This is an article I found at betterhydro.com
One thing a new indoor grower finds out very quick with HID lights, his power bill goes up. This kind of thing sucks. It sucks because you just did so much research on which lights to choose. You think that the decision you made was the best. Most sites you looked at preached HID light, because it was the brightest. The more lumen the better your plants grow. Sounds like your plants should do good with that. Well, my first 400 watt light raised my power bill up $25 bucks a month and the second 400watt light raised it $25 more. I did some research and found some good advice. I went to my hydro shop and found a fluorescent system that was the closest to the HID power I needed. I got the 8 bulb 4ft T5 sun System. The lumen of which are comparable to the lumen of the 400watt HID light. The energy used to run the T5 system is the same (50watts a bulb x8 bulbs), so the energy is not saved from direct light to light watt ratio. The difference came from not needing an ac unit to cool my over heated room from my lights, or an inline fan blowing air through those hot ass lights. Had I started out with the fluorescent system, I wouldn't have had to buy an inline fan and venting in the first place, also saving money. Additionally, the lights can be closer to the plants without burning them. The growth rate was awesome because I was able to mix up the bulbs. With 8 different bulbs it was easy to change the spectrum to achieve the growth I wanted.