The protected horticultural production in tropical countries such as Colombia takes place mainly under passively ventilated greenhouses.The major drawback of the traditional Colombian greenhouse is its low ventilation rate leading to inadequate microclimates.The purpose of this study was to evaluate the airflow behavior, ventilation rates and thermal distribution effects of a commercial-size greenhouse, due to the gradual increase of the roof ventilation areas.A numerical simulation model was developed under a computational fluid dynamics (CFD) approach following an experimental validation of the simulated scenarios.The results showed that increasing the roof ventilation areas reduced the internal average temperatures by up to 16 %, improved the temperature homogeneity and increased the ventilation rates by up to 191 % with respect to the reference scenario.The findings of this research may serve as a basis to develop alternative greenhouse designs that consider increasing the ventilation areas but within the low-tech context that constrains innovation in the Colombian horticultural sector.