Sustainable cannabis cultivation methods boost efficiency and the bottom line

Get realistic market forecasts, state-by-state insights and benchmarks with the 2024 MJBiz Factbook member program, now with quarterly updates. Make informed decisions.


Image of HVAC system on ceiling

(Photo by Leslie C Saber/stock.adobe.com)

(This story is part of the cover package in the July-August issue of MJBizMagazine.)

For decades, cannabis cultivators honed their craft in secret, often in small spaces that were designed primarily to operate without being detected by police or government authorities rather than being optimized for energy efficiency or sustainability.

As states transitioned to regulated markets, those legacy practices persisted.

Newly licensed growers outfitted facilities with less expensive lighting and heating, ventilation and air conditioning (HVAC) systems to get up and running quickly.

Those lower upfront expenses often came with longer-term costs to financial and environmental sustainability.

But with increased state regulation and growers no longer feeling compelled to grow in secret, the clandestine approach to marijuana cultivation facility design and operations has receded, Brian Anderson, a partner at Massachusetts-based cannabis industry design and architecture firm Anderson Porter Design, said in an interview with MJBizMagazine.

“This very close-to-the-vest, special-sauce attitude that has existed for decades now is shining the light of day on, say, what are the engineering techniques, what are the engineering principles by which we keep plants happy?” Anderson said.

“Then, how do we do it sustainably?”

Cannabis cultivation energy use

Indeed, applied science and the grow environment are now just as important to cannabis cultivation as plant genetics, Anderson said.

It’s no secret, however, that indoor grows rely on a massive amount of energy: Each kilogram of final cannabis product contributes 4,600 kilograms (10,141.3 pounds) of carbon dioxide emissions.

That’s far higher than emissions for most agricultural and food products, ranking among beef products such as hamburger and steak, according to research published in 2021 in Nature Sustainability.

One pound of cannabis grown indoors produces more carbon emissions than a flight between Tokyo and San Francisco, the study noted.

While the environmental imperative for energy efficiency and sustainability in facility design is clear, the economic benefits and necessities driving these design changes often are overlooked.

Concurrently, some states have enacted stringent – and sometimes expensive – environmental regulations, such as the California Environmental Quality Act (CEQA).

On the bright side, many energy-efficiency requirements come with rebates, although accessing them often requires a lot of administrative work.

Modernizing indoor cannabis cultivation

There are three categories of common upgrades that improve efficiency in cannabis cultivation facilities, but they all are linked and affect one another, according to Anderson.

It’s well-established that light-emitting diode (LED) lights are far more efficient but more expensive than high-pressure sodium (HPS) lights, which historically have been preferred by many growers, particularly for the flowering stage.

LEDs convert electrons to photons, using roughly 90% less energy than incandescent bulbs and about 50% less than compact fluorescent bulbs.

That’s a significant savings, with lighting accounting for 38%-75% of the total energy used in indoor cannabis cultivation, according to a 2021 report by electric utility company Southern California Edison.

For example, Michigan-based cannabis technology company Agrify Corp. says its lights deliver up to 60% more photosynthetic photon flux density (or light intensity) to plants than HPS lights.

Another critical difference: HPS lights produce much more heat than LED lights.

That means that HPS require more work – and more cost – from HVAC systems than LED lights.

Cool control

Depending on the grow, the mechanical system (or HVAC/HVAC-D system) might require tweaking or a full replacement.

For cooling, Southern California Edison recommends chilled-water systems over direct expansion, air conditioning systems.

Chilled-water systems cool the air and return heat from the building using water, while air conditioners use large amounts of refrigerant chemicals, Anderson explained.

Chilled-water systems also offer lower operating costs and more flexible air-handling capabilities.

For smaller to midsize grows seeking better energy efficiency, mini-split systems, which are also ductless, are good choices.

Edison recommends having a dedicated dehumidification system that’s separate from air conditioning.

Having dehumidification and air conditioning independent of each other is more energy efficient.

Plus, if one fails, the other will continue functioning. The architecture of an indoor grow will also impact energy efficiency, according to Anderson.

Vertical grows are less of a burden on HVAC systems.

But they also can benefit from energy-efficient upgrades, such as reducing or eliminating any wood in the structure, which can house mold and require more dehumidifying.

Insulation

Also, many first-generation marijuana facilities lack ceilings, leaving the grow exposed to a steel truss in the roof that’s vulnerable to the elements outside.

When temperatures change, the steel conducts the heat and cold and can create problematic moisture and even dripping on the plants indoors.

But there are solutions, Anderson said.

“You either want to insulate the outside of your building, which is expensive, or you want to insulate the truss itself, which is difficult and fussy,” he said.

“Or you want to separate your plant entirely with a ceiling in the room.”

The costs of these renovations can vary widely depending on the size and scale of the grow, but LED and HVAC typically will compromise approximately half of the total cost of building a new facility.

“The heaviest, biggest, most costly things that you can spend on, they’re the most important to plant health: lights and air quality, air movement and cooling, heating through that space,” Anderson said.

Demands for regulatory compliance

The CEQA, in effect since 2019, offers an interesting case study in cannabis industry energy-efficiency policy.

One challenge is that local jurisdictions have been slow to write-in their respective regulations, according to Chelsea Haskins, a member of the National Cannabis Industry Association’s Cannabis Cultivation Committee and the director of state and local licensing at MWG Holdings, which owns and operates California cannabis company Perfect Union.

The cost of complying with the CEQA likely is driving many operators away from the legal market, and they aren’t renewing their licenses, Haskins said.

The administrative and reporting work alone can cost $30,000 because specialized work such as biological surveys and cultural reports, which examine whether the site contains archeologically significant remains, are required.

Complying with CEQA rules can be especially hard on legacy operators, said Haskins, who is working to help educate the market on best practices for water use, energy consumption and other issues.

2024 MJBiz Factbook – now available!  

Exclusive industry data and analysis to help you make informed business decisions and avoid costly missteps. All the facts, none of the hype. 

Featured inside: 

  • Financial forecasts + capital investment trends 
  • 200+ pages and 49 charts highlighting key data figures and sales trends 
  • State-by-state guide to regulations, taxes & market opportunities
  • Monthly and quarterly updates, with new data & insights
  • And more!

Carbon credits

Since 2022, as part of California’s license-renewal process, cultivators also have been required to report their own average weighted Greenhouse Gas Emissions Intensity to the state’s Department of Cannabis Control, as well as the energy suppliers for the license period.

If the cultivator’s number is higher, they’re asked to buy carbon credits, which motivates many growers to conserve energy.

That’s why a growing number of cultivators are using mixed-light greenhouses, where the sun and artificial light can be used in tandem.

Breathable blackout curtains prevent light pollution, keep air flowing through the grow and don’t block ventilation.

Some blackout curtains also have a thermal layer that can be used to regulate the temperature inside the greenhouse.

Tech controls

Environmental sensors also can make cannabis grows more efficient.

Growlink’s Environmental Sensor Module, for example, tracks temperature, humidity, carbon dioxide and light sensors to fine tune growing conditions.

But implementing these technologies and complying with the CEQA are expensive endeavors, and the process likely is driving many cultivators away from the regulated market, according to Haskins.

She recommends reaching out to energy suppliers to discuss how to access rebates.

In the long term, Haskins said she hopes that, with enough support, cultivators will be able to both adhere to the environmental regulations and thrive.

“It’s my opinion that if we educate about environmental regulation, what’s going to be required, then cultivators can make a road map for how to plan out their license application and opening their business,” she said.

“Then we’re going to start to see a better cultivation market in California.”