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ASHRAE Journal Podcast Season 1 Episode 7

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Guests, Dan Dettmers and Kyle Booth

What Controlled Environment Agriculture Demands of HVAC Systems

“Lumens are for humans,” but not for plants—including cannabis, says Kyle Booth, Associate Member ASHRAE.

On the latest episode of ASHRAE Journal Podcast, Booth and Dan Dettmers, Member ASHRAE, discuss what controlled environment agriculture demands of HVAC systems, the patchwork regulations born from increasing legalization of cannabis and how cannabis grow facilities are helping the CEA and HVAC&R industries develop equipment as the “grow local” food movement gets louder.

Guests from left, Dan Dettmers and Kyle Booth

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  • Show Notes

    “Lumens are for humans,” but not plants—including cannabis, says Kyle Booth, Associate Member ASHRAE.

    On the latest episode of ASHRAE Journal Podcast, Booth and Dan Dettmers, Member ASHRAE, discuss what controlled environment agriculture demands of HVAC systems (7:55), the patchwork regulations born from increasing legalization of cannabis (26:30) and how cannabis grow facilities are helping the CEA and HVAC&R industries develop equipment as the “grow local” food movement gets louder (40:55).

    Dettmers and Booth start the podcast talking about the three loads CEA facilities demand: lighting, cooling and latent loads (7:55). Then, the duo discusses the high energy use intensity of indoor grow facilities (4:30) and dive into a history lesson of legality and regulations that come along with growing cannabis (4:50 and 22:45).

  • Guest Bios

    Dan Dettmers, Member ASHRAE, member of ASHRAE's Technical Activities Committee, joined Quest three years ago with a 20+ year background in food/pharma processing, industrial refrigeration and HVAC infrastructure design. The bulk of his experienced was acquired at the Industrial Refrigeration Consortium, U.W. Madison, but his extra-curricular activity of curling has led to multiple amusing ASHRAE presentations. For 15 of those years, Dan also moonlighted at his own hop farm. With his partners, they developed a business that covered every aspect from plant propagation to final pelletization of the hops for their brewery customers. This experience naturally parlayed into Dan’s current duty to help the Controlled Environment Agriculture (CEA) industry solve their climate control problems, in particular with the other crop from the cannabacea family that has grown in popularity over the last decade. Dan also works in R&D developing new products for Quest, sits on several industry standard writing bodies and provides technical training both in and outside of the company. 

    Kyle Booth, Associate Member ASHRAE, is a senior engineer and licensed professional mechanical engineer at Energy Solutions. As the lead CASE author for the 2022 CA Title 24, Part 6 Controlled Environment Horticulture CASE Report, he led the research into minimum efficiency requirements for horticultural lighting, dehumidification, and greenhouse envelope measures. He is on the ASABE/ASHRAE X653 Heating, Ventilating and Air Conditioning (HVAC) for Indoor Plant Environments without Sunlight standards development committee. In addition to controlled environment horticulture codes development, Kyle is the lead engineer for several commercial midstream energy efficiency programs across the country. Before coming to Energy Solutions, Kyle performed agricultural energy efficiency audits on farms across the U.S. for seven years with EnSave, Inc. Kyle comes from an agricultural background, growing up around his family’s dairy processing facility in Vermont, Booth Brothers Dairy.

  • Transcript

    ASHRAE Journal:

    ASHRAE Journal presents.

    Dan Dettmers:

    What are we talking in watts per square foot for a typical grow operation? I mean, is it like a warehouse at a half a watt per square foot, maybe one, maybe two watts per square foot?

    Kyle Booth:

    So we're going to want to crank the dial up to 11. We're going up to about 50 watts per square foot, sometimes even high. So we're looking in the 40 to 80 watt per a square foot range.

    ASHRAE Journal:

    Episode seven, Dan Dettmers and Kyle Booth, talk about the HVAC industry's role in indoor farming and the regulations that come along with the patchwork legalization of cannabis in the US.

    Kyle Booth:

    Hi, my name's Kyle Booth. I'm with Energy Solutions. I'm a senior engineer here. I've been a member of ASHRAE for the past five or six years, I believe. I work on some regulations with building codes in California specifically for controlled environment horticulture, and happy to talk about some of the regulations throughout the US today. Dan, you want to give an intro?

    Dan Dettmers:

    I would love to. My name's Dan Dettmers, I'm a senior application engineer at Quest, manufacturer of dehumidifiers and other space conditioning equipment. My involvement in ASHRAE goes back to, oh man, let's just say Kurt Cobain was still alive and I was wearing flannel on the weekends, but I've been involved in a lot of different technical committees, most involving refrigeration, food processing and the like, but also a lot of indoor air quality plant and animal environments and other technical committees along with numerous standing committees. I've kind of made a career out of attending ASHRAE meetings.

    Kyle Booth:

    Dan, what are we talking about today?

    Dan Dettmers:

    Well, we're talking about controlled environmental agriculture I believe.

    Kyle Booth:

    Oh, is that true? I thought we were talking about controlled environment horticulture.

    Dan Dettmers:

    No, no, no, I think we're going to talk about indoor plant environments.

    Kyle Booth:

    Oh, okay. So you mean like urban farming?

