Analysis of temperature distribution in a naturally ventilated single-span greenhouse using computational fluid dynamics

Increasing global temperatures and unpredictable weather threaten agricultural production, intensifying the reliance on greenhouse cultivation. While naturally ventilated greenhouses offer an energy-efficient solution, their thermal performance under high heat loads is a growing concern. This study developed and validated a 3D CFD model to investigate the temperature distribution inside a single-span, naturally ventilated greenhouse. The model, implemented in ANSYS Fluent, considered the influence of external meteorological conditions, including solar radiation and wind, on the internal microclimate. The model demonstrated high accuracy, with an RMSE of 0.847°C and an MAE of 0.714°C for temperature when compared to experimental data. Diurnal analysis confirmed the dominant role of solar radiation, showing a strong correlation between indoor temperature and external solar radiation (r = 0.96) on sunny days. Spatially, the simulation revealed extreme thermal heterogeneity under high solar load, with a total internal temperature variation of up to 25°C (from 296 K to 321 K). The distribution was characterized by a distinct vertical stratification due to buoyancy and a strong longitudinal gradient, with the hottest air accumulating in the upper leeward corner. These findings highlight areas of potential crop heat stress and demonstrate the limitations of side-ventilation alone. The validated model serves as a valuable tool for optimizing ventilation strategies and improving climate control system design.