Indoor Grow Room Costs
Indoor cannabis cultivation needs intensive electricity use
One of the most frequently asked questions by those who are thinking of starting to grow their cannabis indoors is whether the electricity costs are very high. Of course, an indoor garden consumes a lot of electricity but, in exchange, the grower harvests a product that, if he had to buy it, would cost much more.
Indoor cannabis cultivation requires intensive use of electricity. High-pressure lamps, which are the most commonly used, consume much more than a normal light bulb. The most common among growers are 400 and 600 w. It may not seem like much, especially when compared to the consumption of some common household appliances, such as a washing machine or a hair dryer, which can consume up to 2000 watts, but it must be taken into account that a washing machine is used one or two hours a day and a hair dryer only a few minutes, while grow lights remain on for between 12 and 18 hours a day, depending on whether the plants are in the growth or flowering phase.
The electrical consumption of a grow room is not only that of the lights. Fans and extractors usually consume only a few dozen watts, but since they remain on all day, their monthly expense is considerable. If the grow room is cooled by an air conditioner, the expense will be considerably higher, since these appliances consume a lot, but it is not easy to calculate in advance how much they will cost, since it depends on the temperature, the efficiency of the appliance and whether the compressor has to be turned on more or less frequently. To get a rough idea, you can calculate that, while the lights are on, for every 100W of light, at least 30W of air conditioning will be needed.
Electricity is billed in kilowatts per hour (kW/h), which is the amount of energy it takes to keep a device that consumes 1000W for one hour. A 600W lamp therefore consumes 0.6 kW/h. If it is turned on for twelve hours a day, its consumption will be 12 x 0.6 = 7.2 kW/h each day, or 216 kW/h per month (7.2 x 30). It is important to count all the devices associated with the crop and calculate how many hours they are on per day.
What is the monthly cost of electricity for a cannabis crop?
The calculated prices are only indicative since they do not take into account other concepts that appear on the bill such as the contracted power, nor have taxes such as VAT (21%) or special taxes on electricity been taken into account. We have put 0.17 euros on average per KW.
Example 1:
A 400 w HPS for 18 hours generates a consumption of 0.4 KW * 18 h = 7.2 KWh per day.
A 400 w HPS on for 12 hours generates a consumption of 0.4 KW * 12 h = 4.8 KWh per day.
A 25 w oscillating fan and a 15 w extractor generate a consumption of (0.025 KW + 0.015 KW) * 24 h = 0.96 KWh per day.
In growth: (7.2 KWh + 0.96 KWh) * 0.17 = 1.3816 Euros/day * 30 = 41.448 Euros/month
In flowering: (4.8 KWh + 0.96 KWh) * 0.17 = 0.9824 Euros/day * 30 = 29.472 Euros/month
So the total electricity cost for a typical grow in this cabinet would be 41.448 + (2 x 29.472) = 100.392 Euros. With other additional costs, we can assume it would be around 130 Euros or more per growth cycle.
Example 2:
Two 600w HPSs turned on for 18 hours generate a consumption of 1.2 KW * 18 h = 21.6 KWh per day.
Two 600w HPS on for 12 hours generate a consumption of 1.2 KW * 12 h = 14.4 KWh per day.
Two 50w oscillating fans and a 50w extractor generate a consumption of (0.1 KW + 0.05 KW) * 24 h = 3.6 KWh per day.
In growth: (21.6 KWh + 3.6 KWh) * 0.17 = 4.302 euros/day * 30 = 129.06 euros/month
In flowering: (14.4 KWh + 3.6 KWh) * 0.17 = 3.062 euros/day * 30 = 91.86 euros/month
Therefore, the total cost in three months of cultivation would be 129.06 + (2 x 91.86) = 312.78 euros. With other additional costs, we can assume that it would be around 400 Euros or more per growth cycle.
Kilowatts per gram
In the cabinet in example 1, a harvest of between 200 and 400 grams (between 0.5 and 1 gr/w) can be obtained, depending on the skill of the grower and the variety planted. Considering that 590 kW is used for each grow cycle, it turns out that each gram of buds requires between 1.5 and 3 kW/h.
In example 2, the probable harvest ranges between 600 and 1200 grams with a consumption of 1836 kW, so one gram of buds requires the same approximate consumption, between 1.5 and 3 kW/gr.
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Liz Filmer
