Reduction in cold season greenhouse heating fuel via recovery of excess solar heat with heat pumps
Cold Season greenhouses maintained at warm temperatures generally consume large quantities of heating fuel, but also often require ventilation on sunnier days to release excess solar heat. We explored the use of some current air-to-water heat pump technology and thermal energy storage to capture and store excess solar heat for use at night to reduce fuel consumption. Extensive measurements of the system performance were taken, and energy flows were characterized in detail. Predictive computer simulations were developed and used to analyze the results, and show that the system studied reduced the oil consumption of a warm greenhouse in New Hampshire by nearly 45% during February through April. Actual performance was found to be consistent with simulation predictions based on Typical Meteorological Year data. Predictions of best possible results in all months and for a range of thermal storage capacities are provided. We find that, if the redelivery of heat is accomplished in a passive, low energy manner such as bed heating, this approach should be an effective mean to significantly reduce heating fuel consumption in cold season greenhouses, especially during the sunnier shoulder seasons.
Krug, B. and Luce, B. 2017. Reduction in cold season greenhouse heating fuel via recovery of excess solar heat with heat pumps. Acta Hort. (ISHS) 1170:539-546
energy consumption, energy efficiency, computer simulations, computer predictions, thermal energy storage