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Dr. Nadia Sabeh, Ph.D., is founder and president of Dr. Greenhouse Inc., an agricultural and mechanical engineering firm that specializes in the design of HVAC systems for indoor plant environments. Since founding the company in 2017, Sabeh has helped clients across the U.S., Canada, and other nations to optimize their grow facilities.

In this exclusive interview with Cannabis Business Times, Sabeh shares what she’s been working on in 2022, how she got her start in agricultural engineering, current trends she sees in the industry, and what to expect from her speaking session at Cannabis Conference 2022 Aug. 23-25 in Las Vegas.

Editor’s note: Dr. Greenhouse’s Nadia Sabeh will be speaking on the panel session “Creating A Thriving Crop Environment: Lessons In Relative Humidity, Vapor Pressure Deficit, CO₂, Heat Loads And More,” from 11:25 a.m.–12:15 p.m. PST Aug. 25 at Cannabis Conference, taking place at the Paris Las Vegas Hotel & Casino. In this session, Sabeh will share strategies for achieving ideal environmental metrics, as well as how to aggregate and analyze valuable data points from these controls to make project adjustment decisions. Visit www.CannabisConference.com for more information and to register.

Zach Mentz: What’s going on at Dr. Greenhouse these days? What are you currently working on? What has taken up a large chunk of your 2022 and what are you excited about?

Nadia Sabeh: We have been really involved in the last six to 12 months in the energy code and in developing energy standards to help our clients strategize around reducing energy use and improving energy efficiency. It’s been a really interesting year because with all the supply chain issues the slow-to-build process that we’re seeing with a lot of new projects, some of our clients are refocusing on their existing facilities and retooling them and wanting to optimize the operation or troubleshoot challenges that they’ve been having.

Many of them had plans to expand or build into a new facility, and now in the last six months we’ve been having clients say, “We’re going to put the brakes on the new project, and we are going to focus on the facility we have now to try to make it better.” And I think that’s awesome. Because regardless of what you’re growing, a lot of indoor farmers and greenhouse growers may have jumped into a larger scale facility than what they were used to before, or maybe they’re growing a different crop if they came from ornamental horticulture and now are doing cannabis horticulture, [and] there’s a learning curve. And over the past few years, they’re realizing where their deficiencies are [and] what they’d like to improve. Maybe now they have the capital to actually spend on making those improvements, both in terms of being able to purchase the equipment and hire experts like us. So we’re getting a lot more involved in existing buildings and optimizing those facilities and operations, which is a lot of fun and a really big opportunity to help growers with their everyday operations. So that’s a lot of what we’re doing now.

And then I mentioned we’ve been working in California on a project associated with code readiness. So those of you who are familiar with the new 2022 energy code in California, now that maybe the first introduction to implementing energy codes and regulations did not go as smoothly as the energy commission maybe would have liked, they’re stepping back and realizing, “OK, we don’t understand this industry very well.” And so they’ve stepped back and hired us as their subject matter expert to do research to actually understand the state of the industry in terms of energy use and help them identify energy efficiency measures that could be implemented in an energy code utilities, or maybe can incentivize and provide rebates for some of these measures instead. It’s been a lot of fun. We’ve been doing site surveys up and down California to learn how growers are using equipment and technology and get their feedback on how we can make this industry more efficient not just with energy, but with water and other consumables.

And then, of course, we’re designing bigger and better indoor and greenhouse production facilities all over the country. We’re seeing a lot more multitiered, indoor cannabis facilities. We’re seeing more high-tech greenhouses, more positive-pressure greenhouses, more desire to precisely control a greenhouse while still using sunlight.

ZM: Do you think vertical growing will become more of a growing trend in the years to come as the industry matures?

NS: As long as growers adopt LED technology, then yes, because that’s key. You’re not going to want to put a high-pressure sodium or any HID lighting in a racking system where those lights get really hot and produce a lot of radiant energy and are really close to the plants and to the leaves and the flowers. So it’s really going to depend on growers saying, “yes, I’m willing to take the chance on LEDs,” or “I tried LEDs in my single-level production facility and it worked great. And I had the LED lights just a few feet away from the plants, so why am I wasting all this space above?”

But as these cannabis growers who are going vertical are learning, airflow is a huge challenge. It’s so easy to create microclimates; it’s not just in a horizontal pattern, but now vertically as well. So how do you move air around and even how do you move people around up and down, not just left and right, and across a room? So there are logistical challenges to move up and down to do plant maintenance and pruning and harvesting and things like that.

