Infrared (IR) heating as alternative to forced air heating has been studied experimentally for 70 days in two identical, smallscale,\r\nexperimental greenhouses. The two heating options were implemented with four IR electric lamps and an electric forced\r\nair heater correspondingly. The microclimate in the greenhouses was monitored with thermocouples. Parameters characterizing\r\nthe outdoors macroclimate were also monitored. Lettuce was used as the test crop, and the two heating systems were operated\r\nautomatically to maintain a suitable reference temperature at the canopy. The investigation focused on night heating needs. Results\r\nindicated that the internal air temperature in the IR-heated greenhouse was always kept several degrees lower than the value\r\ntargeted for the canopy. This lower temperature resulted in 43% average energy savings for the IR-heated greenhouse, compared to\r\nthe conventionally heated one. A simple numerical model was used to estimate the potential energy savings in a production-scale\r\ngreenhouse.
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