Good airflow is a must for healthy greenhouse crops in any climate, but it’s particularly important in the Yuma area’s high summer temperatures. With a little planning, you can design a greenhouse ventilation system that will help your home-grown vegetables, fruits, and flowers thrive.
Passive (Natural) Ventilation
Natural ventilation in the form of vents or louvers in the roof was the only practical option for greenhouses built before the 1950s and they still work just fine today for most crops. Vents on the roof allow rising warm air to escape the greenhouse. Intake vents that let in cooler outdoor air are typically placed low on the greenhouse walls. The result is a continuous, natural flow of fresh air.
Your greenhouse’s manufacturer can tell you the optimal number and size of vents for the model you have. If you’re gone most of the day or just appreciate convenience, connect your vents to automatic openers. These temperature-sensitive devices open the vents whenever the greenhouse needs cooling.
A passive greenhouse ventilation system is silent, so it won’t annoy you or your neighbors, and it costs nothing to run. On the downside, it’s less efficient and costs more to install than a fan-powered ventilation system. It also requires regular maintenance to keep it free of airflow-blocking debris.
Fan (Powered) Ventilation
Tall, dense crops such as tomatoes, potatoes, and peppers often fare better with fan-powered ventilation. Because it controls humidity more efficiently that a passive system, it can keep your greenhouse around 10 degrees cooler.
Correctly designed, this type of ventilation system should exchange the air in the greenhouse within a maximum of two minutes and ideally one minute. The outdoor-air intake vents are installed on the same side as the door and the fan is installed on the opposite wall. When designing your fan ventilation system, take into account anything in the building that will create a resistance to airflow, such as an insect screen.
If you could use some guidance on designing an efficient greenhouse ventilation system, please contact us at Hansberger Refrigeration and Electric Company.
Our goal is to help educate our customers in Yuma, Arizona about energy and home comfort issues (specific to HVAC systems). For more information about ventilation and other HVAC topics, download our free Home Comfort Guide or call us at 928-723-3183.
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