Solving the 3 Biggest HVAC Challenges of Modern Day Grow Rooms

Designing, building, and operating the ideal cannabis growing facility and getting every aspect right is no small task. Growing at scale is a new frontier for most licensed producers and it’s been referred to by many as the Wild West because of hectic pace of growth and perpetual innovation in a hyper-competitive landscape.

There are countless vendors and consultants vying for your business, but do they really have all the answers? Are they truly experts? It’s not easy to know. There are no cookie-cutter answers and new and better solutions are evolving constantly for virtually every aspect of the industry.

Creating the optimal indoor climate is a mission-critical aspect of your business that has a huge impact on your bottom line. Capital costs, installation costs, operating costs, and maintenance costs are significant, but so are the costs of reduced yield, failed crops, mold, and other environment-related issues caused by underperforming HVAC equipment.

The ROI of Smart HVAC Decisions

The following spreadsheet illustrates some of the ROI calculations to be considered when evaluating smart equipment decisions. The additional cost of superior equipment can often be recovered in the first year (the examples to the right illustrate just over a year).

Here are the 3 major challenges owners face in getting grow room HVAC right.

Challenge #1 – Understanding the HVAC Design, Specification, Selection, and Installation Process.

Typically, procurement follows a chain. The owner hires an architect, who hires an engineer, who hires a general contractor, who hires an HVAC sub-contractor. The process is usually price-sensitive and the winning HVAC sub-contractor is hired at a fixed price to supply and install HVAC equipment that “meets the specifications” set out by the engineer. (Of note, there can be several vendors and several levels of quality that will technically meet specifications; the sub-contractor may be motivated to choose the lowest cost in order to maximize their profits).

Low Cost is Usually Very Expensive

This is one of the biggest challenges owners face in getting a premium quality solution to their HVAC needs. Lowest “first cost” is typically not the smartest money or the best way to ensure best long-term value and performance.


It’s recommended that owners have a clear understanding of the entire HVAC decision process from design to installation. Ask lots of questions, understand what the options are and why specific recommendations have been made. Get all the facts.

A well-informed owner, architect, or engineer can pre-determine the brand of HVAC equipment they prefer or the type of HVAC design they feel strongly about. It makes no sense that the final decision should come down to the lowest cost without consideration of the bigger picture equipment value factors.

Challenge #2 – Getting the HVAC Design Parameters Right

As mentioned in the introduction, designing commercial-scale cannabis grow rooms is still a new frontier, and technologies are changing constantly. There’s also a considerable level of secrecy and competitive confidentiality relating to what works best.

Clearly, there’s a lot of pioneering work being done that is not setting industry standards. That means that even the technically qualified firms have to guess at a considerable amount of the science and mechanics behind creating optimal grow environments. Their jobs are extremely complex and involve dozens more variables than designing traditional HVAC systems for commercial buildings.


The HVAC design team and owner need to work closely to discuss and incorporate all factors that will affect temperature and humidity loads into your ideal specifications. Be certain that they have the expertise to properly model the dozens of load factors and variations that your plants and your grow cycles will require.

Model those conditions and the equipment capacities required to meet them on the most extreme design days. You may find that allowing a few degrees of latitude in temperature and humidity on those extreme days can save a lot of money and not have much impact on your yield or quality.

Challenge #3 – Getting the Right HVAC Solution Design

There is considerable “solution bias” in the engineering community towards traditional HVAC solutions (namely, central plants) that are not necessarily suited to this unique space.

Most projects requiring a thousand or more tons of installed refrigeration capacity (roughly 80,000 to 100,000 sq. ft. of facility), use a central plant for heating and cooling. For these facilities, it would be unfathomable to use smaller unitary air conditioners.

Because a large grow room can require a similar amount of “refrigeration”, many engineers naturally want to apply the same central plant approach. And they do so because they are familiar with that approach.

Doing so forgets the unique requirements of grow rooms, where humidity is the issue. To dehumidify, you need to cool the air down significantly, which turns out to be very inefficient when using the typical chilled water air handlers and chillers mentioned. Furthermore, in lights-out mode, you need to be able to dry the air then reheat it, so as to not over-cool the grow room. That re-heating could use free energy captured from the dehumidification process, if you have the right system. If you don’t, it’s an added energy cost.

So, with chillers, the system you end up with is inefficient, not scalable (central plants are not easily expanded), and not redundant, because there’s a single point of failure.

But a unitary, purpose-built grow room dehumidification system can cool and dehumidify very effectively, while intelligently rejecting heat out of your building when needed. You can easily size the equipment to match the room and create built-in redundancy. Expansion is easy with relatively short equipment lead times. Installation is straightforward and heat rejection even simpler with low-risk, scalable, redundant dry coolers. Additional rooms can easily be added at will — entirely independent of the rest of the facility.


It’s essential to have a solid understanding of your HVAC options as well as the costs, limitations, and advantages of different design scenarios. You want to also weigh the advantages of a more modular, scalable and redundant approach to HVAC control for your facility. Good vendors will be happy to have an open and honest conversation about the options available to you and which might be most suitable for any given facility.


  • Geoff Brown, Director of the Agronomic IQ, is a keynote speaker across North America on the issues of HVAC for grow rooms and is a contributing member to the American Society of Agricultural and Biological Engineers (ASABE) X653 guideline. To learn more, check out

Related posts

Leave a Reply





* indicates required


We hate spam too. You'll get great content and exclusive offers. Nothing more.


Cannabis & Tech Today - SOCIAL MEDIA