How Do I Setup Greenhouse Ventilation?
Ventilation is extremely important to your plants. Without proper ventilation, CO2 levels can become stagnant around plants and temperatures can reach damaging levels. Regular air flow is necessary to refresh the air with a new supply of CO2 while keeping lamps and plants cool in hot weather. While we’ve covered methods of cooling, and the effects of air circulation in your grow room before, we haven’t really spoken on how to properly set up a ventilation system in your greenhouse. You’ll find there are two common types of ventilation: IN/OUT and Controlled Environment Agriculture (CEA).
This is the most common and inexpensive style of ventilation for greenhouses. IN/OUT ventilation uses traditional ductwork and inline fans to move air into and out of your grow room. These inline fans are powerful and have a design reminiscent of a jet engine (without the combustion). Speed controls give this type of fan extreme customizability in flow rate and temperature control for the room. IN/OUT fans require an exhaust fan mounted near the ceiling on one end of your grow room with vents or cracks near the floor on the opposite end. This exhaust fan pulls the air through the room and exhausts it elsewhere, usually outside. This system works even better when designed with two fans, an intake and an exhaust (with the intake pulling air into the greenhouse from outside in place of the regular ground floor vents). Be advised; it’s wise to include air filtration systems to keep outside pollen and other contaminants out of your greenhouse.
IN/OUT systems also work effectively for closed lamp ventilation. When HID lamps are kept in enclosed fixtures, they can get extremely hot and require cooling beyond what the greenhouse requires. In such a situation, ductwork is connected directly to the light fixtures with a simple inline fan pulling air through the fixture and over the lamp to cool it.
Remember: Always pull with fans, never push air into the room. Start with an exhaust fan that pulls air from the room, then add an intake fan that pulls air in from outside.
CEA or “Sealed Room”
Inline fans are inexpensive and simple to set up, but they are also extremely noisy, even at the highest quality levels. Additionally, the larger your growing area, the more fans you will need to install which can lead to a very noisy work environment. And regardless of how much air you’re moving, hot air from outside will still be hot when you bring it inside. CEA systems use air conditioning(A/C) systems for accurate temperature control. With a CEA system, you can maintain a completely sealed room, preventing outside pollen and contaminants completely. When setting up an A/C system for your CEA, it’s best to install an automatic control unit along with a few fans for air-flow. Automatic controls give you the ability to maximize the growth of your plants through differential control as well.
When you are working with a sealed room, you’ll want to add in some method of carbon dioxide enrichment, a humidifier, and an air purification and filtration system to ensure that nothing from outside makes it into your grow room. The size of your A/C unit will depend on the size of your grow room. If you’re unsure of what size you need, it’s best to check with the retailer first. Always get a unit that’s designed for a space larger than what you currently have, as it’s better to run a bigger system part of the time than to overtax a smaller system by having it run constantly.
A constant soft breeze is never bad; it mixes the air, replenishes CO2, and helps to regulate temperature. Moving air also helps to discourage flying insects by making it difficult for them to move about the room. Either of these systems will accomplish this task, but you could also mix the two together, using the A/C system to cool the room, while inline fans and ductwork control the air flow and direction around the room. Which do you use? Or which do you think will work better for you? Let us know in the comments and, as always, send us additional questions, insights, or even pictures of your own grow rooms and ventilation systems through Facebook, Twitter, Google Plus, LinkedIn, Pinterest, or Instagram!