Analysis of Greenhouse Natural Ventilation Under the Environmental Conditions of Central Mexico

Because of the rapid growth of the greenhouse industry in Mexico and the increasing need for relevant information about structural design and management, the internal microclimate of a naturally ventilated greenhouse in central Mexico was investigated. In order to quantify the ventilation rates resulting from inside and outside environmental conditions, tracer gas (TG) experiments were carried out. Properties of an insect screen were determined by a series of wind tunnel experiments. The same experimental conditions were then used to calculate the air exchange rate by means of computational fluid dynamics (CFD). The results showed a significant correlation between ventilation rate and wind speed (R2 = 0.7079). For instances when only roof vents are kept open, high wind speeds (>4.5 m s-1) are required to provide a recommended air exchange rate of one greenhouse volume per minute (6.64 × 10-2 m3 m-2 s-1). The correlation between CFD-simulated and TG-measured ventilation rates was 0.7065 at wind speeds higher than 2 m s-1.