Cannistraro Blog

HVAC Preventative Maintenance

August | 14 | 2017

How HVAC Maintenance Can Help Solve Neighbors' Concerns about Growing Marijuana

There is no doubt about it, marijuana has a potent smell.  The plant’s scent can help determine a strand or its point of curing, but it can also create issues for grow facilities with sensitive neighbors. No matter your involvement or proximity to an operation for growing cannabis, there is an answer that can help tame the smell: HVAC maintenance and air filtration. Let’s take a closer look into typical grow styles and how proper filtration can keep a grow operation under wraps, save energy and help mitigate the risk of moldy plants.

Air filtration systems for grow facilities

Operations for growing marijuana are commonly set up in one of two configurations, with an open or closed system. The open style is designed to exchange the air about every 15 minutes which allows for a fresh, airy environment. While in most cases an open style is ideal for growing, it is not technically efficient. With the air being changed almost every 15 minutes, the ventilation system is constantly expelling any treated air, and filters are being taxed with potent particulate matter. For this type of system, a set of active carbon filters are utilized for proper air filtration.

Active carbon filters are made up of very small granular pieces of carbon, the carbon is treated to be as porous as possible. The more pores a piece of carbon has, the greater the surface area, which means more area to absorb the skunk-like smell of marijuana and other potentially harmful matter. If you do choose to operate a grow facility with an open system you should set up a filter changing schedule based off of the number of air exchanges and the manufacturer’s recommendations. If your facility is not equipped with a team to source, inspect and change the filters, make it a priority to select a knowledgeable contractor that can help. If you do not change your filters at the appropriate time, the ability to catch the odor and dangerous spores decreases substantially. A plugged filter means that static pressure will rise and make every piece of equipment work harder.  Harder working equipment ultimately reduces the life of your HVAC system and increases your energy costs.

Another air filtration option is a closed system.  The closed style system does not utilize any fresh air intake or exhaust. Rather, the grow area would be injected with CO2 instead.  This type of system works great in hot areas where fresh air cannot assist in cooling the grow space. A closed system has the potential to save energy because it’s not constantly expelling air that has been recently heated or cooled.  In addition, there is no exhaust and no associated scent or clues to your neighbors about what’s being grown.

While the closed option may sound appealing to a grow operation with close neighbors or even in a downtown area, it too requires considerable HVAC preventative maintenance.  Code requires that CO2 monitors are placed throughout the facility as high levels of exposure to humans can be fatal. The closed air system should incorporate specialized dehumidification because the plants release a great deal of moisture. The ducted system that dehumidifies the space should be filtered, typically using HEPA filters, but many are now incorporating active carbon filters. In this case the filters are technically removing odor to the air supply but more importantly, they’re removing spores and bacteria such as Botrytis and powdery mildew. After all, the marijuana being grown is considered medicinal, for those suffering from illness – the last thing their medicine should be doing is making them worse.

It’s true that marijuana grow operations produce odors and may have dangerous spores present within the facility.  Fortunately however, we can combat both with HEPA and active carbon filtration. By incorporating a filter inspection/change out schedule you can help create heathier environments and keep grace with the “Jones’”! Carefully planned air filtration should be a priority for you, your team and the patients.  After all, it can be the key to managing happy neighbors and healthy plants.


HVAC Service Sales EngineerGlenn Gould, FMP, MBA

Glenn is a Sales Engineer for the Cannistraro Service Group with more than 10 years of HVAC, engineering & construction experience, working for a wide range of healthcare and other types of facilities.  He is active member of the International Facility Management Association (IFMA) where he earned his FMP certification.  

Discover the Benefits of a Preventative Maintenance Agreement





 Jennifer. "Marijuana Cultivation Consulting." Marijuana Cultivation Environmental Controls - HVAC. MJBA, n.d. Web. 30 July 2017.

Minh, Cosmo Pixard, and Sarah. "Activated Carbon Filters: What They Are & How They Work." Allergy & Air. N.p., 16 June 2016. Web. 30 July 2017.

Schiller  July 05, 2017, Lindsey, and High Times. "Growing Trend: The Closed Cannabis Greenhouse." High Times. N.p., 5 July 2005. Web. 31 July 2017.