    Dan Dettmers:                                                                                         

    Or indoor farming or indoor growing. Okay, there's a lot of terms, but of course, we're going to be talking about growing plants indoors for agricultural purposes. Now, we're going to be talking about a lot of plants today. Lots of different things, lettuce, basil, tomatoes, sweet peppers. But of course the emphasis is on the, well, everyone knows what we're talking about.

    Kyle Booth:

    Sure.

    Dan Dettmers:

    Devil’s lettuce.

    Kyle Booth:

    Mountain cabbage, yeah.

    Dan Dettmers:

    Jamaican tomatoes, sticky icky.

    Kyle Booth:

    Hawaiian Bush.

    Dan Dettmers:

    Mary-Jane.

    Kyle Booth:

    Yeah, the electric lettuce. All right, let's do it. Cool.

    Dan Dettmers:

    Well, of course, what we're talking about everyone is what everyone's really interested in, cannabis! And we'll cover that topic, but we also want to cover other topic and other plants as well, because it does apply. But I know most of you are tuning in for cannabis, otherwise known as marijuana.

    Dan Dettmers:

    Before we get going, I know ASHRAE has all their own disclaimers. Well, I want to give a little bit of a definitions and a little disclaimer, a little apology right off from the bat. So as we go throughout today, we're going to talk about marijuana, cannabis, possibly hemp. These are all the same plant. Cannabaceae Indica, Cannabaceae Sativa, is all the same plant. The differentiation is by legal definition, hemp is a cannabis plant where the THC level is 0.3% or less. Marijuana is, well, 0.3% THC or more. That's the primary differentiation. And it's all about how you grow it and how and when you harvest it that differentiates what that plant is for. Currently, hemp is part of the 2018 farm bill and legal for interstate transport and commerce with the caveat of individual state laws will regulate whether it could  be grown or distributed within that state. But under the farm bill, you can distribute hemp throughout the United States for the purpose of providing CBD. Marijuana is on a state by state basis.

    Now the disclaimer I'd like to put out is it has been made aware to me through publication in ASHRAE that marijuana is considered to be a racist term based on the origins of the word. But since it is a federal definition, we're going to use it throughout this podcast. And I apologize for anyone who might be offended by that.

    Kyle Booth:

    So, yeah, cannabis is one of the main crops we're talking about. It's got a very high energy use intensity and we are talking about the energy consumption and energy efficiency within the controlled environment horticulture or agriculture space. Looking at the history of cannabis and growing it, we've got to do a little history lesson first. So why don't we take it back to, let's say the 90s when you got into ASHRAE Dan, when you were wearing flannels? So back then, there wasn't a whole lot as far as legality in growing cannabis. It was mainly done black market, indoors to hidden and the main priority was not to get caught by the cops or the DEA. So, there was not as much thought to energy efficiency and what type of equipment I'm using. Is it the most productive? It was, what can I get cheap to set up a grow and make some product? I think that's a good baseline maybe for where things started with a lot of indoor growing. There was of course the medical cannabis industry. And there has been a little more standardization there earlier on, but really the black market is where a lot of indoor growing started. Dan, you got anything to add to that?

    Dan Dettmers:

    Absolutely. My earliest exposure to indoor growing of marijuana was actually helping out a police detective trying to figure out what was going on with a house down the road from me. The huge electric bills, the strange smell coming out and a huge thermal signature, you're absolutely right. In the early days, the whole point of the HVAC system was it had to keep everything underground, keep the temperature down, keep the smell down. And you obviously couldn't use your local HVAC contractor to install the equipment. So early on, the equipment that the black market used was going to be split system or packaged AC, small units, whatever dehumidifier they could find to take care of that latent load and keep everything really on the down low. And as far as regulations go, Kyle, what regulations existed?

    Kyle Booth:

    The main regulations that existed were on the actual growing of it in the legality there, not on equipment at all. So it was largely unregulated. And there is, I will note that there is still a black market and it's pretty hard to regulate an illegal business. So there are people still kind of doing the wild west growing where they're not under regulations.

    Dan Dettmers:

    I mean, going back to the days of anyone who went to a Grateful Dead or probably even a Phish concert knows pre-2005, there wasn't any legal marijuana grown in the United States. So everything was black market. It was hidden, the space conditioning equipment, the whole point of it was not efficiency. It wasn't getting everything perfect. It was keeping it on the down low. Low thermal signature, low energy consumption, trying to keep the cops from finding your operation. As far as regulations go, Kyle, I assume there weren't any, right?

    Kyle Booth:

    Not that I know of other than just not being federally legal to grow cannabis. That was the main regulation, but that doesn't really stop a black market business.

    Dan Dettmers:

    So as we move on through today's conversation, Kyle, regardless of whether we're talking about black market, we're talking about modern times or whatever's to come in the future, whenever you're growing plants indoors, regardless of the plant, there's three major things that we need to consider. We need to consider a lighting load because plants need light to live. We need to consider cooling because all those lights add major amounts of heat to the space. So, that's got to be taken off. And then of course, we've got this huge latent load. I mean, swimming pool level latent loads. Now they're not difficult to manage, but they're there and we need to think about them and we need to think about the efficiency of removing that. But let's kind of digest these at first. Tell me about the lighting loads that you see in most controlled environmental horticulture spaces, and what are they? And what's the impacts? And what's the current regulation that you see in the market?

