A CFD evaluation of naturally ventilated, multi-span, sawtooth greenhouses

A computational fluid dynamics (CFD) program, Fluent V4, was used to predict natural ventilation rates and airflow patterns of a multi-span sawtooth greenhouse for various roof and side vent openings and outside wind speeds. Predicted rates were found to be both well above and well below a standard volumetric air exchange rate of l.0 A.C. min^-1. The maximum and most acceptable ventilation rates were obtained with the combined use of a windward side vent and leeward roof vents on all multi-span sections. Ventilation rates ranged from 1.4 to 4.01 A.C. min^-1 for the best two-span case and 0.14 to 2.0 A.C. min^-1 for the similar four-span case for outside wind speeds of 0. 5 and 2.0 m s^-1, respectively. Predicted ventilation rates ranged from 0.17 to 0.7 A.C. min^-1 when no side vent was used and the roof vents were fully open.