Mechanical greenhouse ventilation moves air along the length of the greenhouse using an exhaust fan at one end to force air out creating a vacuum which draws air in through intake shutters on the other end of the greenhouse. Louvers are motorized, and along with fans, are connected to a thermostat and accompanying sensor to first open the louvers and then fire up the exhaust fan(s). It is very important for thermostats and sensors to be properly placed and exhaust fans to be properly sized or they will not be able to ventilate the greenhouse efficiently. In some very hot climates, mechanical ventilation may need to be paired with other cooling equipment like evaporative cooling pads.

Active greenhouse ventilation uses mechanical features to create airflow and circulation. These systems can be automated using control boxes and computer monitoring to provide a high level of environmental control. Active ventilation systems do not rely on external conditions like wind or outside air temperature to cool the greenhouse and have the added advantage of providing a closed environment that reduces pest exposure.

Some active ventilation systems are simple systems using just exhaust fans and shutters. Greenhouse ventilation can get much more intricate by utilizing circulatory fans, heaters, heat exchangers, forced air tubes, and other technologies. Many options are available to design highly controlled greenhouse environments.

When it comes to natural vs mechanical ventilation, mechanical ventilation is going to be more costly than natural ventilation. However, in certain climates and with particular crops, mechanical ventilation might be a must. Here are some of the common types of mechanical greenhouse ventilation equipment:

Hortitech Direct offers many options for greenhouse kits with both automated and manual ventilation!