    Kyle Booth:

    Lighting does play into HVAC and dehumidification. So with the original kind of the black market lighting systems that were used, we're looking at a single ended high pressure sodium or metal halide. These are some of the least efficient horticultural lighting products. And that means that a lot of that is, is going to heat and not to actually growing the plant. So, that increases the HVAC load that you're going to have. So there's a lot of interactivity in the controlled environment horticulture world, and the interaction between lighting and HVAC in plant respiration with lights on and lights off, is something that's kind of really important in this space. There's a variety of horticultural lighting products that are currently in use. I'm going to do a quick rundown from kind of lowest efficacy to highest efficacy. On the low end of the spectrum, we've got single ended high pressure sodium and metal halide lights. Moving up in efficiency, we've got ceramic metal halide, which is slightly more efficient. We've got a jump in from my supervisor, Cricket the cat there. So we've got double ended high pressure sodium lights which are more efficient yet. And then jumping into the highest efficiency levels is LED lighting, LED grow lighting. So not your typical screw in LEDs, but dedicated fixtures for growing plants indoors.

    Dan Dettmers:

    But now I got to ask is a light, a light, a light? Because you just told me a whole bunch of different lights, but I hear from growers that they want specific lights for, what, specific spectrums?

    Kyle Booth:

    Yeah. So, there is a big difference between human lighting and plant lighting. And one term that I've heard in the industry is that lumens are for humans. So we're not talking in lumens like you would look at for human occupancy. We're looking at a few different terms, but we're looking at PPFD, which is Photosynthetic Photon Flux Density. So that's how many photosynthetically active radiation photons are actually hitting the plant leaves at the canopy level. So that is similar to like a lumens per watt measurements. Or actually PPE. I'm mixing up my terms a little bit. Let's go through them real quick. So we've got PAR light, which is photosynthetically active radiation. That is saying how much light is in the usable plant growth spectrum. So we're trying to utilize typically between in 400 and 700 nanometer wavelength light that's within the photosynthetically active or PAR radiation level. There are some kind of special treatment lights slightly outside of that wavelength that are used for various treatments to plants. But for the purposes of today, that's the primary wavelength range we're working in. To look at how much light per unit of area, so per square foot or per meter, we're going to be looking at photosynthetic photon flux density. So that's how much usable plant light is hitting the canopy per unit of area. And then our efficacy metric is PPE or photosynthetic photon efficacy. So that is measured in micromoles per joule. So looking at how many photons are hitting the plant per joule of energy that's put into the light. So these are kind of the main metrics that we're using in the horticultural lighting space. There's a lot of analogs to human occupancy lighting and lumens per watt, that's micromoles per joule is our plant lighting term. So yeah, there's a quick breakdown. Not too quick, but yeah, that's kind of what we're working with for horticultural lighting.

    Dan Dettmers:

    Okay, Kyle, so you told us all about, what, photon torpedoes or something? Can you put this in terms for us HVAC engineers to understand? What are we talking in watts per square foot for a typical grow operation? I mean, is it like a warehouse at a half a watt per square foot, maybe one, maybe two watts per square foot?

    Kyle Booth:

    So we're going to want to crank the dial up to 11. We're going up to about 50 watts per square foot, sometimes even higher. So, we're looking in the 40 to 80 watt per square foot range. This is not your human occupancy.

    Dan Dettmers:

    Hold on. No, you mean four to eight, right?

    Kyle Booth:

    Times 10, yeah.

    Dan Dettmers:

    40 to 80 watts square foot, but that's the HPS, right? What about LED?

    Kyle Booth:

    Even LEDs are on the lower range of that. So, I mean, you may be able to get down into the 30s but typically to get the production that commercial growers are looking for just even with current LED technology, you're still going to be in the 30 plus watt per square foot range. So it's a really an important distinction to note that this is different than human occupancy lighting. And when looking at regulations, you don't want to start from a baseline of human occupancy lighting and the levels that we typically see there because that's something we've seen try to happen. And it's just, you can't grow a plant with that amount of energy indoors. I mean, we're replacing the sun. So we've got to remember that.

    Dan Dettmers:

    I've given talk at a few local ASHRAE chapter meetings. And once I get to the watts square foot, I had one meeting in particular, one fine gentleman stood up and said, “No, you're wrong. That is impossible.” He's like, there is no way you can fit that much lighting in. So I had to produce pictures of massive amounts of lighting and everything so bright that everyone was wearing sunglasses indoors. He backed off, but he still thought I was a little bit on the high side.

    Kyle Booth:

    Yeah, and I've heard similar things, Dan. It's something until you see it, it really is a hard number to digest and that's something in working through regulations that it's really important to understand that. That this is a process load. This isn't lighting for human occupancy. This is literally recreating the sun so that the plants can grow and growing it in a controlled way. So, it's taking away the variability of nature and really trying to reproduce the optimal conditions to grow. So with that, comes a lot of energy use. And although the lighting energy use is high, I've heard the HVAC can get pretty high. Dan, you want to talk about that a little bit?

    Dan Dettmers:

    Well, obviously when you're talking 40 to 80 watts per square foot, I'm sure by this point, every single person listening to this podcast has pulled out a paper and a pencil and started translating that watts per square foot into square foot per ton. So let me save you. You're starting at about 25 to 40 square foot per ton for the cooling load. And as we talked before, there's a huge cooling load, but there's also a huge latent load. Those exist at two different times. There's the lights on period and the lights off period. So when the lights are on, the plants are sucking up water, they're transpiring that water in the air and that huge air conditioning load actually captures a lot of the latent load for us. So we don't have to worry about sizing dehumidifiers for the lights on period, because our air conditioners are cranking that water back out. What happens when the lights go off? The plants don't stop. They just kind of go to sleep. The way I like to put it is when you go to sleep at night, Kyle, do you stop breathing?

