How do I accurately measure my Grow Room Efficiency?

How much juice you burn to grow a gram..

Standard methods of reporting garden yields are imprecise and don't take the factor of time into account. This is a summary after discussion on a new standard formula for reporting yields and efficiency.

The GE Rating is based on the amount of kilowatt hours used to produce one gram. This factors in how long your strains flower and the resulting number makes it simple to compare 4000 watt gardens with 400 watt gardens. The calculations are easy, here is an example:

2000 watt flowering area
60 days of flowering
12 hours on light cycle
total yield: 49.5 ounces

1) Divide the total wattage of your lamps by 1000 to determine the kilowatts per hour:

2000 / 1000 = 2 kw/h

2) Multiply the previous result by the hours of the light cycle (usually 12):

2 x 12 = 24

3) Multiply the previous result by total days in flowering to determine how many kilowatt hours you used:

24 x 60 = 1440

4) Make sure your yield is in grams, so:

28.4 x 49.5 ounces = 1405.8 grams

5) Now simply divide grams by kilowatts:

1405.8 / 1440 =

0.97 grams per kilowatt hour, or a GE Rating of 0.97! Good job to the hypothetical grower, approaching a GE of 1 is the first plateau to be reached and is a sign of an experienced grower.

The secondary additions to the GE formula would be for the "Whole Garden GE Rating" which must include time spent in cloning and in veg. Figure it out the same way, with days spent under cloning lights, hours per day, and add those totals to the watt usage before dividing. This will give you a much lower rating than the standard Bloom GE Rating, but is more accurate for SCROG gardens, and anyone who is involved with extra vegetation time.

We have had a few contributors that have posted their monstrous GE Ratings..

OT1 - average 1.43, high of 1.89
Cobber - 1.75
Sharrina - 1.63
Quimik - 1.58