After I've put T5's in the new shop I want to get rid of the rest of the T12's on the farm as fast as I can. New shop has four-six tube 54 watt light fixtures with mirror reflective backing for a total of 24 tubes. Old shop is approximately the same square footage and it has a total of 24 of the 48" T12's that are in fixtures that came out of a school thirty years ago. When I leave the new shop and step into the old shop it seems dark there. There is no comparison in the available light.
I'm not an electrical mathematician by any means, but by my figures 54X24=1296 Watts of usage in the new shop. 40X24=960 watts of usage in the old shop. So the new shop is using more electricity by my uneducated figures, but there is at least twice the light hands down.
The T5 fixtures in the new shop are commercial grade and cost about $120 apiece so they aren't cheap but they give out a heck of a lot of light. Jim