Overview of Chilled Water Systems

Video transcript

I’d like to quickly talk about chilled water systems and their heritage in this marketplace.

As legalization occurred throughout North America, large customers, large growers, started involving the engineering and mechanical contracting community in their grows, and engineers were faced with a brand-new market that they didn’t understand. And they applied the knowledge they had. I can tell you from my experience on committees, there are no standards for engineers in controlled environment agriculture. They still don’t exist today, let alone 10 years ago. And so, what you had was you had engineers who applied large capacity systems, the type of systems they’ve used in the past – things like university campuses or large office towers – and that was primarily chilled water.

And I’m talking here about four-pipe chilled water – so, a chilled water system that handles all of your space’s demands: heating, cooling, and dehumidification. They’re roughly 60% more expensive to install than a cooling-only chilled water system – and part of that is just the extra piping required. But they also require a very cold chilled water, as a result of needing to achieve dehumidification. That very much reduces the efficiency of chillers. It can have a 30 to 50% impact in the efficiency, of the state of deficiency, of chillers.
And that cold water is required for the dehumidification. You can’t get to your cold and dry condition at the end of the grow without that very cold chilled water. But when you got that very cold chilled water, you’re producing a very cold airstream that you need to heat back up so you’re not shocking your plants. So, you’re trying to achieve dehumidification without shocking your plants, and that’s where you need that four-pipe system. And that’s where you end up with a very expensive energy footprint.

Chilled water systems are great at achieving diversity. So, when you’ve got a thousand-ton building, a large campus, your building isn’t all at full demand at once. And it’s called diversity in central plant systems where you may be able to get away with 30 to 40% of your installed demand in central plant tonnage. So, if you’ve got a thousand-ton building, you can probably get away with a 400-ton plant because the north side of your building isn’t getting sun in the middle of the afternoon. Only the south side is, or your building isn’t fully occupied or whatever. That doesn’t exist in a grow room. Diversity just isn’t there. Your lights are all on. And we’ve seen cases in the past just where growers or engineers have instructed growers to do 12 hours on, 12 hours off in half of their rooms at opposite schedules. One of the big challenges with doing this is you halved the size of your plant, so you can’t go back. And now you, as a CEO or as a master grower, you’re trying to find a reliable workforce in two completely separate shifts, potentially paying shift premiums for it. And you can’t go back. You can’t just increase the size of a central plant. By its very nature, it is not designed to be scalable.
So, there’s a lot of challenges with a chilled water system. I absolutely understand why they became as prevalent as they are in this marketplace. They can offer very tight space control if you get your controller working well – and doing that is expensive. Redundancy is expensive. If you have a single chiller that feeds your entire building, you have a single point of failure that could take down a million square feet. Things like that are really challenging. And building in redundancy – redundant chillers, redundant boilers, redundant pumps, redundant air handlers – you now have an incredibly expensive system that uses more energy to achieve marginal increases potentially in space control. So, again, it’s a very capitally-intensive thing. It’s the way that you may get pushed by an engineer who is using their experience in large facilities and applying it to an ag environment where it may not be totally applicable. Again, you may spend 50 to 60% more in energy costs in this manner because the default is central plant is cheaper to run long term. Central plant is more efficient. And historically, that has been true in other building types. In this market, it is not. So, don’t let those existing biases from the people that you’re involving in your design process influence you in a way that unfortunately you may regret later on.

If you’ve got any questions about a specific design, again, I would love to be able to have a conversation with you. So, I’m absolutely available for it and look forward to it.