LIMITING THE RELATIVE HUMIDITY IN INSULATED GREENHOUSES AT NIGHT

Insulating greenhouses to reduce energy costs produces an increase in relative humidity of the internal air which can have adverse effects on the plants.
A steady state thermal model of a greenhouse was used to investigate the water balance of single and double glazed houses at night and to assess two methods of reducing relative humidity.
Controlled ventilation increased the cost of heating by up to 40%, but when ventilation was combined with heat recovery the cost increase varied from -5 to 10% depending on the efficiency of heat recovery.
Dehumidification using a heat pump reduced the overall energy consumption, for greenhouse heating and operating the heat pump, by 30%. Price differentials between heat pump and greenhouse heater fuels would give smaller reductions in total operating costs.

III International Symposium on Energy in Protected Cultivation

B.J. Bailey

https://doi.org/10.17660/ActaHortic.1984.148.52