What controls really mean in the cannabis industry

Photo Courtesy of Surna

In general, controls will remove the human element from cultivation operations, minimizing the impact of mistakes or oversights and ensuring what is supposed to happen, happens, when and how it's supposed to happen. However, correctly applied controls systems can have enormous additional benefit, far beyond simply enabling lights or irrigation pumps at the right time. In order to understand what your controls system can do for you; you must first understand what it is you're getting from your chosen supplier.

Most cultivators think of "controls" as the dashboard where they can see their room parameters and adjust photoperiods or temperature setpoints, and a lot of folks make their decisions around controls based solely on that user interface. This is an important part of the toolkit but is really the least critical piece to a controls system's functionality.

The real complexity, and expertise, lies in the programming between the dashboard and the critical processes. For instance, when the temperature setpoint on a user interface/dashboard is changed, any number of important actions must take place, from simply providing power to a compressor in the most basic systems to reading a leaving air temperature and modulating a valve in more sophisticated systems.

Understanding and optimizing those sequences is what really differentiates a good controls company.

Sometimes, cultivators might think they're getting a controls system, when really, they're just getting a good-looking dashboard. Then they're unpleasantly surprised when they realize that the dashboard isn't really controlling anything. When evaluating controls systems, it's important that the companies you're considering have been vetted by your lighting, HVAC, and irrigation system providers to ensure they're really giving you all the functionality the critical systems in your facility require. Here's some help on what to ask a controls and automation vendor.

In industry-speak, when someone says "controls" it can mean a number of things: actual controls (enabling and disabling critical functions in the facility), automation (performance of critical functions in the facility) and data collection (collecting data relevant to critical functions in the facility). These systems generally fall into three categories of sophistication.

The first is what we'd refer to as entry level, or simple enable/disable controls paired with some data collection and limited alarming. This is the category that the vast majority of controls companies in the cannabis industry fall into. These companies enable and disable lights, CO2, cooling and dehumidification, and irrigation based on timing, thermostat set point, and/or EC or moisture reading in the cultivation media. Or, more simply: when this happens, turn it on, and when this happens, turn it off.

The sophistication associated with true building management systems is lacking in this type of approach, but the dashboards are usually tailored to the needs of the cultivator and this type of approach is certainly better than no controls at all.

More sophisticated controls systems will step up the data collection to include run time and energy use associated with equipment, and additional zones where data is gathered. More importantly, they allow for modulation of the equipment being controlled in the facility. Most commonly this modulation means adjusting lighting levels based on spectrum or PPFD, and modulating HVAC equipment to respond with precision to changing loads.

In addition to improving precision, modulating controls for HVAC in particular can have significant energy benefits—essentially, the same effect that highway miles on cruise control vs. stop and go traffic have on gas mileage in a car. In order to take full advantage of modulation in controls systems, the HVAC system design must have modulating capability, whether that's modulating hot gas reheat in DX systems, where refrigerant volumes, compressor speeds and sometimes fan speeds are modulated, or four pipe chilled water, where water temperature and volume, compressor speeds, fan speeds and pump speeds can be modulated.

We've found that this modulation component has been very difficult for most controls providers in our industry to achieve but is necessary for maximum performance at minimum energy use. More sophisticated systems can also provide the option of alarms associated with equipment failure, so the cultivator knows there is an issue to be addressed before that issue impacts the cultivation space.

Further benefit can be realized by ratcheting up the sophistication and adding analytics into the mix—taking the data that has been collected and reviewing it against cultivation functions to improve performance.

This can be as simple as adjusting the controls sequence of operation to minimize energy use in an HVAC system, or as complex as identifying trends between two seemingly unrelated events to tweak SOP's. There are some companies that provide grow room analytics, which are usually integrated with controls. Many cultivators, with the proper level of data collection, can perform these tasks manually as well.

Any of these levels of sophistication can have enormous value to the cultivator. Simply enabling and disabling critical processes reliably will remove the element of human error and limit risk, along with reducing manpower requirements and improving efficiency. However, the more sophisticated the system, the greater the potential benefits.

Lighting

Entry level controls systems enable and disable lighting based on the time of day, or photoperiod defined by the operator, which ensures that plants remain in the correct photoperiod at all times. More sophisticated systems can help cultivators reduce energy cost. Lights can be staged on to reduce peak demand and associated demand charges, which can be significant in some municipalities. Lights can be dimmed or disabled in case of temperature anomalies. Very sophisticated lighting controls systems can adjust light levels based on desired PPFD associated with a specific stage of plant growth. This is usually only utilized in LED applications to avoid spectrum change but can be beneficial both in perfecting the cultivation strategy and ensuring energy consumption is limited to what is absolutely necessary at any given time.

HVAC

Entry level controls systems work the same way as web-enabled thermostats: turn on cooling when the room gets too warm, turn it off when it cools off. Or turn on the dehumidifiers when the room gets too humid and turn it off when the humidity is reached. The result is a constant on/off throughout the day, which results in a controls trend line that looks more like a sawtooth, where the room parameters bounce up and down off setpoints. This uses more energy than absolutely necessary (refer to the cruise control analogy previously referenced). Unfortunately, with most HVAC systems designed primarily for comfort cooling, this is the best they are capable of, so upgrading the controls system has limited benefit. Some, more sophisticated comfort cooling systems such as VRF may have internal controls to modulate the cooling function, but the dehumidification function will still operate as a simple on/off in most instances.

However, with a well-designed HVAC system, where dehumidification is carefully considered and, often, integrated with the cooling system, modulating controls become not just beneficial, but necessary. These systems are a clear step up from systems intended primarily for comfort cooling, and the required controls systems do far more than just manage temperature and humidity.

Modulation of every critical process associated with environmental control ensures precision—a controls trend that resembles a flat line as opposed to a saw tooth. This same modulation allows the system to use only what it needs at any given time, slowly ramping up cooling or dehumidification processes if setpoints start to drift out of spec, instead of flooring it after it's already fallen behind. This level of sophistication allows for the monitoring of each piece of equipment associated with HVAC, which has a dual benefit. First, if something is operating abnormally, you have the opportunity to catch it before it impacts the grow. This can potentially save a crop, but less dramatically can help you to understand that something needs maintenance before it's broken. Second, watching the time of operation, and associated loading, can provide a good mechanical engineer information that they can use to tweak and perfect controls sequences to improve performance and reduce energy use. In some HVAC designs, cultivators have the ability to actually change the way the system is operating to respond to changes in the grow, as opposed to simply responding to a temperature set point.

Irrigation and Fertigation

This is the area in cultivation operations where we find some level of controls and automation is most common, primarily because hand watering is so labor intensive that it almost has to be automated in some way. Some cultivators manage fertigation (nutrient mixes) manually and automate the irrigation component (delivering to plants). Others automate both—but few controls systems handle both nutrient mixing and delivery of the nutrient mix to the plants so in these cases some level of coordination is required.

Some irrigation systems operate based on a schedule, some operate based on moisture sensors, and others operate based on EC of the grow media. The most efficient systems minimize run off by delivering only what the plants can consume and minimize nutrient waste by dosing only what nutrient is lacking. This is opposed to managing based solely on EC without understanding which nutrient is actually low. In the absence of moisture sensors, minimization of run off can be accomplished by measuring and understanding the volume of run off and adjusting irrigation schedules and volumes accordingly.

Analytics

Whether through an analytics platform, or manually, data collected through controls systems isn't valuable unless it's being analyzed and reviewed. Collecting data around climate, irrigation, revenues, yields, and quality, and then looking for trends is vitally important to continuous improvement. Performing data collection and analytics can help you make positive changes in the facility in nearly every area—from reducing energy use by changing irrigation strategies to modifying temperature and humidity setpoints for a specific strain. Constant review of data allows cultivation companies to identify correlations between seemingly unrelated events, or review anomalies when harvest totals are a surprise to identify root cause. If utilizing an analytics platform, it can be very helpful to ensure that the controls provider who is collecting data can easily export that data to the analytics platform—or, better yet, that they coordinate from the outset.

Blog author and Surna's Co-founder and Sr. Technical Advisor recently spoke at a USGBCWM.org virtual event on this topic.
You can listen to the webinar here.

Source: Surna

Photo created by jcomp -freepik

Source: Surna