Sustainable Cooling Solutions for Greenhouses under Humid Tropical Climate: A Preliminary Study of a Ground-to-Air Heat Exchanger Cooling System

Greenhouse agriculture in humid tropical regions faces significant challenges due to excessive heat and humidity, which compromise crop productivity and necessitate energy-efficient cooling solutions. This study evaluates the performance of a ground-to-air heat exchanger (GAHE) for greenhouse cooling under the humid tropical climate of Ibadan, Nigeria. The GAHE system, comprising underground PVC pipes at 1 m and 2 m depths, was designed. Experimental trials measured inlet and outlet temperatures over 35 days, revealing that the 2 m depth achieved a mean cooling of 2.99 ± 1.01 °C, with maximum reductions of 4.45 °C. In contrast, the 1 m depth provided negligible cooling (0.06 ± 0.43°C) and occasionally increased air temperature due to soil heat absorption. Results demonstrate that deeper installation leverages stable subsurface temperatures, mitigating daytime thermal fluctuations and solar influence. The findings align with prior studies emphasising depth-dependent efficiency and validate GAHE’s potential as a low-energy cooling strategy in tropical greenhouses. This study concludes that GAHE systems installed at 2 m depth offer a sustainable and practical solution for greenhouse temperature control in humid tropics.