Optimal cooling strategy for energy management using multi-temperature acquisition points in a protected cropping facility

Energy management in protected cropping is critical due to the high cost of energy use in glasshouse facilities. The main purpose of this research was to investigate two different methods of regulating cooling energy consumption, by adjusting the settings (opening/closing) of either vents or curtains during the day, at the protected cropping facility at Western Sydney University in Australia. This research study adopted an experimental approach to investigate energy consumption under four different open/closed combinations of vents and curtains (vents open/curtains open, vents closed/curtains open, vents open/curtains closed, vents closed/curtains closed) and develop an optimal cooling strategy for energy management using multi-temperature acquisition points. The daily average consumption and the temperature (both gutter and rooftop levels) during the day at the protected facility were measured over four different open/closed combinations of vents and curtains. The results show significant differences in temperature between rooftop and gutter levels during the day across all four combinations tested. Furthermore, analysis of energy consumption shows significant differences in daily average energy consumptions, including the highest daily average of 121 kWh using vent (closed)/curtains (open) and the lowest daily average of 70.5 kWh using vent (open)/curtains (closed). Since the combination of open vent and closed curtain is the better experimental setting with the lower daily and average energy consumption among four combinations evaluated, adjustable settings for the opening of vent and closing of curtain, based on the required temperature and tolerance levels, are recommended as the optimal cooling strategy for energy management using multi-temperature acquisition points at the selected protected cropping facility, taking into consideration of the type of crop and stage of the crop cycle. These findings can be used as a guide for developing timeframes for adjustable settings of vent opening, depending on the measured temperature differences inside the facility and external temperature. Although vents opening using the adjustable settings could provide better cooling energy consumption, taking the advantage of the warm temperature outside, a longer period of vents opening could have adverse effects on other conditions such as level of CO2. Therefore, a holistic approach to energy consumption taking consideration of key control variables is recommended for future research.