Optimizing Vents Opening Configurations and Orientations for Effective Natural Ventilation in Sustainable Greenhouses: A Case Study

For sustainable greenhouse design, natural ventilation is a vital component; it depends on the local climate. Therefore, optimizing the greenhouse orientation and vent opening configuration is a critical issue that needs to be addressed for a specific location (e.g., the central region of Saudia Arabia). Experiments were conducted in winter, in a curved-roof, single-span, N-S oriented greenhouse that includes roof and side-wall vents. Five different vent opening arrangements were examined. The outside and inside greenhouse environmental parameters were measured, and the ventilation rate (kg·s−1) and the number of air exchanges per hour (Na) were estimated for each opening case using a modified energy balance equation. The results showed that the common wind directions are N-S and NW-SE. For effective ventilation, greenhouses should be oriented in the E-W or NE-SW directions. Opening the side-wall vents exhibited the highest wind-driven ventilation rate that is essential to control temperature and humidity at the crop level, while only opening the roof vents is not recommended. In the central region of Saudi Arabia, natural ventilation is sufficient for operating greenhouses (N¯a > 30). Opening the roof and side-wall vents (combined wind and buoyancy effects) is the most efficient as long as the greenhouse axis is aligned perpendicular to the wind direction. Such information is essential for sustainable greenhouse management in an arid environment.