Energy performance evaluation and modeling for an indoor farming facility

Abstract

Indoor farming refers to a method of growing crops on vertically stacked layers in a soilless cultivation system (e.g., hydroponics) in a controlled indoor environment. In comparison with conventional open-field farms, indoor farming has advantages such as significantly improved productivity and water use efficiency, and reduction in food miles. However, indoor farming facilities are energy-intensive for maintaining favorable crop growing conditions.In this study, we evaluated the energy performance of indoor farming operations using both measurements and simulation results. Key performance parameters were first analyzed based on utility bills and continuous measurements from an indoor farming facility. Several operational issues were identified for the mechanical system. An energy model for an indoor farming facility was created using building energy simulation software EnergyPlus and calibrated based on measurements. A novel modeling approach simulating the unique mechanical system—misting systems—for indoor farming was developed using one of the advanced features in EnergyPlus— energy management system (EMS). The energy model was used to evaluate the effectiveness of energy-saving strategies to improve the energy efficiency of facility operations. These include simultaneous heating and cooling, hardly met temperature setpoints and improperly controlled dampers. These energy efficiency measures include fixing motorized damper control, eliminating simultaneous heating and cooling, and having wider ranges of temperature setpoints. Up to 48.1% of reduction in annual natural gas consumption was predicted with energy-saving measures. In addition, the limitations of using building energy simulation software for indoor farming modeling were discussed.