Karhlyle Fletcher   |   December 28, 2021

How HVAC Can Make or Break an Indoor Cannabis Operation

Keeping conditions consistent in an indoor cannabis grow starts with proper HVAC equipment.
Detroiter Karhlyle Fletcher is the host of High Lit, a cannabis research and classic literature podcast featuring leading voices and independent music. In addition to years in written and video cannabis journalism, he is also a traditional author.

Cannabis is among the plants with the most personality as even the slightest fluctuation in its environment can transform the plant. Indoor farmers have the perk of direct control over most variables, yet without proper heating, ventilation, and air conditioning (HVAC), the harvest will fail.

What Issues Can Improper HVAC Cause?

Unsurprisingly, water is a crucial element in growing cannabis. Without water, the plants will wither and die, and with too much, they'll drown. However, a room’s humidity also dictates the quality of an indoor farm. An obvious error some cultivators run into is an improperly sealed room.

The advantage of indoor growing is having a controlled environment, but cracks and holes in the ceiling and floors can ruin that. Without proper control over humidity and airflow, there's no control at all. Additionally, improperly sealed indoor farms can leak odor, leading to legal trouble or neighborhood conflicts. Popular solutions include carbon filters and bi-polar ionization.

Either way, best practices are to review the grow room thoroughly and ensure there are no unwanted weak points. Watch out for cold roofs and pipes, as accidental condensation is a common flaw in many farms. Such an issue can completely disrupt the balance of the vapor pressure deficit (VPD).

To summarize, VPD is the difference, in terms of pressure, between water content in the air and its saturation point. Comparing these two measurements allows an understanding of the VPD of your cannabis farm.

How Does VPD Impact the Plants' Health?

Throughout the life cycle of cannabis plants, they react to their environment in real-time. With too high a VPD, the stomata, or mouths of the plant, will close up, attempting to save their water. This closing results in curled leaves and tip burn. If the vapor pressure deficit is too low, then the plant can become soggy, the perfect environment for molds and rot to take hold. Thus, any design flaw in the HVAC system can ruin the crop.

The other component in VPD is temperature. So, similar to humidity, any opening can seriously threaten an operation. Even an often-used door can pose a threatening new variable; therefore, it's paramount to reroute any traffic away from the grow room.

Improper measurements can similarly doom an operation, so sensor placement is also essential. When measuring the environment plants are growing in, it's better to take measurements from among the canopy, not from anywhere distant from the plant. With automated systems, regularly check the connection between the sensors and the HVAC systems. Well-placed sensors can still be an issue if they're not correctly connected to the system.

A Disrupted HVAC System Is No HVAC System

Failure to incorporate regular scheduling or backups into the HVAC system could be as bad as not having one. While HVAC systems can be expensive, having backup equipment in case of failure isn't optional. A simple error or unlucky week could threaten an entire harvest. Having alternatives immediately available is a professional requirement.

Management of the HVAC must be kept up perfectly, ideally with timers or a software program. Whether AI or another form of software, several programs can manage data from sensors and manage farms throughout every hour of the day.

Balancing HVAC Requirements with Energy Preservation

As always, the only way to master the environment is through understanding the needs of each particular location. Familiarity with the system and environment is the first step to mastery. Additional data may be the best way to improve visibility into problem areas, and it may be beneficial to increase the number of sensors. Smart sensors take several readings throughout the day to create a better picture of what's going on.

While managing a cannabis cultivation facility, growers understand that each crop has unique needs and environmental conditions often need changes in airflow, temperature, and humidity. Yet while balancing these varying HVAC requirements, energy preservation is also an important aspect. Cultivators often work with local HVAC engineers to find the right equipment for their facility.

While many in HVAC are talented, not all HVAC engineers understand cannabis grows. Traditional HVAC methods may overlook critical factors unique to cannabis, and some suggestions may hurt more than they help. Try to work with someone familiar with the specific needs of a cannabis operation. Otherwise, alternative and updated HVAC options like Indirect-Direct Evaporative Cooling can offer an adequate amount of HVAC without demanding too much power.

An automated and properly managed HVAC system helps keep cannabis happy, healthy, and thriving throughout the growing period. With the correct airflow, humidity, and equipment, then harvests will be lush, sturdy, and bountiful - as long as the plant’s nutritional needs are also met. Once the correct balance is met, the magic happens.

 

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