How do you do that? Do you do that with a scissor lift? Do you do that with ladders and platforms? Do you do that perhaps with automation and cameras? So we’ll see.

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ZM: How did you first get into crop sciences and HVAC expertise and facility design? Where did it all begin and what piqued your interest?

NS: It all began as an undergraduate at UC Davis in biosystems engineering. I took an internship on a mushroom farm in Southern Idaho. We were trying to grow shiitake and oyster mushrooms in greenhouses, and we had a humidity control problem—we couldn’t keep the greenhouses humid enough to grow mushrooms well or to keep them from drying out before we harvested them. We had [Horizontal Air Flow] HAF fans that we stuck a hose in, we were hosing down the floor, we had evaporative cooling—anything we could do to just dump water into the space.

While I was on this internship, I lived in a 20-foot trailer right on the farm. The workers would arrive at 4 a.m., and the first few weeks I was so annoyed that I’d be woken up at 4 in the morning, but by then it was just like, dude, why fight it? Just join it. So I got up with them and I helped them and I worked with them side by side, and I loved it. I loved agriculture. I loved the farming life. I loved getting up early in the morning. I still get up at 5 in the morning almost every single day. And I told myself I really want to help farmers control their environment, because that was the main challenge we were having while I was there. And at the same time, I saw this as an opportunity to feed the world through greenhouses.

I was at UC Davis, which is arguably the best agricultural school in the world, and then I went off to Penn State and studied air distribution and mushroom production facilities, which, if you’ve ever been in a mushroom production facility, they’re like vertical farms. There are trays of compost and mushrooms, and they had a challenge with moving airflow uniformly through these stacks. So I was doing air distribution in vertical farms before vertical farms were cool.

Then I decided I should maybe try a different crop, so I went to the University of Arizona at the Controlled Environment Agriculture Center and studied evaporative cooling and natural and passive ventilation for commercial tomato production. One of the things that I studied was water use efficiency. One of the big things that I tested was how much water is used to cool the greenhouse, not just irrigate the plants. And once you added that into the equation, it wasn’t as pretty.

As a grad student, one of the things that I came to realize going to three different schools in different regions of the country is that all these land grant universities, all the people who are in controlled environment agriculture know each other. They’re all learning from each other, collaborating with each other, working together, which is awesome, but the same ideas get recycled over and over.

When I was at Penn State, I actually took some architectural engineering classes and took HVAC classes, specifically. I said, there’s this whole other world of climate management and HVAC that is not related at all to agriculture. I want to go out into the “real world” and see how HVAC systems are designed, how buildings are built, and hopefully one day bring that back to agriculture as a new idea. I worked as a mechanical designer and then a mechanical engineer for about nine years.

And at the time in 2012, cannabis legalization came on board in Colorado and Washington, vertical farms were becoming more popular, and the vision was starting to actually be attempted in real life. And I started going to conferences and found a place for myself and realized, “OK, this industry is ready for these new ideas.” So I started Dr. Greenhouse Jan. 1, 2017. We’ve been in business now for 5 1/2 years and have worked on about 150 projects all over the country. We’ve been in 31 states and D.C., five provinces in Canada, and a few countries around the world helping growers of all crops achieve their goals and their dreams to feed the world and nourish the world and provide medicine to people who really need it or can enjoy it.

ZM: What advice would you offer to a new or existing cultivator who wants to succeed in the cannabis industry?

NS: There are a few things. One, of course, is know your market. If you’re in California, the market looks a lot different than if you’re in Oklahoma or Tennessee or Mississippi. And understanding who your customer base is going to be is obviously key.

One of the differences between indoor and greenhouse is your ability to precisely control the environment. Irrigation, you can mostly precisely control; it’s a lot of the same technology. Light, you obviously get the natural sunlight if you’re in a greenhouse whereas you’re relying on electrical lighting indoors, but there’s a lot of science and technology and research around getting the right spectrum and the right intensity to your plants.

