Analysis of Cooling Energy Consumption in Greenhouses Using Hourly Temperature Based on the Heat Balance Method in Hot Summer

Coupling equipment operation parameters with the hourly heat balance model, this study realized the integrated estimation of energy consumption and costs. Meanwhile, two typical greenhouse growth settings were investigated: one at an average temperature of 22.5 °C (25/20 °C and 30/15 °C) and another at 25 °C (35/15 °C and 30/20 °C). Based on the simulation results, in an average temperature of 22.5 °C, the target temperature of 30/15 °C is suggested, whereas in an average temperature of 25 °C, the target temperature of 30/20 °C is suggested. Moreover, two different electricity rate systems, mainly unit-form and time-of-use rates, were used to analyze the running costs of the greenhouse. Due to the energy demand, peaks often happened between 12:00 and 14:00, requiring the manipulation of mechanical environmental control strategies to keep the target temperature; the total electricity cost in time-of-use rates system was a little higher than that in unit-form rate. Results of the dry weights analysis suggest that the DIF30/20 scenario is more practical due to the substantial rise in electricity costs relative to its modest yield improvement for the others. This method achieved an RMSE of less than 2.7 °C for estimating summer greenhouse cooling energy consumption and can provide growers with quantitative temperature setting schemes during hot summers.