Greenhouse Heating and Cooling with a Heat Pump System using Surplus Air and Underground Water Thermal Energy

Energy saving is an important issue for greenhouse farming. Natural and sustainable energy sources are critical to energy conservation. In this study, greenhouse heating and cooling technology was developed using a heat pump system that used surplus air thermal energy (SATE) and underground water thermal energy (UWTE) as heat sources. The greenhouse system was operated during February and March 2012. The SATE and UWTE system was successfully utilized for heating. Temperature control between desired set-points was also achieved. The heat pump system performed at average COP of 3.25 and 2.84 in February and March, respectively. In conclusion, greenhouse energy conservation was achieved by utilizing SATE and UWTE.