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This article outlines types of cooling equipment that contribute to sustainability and energy-efficiency; how to develop a customized cooling strategy that meets growers’ sustainability goals; and steps growers can take to simultaneously improve energy efficiency and operating costs.
As the emphasis on sustainability grows to battle climate change, grow house owners want to improve their energy-efficiency and reduce energy waste. Energy-efficient cooling equipment vastly improves grow house sustainability and even saves operating costs. To develop a cooling strategy that reduces energy waste, cooling experts consider everything from high-tech, automated controls to the heating, ventilation, and air conditioning (HVAC) equipment itself. For indoor growers to maximize sustainability in their farms, they can invest in systems that save more water and more energy than others. This article outlines types of cooling equipment that contribute to sustainability and energy-efficiency; how to develop a customized cooling strategy that meets growers’ sustainability goals; and steps growers can take to simultaneously improve energy efficiency and operating costs.
As the world seeks ways to tackle climate change, sustainability has become increasingly popular, not just for large corporations. Although sustainability may not be the primary consideration for all growers shopping for heating, ventilation, and air conditioning (HVAC) equipment, there are also business reasons to strive for greater energy efficiency.
HVAC equipment and lighting tailored to indoor legally licensed cannabis production can help decrease a grower’s carbon footprint while minimizing disruptions and expense from future equipment upgrades to replace under-performing off-the-shelf equipment.
The concern is growing over the substantial electrical needs of the cannabis industry. Many believe it’s just a matter of time until municipalities and states implement regulations aimed at increasing energy efficiency. Forward-thinking growers and their investors can anticipate regulations and be energy-efficient, which saves operational costs. Efficiency can also translate into a competitive advantage in some saturated sales markets experiencing downward pricing pressures.
At present, a grow operation can feasibly become carbon-neutral by adding renewable (solar or wind) energy, either on-site or remote. But as with any lofty goal, taking steps—even small ones—will move a grower closer to carbon neutrality. Here we present seven key steps to staying ahead.
An October 2018 report from New Frontier Data identified cannabis as the most energy-intensive agricultural crop produced in the United States (1). The report predicted a 162% increase in electricity consumption from cannabis cultivation between 2017 and 2022, with an estimated 472,000 tons of electricity-related carbon produced in 2017 alone.
The rapid growth of energy-intensive indoor cultivation facilities has strained the infrastructure of electric utilities. In the summer of 2015, shortly after Oregon legalized recreational cannabis, Portland’s Pacific Power experienced seven blackouts traced to cannabis production facilities, according to an article by the National Conference of State Legislatures (2). The piece also noted that 45% of Denver’s increase in energy demand is for electricity to power marijuana facilities.
Because the expanding cannabis cultivation industry is drawing attention to its energy use, it’s a matter of when, not if, regulators across the country implement efficiency standards to manage energy use.
California’s Building Energy Efficiency Standards (Title 24, Parts 6 and 11) is updated every three years, with the next code change slated for January 1, 2023. One expected change would prohibit energy-intensive lighting technologies, such as high-pressure sodium (HPS) and high-intensity-discharge (HID), in favor of light-emitting diode (LED) lights for all new installations or significant upgrades.
LED grow lights reduce a grow operation’s electricity use in two ways. One, they use less electricity by having greater luminous efficacy, or how well a light source produces visible light, measured in lumens per watt. Second, they also produce less heat than legacy designs, resulting in less heat that must be removed by air conditioning, which saves on cooling
It can tempt some growers to take the easy way out and purchase HVAC equipment off the shelf. It’s readily available, less expensive, and there are fewer options to consider.
But HVAC equipment that isn’t designed for indoor agriculture is often not up to the task of maintaining a low enough humidity in the facility, which is necessary to prevent mold, micropests, and poor yields. So, a grower often resorts to buying multiple portable dehumidifiers at a big box store. As a result, the HVAC system “fights” to remove the heat output of the dehumidifiers.
Lower costs of equipment and installation, known as “first costs,” quickly turn into long-term headaches and additional operating expenses. Instead, consult with an HVAC system expert who’s aware of an indoor grower’s unique needs. Collaboratively, they can design an integrated system that performs better and uses less electricity, which adds to its bottom line while aiding sustainability.
As an example of purpose-built equipment, one type of unit designed for a smaller indoor agriculture operation is a packaged rooftop unit. Such packaged rooftop units include all equipment needed in one unit and are available in varying capacity ranges, capable of removing up to 600 lbs of water per hour. They can also be paired with modulating hot gas reheat, which means the heat produced as compression during the dehumidification process is recaptured to use as building heat instead of being lost to the ambient environment.
That said, there’s not a one-size-fits-all solution. Facility size, number of plants, and watering strategy are all parameters that factor into the appropriate equipment choice. For some large facilities needing high cooling capacity, it will be more cost-effective to install and operate an efficient chilled-water system rather than a “sea” of rooftop units.
Assess your needs as a grower. Have realistic goals for the facility’s needs. During a needs assessment consultation with an HVAC expert, be upfront about operational plans for the facility. The building configuration, including how to designate rooms for various growth cycles, will influence how to equip it.
Growers are often reluctant to share too many details of their environmental recipe for fear they’ll share their “secret sauce,” but this hampers the supplier’s ability to install the equipment that’s just right for them. More space and more plants mean more heat and humidity that must be removed, requiring equipment of the proper capacity.
Electric utilities often implement peak demand charges, charging a higher rate when there is a high demand on the electrical grid. Because most of the grow processes can be scheduled when electricity costs are lower, automated controls can automate this instead of relying on staff to turn switches on and off manually.
Day cycles, with lights on, use much more energy than night cycles. The mechanical and electrical systems must have adequate capacity to handle the maximum number of rooms in a day cycle at any time. By staggering the day cycles between growing rooms, the cultivator can dramatically reduce peak demand and system capacity. Many utilities offer cheaper rates at night and peak demand charges during the day. Electricity available at night is not only cheaper it is typically “cleaner” because the overall demand on the grid is lighter and peak plants are not being used to produce electricity at night.
Using controls helps reduce electrical demand charges and allows a grower to capitalize on the most affordable time of day electricity rates.
Use a building automation system (BAS), a web-based user interface, to streamline facility management, scheduling, and turning on and off equipment. A BAS is accessible from most PCs, tablets, and smartphones and it’s a flexible, cost-effective solution for programming and managing the facility conditions. It can also control lighting, monitor energy consumption, and integrate with equipment that controls other processes, such as carbon dioxide (CO2) injection and fertigation of the plants.
Growers weighing their HVAC options should look for a supplier that values sustainability. Does it publicize those goals? A supplier focused on sustainability likely designs products with a priority on high efficiency, and they likely ensure that their supply chain partners also employ sustainable practices. Aligning with such a supplier can help growers meet their green goals and help them market to their investors and customers.
Even if sustainability is not part of the company’s social responsibility goal or mission statement, growers should plan now to get as close to carbon-neutral as possible. Investing in systems that have a lower cost of ownership over a long period of time can ultimately reduce electricity costs, adding to the bottom line. The effort also makes you more resilient to potential future regulatory changes.
As the National Account Executive at Trane Technologies, JUSTIN BARNES optimizes indoor agriculture environments by providing expertise on cooling strategies, automation controls, energy-efficiency, and services. In collaboration with Trane engineers, he designs systems for indoor growing facilities that help achieve high-yield growing environments and energy efficiency.
Direct correspondence to:
J. Barnes, Cannabis Science and Technology 4(5), 28-31 (2021).