Ask an Expert: Can efficiency help me save in my cannabis growing operation?

July 5, 2022 | 6 min read

Vermont is the latest state to legalize cannabis sales, following early adopters like Colorado, California, and Massachusetts. These states found that the legal cannabis industry made a big impact on the state’s electric use. A study found that the cannabis industry in Massachusetts made up an estimated 10% of industrial electricity usage in 2020.

The Vermont market is prioritizing small growers, facilities that are 1000 ft2 or less.  Small growers will use less electricity than the larger operations, but energy will still make up a significant portion of their costs. For these small businesses, reducing energy bills can make a big difference in their long-term viability. That’s where Efficiency Vermont can help. We have helped Vermont farms and growing operations benefit from efficiency throughout our history. As new businesses start growing or expand their operations, we can help them implement established best practices for saving energy and money. We can help growers choose between different technologies and compare costs and savings. We sat down with Dan Edson, Senior Engineering Consultant for Efficiency Vermont, to learn more about how small hemp and cannabis farmers can benefit from energy efficiency.

What’s the most important thing cannabis growers can do to reduce energy use and costs in their growing operation?

Dan: Grow outside as much as possible. Indoor growing is extremely energy intensive. Resources Innovation Institute cited it as one of the most energy intensive processes in buildings. Indoor growing uses a similar amount of energy as data centers. It requires specific lighting designed to replicate sunlight (grow lights), temperature, and humidity controls, managed watering, and more. That makes energy bills a significant portion of the indoor growing industries’ operational costs.

Greenhouses and hoop houses have been a successful option for farmers to extend the growing season in Vermont with many different crops. These may offer some growers a more controlled environment and longer growing season than field crops. And they are far less energy intensive than indoor growing. We know some growers are also experimenting with adding lighting to increase production.

We do understand that many growers will still choose indoor growing. Cannabis is a growing, competitive market. Growers want to establish themselves early with high quality production. For many, indoor, year-round growing is the way to do that. If so, there is a lot growers can do to save energy and money – that’s where Efficiency Vermont comes in. We’ve been working on advanced lighting and HVAC since our inception over 22 years ago. We’ve seen it all, and we can support growers no matter their setup. We always advise growers to reach out to us early in the process.

As a quick aside, starting seeds indoors for a home garden (like vegetables) can work well to jump start the gardening season. We have a guide on seed starting that can help maximize efficiency when you’re starting indoors.

Hemp plants growing outside at Northeast Kingdom Hemp

What if a grower decides on indoor growing – how can they save energy?

Dan: There are four big components that will impact energy use:

  • Lighting
  • Heating, Ventilation, and Air Conditioning (HVAC)
  • Dehumidification
  • Building tightness (air sealing & insulation)

The best time to think about energy is when a facility is just getting started or planning to expand. If growers design their space well and choose efficient, right-sized equipment, they’ll save money over the life of the business.  

Let’s talk lighting: what should growers consider when they are buying grow lights?

Dan: Choosing LED fixtures designed for growing can cut energy use for lighting dramatically. Grow lights are energy-intensive by their nature – they’re trying to replicate sunlight. LED grow lighting has been available for about ten years. While that makes it relatively new compared to high-pressure sodium (HPS) grow lights, LEDs are readily available and many commercial cannabis growers are using them. Considering the cost of electricity, LEDs lead to higher yields than HPS, on a dollar-to-dollar comparison. They use less than half the energy of HPS fixtures, with comparable light output. LEDs also have a long lifespan, as much as 5-10x longer than HPS lighting. Efficiency Vermont incentives help offset the cost of high efficiency LED lights and controls.

One benefit of that increased efficiency is less heat. Any light fixture emits some heat. That heat is essentially wasted energy (electricity that’s being turned into heat rather than light). In a grow space, the high wattage fixtures can translate into a significant amount of heat which will drive the cooling needs in the space.

Having a lighting design that maximizes plant health, crop production, and energy efficiency will improve the operation’s long-term viability.  Lighting manufacturers can help growers understand the best design for their facilities. The manufacturer can also calculate the heat output of the lighting, which will help in the HVAC design. Larger operations may benefit from dedicated lighting design services.  

What about HVAC in a small grow operation? Are there efficient options for heating & cooling indoors?

Dan: Heating, cooling, and ventilation will be critical to maintaining the growing environment. Systems vary significantly based on the size of the building. High performance heat pumps can help assist with cooling needs. 

Cold climate Heat Pumps can work well in Vermont for small- to medium-sized grow facilities. They will also provide heating during lights-off periods in the coldest months of the year. Heat pumps also dehumidify, which will help supplement the facility’s dehumidification needs.

Heat pumps are energy efficient but are not specifically designed for grow rooms. Since cooling is required year-round, we recommend that you work with your HVAC team to ensure that your equipment can provide reliable cooling at low ambient temperatures. Customized packaged air handling units can be designed to meet the specific needs of small-to-medium-sized facilities. We also recommend a regular cleaning schedule based on the manufacturer’s recommendations.

For larger buildings, we recommend considering a custom-designed central system that can handle all HVAC needs. There are a lot of energy efficiency opportunities available with larger custom HVAC systems. We recommend working with a mechanical engineer and manufacturer representatives familiar with designing systems for indoor grow environments.

What’s the most efficient way to dehumidify the growing space?

Dan: On a given day, a facility will need to remove hundreds of gallons of water from the growing space. If the facility has a central HVAC system, consider integrated dehumidification rather than stand-alone dehumidifiers. If using stand-alone dehumidifiers, Efficiency Vermont can help growers find the most energy efficient products available and provide incentives to reduce the cost.  The right commercial dehumidifier will have a longer lifespan and cost less to run. Over its lifetime, one commercial dehumidifier will make up for several smaller dehumidifiers.

Why does building tightness matter?

Dan: Construction and renovation best practices will make the building airtight. Tight interior wall surfaces reduce the risk of water vapor condensing within the wall cavity, which can create a perfect environment for mold and mildew. In leaky buildings, the HVAC and dehumidification equipment work overtime to try and keep up with outdoor conditions. The entire facility should be built or renovated to meet the Vermont 2020 Commercial Building Energy Standards. Weatherization is most important in the growing spaces. But insulating and air sealing the entire building will help keep your grow operation efficient and healthy.

What other resources are available to cannabis growers?

Dan: There are a lot of other resources available to help growers along the way: