First-time fruit, vegetable, and plant growers sometimes fail to account for increased electricity costs when they decide to put together their own indoor grow kit. These folks are surprised when they realize just how much energy it takes to grow their plants indoors in comparison to typical electricity consumption.
We’ve put together a handy guide with tips and tricks to help you save energy and lower your electric bill when growing. If you’ve found yourself battling high electricity costs, or you simply want to make sure you’re factoring in potential costs before you start growing, we’ll guide you through a few steps for minimizing those costs.
Before we do that, though, let’s take a look at how indoor growing operations affect electricity consumption.
Understanding Electricity Consumption for Indoor Growing
Indoor grow rooms consume much more energy than the average household. Fruits, vegetables, and other plants need grow lights, ventilation, water, and climate-controlled growing conditions for photosynthesis and healthy growth. However, these grow lights and climate control systems are powerful, and they tend to consume a lot of energy.
Note: Experts estimate that indoor growing requires about 10 times more energy on average than the amount of energy that is used by a standard office building.
Take your standard compact fluorescent lamp (CFL) for example. On average, one single CFL light bulb would be around 14 watts. If you calculate the kilowatt-hours (kWh) the bulb uses and factor in an electricity rate of 0.10/kWh, it would cost roughly $6.13 to run that CFL light bulb for 12 hours a day.
Now consider a 1200w LED lamp with 4ft x 4ft grow coverage for an indoor grow room. It would cost roughly $525.66 to run this 1200w LED light for 12 hours a day using the same electricity rate.
The consumption cost for this grow light is more than 85 times higher than a standard light. It’s important to note that this increase in cost is specifically from one LED grow light — grow rooms require a lot more energy-draining equipment in order to help plants produce healthy yields.
Now that you have an understanding of how an indoor grow room can affect your energy usage, what can you do to lower your electric bill when growing?
Audit Your Energy Use
The first step to a lower electric bill is to determine how much electricity you’re actually using to grow fruits, vegetables, or other plants. Some energy companies will break down your bill for you — that said, can do this on your own by following a few simple steps for each of the devices that consume energy in your grow room.
Figure Out the Watt-Hours Used Per Day
A watt is a unit of power that shows how much energy a device uses to operate. You'll want to figure out how much energy your grow room is using is to determine the number of watts that are used each hour.
In order to find the watt-hours (Wh) each device uses per day, simply multiply the wattage of a device — like your grow room fans, LED grow lights, and other essential growing equipment — by the number of hours you use it each day.
For example, if your grow room fan is 125w, and you use it for two hours a day, it consumes 250 watt-hours per day.
Once you have this number for each of your grow room devices, you are ready to take on the next step.
Convert Your Devices’ Watt-Hours Into Kilowatt-Hours
Your energy bill is going to measure your power consumption in kilowatt-hours (kWh), so you’ll need to divide the watt-hours you figured out in the previous step by 1000.
The grow room fan from the example above would consume 0.250 kWh per day.
Determine Your Usage Per Month
Once you have figured out the number of kilowatt-hours your devices use each day, you need to multiply the kilowatt-hours by the number of days in the month listed on your energy bill. This will help you determine how much energy these devices consumed for that month.
If, for example, you were calculating energy usage for March, the grow room fan would be using 7.5 kWh of energy for that month.
Determine the number of kilowatt-hours each of your devices uses for the month, and then you can move on to the last step.
Multiply That Number by Your Electric Rate
Once you have added up the monthly kWh consumption for all of your devices, you can either subtract that amount from the total energy used on your bill or multiply this number by your electric rate if your electric bill only shows a dollar amount and not a total consumption amount.
Note: While electricity rates vary by state and region, the average electricity rate in the United States as of January 2020 is 13.19 cents per kilowatt-hour.
Add up the energy consumption of all of your grow room devices in kWh and multiply it by your area’s electric rate. The results will show you exactly how much energy your growing operation is consuming and how much that consumption is costing you.
When you have an idea of how much energy you are using, you’ll have an understanding of your baseline energy usage for growing. You can then determine whether it’s too high, as well as figure out ways to make adjustments and lower your electric bill when growing.
Choose Energy-Efficient Lights
You can follow the steps listed above to determine how much energy your grow lights consume each month. The next step is to choose energy-efficient lights such as LEDs and CMHs.
LED Lights
If you want to reduce the amount of energy you need for your grow room, consider switching to energy-efficient LED grow lights. With LEDs, you’ll get the same light intensity as higher wattage HID lights while also generating less heat. Less heat means you won’t have to run as much ventilation and cooling equipment to keep your grow room cool. This, in turn, means you’ll lower your energy consumption rate even more.
