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Jul 18, 2022 | Products

Indoor growing is a rapidly expanding sector in agriculture and there are plenty of reasons why. Indoor cultivation enables full control over the growing environment, which allows cultivators to grow year-round no matter the season. Along with these benefits comes the challenge of controlling humidity.

Growing in a closed environment results in elevated levels of moisture in the air. If left untreated, these high humidity levels often lead to mold and additional cultivation challenges that can completely deteriorate your crop. With that said, specialized dehumidification systems are often overlooked in favor of generic HVAC systems that are not optimized for controlled environment agriculture (CEA) settings.

What is the Difference Between HVAC and HVACD?

HVAC typically refers to the cooling, heating, and ventilation systems in a building. This umbrella technically includes dehumidification, but we prefer to use the acronym HVACD (Heating, Ventilation, Air Conditioning, and Dehumidification) when referring to fully integrated systems with supplemental dehumidification for redundancy. That’s because the importance of dehumidification is often overlooked in indoor grow rooms where standard commercial HVAC systems aren’t designed to maintain the optimal vapor pressure deficit (VPD) needed to keep plants healthy.

Removing humidity from a room full of plant water vapor is ultimately one of the most difficult environmental challenges to manage in controlled environment agriculture (CEA). Therefore, fully integrated dehumidification is something every facility should prioritize when building out and designing a controlled environment.


The Benefits of an Integrated Dehumidification System?

Indoor cultivation facilities are naturally humid due to the plants’ transpiration process. In other words, plants release water vapor into the air as a normal part of the growing process and that water needs somewhere to go. Without the help of a dehumidification system, the high levels of humidity foster mold development in the form of bud rot and powdery mildew. When it comes to cannabis, not only will this ruin the overall quality and yield, but it also means your product won’t pass stringent testing measures.

Space is a precious commodity for indoor grow facilities and most first-time indoor growers choose all-in-one HVAC systems as their main solution for both temperature and humidity maintenance. Unfortunately, HVAC systems alone are not able to properly control indoor humidity 24/7. Specialized grow room dehumidifiers are designed to perform one task – control humidity, and they do it with extreme efficiency. Using the right dehumidifier can save 50-60% on energy, when compared to HVAC alone.

How to Choose the Right Dehumidifier for Your Grow Room? 

Determine the Required Dehumidification Capacity

Matching moisture removal with the plants’ transpiration rate is critical. If you don’t remove enough water from the air, the humidity will climb up until it reaches 100%. Therefore, it’s important to consider your maximum transpiration rate, meaning the period when your plants release the most water vapor.

Factors That Influence How Much Plants Transpire

1. The amount of plant matter in your grow room
2. The climate conditions in your growing environment
3. The size of your grow room
4. The volume and EC of fertilizer/water introduced through irrigation

Access our in-depth white papers to dive deeper into the science and biology behind plant transpiration.

Energy Efficiency

Energy usage is always a top concern when it comes to indoor cultivation and optimizing your energy consumption will have a major impact on your bottom line.

Different dehumidifiers and humidity control systems have different efficiency levels. The best way to compare dehumidifiers would be to measure the water extraction per kWh. It is also important to compare dehumidifiers under similar conditions, or you risk getting wildly varying results.


As previously mentioned, grow room space is precious and expensive. Each and every piece of equipment or machinery should be as compact as possible, without compromising performance. A compact dehumidifier can fit snugly between your plants. You can also opt for dynamic placement options, to fully optimize your grow space.

Air Distribution and Flow

Simply removing moisture from the air is just one aspect of dehumidification. Without powerful fans and proper air distribution, your dehumidifier won’t be able to treat the entire space. Many dehumidifiers fail to take this factor into consideration, leaving growers with local humidity treatment and creating different conditions in different areas in the grow room.

Molds only need one plant that’s surrounded by high humidity. Once they develop, they can spread freely throughout the grow room, infecting more plants. Even if humidity is kept under control in their area. Therefore, making sure your dehumidifier reaches all corners of your grow room is very important.

Air circulation is another important aspect of air distribution in grow rooms. It is used to enhance climate control systems by achieving an even climate and promoting active plants. With the use of proper air circulation, growers can foster homogeneous climate parameters. While maintaining uniform humidity temperature, and optimal VPD. Therefore, using a dehumidifier with a well-designed airflow concept can reduce your need for additional fans while improving your air distribution.

How to Source and Design an Optimal Dehumidification System

At RMJ, we understand the challenges of growing cannabis and one of the biggest problems in cultivation is humidity control. That’s why we partner with DryGair to offer customers world leading dehumidifiers designed specifically for commercial greenhouses, grow rooms, and drying rooms.

Correctly installing and sourcing the best dehumidification system to fit your facilities needs often results in a substantial return on your investment (ROI) due to energy savings and the overall prevention of plant diseases. Contact us today and a member of our team will help you find the right dehumidification solution personalized to your cultivation facility.