Lowering Electricity Bills Without Sacrificing Crop Yields

Electricity consumption is typically the second-biggest cost incurred by indoor cultivation facilities (and often greenhouses), behind labor. According to cultivation company data analyzed by the nonprofit Resource Innovation Institute, grow facilities on average expend about 275,000 kilowatt hours per square foot of canopy. Some grows spend much more, while outdoor grows spend little or nothing on electricity, according to Derek Smith, executive director of the Portland, Oregon-based research organization.

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The high cost of electricity for indoor growing shouldn’t come as a shock, so to speak, given a grow facility’s need for lighting, air conditioning, dehumidifying and other demands. “ The more competitive the market gets, the more people are going to have to pay attention to resource management,” said Casey Rivero, head grower at Yerba Buena in Hillsboro, Oregon. “Power is one of your biggest costs, and being able to efficiently maximize your power is key.”

While reducing your cultivation site’s electric bill without making major sacrifices on yield and quality may sound like a tall order, there are ways to do it. The two biggest consumers of electricity, according to a 2014 study performed by the Northwest Power and Conservation Council, are lighting, which accounts for about 38% of energy consumption, and dehumidification and ventilation, at 30%. Cooling takes up 21% of power demands, while the remaining 11% of power use can be attributed to heating, water management, CO2 and curing. That said, the easiest place to seek energy savings is through lighting – in addition to heating, ventilation and air conditioning, or HVAC. Here are three ways to cut your electricity bill.

1) Determine How Much Juice You’re Consuming

To save on power, you first must know how much electricity you’re consuming and what it is being used for, such as lighting and HVAC. The simplest way to measure how much you’re using is to calculate your kilowatts per day.  Next, estimate how many hours per day your lighting and HVAC equipment are running and at what power level to understand how much juice is going to each. Growers should know that the amount of lighting and HVAC being used will depend where plants are in the growth cycle. Outside conditions play a role, too, because air conditioners and dehumidifiers must work harder on hot and/or humid days, respectively.

“It’s kind of a guestimate, but it’s better than nothing,” Rivero said. To get more accurate data, Rivero suggests using power monitors that can be placed on breaker boxes to track electricity consumption based on a particular power source, such as a specific wall of air conditioning units or lighting panels. How many breaker boxes a cultivation facility has varies on the size and design of the facility as well as what kind of power service systems (single phase or three phase) and voltage power the site. Yerba Buena, for example, has individual subpanels for lighting in every room as well as a panel for each of the facility’s 10 HVAC units. There are also panels for less power intensive equipment, like water pumps. Basic power monitors cost between $600 and $1,000, while the most expensive models can hit $10,000, Rivero estimated.

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A cultivation site doesn’t need to buy a power monitor for every breaker. But having several makes it easier to run comparisons, say between different grow rooms, different days or between lighting and HVAC units within a room. In addition, energy-management companies can install data equipment to make it easier to track and manage power consumption.

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2 ) Get the Lowdown on LEDs

While lighting uses the most electricity at indoor grow sites, most cultivators still use high-pressure sodium lights, typically 1,000 watts. Not only is the wattage a major energy drain, but HPS lights produce high heat, forcing air conditioners and dehumidifiers to work harder adding to utility bills. More efficient and environmentally friendly LED lights have been around for several years, but only a small number of growers have adopted them. Many growers acknowledge that LED lights are more efficient but argue that they don’t produce the yields that HPS lights do and, therefore, reject them. For example, Massachusetts marijuana industry executives were up in arms in March after regulators imposed a cap on electricity use amounting to 36 watts per square foot of cultivation space. The move, in effect, forced growers to adopt LED lights a move some executives hope to overturn.

When Allison Justice arrived at San Diego County, California-based OutCo in late 2016, she also was told that LED lights couldn’t perform like HPS lights, and that whatever the cost savings, they would be lost to the lower yields that were expected. Justice, OutCo’s director of cultivation, wanted to see for herself, so last year she started running trials comparing 1,000- watt HPS lights with LED lights from Fluence, a commercial LED firm whose wattages were 330, 560, 660 and 1,000. More wattage equals more light intensity. Testing on two strains, Justice and her colleagues found the LED 1,000-watt lights produced 21% higher yield than 1,000-watt HPS lights, while 660-watt LEDs resulted in 13% more yield and a 37% drop in energy use. At 37% decrease, Justice noted, didn’t account for savings from the air conditioners, which ran less because LEDs give off less heat. Justice acknowledges that LEDs are more expensive – a Fluence 660 is about $1,280, while a standard HPS light is around $400 but the cost is more than outweighed by the energy savings and increased yield.

Another advantage of LED’s: They allow growers to “double stack” a layer of plants on top of another one, effectively doubling the cultivation space. How? Because HPS lights are so hot, they must be farther from the plants than LED lights, which are cooler. “It’s like getting another facility for free. The ROI on that is a no-brainer,” Justice said, referring to return on investment.

Following the successful tests, OutCo started retrofitting its facility for LED lights late last year, essentially interrupting production for six weeks to tear out old benches and lights and install new rolling benches, irrigation, drainage, HVAC and other equipment. Since then, Justice and her team have harvested two crops each of several strains, including Mendo Breath, Cookie Pucker, Grape Pie, Strawberry Banana and Black Jack. “Yield and quality is phenomenal,” Justice said. “ There’s always tweaking to do when you start something like this. Overall we’re very happy.” Other cultivators are also gaining confidence in LEDs. “I was a holdout because I never saw the production that I could get out of an HID (high-intensity discharge) with an LED. They are now rapidly catching up,” said Eli McLean, a cultivation consultant and commercial grower in Salem, Oregon. “Once you run the numbers, you realize that you get good yield of top-shelf cannabis that cost me a third less to produce.”

McLean is now researching LED lights with quantum dot technology that he said operate at about 91-92 degrees Fahrenheit. The lights are manufactured by a company called QD Grow. “ is means you’ll need far less latent cooling because you have far less latent heat,” McLean said. “I think you can see savings on your cooling costs of up to 65% for LED versus what’s being used today.”

3) Make Your HVAC Less Power Hungry

Finding ways to reduce HVAC power use is good for the environment and your company’s finances. Yerba Buena was able to get rid of its dehumidifiers, for example, which significantly reduced the company’s utility bills. How did the Oregon grower do it? It adapted sensors that measure leaf moisture and air humidity and wired them to activate air conditioners (which also perform dehumidification) when the leaf surfaces reach a certain moisture level. Remember that leaf surfaces can transpire moisture because of heat from grow lights. By activating air conditioners when leaves start to transpire – versus waiting for a preset interval Rivero can both absorb air humidity and lower temperatures that had risen because of light heat. That, in turn, reduces leaf transpiration even more.

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By reducing overall plant transpiration, and more efficiently timing air conditioning use, Yerba Buena was able to regulate and reduce humidity, so it could be handled by air conditioning alone. e company ditched its last dehumidifier in February. “Our goal is to stabilize that humidity and heat. You need to pay attention to the leaf surface, because the leaf surface temperature is what’s going to allow that water to come out of the plant,” Rivero said. “ The more sensing and control equipment you have that talks with HVAC and lighting together rather than separately, the easier it is to achieve that balance, as opposed to having those things separate and hope they line up.”

This article was originally published in Marijuana Business Magazine • July 2018