    Kyle Booth:

    Not usually. I hope not at least. Sometimes I wake up in my sleep and let's say, I got a bad dream, I wake up sweating. And that's something that when the lights go off, the plants do.

    Dan Dettmers:

    They sure do. When the lights are off, the plants are still transpiring at, eh, somewhere in the range of 20 to 30% of the amount they transpire during the day. But without the lights, that air conditioning load is gone. And in fact, it's kind of the opposite. The plants are now still transpiring, so you get evaporative cooling. So you often need to add heat, but you also need some form of dehumidification. And so that's where we need to put in dehumidifiers, hot gas reheat with the rooftop unit, any number of different types of HVAC equipment to properly take out that moisture load that's still occurring during the evening, well, lights out, period. I hate to use the word evening, day and night because honestly they flip the lights on and off. Since it's an indoor grow, nighttime could be during the middle of the day for us, or it could be in the middle of the night. It's whatever they want to do to manage their electric bill.

    Kyle Booth:

    Yeah. And Dan, that brings up a good point of photoperiods. So I want to touch on photoperiod a little bit, because this is really important for all crops, but specifically cannabis because it has a couple growth stages and they have different photoperiods. So photoperiod is the amount of time per day that the plant wants light. So at the beginning stages, you're looking at 18 hours a day of daylight and six hours off. So that would be propagation and vegetative. Some people do full 24 hours sometimes, give no break. So there is some variation throughout the industry, but those are kind of two common photoperiods used in the vegetative state. And then we get to the main action, the flowering stage. So this is where you're growing your buds. This, you turn the light down to a 12/12 photo period. So 12 hours on, 12 hours off. What this does is the reduction in photoperiod tricks the plant. It tells it its fall outside and then it needs to start reproducing. So when you create feminized plants, you don't have seeds, you just have the buds. So it's flowering, it's trying to get to the end of its life cycle and reproduce. So that photoperiod change is really critical. And if that is upset at any time during the flowering period, it can do some funky things to the plants. So it's really important to have that set structure, and you don't want to interrupt that.

    Dan Dettmers:

    You use the term vegetative room and then flowering room?

    Kyle Booth:

    Yes, vegetative and flowering. Those are two primary things that we're going to be looking at in an indoor grow or greenhouse grow. But with that, they're often done in separate rooms. So you started to mention rooms. I was just kind of talking about the plant growth stage. But I think looking at how this fits into a building is important. And Dan, do you want to talk about some of the differences between HVAC load in vegetative stage versus HVAC load in flowering stage? Because it is definitely a progression as the plant grows and that changes as well. And so photoperiod is one thing that changes, but HVAC load changes significantly as well.

    Dan Dettmers:

    It does. So in the vegetative room, we're really starting with clones, right? Plants in the Cannabaceae family, if you let, them go all the way to seed and plant the seed, you don't get the same flavors. You don't get the same aromas, the same, well THC or CBD levels. So it's always a clone. So you're starting with mother plants, cutting little pieces and going from there. So in the vegetative room, as Kyle said, the lights are on most of the time. So the load is pretty constant and the watering load is very small, because the plants are very small. And when you're sizing for that latent load, the easiest way to think of it is water in equals water out. Any water that you're pouring on those plants, it's either going to evaporate from the growing media. It's going to pass through the growing media and hit the floor, hopefully running down a drain or the plant is going to suck it up, use it to go through its growth cycle and then evaporate it back into the air. So the easiest way to size your latent load is to look at how much water the grower is putting into the plants to begin with. And when they're small, it's not much. Once we move to the flowering room, everything's different.

    Now we go into that 12 hour on 12 hour off cycle. So again, when they start out, they're pretty small. So our latent load is also pretty small, but our sensible load is pretty high. So in the beginning of the flower cycle, we've got tiny plants with bright lights. Bright lights means lots of heat, lots of air conditioning. So a lot of times the air conditioning takes out too much latent load, and I often see growers actually putting humidifiers in there to help their plants stay in a level where they're comfortable. As they grow though, our watering rate increases and well, our sensible load stays about the same. So eventually we hit this happy medium where the latent capacity of the air conditioning meets the latent low put off by the plants. That's when everything's good, but unfortunately it doesn't stay there. Just like our kids, the plants keep growing. As they grow, they suck up more water and eventually you're going to see them taking up to, well, I mean, it changes from every plant to plant, but two to four pints per day per plant. So when you start looking at the growing operation, you want to look at how are they growing it? Are they growing short, fat plants? Are they growing tall plants? Are they giant bushes? Are they trees? You're going to want to work with the grower to determine how much water they anticipate feeding to those plants at the end of life, because that again is going to determine the latent load that you need to remove.

    And once you start doing the math and start figuring, okay, one plant takes up anywhere from about one to three square feet and you start adding two to four to maybe even six pints per plant, that latent load gets pretty high pretty quick. And the way that you're removing it and the efficiency at which you're removing it becomes really important.

    ASHRAE Journal:

    Thanks for listening to the ASHRAE Journal Podcast. We want your ideas. What topics do you want to hear about and who do you want to hear it from? Email us your ideas at podcastat@ashrae.org. That is podcast@ashrae.org. Let's get back to the episode.

