By Jeremy Elkins
The sun produces heat. Add water and heat produces humidity. And humidity? It produces a major problem, at least for your climate control system. Why are we talking about heat, humidity and climate control when most people are just looking to cool down a horticulture room?
When you’re talking about horticulture, you are not talking about air conditioning. AC plays a role in helping maintain your horticulture environment, but that is the equivalent of saying gasoline plays a role in driving your car to work. It’s only one small part of a much larger picture. If you want to cool down your house, install an air conditioner. If you want to maintain a certain environmental element that best suits your plants’ ability to reach their maximum potential, you need to control the climate.
There are no short cuts to efficient climate control. However, there are ways to ensure you’re not wasting time and money. Many different methods for cooling a space exist, but there is only one correct path to get there, and that’s through knowing your true BTU (British thermal unit) heat load.
If you do not properly size the system accordingly, it will never keep up with your demands, regardless of whether you are using a conventional on/off air conditioner, or a variable refrigeration flow heat pump.
So, why is it important to know how many BTUs you have in a room? It may not be if you’re talking about cooling down a house on an early summer afternoon for the sole purpose of human comfort. In fact, most of us could probably do without having air conditioning all year long, depending on what area of the country we live in.
Of course, if you’re talking about trying to cool down a room that has 20,000 watts of high-intensity artificial sunlight hanging directly above water-saturated live plants emitting large amounts of moisture in the air, then that’s a different story all together.
Cooling down a home and cooling down an indoor horticultural operation are two very different climates that require separate sizing formulas. Normally, when designing a cooling system for a house, builders tend to primarily base their configuration off the square footage of the home.
When designing a climate control system for horticulture, engineers do look at the square feet, but more importantly they need to know the building insulation R-factor, light BTU load count, humidity levels, hydroponic or soil usage, organic or synthetic plant strains, cubic feet per minute (CFM) of air circulation, and much more. These core factors are what make up the distinct difference between conventional cooling methods, and horticultural climate control.
Have you ever wondered why the temperature outside feels much warmer than it really is on a hot a summer night? No, it’s not that your bargain-priced thermometer turned out to be nothing more than an inaccurate wall decoration. It’s because there is a higher relative humidity in the air, which is called “latent heat.”
To better understand the relationship between latent heat and climate control, let’s compare it to the scenario of trying to drive up a snow-covered mountain pass in your car. In order for vehicles to make their way up the pass, they need to be able to grip the road. If the road is covered in snow and ice, drivers will be struggling to move forward. Some vehicles, such as a four-wheel-drive truck with winter tires, will be able to climb the mountain much quicker. Other vehicles, such as a rear-wheel-drive muscle car, will have to go much slower or may not make it to the top at all. Think of your room temperature as the mile markers on the road, your climate control system as the vehicles trying to drive, the top of the mountain as your target temperature, and the snow on the road as humidity.
When designing your climate control system, if you do not take in consideration all the contributing factors of your environment, then you might be stuck trying to drive a Ford Mustang over the Rocky Mountains in the middle of winter. Or, in the case of indoor horticulture, trying to cool down a 110 degree room at 75 percent humidity with only a portable air conditioner.
One aspect of climate control that is often overlooked due to its simplicity, is ensuring proper air circulation within a room. A common scenario that is played out repeatedly throughout the indoor horticulture industry is having the right amount of cooling BTUs, or tons of air conditioning (a ton being a term from when ice was still being used for cooling; 12,000 BTUs equals one ton) needed to cool down a room, but with only a limited amount of wall fans trying to circulate the air. This issue can be further compounded if the air conditioning unit is a wall-mounted ductless split, rather than a spiral-ducted conventional AC system.
The main difference between these two systems is that spiral ducting delivers cool air through an evenly dispersed supply duct usually running the entire length of the room, compared to ductless split indoor wall-mounted units supplying cool air directly to only one location. Either type of system will be effective for maintaining a desired room temperature when properly sized, but only if each of them have the adequate air circulation needed to fully operate.
If you were to take a look at an active indoor horticultural operation through the eyes of a thermal imaging camera, you would see extreme temperature differences throughout a room, especially between the amount of heat near the lights, and the heat lingering by the return air. Being able to move hot air away from the source of heat, and direct it into the return ducting of the air conditioning system to be cooled down for resupply, is key to maintaining even temperature uniformity throughout the entire room.
The easiest method for circulating air throughout a room to achieve the right amount of cool air disbursement is to simply place the correct amount of air fans as determined by the amount of needed CFM, and placed in the right location. In addition to wall fans, it is equally important to add multiple temperature averaging sensors throughout the room in order to capture a more accurate reading for the thermostat controlling your climate control system.
These vital measures will keep your room temperature even across the entire space, giving you complete control over the environment, and disallowing hot air pockets to potentially damage your plants.
Knowing what you need for cooling is half the battle to maintaining a stable environment for your plants to thrive. When we talk about climate control, what we are really talking about is much more than just heating or cooling though. The earth’s climate is made up of many factors such as variation in temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables.
Your indoor horticultural environment also includes many of these same elements such as CO2 levels, air circulation, moisture content and, of course, temperature control.
One thing to always keep in mind when thinking about having your next climate control system designed is to ask yourself what you want out of it. If you are looking to most closely replicate nature at its best in order to create a matching environment that mimics your plants’ natural thriving climate, then you have your work cut out for you. If not, then there are always plenty of online retailers biting at the bit to sell you what they call the world’s best and cheapest air conditioner.
Jesse Elkins, Jeremy’s brother and co-owner of Elkins Inc., is the founder and developer of the proven cannabis climate control system, ClimaGrow (www.climagrow.com). He has more than nine years of experience helping growers increase quality and quantity through proper climate control and monitoring methods.