The Many Things to Look for When Selecting HVAC Equipment for Your Indoor Farm

When I sat down to write this blog, I started with a list of a half-dozen bullet points stemming from a recent phone call with a client, who identified these factors as most critical when deciding between their top two HVAC options. But as I came to the end of this short list, my brain rattled on and the list quickly grew into ten and then more. Some of the items on this list are essential to the successful launch and operation of a building. Others may be more “nice-to-haves” or optional features that may provide desired or even unexpected benefits.  The bottom line: There are A LOT of features to look for when selecting the right HVAC equipment for your indoor farm or greenhouse.

1. Can it perform?
The most essential question to answer is: will the HVAC equipment adequately cool, dehumidify, and heat the indoor farm when needed? Most commercial HVAC equipment was developed for human comfort, with the purpose of maintaining a fairly constant temperature in the room it serves. That’s great when you need cooling, but as any good grower knows, humidity control is critical for cultivating a healthy crop, free of mold and calcium deficiency and overall stress. Additionally, the temperature and humidity setpoints can vary through the life stages of the crop, when lights turn on or off, or when the grower purposely stresses the plants for quality. When working with your mechanical engineer or talking to equipment providers, make sure they recommend equipment that not only removes the heat generated by lights, but that it will also remove water vapor (humidity) generated by plant transpiration. And even better? That the equipment can adjust its operation to meet the varying amounts of heat and moisture generated by the lights and plants, respectively. The first clue: Can the equipment be controlled by both temperature and humidity sensors? If the answer is no, then you will need separate equipment to do each function independently. If yes, then you have a contender. And if it comes with variable speed components (fans, motors, compressors, etc) and a good software package, it will likely be able to respond to the fluctuating room conditions. 

2. Does it fit?
One of the most overlooked aspects of the HVAC equipment is the space it requires. HVAC equipment can be quite large – we’ve specified some that are as tall as 10 ft and as long as 20 ft. They can also be really heavy – we’re looking at one now that weighs over 20,000 lbs! And don’t forget the extra space they need to access the control panels, change out filters, or perform general maintenance. The physical features of the equipment will help determine, first and foremost, where the heck you’re going to put it (eg. heavy equipment may need to go on the ground). This decision can have major ramifications on the facility layout and design, installation costs and methods, and day-to-day operations. Think: property line and corridor size to accommodate equipment; structural reinforcement to support equipment; the need for a crane or specialty contractors for install; and equipment orientation to provide clearances for maintenance. For some projects, the physical attributes of the HVAC equipment alone can signal a “go” or “no go” decision without looking at anything else. 

3. How much does it cost?
Of course, cost is one of the most significant decision-makers in the selection of HVAC equipment. Some projects are very budget-driven and must limit the cost – sometimes only for the initial phase of the project – to make a project feasible and quickly turn a profit. Typically, when cost is the driving factor, performance and control are sacrificed, as are energy efficiency, operating costs, and the technical support provided during and after install. Like most anything else, you often get what you pay for. Therefore, most growers who start with low-cost equipment are usually eager to upgrade once their facility turns a profit and the concept proven successful. It’s also important to mention that depending on the equipment, there may be hidden costs not directly associated with its purchase, including startup support, the cost of labor and materials to install the equipment (like renting a crane to lift it onto the roof), and the structural reinforcement required. We once saved a client over $1M in structural costs alone during a peer review of their local engineer’s equipment selections, which were more than 2x oversized because they didn’t know how to properly calculate the cooling and dehumidification needs. So they added a huge safety factor (as engineers tend to do), resulting in oversized equipment and unnecessarily high costs, not just to purchase, but also to support.


4. Will it arrive in time?

In other words, what is the “lead time” for the equipment to arrive on site? For projects on a fixed timeline, the lead time can be one of the most constraining factors to selecting the HVAC equipment. We’ve seen lead times for HVAC equipment range from 12 weeks all the way up to 24 weeks. This range can depend on many factors, including the choice of standard versus custom product lines; requests for optional features; and even when you place your order. Like all HVAC equipment, those that are used for indoor farms compete for factory floor space with other product lines. When an order for your equipment comes in, essentially it gets in line behind the other, previously ordered equipment. Therefore, depending on how many orders came in before yours, the lead time could be different. As you might expect, most construction projects occur during the summer. Therefore, if you purchase equipment in the Winter or Spring, you might be waiting longer than if you ordered in Summer or Fall. Of course, if you’re buying standard or off-the-shelf equipment, then your lead time could just be the time it takes to drive the units from the factory (2 weeks?) or Home Depot (20 minutes?). But if you’re looking for something more purpose-built for an indoor farm, plan on at least 3-4 months before it is delivered and installed.

5. How is it controlled?

The question of sensors and controls is often overlooked by growers who assume that the equipment they buy will come with the hardware and software needed to operate the unit as desired. It’s true, most HVAC equipment comes with a standard package of sensors and onboard controls; however, they are not always suited or programmed to the indoor farm environment. In larger indoor farms or in rooms served by multiple units, the grower may choose to use 3rd party sensors and controls to operate the equipment. In this case, it’s important to determine if the equipment can receive inputs from external sensors and commands from a central building management system. Up until recently, it was difficult to find HVAC equipment and traditional horticultural controls systems that could communicate with each other. But now, as these controls companies add BACnet and Modbus protocols and the HVAC manufacturers have agreed to take external commands (just don’t touch the internal workings of the equipment), growers have many more options for the hardware and software they use to manage all their facility operations. 

6. What is the available technical support?

HVAC equipment and its operations can be quite complicated and understanding how it works and how to modify its operation is not always intuitive. Plus, the grower usually wants to focus more on fertilizer recipes and lighting regimes, not fussing with the functionality of the HVAC system. In fact, the best-case scenario for the grower would be to “set it and forget it.” Having startup support and training before the facility is fully operational can be extremely helpful, not only to ensure the successful startup of the facility but also to further optimize and improve performance in the future. When talking to potential equipment providers, ask about their options for startup support and training, future technical support and recommissioning, and a list of qualified and experienced contractors who know their equipment, especially with the specific model you are considering to purchase. 
The preceding list represents those criteria that many of our clients regularly cite as most essential to their decision-making process. But there are many others that could be similarly important, depending on the grower, the facility, and the project goals. Below is a list of other features you may want to consider to help you determine what is the right HVAC equipment for your indoor farm. 
7. Does it meet building code requirements?

8. Can it be integrated with other building functions?

9. Is there redundancy built in?

10. What are the maintenance requirements?

11. What is its life span?

12. How is it installed?

13. What is the installation history of the equipment?

14. How does the equipment operate in extreme outdoor conditions?

15. Is it efficient/sustainable? 

16. What are the available options?

• Air cleaning
  
• CO2 port and valves
  
• Quiet/noise abatement
  
• Colors and logos
  
• Variable speed
  

We’d love to hear from you: Which are your top 3-5 criteria for selecting the HVAC equipment? Did I miss anything? Was there something on the list you hadn’t thought of before? All feedback is welcome!