradient is not probably the main thermal phenomenon;
- with the same water we observe little difference in air but generally the duct system produce more agricultural yields than classical pipes. The pipe system produce more than air heater system. For these reasons the air temperature is not a good index of plant comfort.
Therefore the differences in consumption measured between the various heating systems must therefore be explained, together with the differences in agricultural yield observed, in particular with tomatoes.