Nick Collins, ERS, for Zondits
Zondits recently interviewed Walter Stark, CTO of MSP Technology, on the dehumidification equipment they have designed for the indoor agricultural and cannabis markets. We hoped to get a better understanding of the systems that MSP offers, the energy advantages, and what brought them to the indoor cannabis cultivation market.
What is a wrap-around dehumidifier?
Wrap-around is a term used to describe a family of dehumidifiers with varying degrees of energy efficiency. A heat exchanger is wrapped around a traditional cooling coil. The heat exchanger provides precooling to the cooling coil and heating after the cooling coil. The efficiency of the dehumidifier is directly related to the efficiency of the heat exchanger. The types of heat exchangers used in this process are run-around, heat pipe, and plate. Of these choices, the plate is inherently the most efficient.
What are the advantages of this type of system?
The primary advantage of a wrap-around plate dehumidifier is energy savings from 30% to 65% and the extended life due to no moving parts. The high efficiency of this system qualifies for utility incentives that can help reduce any increase in capital cost to purchase and install.
This was independent testing conducted by researchers at the Western Cooling Efficiency Center WCEC) at UC Davis. Cost for testing was paid for by Xcel Energy, a western utility that is facing problems with excess power draw from the grid because of cannabis facilities. MSP had no influence over the testing except to provide input for the rating conditions.
The unit was instrumented and tested in WCEC’s environmental chambers to determine system power, capacity, and efficiency for each of the 29 steady-state tests conducted at controlled outdoor air temperatures, indoor conditions, and indoor airflows.
To estimate the difference in energy expenditures of MSP Technology’s dehumidification system compared to a traditional dehumidification system as applied to an indoor farm, WCEC created two numerical models based on three factors:
- Indoor building loads from plant transpiration and lighting
- Hourly weather forecast data
- Equipment performance data
The models calculated the annual energy expenditures of each dehumidification system required to meet the humidity setpoint for the greenhouse, as well as any additional energy expenditures necessary to recondition the air to the desired indoor air temperature after dehumidification loads were met. The difference in the energy expenditures per square foot as well as the percent difference in energy expenditure per square foot were calculated.
The MSP unit was tested under conditions typical of an indoor agricultural environment. The results were outstanding, showing energy efficiency far greater than competitive technologies, including other wrap-around technologies.
MSP has identified the cannabis industry as a target market. What has drawn you to this market?
Indoor farming in general is a rapidly growing industry. Cannabis, as a subset, is growing the fastest, so we are compelled to give this more attention. When we first discovered this opportunity, we evaluated how MSP Technology would fit in this application and discovered that it was astonishingly efficient. This is primarily due to the high efficiency of wrap-around plate dehumidifiers and the extended operating hours, which optimize return on investment. The cannabis cultivation industry also has one of the highest energy consumption rates and, therefore, we saw our technology as helping to solve a critical problem.
What have you seen for standard practice as far as dehumidification in indoor cannabis cultivation?
Standard practice is to use off-the-shelf air-conditioning equipment, portable dehumidifiers, and plenty of heating equipment to avoid overcooling. So cooling runs to dehumidify, while heating runs to prevent overcooling. This scenario more than doubles the operating cost in a cannabis cultivation facility compared with the MSP wrap-around plate system.
Cannabis is federally illegal and therefore very little real research on the plant species has been done. Most data available for cannabis is anecdotal. Horticulturalists are uncertain about critical information that HVAC designers need. For example, different horticulturists have stated anywhere between 0.5 and 1.0 gallons of irrigation is needed per day for a flowering plant. This range is too wide; the high end doubles the equipment capacity compared with the low end. And the growers who have taken the time to record irrigation rates are reluctant to share their information.
Because cannabis is federally illegal, the usual equipment financing and leasing options are scarce. Well-meaning but uninformed contractors and suppliers of traditional HVAC equipment offer inefficient yet financially attractive options that result in a slow drain of capital from the owners. For example, an owner will add another low-cost portable dehumidifier to reduce humidity one month and the following month add more air conditioning to compensate for the heat rejected into the room by the portable dehumidifier. This slow drain of capital is often preferred because the facility is operating and producing income.
Most facilities are faced with financial challenges and place a major focus on opening their doors. They go with the lowest bidder and are willing to deal with the high cost of operation and other problems later down the road.
Even facilities that are well funded are often confused about what system to choose because of the chatter surrounding the industry and well-meaning contractors and engineers who are using conventional wisdom on these unconventional applications.
The solution to this dilemma is education and financing. Utility companies can help implement these solutions. Incentives to help defray the added cost for energy efficiency are already in place with many utilities. What remains is education. Utilities or state governments, or both, should promote educational seminars to educate and perhaps certify individuals to design indoor agricultural facilities.
It is common to hear about the energy impact of lighting loads associated with indoor cannabis cultivation. What about the energy associated with HVAC and dehumidification – is that a significant part of the overall energy use?
Yes, lighting is a primary focus of cannabis growers, yet the science of lighting is mysterious to most growers. In addition to the nutrients and hardware needed to operate a facility, they see lighting as one of the most important ingredients to a successful crop. There is much debate about LED versus HPS.
The science of dehumidification, on the other hand, is not perceived as mysterious. Dehumidification is considered least important because of “a nationwide network of engineers and contractors who understand how to design a proper HVAC system.” Unfortunately, nothing could be further from the truth. We have observed the pitfalls in this way of thinking in speaking with cultivation facility managers and engineers who do not have a full grasp of the importance of the right dehumidification technology in not only reducing operational costs but helping to cultivate strong, healthy plants.
We would like to thank Walter for sharing his insights into the energy challenges of this new market, particularly as it relates to the need for considerable thought regarding the energy and quality impact of dehumidification in this market. MSP Technology can be found online at www.msptechnology.com.