Vertical Temperature and Humidity Gradients in a Naturally Ventilated Greenhouse

Experiments were conducted in a full-scale, commercial greenhouse, to study the vertical distributions of temperature and humidity ratio under closed and naturally ventilated conditions. A comparison was made between ventilation by continuous roof openings only and ventilation by opening both roof and side windows. Two cases were considered for each of the ventilation modes: (i) the plants in the greenhouse were mature and big, and (ii) the plants were young and small. With mature plants, the gradients of temperature and humidity ratio before opening the ventilation windows were considerable and they remained so after the windows were opened (either roof only or both roof and side windows). Smaller gradients were observed with only roof ventilation, than with ventilation via roof and side openings. With young, small plants the gradients were much smaller than with mature plants and they could be assumed negligible for either ventilation mode.