Calculate the amount of energy your current grow lights need to operate and find out which LED grow lights will be a good fit for your grow room and your wallet. Swapping from HIDs to LEDs is a great way to lower your electric bill.
CMH Lights
CMH lights are more expensive upfront than your average MH lights, but they consume less energy, which means you’ll ultimately see a lower electric bill. Watt to watt, CMHs are able to produce more PAR light — the measurement of light that’s used for photosynthesis — than MH lights. That means a 315w CMH light, for example, will give you the same light intensity as a 600w MH light.
CMH lights also run a lot cooler than MH lights. That means you don’t need the same amount of cooling equipment, which means an overall lower electric bill.
Determine How Much You Need to Grow
Once you have determined the amount of energy your grow room consumes, you need to determine the size of your garden. It’s important to really take into account how much you need to grow. If you’ve already had a few successful grows, ask yourself this question: Do I need as many plants as I’m growing? If not, think about how you can shrink the size of your garden.
Fewer plants mean less lighting and cooling equipment. Growing two plants, for example, would use far less energy than, say, growing eight plants because you don’t need the same coverage of light or the same number of fans.
Check Your Grow Room Insulation
Another simple way to lower your electric bill when growing is to make sure your grow room is properly insulated and to factor in what’s best for it.
Heat is essential for the germination phase of growing, for example, and it helps make sure your plants are able to survive and grow. In order to give your plants the warmth they need without wasting money, you need to make sure your grow room is properly insulated.
Insulation not only promotes growth and contributes to the humidity that helps plants survive, but it also preserves the warmth of the grow room. If you overlook your insulation, you will end up overworking your HVAC system and paying excess energy costs.
You should make sure that the windows, doors, and vents in your grow room are insulated well so that neither heat or cold air are not escaping or entering your grow room and causing your HVAC system to work harder than they need to. If these areas are not insulated properly, your HVAC system will continue to heat and cool areas that would not otherwise need heating or cooling.
It is also important to make sure your pipes are properly insulated. If not, your HVAC system will have to work harder so your grow room is at the correct temperature, which will result in higher energy bills. Properly check your insulation and make sure external environmental conditions aren’t affecting your grow room from outside the growing space.
Check Your Airflow Efficiency
Keeping the airflow in your grow room is important for the health of your plants. You need to make sure the temperature is just right, and you want to be able to control humidity, odors, and air circulation.
Some growers make the mistake of choosing the wrong fans or using too many fans. These two critical mistakes end up significantly increasing energy consumption and electricity costs. You can avoid high costs and lower your electric bill by being a bit more strategic when it comes to airflow in your grow room.
Choosing the Right Fans
While it might seem more cost-effective to use cheap clip-on or tabletop fans priced at less than $20 a pop, using too many of these fans will rack up your electric costs. Rather than using multiple smaller fans, it’s actually more cost-efficient to invest in a high output fan.
For example, if you’re using a 2ft x 4ft x 5ft tent — like the Yield Lab Reflective Grow Tent — you’re better off utilizing either a 390 CFM fan or 440 CFM fan versus five or six smaller clip fans. A high output fan will cost you about $90, but you’re likely to spend just as much on a lot of smaller clip fans, if not more.
Where you’re really saving, though, is in your electric bill. A 440 CFM fan will run approximately 150 to 170 watts. Using six to eight smaller fans to provide a similar amount of cooling, however, can surpass 200 watts. This adds up, and so does the cost on your electric bill.
Don’t Use Too Many Fans
Some growers believe that using a lot of fans will cool the air in their grow room, so they purchase several small fans. This leads to high energy costs and provides very minor benefits for their plants.
Instead of doing this, you should invest in a good system for venting out heat and a single exhaust fan for your grow room.
Lowering Your Energy Bill When Growing Plants
Most folks, whether they grow plants, are interested in lowering their energy bill. That said, some of you might be hesitant to give the tips outlined in this article a try because you’re worried that lowering your energy consumption will negatively affect the quality of your plants. Thankfully, that’s not the case.
Choosing the right LED or CMH grow lights and exhaust fans will allow you to maintain the quality of your plants. Furthermore, making sure that your grow room is properly insulated and incorporating a way to vent out heat will actually help you produce healthier, higher-quality plants because they will be able to grow at the proper temperature.
If you want to lower energy costs when growing fruits, veggies, or other plants, you should consider trying out some of these tips. You’ll be surprised by how much you’ll save when you grow indoors.