    Dan Dettmers:

    So, now as you come forward in time, when I first got into pitching dehumidifiers to the indoor environmental market, to the Jamaican tomatoes, as it were, because when I first started, we were aren't really even allowed to mention the word marijuana on the phone. Again, we talked about Jamaican tomatoes, devil’s lettuce, lightning lettuce.

    At that point, even though it was starting to become legal at the state level, we can talk about the banking act. We can talk about all the rules, but at this time, cannabis is still considered a class one narcotic. Is that right?

    Kyle Booth:

    Yes, I believe so.

    Dan Dettmers:

    Class one—

    Kyle Booth:

    Schedule one.

    Dan Dettmers:

    Schedule one controlled substance.

    Kyle Booth:

    That's what it is, yeah. Which is the highest risk for abuse and little to no medical purposes. So there has been a lot of talk of wanting to reschedule this because I think what are some of the other ones that are in schedule one like heroin? Yeah.

    Dan Dettmers:

    Heroin.

    Kyle Booth:

    You think of things that are like—

    Dan Dettmers:

    Opium.

    Kyle Booth:

    ... Bad, even a lot of opiates are scheduled two—

    Dan Dettmers:

    Crack.

    Kyle Booth:

    Yeah. And some things that you think would be bad are actually lower than cannabis. So it's looked at as in the most harsh way in terms of controlled substances.

    Dan Dettmers:

    So going back three years ago when I joined this industry, when we really couldn't say the word marijuana even on, on a phone call. Even though things were starting to become legal at the state level, people were still in that black market mentality. So most of the equipment that was being purchased was split systems, standalone dehumidifiers. They were working up to larger units than the bucket things that you get at your retailer and a lot of package units with hot gas reheat. In the last three years, we've really seen everything evolve within the space conditioning market. And I actually have to give a lot of the credit to Canada. Canada went and took the major step of legalization.

    So by making marijuana a legal substance to be grown in every province across Canada, allowed engineers to come into the industry and feel free to help this industry pull themselves out of the wild west of putting in whatever you can get and start looking at proper HVAC systems, better performance, better efficiency, and start thinking about regulations.

    Down here in the United States, Hawaii and Alaska included, we're slowly legalizing on a state by state basis, but at the federal level, it's still a class one controlled substance. Which means most of the growers in the United States don't have access to the typical financial tools that are needed to invest in large HVAC equipment. Where in Canada, they're going after integrated HVAC systems, which basically were swimming pool dehumidifiers that evolved into cannabis or controlled environmental agriculture systems. Other ones are looking at chilled water systems. Some are even looking at built up systems using ammonia or carbon dioxide to do the space conditioning and refrigeration.

    Down here in the US, most of the operations are still limited to packaged equipment, split systems, standalone dehumidifiers, and the like. We're only starting to see in the last, actually since the pandemic started, the business has really accelerated because apparently when people have nothing to do but sit at home, one of the things they do is light up.

    So the industry has seeing an enormous growth over the last year. And with it came the funds into the industry to invest in larger equipment, larger grow operations. So no longer do you see a large operation as six to eight flower rooms. Now we're seeing operations going in with 20 flower rooms, 40 flower rooms, massive operations that could produce a lot of product for an ever-growing demand in particular, California, Illinois. And when it comes online, I think we'll see big demand out of Texas and New York as well.

    Kyle Booth:

    Yeah, and one thing I wanted to talk about since we're talking about kind of the patchwork of regulations in the US and which states are legal is some of the barriers that come to the industry with having it legal in a state, but still federally illegal. I think you mentioned the banking, Dan. That's a big one. Any federally insured bank usually steers clear of cannabis, even though it is legal in that state. It's not legal at a federal level and this is federally insured finance. So they don't touch it. There have been, I've heard, some local kind of credit unions that will do a little bit, but you're dealing with a lot of cash. And when you're trying to pay utility bills and purchase HVAC equipment, sometimes you might see a big bag of cash come. And Dan, I'm sure you've got some experiences with that. The lack of finance is a big barrier to the industry and what they can purchase for equipment. So they might see that a piece of equipment is a better efficiency. It's going to be a lower operational cost, but that first cost really rules because they are literally scrounging up cash to go pay for it.

    Dan Dettmers:

    I've heard lots of stories of growers having to take their piles of cash and go to multiple banks around a city to turn them all into money orders or cashier’s checks of $1000 or less and gathering up all of those to pay their engineer, to pay their manufacturer, to pay the manufacturers or have to pay the contractor.

    It is a big barrier to entry not having those banking services. When you look at regulations at the federal level, there's several efforts going on. There's the safe banking act, which is basically to allow banking services to be extended to the schedule one substance, marijuana. There's also federal decriminalization and there's also federal legalization.

    There's little fine nuances between all of them. Some of it has to do with going back and letting people out of prison that were put in for things that are completely legal these days. Others have to do with just decriminalizing the substance so it can be part of interstate travel and interstate commerce.

    And then the rest of it is actually making it legal to be grown at a federal level. At this point, I've listened to numerous conversations and presentations by experts in the industry. The consensus is federal legalization will happen somewhere between now and never, but most likely between the next two and 17 years. That's about the best prediction that my crystal ball can make for you.

    Kyle Booth:

    That's a pretty good range from what I've heard.

