I worked in the stores part of the university I went to part time, we had all of these large incandescent flood light type of fixtures all over the place. This area was the basement, and in the summer it was so hot in there, we had to keep the candy bars in the fridges, or they would melt. One day, my boss noticed that they were tearing out all of the fluorescent lights in a near by building and tossing them in the dumpsters, he asked it we could have them, they said yes. We hung them from chains and ran a wire up to the box that had held the incandescent light fixture. The old flood lights were 150w and as I recall we got about 75w of light and 75w of heat from those floods, the new fixtures were also 150w (two 4' tubes, IIRC) and we got 140w of light and only 10w of heat, or something like that.
There were 65 flood lights in this enclosed space they ran 24/7 so it was like having a 5000w heater on all the time. With the new fluorescents we just about doubled the light, and reduced the heat output to the point it was no longer a factor.
One thing to remember about lighting for your shop is to have too much, you can put them on two circuits so you don't turn them on all at once, but I've been told that as you get older, you will need more light to see by, and it is much better to be up on a ladder installing lights when you are younger than when you are older and need them, just what I was told by those older than me
I've got 25 of so of the 4' fluorescent tubes in the Dungeon, and I could really use a few more, but task lighting takes care of any dark spots.
Cheers!