There are two common ways to set up a ventilation system in a greenhouse: naturally or mechanically. A greenhouse utilizing natural ventilation will have either retractable or removable sides or roof panels, or a series of vents. Hoop houses with retractable sidewalls are great examples of the use of natural ventilationówith the sides raised, the wind can flow through the greenhouse and replace warm, stale air with fresh air from outside.
Mechanical ventilation in greenhouses is very similar to that found in indoor gardens. Fan systems create air movement, which brings fresh air into the greenhouse and exhausts unwanted heat and humidity.