    Dan Dettmers:

    Yeah. There's several parties at play. Some of the Democrats under Chuck Schumer are pushing for an all or nothing plan where they want everything legalized right off the bat. There's other groups that are trying to back into it with first, let's get the banking, then let's get decriminalization and get the people out of jail. And then let's start looking at federal legalization. Personally, when I look at what's happened on the state levels, nothing ever happened in any state all at once. It was all in stages. Do you want to comment on that, Kyle?

    Kyle Booth:

    Yeah, sure. I think why don't we start with Colorado because that was one of the first recreational legal states. And that's going back to what, 2014-ish.

    Dan Dettmers:

    Hold on. I've got to look that one up quick. I thought it was earlier than that.

    Kyle Booth:

    It may be 2010. We'll have to double check that one, but yeah, just going back into Colorado. Colorado was one of the first legally states where cannabis was legal for recreational use. And the city of Denver has actually been very proactive with looking at energy consumption in cannabis facilities.

    So yeah, let's start with Colorado. Cannabis for medical use has been legal since 2000 and they opened up for recreational use in 2012. The city of Denver has been pretty proactive with looking at energy consumption in cannabis facilities and in applying regulations to that. I think one of the first energy consumption studies I saw showed that once the recreational grows were up in Denver, that it actually constituted 5% of the city's energy use. Which just to kind of like look at the scale, you're saying that cannabis growing in Denver uses 5% of that city's energy.

    And that's looking at starting in 2000 is a few medical facilities, and then 2012 kind of open the floodgates, we're recreational now. So that's a huge load growth that might be an unplanned load growth for the utilities in the area. So that's something that adds a lot of costs to grid infrastructure when you're looking at the amount of energy that people are calling for as a utility, your job up is to have that energy ready at any time for your customers. So that might mean putting in new power plants, procuring new energy, making investments to the grid so they can handle the higher load. That could be a new substation. So there's a lot of infrastructure costs that happens with this load growth.

    And one of the main concepts of putting energy regulations in place is to help curb that load growth and to utilize that as a tool to not have to build new power plants or procure energy. So Colorado was one of the ones that kind of led that.

    Dan Dettmers:

    Kyle, wasn't Denver the first place to put some sort of regulation in place for energy consumption in cannabis industry?

    Kyle Booth:

    Yes, it was. The city of Denver was one of the first.

    Dan Dettmers:

    So, Denver was the first to put together a prescriptive energy requirement. Since then, I mean, we've seen everything under the sun. For example, Illinois put together not so much in efficiency, but an equipment requirement. I believe there's mandated one set of equipment for growers under 6,000 square feet of canopy and a different set type of equipment above. And if you want to use anything else, you have to prove a higher efficiency than that existing equipment.

    Kyle Booth:

    Yeah, there's a fair amount of variation out there between the states and how they have decided to regulate energy consumption in controlled environment horticulture and cannabis. Let's look at yeah, Illinois and Massachusetts are similar. For lighting, they both use lighting power density. So that a watts per square foot metric to say we want you under this watts per square foot. Now where they made that metric essentially mandated LED lighting. The industry wasn't quite ready for that. Massachusetts actually revised theirs and added an alternate pathway where you could use DesignLights Consortium, which is an organization that does standards and ratings for lighting, both human occupancy and horticultural. So with that, they have a qualified products list of horticultural lights that you can look at. And I think they set it at 15% above the minimum qualifying for their qualifying products list. So if we're talking in that PPE metric again, the minimum to meet the DLCs list was 1.9. So you had to hit a 2.2 in Massachusetts, but you could, if you just pick lights from that list, that was your alternate path instead of calculating out the lighting power density and being below that number. So that's kind of one style on lighting

    Dan Dettmers:

    On the HVAC side of the world, looking at the regulations, we mentioned Illinois specifying equipment. Other states, and look Massachusetts and the rest of the Northeast, I'm kind of looking at you here. There's a little bit less regulation, a little less definement. A lot of the states are basically saying you have to do an engineering report to show that you're more efficient than the baseline. Well, the problem is when you're looking at the wild west of HVAC equipment, it's hard to define what the baseline is. So I've seen a lot of crazy stuff happening.

    What I'd really love to see, ASHRAE standard 90.1 I'm looking at you, is some sort of fine, define prescriptive energy requirement for controlled environmental agriculture. I know, it's sort of on me because I'm sitting on the MTG for controlled environmental agriculture and we promised you some data, but we're getting there. Hopefully by the time this podcast is published or by the time everybody starts listening to it, we'll have something moving. I do want to bring up one state, the state of California with their Title 24. This is where Kyle and I first started actually. Well, we were kind of on an opposite sides of the fence, but eventually we figured out how to work together to try to figure out appropriate space conditioning requirements for Title 24 for controlled environmental agriculture. Kyle, you were heavily involved in that. Do you want to talk about what California did?

    Kyle Booth:

    Yeah, sure Dan. So as Dan said, we met during the 2022 Title 24 part six code cycle. It's a bit of a mouthful, but that is the term for the California building energy code. Dan was a stakeholder. So it's a public process where we propose regulations and then go through a series of public stakeholder meetings and outreach to get input on our proposal, help refine it from the experts in the industry, and kind of refine it to a place where we actually bring it to code adoption at a code adoption hearing.

