The icy weather that enveloped much of the US recently is not a friend to indoor marijuana cultivation operations.
Temperature control accounts for a sizable portion – 10% to 20% – of the energy bill for major indoor medical cannabis grows. Much of the cost goes to cooling rooms down in the summer, but when the outdoor temperature hits deep-freeze levels in the winter, heat costs go up too.
How can cannabis businesses that grow indoors beat the cold?
Jay Czarkowski of Canna Advisors said the best strategy is to ensure you have a well-operating HVAC system and indoor corridors for transporting plants.
Beyond that, Czarkowski said there are a few tricks you can use to help trim energy costs in the winter months and avoid pitfalls created by the cold:
Invest in a Low-Ambient Kit for Your AC Units
Typical air-conditioning systems have trouble operating below 50 degrees Fahrenheit, and most were not designed to cool a room filled with cannabis plants and heat-producing lights during the winter.
During extreme cold, a typical AC unit’s air condenser can actually freeze up and break, which spells disaster for the heat-sensitive plants indoors.
A quick and inexpensive fix for this problem is to purchase a low-ambient kit for each commercial air conditioner. In layman’s terms, the kit slows the fan speed to maintain a high head pressure in the condensers and prevent freezing. They are commonly found in AC units at large hotels and conference centers, which maintain air conditioning during the winter months.
The kits do require mechanical knowledge to install, and Czarkowski recommends paying a professional to install if the buyer lacks technical knowledge.
“It’s a couple hundred bucks and it could save your grow,” Czarkowski said. “That’s not a lot of money.”
Insulate Exterior Walls
Smaller cultivation rooms that do not have outside-facing walls won’t need much adjustment in the cold.
But most indoor warehouses have a simple cinderblock design, and when these blocks touch the cold air, there is going to be heat transfer. In the dark cycle, this can actually cut down on costs, as the plants can tolerate lower temperatures. But during the light cycle, the cold could be a problem.
Czarkowski said normal house-grade insulation can prevent heat loss in the winter, and he runs four inches of foam insulation on the ceiling and between R-12 to R-15-thickness insulation on walls.
Don’t Bank on Outdoor Air
Every grow operation looks for ways to shave costs on the electricity bill, and in the winter, many see the cold outdoor air as a cheap replacement for air conditioning. Czarkowski, however, advises against rigging up elaborate cooling systems that use outdoor cold air to circulate through the grow facility.
Outdoor air can introduce contaminants. And the cold outdoor air will be substantially dryer than the air inside, so introducing it will throw off the humidity balance and either damage the plants or put strain on a humidifying system. Also, the introduction of cold outdoor air will cause condensation on the lights, ducts and plants.
“The next thing you know you’ll have water in your ducts and hoods, and your ducting is dripping all over the plants,” Czarkowski said.
Photo Credit: Fred Dreier