Building Energy-Efficient Greenhouses in Michigan
As any cultivator who has ever struggled to keep a leaky indoor greenhouse going over a long Michigan winter will attest, cannabis is an energy-intensive industry.
With those concerns in mind, Women Grow-Southeast Michigan chapter brought Jeff Massay to its September meeting to analyze the Michigan growing climate and share ideas on how to build an energy-efficient indoor greenhouse.
Massay is an accredited Green Commissioning Process Provider (GCxP) with expertise in LEED (Leadership and Environmental Energy Design) Commissioning and Mission-Critical Facilities, an accomplishment he credits to his more than thirty years working as an HVAC/R technician, facility maintenance engineer, and consulting engineer designing HVAC systems. Drawing on his energy-efficiency expertise, he founded Key Commissioning, LLC to provide growers with full-lifecycle commissioning services. His premise, one few cultivators or patients will dispute: A healthy, mold-free, pesticide-free cultivation room environment will produce healthier, pest-free plants.
The construction process gradually became “broken” over the past twenty-plus years. Subcontractors would construct their piece of a project but the general contractor often did not have experience to ensure all of the pieces fit together as a whole. Buildings would not operate as expected, indoor environments were often unhealthy, and utility costs were often much higher than expected. The goal of commissioning is that quality assurance practices are performed during design, construction, and prior to occupancy to ensure that facilities achieve the basis of design requirements, owners get what they paid for, and building occupants (or plants) have a healthy environment to occupy.
I have a good ability to design, construct, repair, and replace mechanical, electrical, and plumbing (MEP) systems. This experience allows me to ensure that MEP components and equipment are installed correctly, function individually, and interact together to become a system. Testing requires fundamental knowledge of how each system should operate and how to modify component control and equipment operation in order to achieve the highest performance and functionality possible for the constructed systems.
Current Indoor Cultivation Practices
Massay hesitates to endorse must-have advances in indoor cultivation because he is an environmental expert. But, he says:
What I see with current cultivation practice is somewhat like the building industry went through: poor construction techniques, systems that don’t perform as expected, and ever-increasing energy consumption. Articles have been published that estimate indoor cultivation currently consumes 1% of all electricity generated in the continental United States.
For those farmers who can afford it, photovoltaic systems (solar), some geothermal systems, and possibly windmill electricity generation are ways to reduce their carbon footprint. When looking at technology used for greenhouses in the Netherlands and Spain, it appears they are years ahead of the U.S.
Although professionals should be consulted when necessary, he encourages Michigan indoor growers to
- perform basic energy mitigation techniques, such as caulking and insulation, themselves;
- use outdoor air for free cooling when conditions permit;
- operate lights during off hours to save a few cents per Kw (kilowatt); and
- start an automation process to achieve good system operation.
He sees LED lighting systems continuing to help reduce electric consumption and heat loads as they evolve.
Michigan’s Climate Challenges
Massay, whose business has offices in Southeast Michigan and Southeast Florida, believes that Michigan is a great place to grow indoors due to its moderate temperatures and average humidity, unlike Florida. But he notes challenges:
Having enough electric service to the room and facility overall along with proper temperature control tend to be the biggest challenges for small and noncommercial operations. The lowest-cost good solution is to ventilate your room with filtered outdoor air when conditions permit. Year-round “free” or economizer cooling can be utilized to supplement existing cooling equipment if proper humidity control is provided.
To prevent mold, mildew, insects, and other pests?
Environmental stability is key. High indoor temperature reduces humidity and vice versa. Effective air circulation prevents condensation build-up, thus reducing mold or mildew issues. Insect infestation must be treated preventatively. Utilizing glue strips placed inside the room along outside walls is a good way to capture crawling insects, spiders, and other pests.
He sees inadequate ventilation and air conditioning, electrical and control issues, and lack of maintenance as the most common causes of faulty indoor systems.
Want to control contaminants from one zone to another?
- Don’t transfer un-treated air from one room to another.
- Use walk-off mats—slightly sticky floor mats—at all entrances to rooms.
- Don’t drag watering hoses from one room the next.
- Practice cleanliness.
Massay defines small environments as less than 500 square feet, with utility bills less than $1,000 per month. Medium-size gardens range from 500 to 5,000 square feet and typically incorporate multiple rooms with different environments, high-end metal halide lighting, more ventilation, and much larger air conditioning systems, which combine to increase utility bills substantially.
The HVAC requirements are the same, just different scale. You can’t control ambient conditions in a seasonal greenhouse, unlike a sealed room; but they must maintain the same qualities of air, light, and water. Minimum features or design begins with what you want to achieve and a budget. Economy of scale does not work if you don’t have a market for your product.
Costs to break in as an indoor cultivator vary according to the size of the room. “Start with a $5,000 outlay in your basement and build your way out of the basement into a commercial operation. You can spend $100 per square foot for commercial-quality indoor cultivation rooms if newly constructed; existing retrofitted building half of that.”
Looking to the Future
Massay won’t pretend to know the secret to getting a license application approved but he is willing to offer an educated guess: “Network, be prepared with responses and requirements to the information LARA (Michigan’s Department of Licensing and Regulatory Affairs) presented so far, have financial means, and, if you really want to gamble, begin constructing your facility.”
But he is convinced that the cultivation business and the cannabis industry offer great potential for those willing to invest the effort:
After medical marijuana commercialization (MM) is permitted, I foresee cultivators primarily growing indoor crops due to competitive quality requirements and a limited distribution market, the amount of registered MM patients. If cannabis use eventually becomes legalized in Michigan, farmers will begin growing both indoor and outdoor crops.
Regarding LARA’s preparation for December 15, he says, “The importance of working together to ensure patients continue having access to quality medical cannabis must be the common goal.”
One Quick Tip for Each System
In his talk at Women Grow, Massay referred to six systems that are required for year-round success. He concludes with a tip for each system:
- Air conditioning: Buy the best you can afford. Do not undersize.
- Heating: Operate lights overnight during winter in lieu of supplemental heat. Keep a few portable kerosene heaters on hand in case of power outage.
- Dehumidification: Small-scale gardens can be controlled well with just a residential-style dehumidifier from a hardware store if good air circulation is used.
- Humidification: Utilize a vapor pressure deficit chart (VPD) to determine proper humidification level to be maintained in relation to the room’s ambient temperature.
- Carbon Dioxide (CO2) Generation: Splurge on the CO2 generator if your room is large enough.
- Ventilation: Have lots of it. Use some outdoor air to maintain good air quality.