    So there's a very formal process there with several steps for public stakeholders to engage. And I think that's a really important process. So we want to learn from the industry, see where the industry's at and propose regulations that are not going to adversely affect the industry. We really want to do things that help the industry be better and save energy and operating costs while reducing load growth.

    That's the ultimate goal of the codes in California. I'll talk to lighting side first and then we can get into the HVAC. Instead of a lighting power density, we went for a product efficacy metric. So we're looking at the individual lighting product being used and what that rating is. So I talked about photometric photon efficacy, or PPE earlier. That's the metric that we ended up utilizing for lighting and setting a minimum PPE for both indoor and greenhouse growing. So we recognize that greenhouses there's a wider variety of crops. It's more diversified use. Indoor is predominantly cannabis. So there's a bit lower of a regulation on the greenhouse side.

    It also, as far as square footage of canopy grown, I think it's about three or four times as much greenhouse canopy that's supplementally lit than indoor canopy in California. Yeah, that's kind of what we looked at as far as lighting.

    And then on the HVAC dehumidification side, and this gets a little bit into that need for kind of a unified metric or standard to look at dehumidification, we had to look at multiple technology paths since there's several different technologies that are utilized and they all have slightly different ways of measuring their energy efficiency at different test procedures.

    So what we did was we gave a few options depending on the system types. So there's standalone dehumidifiers. They are essentially at the federal DOE regulation minimum requirements, integrated HVAC units that have both sensible and latent cooling, they have an option in that it requires least 75% site recovered energy for the reheat air.

    We have that on chilled water systems as well, same heat recovery requirement there of 75%. And then desiccant systems if they are designed for a dew point of 50 dry bulb or below, I believe. So it sounds a bit hodgepodge and multiple paths, but that's really the best option at this point until we have a unified metric, it's very similar to what the city of Denver did. And Dan, maybe you can talk a little bit about where we would want to go and looking at that unified metrics so that we have apples to apples comparisons across different system types.

    Dan Dettmers:

    Sure. For clarity to the audience, prior to the state of California doing Title 24, as the dehumidifier manufacturer much like the marijuana industry, we were kind of living in the wild wild west. So there is energy performance requirements from the DOE under 10 CFR 430 for consumer products that does specify minimum efficiencies for dehumidifiers. But these are for consumer product dehumidifiers, which the definition really is, is units built for sale to residential people on a one by one basis. When we're putting 10s, 20, 40, or more dehumidifiers in an ag situation, it can't really be considered a consumer product at that point. So there is no efficiency requirements.

    There's technically not even a rating performance standard that we have to follow. So it created this wild west scenario where anybody could do anything and you would think as a manufacturer, hey, this is awesome. I can build whatever I want, but let's keep in mind, I'm also an engineer and I really like constraints and rules and rules to follow. So give me those rules. So when we hit California in Title 24, Kyle and his team were trying to come up with some rules for space conditioning of the indoor ag facilities. And myself and some other stakeholders we got together and we thought we came up with some pretty good rules for standalone dehumidifiers.

    Like Kyle said, there was rules created for minimum efficiency for standalone dehumidifiers based on basically the case size of the dehumidifier. There was rules created for desiccant dehumidifiers. There was rules created for integrated HVAC and other space conditioning systems. But at the last minute, the legal team kind of got involved and now all dehumidifiers are back to 10 CFR 430, which again, that's fine. We at least have a set of rules that are going forward. I think we've hit on cannabis enough at this point. As I promised, we are going to talk about other plants that can be grown indoors. And honestly, a lot of this industry, we're using cannabis as the profitable product to develop equipment for other markets.

    Just like think way back, you go back to the 1800s, late 1800s, there was this guy named Mr. Swift and Mr. Armour that were working with refrigerated rail cars to try to ship beef across the United States. They were having some luck, but it wasn't until Mr. Stroh up in Milwaukee said, I can use this to ship beer, that there was the money available to get this product moving. I kind of see the same thing in this market. We're using cannabis to develop this equipment to start moving it into the indoor ag market. I'll guess I'll say anyone listening to this podcast 10 years from now, go back to Wikipedia and look up the shipping shortage of the pandemic. You'll read all about how shipping containers were lined up at ports, boats were lined up, there wasn't enough trucks to haul them and shipping has become a huge issue.

    So the feasibility of growing our food in Central America to ship up to the United States in the winter or Kiwis in New Zealand to ship to the United States throughout all times, it's kind of becoming a pipe dream at this point. So a lot of people are looking at growing their food locally. Well, I'm here in Madison, Wisconsin. There's not a lot of stuff that can grow starting in late December until at least March, because it's pretty frozen up here. So we start looking at greenhouses, at controlled environmental agriculture as a way to grow our lettuce, our tomatoes, our other fruits and vegetables that we really want.

    But as we've touched on already, when your margins are so slim, you not only have to watch capital costs, but you also have to watch your operating costs. That means good HVAC design, proper lighting. Do you want to touch on lighting for other products at this point?

    Kyle Booth:

    Yeah, sure. And with touching on lighting, I also want to touch on vertical farming because this is something with produce that is done in cannabis as well, are stacking plants. But in the produce industry for indoor growth, vertical farming is very popular. You can put a lot of product in and really maximize the square footage of a space by stacking product or rotating. There's a few different designs out there. But with that, in indoor vertical farming for produce is majority of them are using LED lights. That's just what you have to use to be profitable in that industry.

