Liquid radiation filter greenhouses (LRFGs) and their use of low quality hot and cold water, for heating and cooling

LRFGs offer improved control of greenhouse air temperatures in comparison with conventional greenhouses. This permits keeping the LRFG closed for most daylight hours even in sunny and warm climates. Furthermore, LRFGs offer the possibility of using locally available heat sources and sinks for backup heating and cooling. This possibility has been studied via computer simulation which has been verified with data from a 330 m2 experimental greenhouse. The exploitation of low quality heat sources or sinks for greenhouse cooling and heating has been studied for two extreme climates: one for a cold Canadian climate, and a second for a hot Israeli climate. For the cold climate, the simulation model predicts that acceptable air temperatures can be maintained in the LRFG during all winter days when a geothermal source of 45°C is available. For the hot climate, a cold water source of 16°C is predicted to be sufficient to permit closure of the LRFG during 81% of the daylight hours of the peak summer months.