Fine-tune your greenhouse cooling and ventilation

When installing your ventilation fans, A.J. Both of the Department of Environmental Sciences at Rutgers University advises growers to take note of the various resistances to air flow that are associated with the design of the greenhouse. For example, adding an evaporative cooling pad to the inlet opening or adding an insect screen will increase the resistance to airflow. As a result, additional fan capacity is needed to overcome these resistances.

In addition, wind conditions outside may generate small air pressure differences between the windward and leeward side of the structure that can interfere with the ventilation system. A properly designed ventilation system will take this into consideration and result in the installation of sufficient ventilation capacity.

“This is a critical issue that growers and designers have to keep in mind. They have to match whatever resistances they think the system will impose on the fans and make sure that the selected fans are able to pull sufficient air through the greenhouse to make sure there is enough ventilation capacity,” Both explains.