    They are a little different from what you would see in a cannabis facility. The cannabis lights are typically a big, high powered light that's putting out a point source in covering maybe a four by four or a five by five area per light. In indoor farming, you're seeing more of the strip type of lights. So continuous row of LEDs looks more like a strip light. You can be a lot closer to the canopy with LEDs. So you might see lights six to 12 inches from the produce instead of four to eight feet above the plants. So we're looking much more compact and this could be microgreens. This could be leafy greens, herbs, all sorts of plants being grown indoors, but those are some of the more popular ones.

    They have a shorter growth cycles. So I mean, you can harvest microgreens in a week. You can do a harvest. For regular leafy greens you're looking at about a month, 28 to 34 days. So you're talking quick turnover, you're doing 12 cycles a month, you're doing 12 cycles a year. You're doing like four cycles a month for microgreens. So you're constantly harvesting and planting new crops. Whereas on the cannabis side, we're looking at maybe three to five grow cycles a year in an indoor operation, kind of a different pace. The plants grow at different lengths of time. So that's kind of what we see with lighting.

    Dan Dettmers:

    When we look at farming other vegetables in an indoor environment, the first question people ask me is why don't they just grow it in greenhouse? Why are they worried about all these other growing methods? Because you have vertical farms, you have hydroponic, you have aquaponic. Aquaponic being a hydroponic where fish are involved.

    There's other are hybrid greenhouses. There's lots of different ways of doing it and the traditional greenhouses by far are the cheapest way to go at it. But the problem is when you have a barely insulated building without any space conditioning, well, it's hard to even grow stuff inside in that in January in Wisconsin, because it's going to be so cold, there's going to be condensation. There's going to be high humidity and you're going to end up with a lot of diseases. Same thing in the middle of summer when it's hot and humid out. You just can't use greenhouse the entire year. So you have to switch to some other controlled system. Now, if you're looking at your space cooling, that's again pretty easy to calculate because it's based on what Kyle's talking about, the lighting load.

    When you start looking at dehumidification, again, we're looking at how much water are you putting in on the plants? A lot of times there's not going to be a lot of ventilation in these operations because they're going to run at an elevated CO2 level. 1000 to 1500 parts per million for cannabis, kind of similar for lettuce and other microgreens.

    They're also going to run at an elevated temperature and humidity. So for cannabis, when the lights are on, we're talking 80/50%, when lights are off we're talking 70/50%. And don't use this as a Cardinal rule because the one thing I've learned in a controlled environmental agriculture, no two growers like the exact same condition. They're going to be all over the place. With leafy greens, you're usually running something warmer and more humid, 80/80% because the greens like that moisture. Tomatoes, peppers, you're going to be running at something lower, but in either of those cases, you're either using some form of ventilation to get rid of it, or you're going to have to run some form of dehumidification.

    And now you need to get pretty creative on how you're going to do that with low install cost and low operational costs so that they can maintain a profit margin that looks acceptable to their investors. As the United States follows Canada's lead and moves to more of a national production model for both cannabis and other plants and vegetables, you've got to wonder, are we to develop some sort of uniform energy code on controlled environmental agriculture? Or is everybody just going to have to copy California? I will say I'm really disappointed in our neighbors to the north. They went ahead with federal legalization of cannabis and Ontario even did a study showing the drastic impact on their electrical grid and the need for energy efficiency. But to my knowledge, nothing's been passed up there to try to regulate the amount of energy used.

    Let's bring it back to ASHRAE. ASHRAE in conjunction with ASABE, the American Society of Agricultural and Biological Engineers, developed X653, a standard called HVAC for Indoor Plant Environments without Sunlight. It's being published as a standard by ASABE. I believe by the time this podcast is released, it's also going to be available through the ASHRAE bookstore.

    The standard would be a nice starting point for a lot of those of you trying to get into the indoor environmental agriculture HVAC design market. So I recommend picking up a copy of that, but it still doesn't set minimum energy efficiency requirements. I'm looking at you, Standard 90.1. Now, I know the lighting committee did something. Kyle, can you touch on that?

    Kyle Booth:

    Sure, yeah, I'll touch on the 90.1 lighting subcommittee. They have proposed a very similar proposal to what we did in California, looking at a product efficacy of 1.9 PPE in indoor and 1.7 PPE in greenhouse operations. So this is currently in proposal. If it passes, it will be similar to California and this will give a framework for other states that legalize or for federal, if we ever do see federal legalization, to adopt unified energy regulations.

    Dan Dettmers:

    At this point 90.1 has put out information for lighting. I'm sure it's just around the corner for 90.1 mechanical subcommittee to also start addressing cooling and dehumidification equipment, as well as HRI and other organizations. Because it's really critical that we get a uniform set of regulations across the United States. And as a member of TC 2.2 Plant and Animal Environments and the CEAMTG at ASHRAE, well, we're volunteering our help.

    Kyle Booth:

    And if we can get some of these uniform regulations in place, then that leaves more time for Dan and I to go ice fishing.

    ASHRAE Journal:

    ASHRAE Journal Podcast team is managing editor, Mary Kate McGowan; producer and associate editor, Chadd Jones; assistant managing editor, Jeri Alger; and associate editors, Tani Palefski and Rebecca Matyasovski. Copyright, ASHRAE. These expressions in this podcast are those of individuals only and not of ASHRAE, it sponsors or advertisers. Please refer to ashrae.org/podcast for the full disclaimer.

     

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