# FORMULA FOR ESTIMATING ENERGY CONSUMPTION

Discussion in 'Growing Marijuana Indoors' started by Judge Dredd, Jan 24, 2014.

1. If you're new to indoor growing, you may want to read up. Don't be stupid. Don't get in over your head with utility bills. Never assume you know how much your grow room is going to cost.
\nUse this formula to estimate the cost of your lights (can be applied to anything that draws electricity):

(watts x hours per day) / 1000 = daily kilowatt-hour (kWh)
\n1 kilowattkW = 1000 watts (W)
\nOnce you've determined the daily cost to run the lights, multiply it by the number of days you run them during the year.
\nExample: My 2400W grow tent (4 x 600W):
\nVEGETATIVE PHASE
(2400W x 18 hours per day) / 1000 = 43.2 kWh per day
\nIf I veg for 4 weeks, that's 28 days. 1 month out of every 3 translates to 4 months per year.
\n28 x 4 = 112
\n43.2 kWh per day x 112 days per year = 4838.4 kWh per year
\n4838.4 kWh per year / 4 months per year = 1209.6 kWh per month
\nBLOOM PHASE
(2400W x 12 hours per day) / 1000 = 28.8 kWh per day
\nIf I flower for 8 weeks, that's 56 days. 2 out of every 3 months translates to 8 months per year.
\n56 x 4 = 224
\n28.8 kWh per day x 224 days per year = 6451.2 kWh per year
\n6451.2 kWh per year / 8 months per year = 806.4 kWh per month
\n\nNow that you've determined the monthly cost of both the veg and bloom phases, you need to find out what your utility provider's monthly fee is. You also need to find out their rate per kWh.
\nMine: \$20.08 / month + 10.05 Â¢/kWh
\nVEG PHASE
1209.6 kWh x 10.05 Â¢/kWh = 12156.48 Â¢/kWh
\nDivide by 100.
\n12156.48 / 100 = 121.56
\n121. 56 + 20.08 = 141.64
\nThis is the dollar amount it will cost me per month during my veg phase.
\nBLOOM PHASE
806.4 kWh x 10.05 Â¢/kWh = 8104.32
\n8104.32 / 100 = 81.04
\n81.04 + 20.80 = 101.84

Now that you've determined the cost of your lights, which will be the bulk of your utility bill, you can do the same thing to calculate the cost of the inline fans and everything else.
\nCheers.
\n- Dredd 