This is an exciting time for Cannabis. An estimated 84 million Americans will be affected by proposed cannabis legislation on the ballot next week. This is significant for the industry, marking a turning point in our country’s relationship with the plant. However, as more and more states come on board, it is inevitable that cultivation operations will begin multiplying at incredible rates. It is important that this innovative industry approach these new opportunities responsibly and in a way that shows the world that we understand and respect the resource constraints we are facing. The good news is that, because the industry is so young, we have the chance to set standards on how we will utilize resources.
Here at Surna, we prioritize efficiency. So in the spirit of getting things off the ground in an environmentally responsible way, we’ve put together some ideas on energy and resource saving options for running a successful indoor garden.
Considering a hydronic cooling option for your indoor garden is a no brainer for cultivation because it is usually about 15 - 20% more efficient than other, more traditional HVAC options. Hydronic cooling works by circulating a chilled water-glycol mixture through a series of pipes to individual air handlers, where cool air is produced. Using water to remove heat is important because water has 20x the heat absorption rate and 4x the heat capacity of air. This means that water can hold 4x as much heat as air and can absorb it 20x as fast, allowing a chiller to remove the same amount of heat with much less energy.
Another reason this system is so energy efficient is because air handlers and chillers work independently of one another. The chiller, which uses the most energy in any cooling system, only needs to turn on when the temperature of the water it circulates drops below a certain point. And because of the high heat absorption rate of water, the water inside these systems can stay much cooler much longer than air would. Cold air can then be delivered to desired locations through an independent air handler without needing to engage the chiller compressor, saving significant energy.
Geothermal cooling is a great, energy efficient alternative to using the energy intensive chiller, but it does have some down sides. Geothermal cooling works by harnessing the ground’s constant cool temperature of about 55F, regardless of where you live. This system works by pumping water down into piping that is laid underneath the ground. The water picks up heat from the your rooms and the rejects that heat into the cool ground, cooling the water. That water can then be used in air handlers to cool the air in the room.
However, it is important to note that despite this being an extremely energy efficient option, some people find it can be quite costly to install this type of system and that the payback period on a system like this just too long to make it worth it. It also produces water for your cooling system at about 55F which will still cool your rooms significantly but will not allow for as much dehumidification, which is critical for an indoor garden.
Another way to use a hydronic cooling system while minimizing your energy consumption is through using a dry, or free, cooler. This is basically a compressor-less chiller that uses ambient temperatures to cool water. Its employs a cooling tower style fan which draws much less energy than a compressor. It works to supplement the chillers when the outside temperature is between 35F and 45F and can completely replace a chiller when the outside temperature is at or below 35F. In places like Alaska and Colorado, it can be a great option for the winter time and could cut your energy consumption by as much as 75%.
LED lights are a great way to reduce your energy consumption in an indoor cultivation environment because they can create the same amount of usable light with less wattage (and thus less electricity) than other types of bulbs. This is because all bulbs convert electrical energy to light and heat energy but some are simply more efficient at making that conversion than others. For example, a high pressure sodium (HPS) bulb is about 31% efficient whereas LEDs are about 53% efficient. This means that with the same amount of electrical energy, the LED produces more usable light than the HPS. Kind of a no-brainer is you can get comfortable working with them. Just be sure you check the spectrum on whatever light you choose to be sure it’s in line with what plants need.
Obviously, adding additional, renewable sources of power can save significant amounts of energy. Solar is a great option for those who want to be able to cultivate off the grid or who just want to supplement their power usage. Solar is becoming increasingly popular among growers in areas with frequent blackouts as a way to ensure plants always have access to power and light. If you can swing the initial investment, and you’re in a sunny place, we highly recommend it.
Energy consumption is often the most talked about part of designing a sustainable operation but resource consumption should not be overlooked. Indoor gardens use an enormous amount of water everyday. Depending on how your cultivating, you can be looking at between 2 and 5 gallons of water per light which can add up quickly in larger, commercial cultivations.
In order to conserve water, we recommend a water reclamation system which works by collecting condensate from dehumidifiers and air handlers and turning it back into usable water. These systems are powerful because they not cut down on how much water you have to bring in from outside, but they will also oxygenate, PH, sterilize and filter your water. This allows you to have reverse osmosis level water without having to waste so much of it in the process.
These are just a few of our suggestions on how to build a sustainable and efficient indoor garden. We know that cultivation can be an energy intensive process, but with a little thought and planning, you can reduce both your operating costs as well as your footprint, setting a standard for this new and exciting industry!