In this article, a new insight into natural ventilation performance is presented that takes into consideration not only the ventilation rate itself, but also the distributed climate inside the greenhouse, especially at plant level. Criteria are provided to determine the best vent configuration, particularly during critical periods when the wind is very weak. The study was conducted using a computational fluid dynamics (CFD) simulation tool. Side vent opening location and roof vent opening combinations were studied with respect to ventilation rate, airflow patterns, and temperature distribution. Simulations were carried out on a four-span greenhouse with continuous roof vents equipped with benches supporting ornamental crops. The ventilation rate of the greenhouse was estimated by means of the tracer gas (N2O) method, using the impulsion peak technique. Temperatures were simultaneously recorded inside the building and along the walls. A mathematical approach based on the Navier-Stokes equations with the standard k - e model was used. After validation of the model with measured temperatures and ventilation rates, simulations were conducted on the same design but with the addition of a windward side vent and considering windward only, leeward only, and a combination of both roof vents, successively. In each case, the cooler outside air enters mainly through the sidewall opening and through the roof openings of the windward span directly exposed to the wind. It exits through the roof windows of the three other spans. The lowest side vent position should be avoided because it may cause an air jet directly aimed at the crop. Configuration with a side vent combined with windward roof vents leads to the maximum flow rate: 12.3 air changes per hour at a wind speed of 0.5 m s-1. This configuration, however, enhances the risk of damage to the mechanical structure due to a high wind pressure exerted on the vents. Configurations with symmetrical roof vents are less efficient (by about 35%) in relation to the ventilation rate, but result in similar temperatures at plant level compared to the windward roof vent opening configurations. Consequently, they should be preferable to windward roof vent configurations. However, in addition to the ventilation rate, other parameters such as the mean temperature and uniformity were investigated in order to define the most effective ventilation configuration.