Selecting Optimal HVAC Systems for Indoor Grow Room Based on Performance and Energy Usage

Indoor plant growing is quite popular because it allows for maintaining optimal growing conditions year-round, regardless of outdoor conditions. One downside is that it can be an energy intensive endeavor because it requires maintaining tight temperature and humidity control while there are large swings in cooling and dehumidification loads corresponding to changes in plant transpiration rates and lighting schedules. A tool has been developed to estimate the annual energy usage of multiple HVAC systems to determine which is the most energy efficient system. The following systems are analyzed: 1.A packaged direct expansion (DX) system with hot gas reheat, 2. A dual compressor heat pump dehumidification system, and 3. A packaged DX unit with separate desiccant dehumidification. The developed energy analysis tool uses psychrometric calculations to estimate energy usage every hour for an entire year. It calculates cooling, reheat, and dehumidification loads based on lighting power, plant transpiration rates, and building envelope loads calculated by a separate load calculation software. Most commercially available energy modeling software do not have built in capacity to model many of the systems used in grow rooms, hence the need for the development of this tool. A model has been created using a commonly available commercial program that can model hot gas reheat to estimate the energy usage of the packaged DX system as means of comparison to commercial tools. The results from the created tool are compared to the results from the commercial model. Then the tool is used to estimate the performance of the systems. The analysis is completed for two locations, Bend, OR and San Jose, CA. The results for the locations are compared.