The Math

Quote:As an example:
Forty 100-watt incandescent lamps (4,000w = 68,000 lumens) require 12,283 Btu of cooling (slightly over one ton). The same site could use 27 four-lamp fluorescent fixtures (or about 4,000 watts = 240,000 lumens) at the same one ton of cooling load, yet produce 172,000 more lumens.
(Please see: Related Efficiency Upgrades - Lighting for more information on this.)
Fluorescents produce more light per watt used then any incandescent can ever do. HID (HPS in particular) produce WAY more light for every watt used. Let’s do some math:


150w incandescent = 2,550 lumens or 17 lumens per watt
150w halogen = 3000 lumens or 20 lumens per watt
150w of Fluorescents = 9,000 lumens or 60 lumens per watt
150w of Compact Fluorescents = 10,500 lumens or 70 lumens per watt
150w Metal Halide = 13,500 lumens or 90 lumens per watt
150w High Pressure Sodium = 16,000 lumens or 107 lumens per watt


Now since you’re paying for each watt used wouldn’t you want that watt to put out as much light as it could? Using an incandescent bulb you are going to pay way more in electric costs then you would if you used a

HID because you’ll need more watts for the grow to come out good. To produce killer bud you will need about 7,000 lumens per sq ft in your grow room. So, in a 5sq ft grow room you would need 35,000 total lumens (7,000 * 5 = 35,000) to reach the optimum 7,000 lumens per sq ft. To get 35,000 lumens you would need:


13.7 - 150w incandescent or 2,058 watts = 35,000 lumens
11.6 – 150w Halogens or 1750 watts = 35,000 lumens
3.8 - 150w Fluorescents or 583 watts = 35,000 lumens
3.3 – 150w Compact Fluorescents or 500 watts = 35,000 lumens
2.5 – 150w Metal Halide or 389 watts = 35,000 lumens
2.1 – 150w HPS or 327w = 35,000 lumens