But when it comes to the climate, in a greenhouse, you’re just way more susceptible to what’s going on outside of the walls of the greenhouse, so the precision of control is a lot harder unless you invest tens of millions of dollars for air conditioning, which we have seen happen. And I like to call it “air conditioning the sun” because the greenhouse is the greenhouse effect; they were originally designed to trap solar radiation and naturally heat the greenhouse in a cold climate. Now we’re going to try to air condition that? It just is ludicrous to me. But if you want to get that same precision of control while still using that natural sunlight to produce a wider range of terpenes, then maybe that makes sense. Probably 9.5 times out of 10, I would advise against it. The difference is, again, thinking about your market and medicinal versus recreational, extraction versus flower, etc. In a greenhouse, the wide ranges of terpenes can be really beneficial. If you’re selling extracted products, if you’re selling in bulk and you don’t necessarily need the high level of flower quality that people might expect.

One thing I want to add for people who are getting into it real quick is about expectations around the HVAC system, and not even the design and selection of the equipment, but the budget and the schedule. Over and over, we are constantly challenged with clients’ expectations around how much the HVAC system is going to cost and how long it’s going to take to design, coordinate and get to the site. Everyone right now is aware of supply chain issues, which has only exacerbated the issue, but pre-supply chain issues, it would take anywhere between 20 and 40 weeks to get equipment to the site once the clock had started with purchasing and procurement, and that doesn’t include the design time ahead of that. For growers who think, “oh, we’re going to be up and running in six months,” a lot of times it’s the HVAC system that drives the schedule. So that’s one of the things I want people to be aware of. Now we’re looking at 52 weeks and greater in some cases.

And then in terms of budget, a lot of investors and owners and clients underestimate how much HVAC equipment costs. For new growers, pick a number for your expected HVAC cost and multiply by five. It’s also not even just the equipment itself; it’s the shipping. These are big pieces of equipment that have to be shipped and assembled, tested and then installed, and then you add controls on top of it. Depending on the size of the project, the HVAC system alone can be 25% to 35% of the total cost of the project. So what happens a lot of times is the project scales back. They had a grandiose idea and then they say, “OK, well, we totally underestimated the HVAC. For the size we wanted, the HVAC is actually $15 million, so now we’re going to scale it back.”

Again, going full circle to what we’re up to, growers are now taking that capital and improving what they have rather than necessarily getting bigger because, as prices are going down as the market is changing, maybe it’s better for them to focus on better quality and getting an efficiency rather than just growing more for the sake of growing more.

RELATED: Dr. Greenhouse Launches Vapor Pressure Deficit (VPD) Calculator App for Indoor Grows and Greenhouses

ZM: What should Cannabis Conference attendees expect to learn from your speaking session, “Creating A Thriving Crop Environment: Lessons in Relative Humidity, Vapor Pressure Deficit, CO₂, Heat Loads And More”?

NS: We actually do a full one-day and two-day workshops just on HVAC fundamentals and design and considerations, so I’m going to be condensing a lot of that and talking a lot about the balance of the plant—the environmental interactions, how the HVAC system affects plant responses, including transpiration, vapor pressure deficit and how that affects how the plant uses water, translocates nutrients and just generally grows.

We’ll also talk about the other environmental parameters that are important. We talked earlier about the relationship between lights, air temperature and leaf temperature, so I’m going to expand on that. I know some growers are going to be in the room who use LEDs and some who use be HPS, and there’s going to be skeptics and adopters within there, so I want to root out some of the myths around that and just help some people understand the science a little bit behind what exactly is going on there.  Also, the interplay between carbon dioxide and temperature and light—it’s not just one or the other. They can all work together and every plant has a point of optimization for those three variables to grow its best.

I’ll probably talk a little bit about abiotic and biotic deficiencies and talk about HVAC equipment. Why is HVAC so hard in these cannabis facilities, or in any indoor grow facility, in terms of sizing it and selecting it? There’s so many options to weed through. So I’ll talk a little bit about that to help growers navigate their choices a little bit.

And I’ll probably talk a little bit about loads. What do we mean by a cooling load? I want to set some definitions in place because, as engineers, we have a certain lingo. We say cooling load, sensible load, latent load—what does that mean? I want to start giving the lingo to the growers so when other engineers use this terminology you have an idea that latent load really means how much moisture is in the air. It’s that simple. So I want to define some of those terms so growers feel armed with their information.

One more thing: We’ve been interviewing growers on our “The Doctor Is In” podcast. And within that, we created a special series where I’ve been specifically interviewing growers of cannabis as well as lettuce and other crops. I’ve interviewed about 20 people now and some well-known names are included in that list. So I just encourage the growers out there to check out the podcast and learn from the experts. These growers are not afraid to share what a lot of people think are trade secrets. They give some really great tips, everything from root aphids to balancing the plant and more.