Innovative ground air heat exchanger system for climate regulation in cold climate greenhouses

Greenhouse adoption is increasing globally to enhance food security, particularly in cold climates. However, their operation often faces substantial heating demands and significant heat loss due to traditional dehumidification methods. This study presents a novel, energy-efficient dehumidification approach designed to reduce heat and CO 2 losses in greenhouses. Specifically, it investigates the use of a Ground Air Heat Exchanger (GAHE) system, which utilizes the stable ground temperature to cool humid greenhouse air below its dew point, effectively condensing excess humidity. Additionally, the GAHE system provides cooling during warmer periods when indoor temperatures exceed desired setpoints, offering dual-function climate control. An analytical–numerical model of the GAHE system was developed and coupled with a greenhouse climate simulation platform to evaluate its dehumidification performance. The system was optimized using a Genetic Algorithm to maximize moisture condensation per unit length of GAHE pipe. The optimized GAHE configuration was assessed across six Canadian cities, with varying installation areas. Performance results were compared against conventional dehumidification methods, including Natural Ventilation (NV) and Mechanical Cooling and Dehumidification (MCD). Results indicate that GAHE system reduces annual average deviations of air temperature and relative humidity from their setpoints, reflecting improved dehumidification and cooling performance, by up to 35% and 18.4% compared to NV and MCD systems, respectively, and by up to 79% and 75% for cooling performance relative to the same systems. Moreover, the GAHE system reduces the greenhouse heating load and CO 2 supply requirements by 30–44% and 36.82–58.83%, respectively, relative to NV, without significantly affecting crop productivity.