What I like about the 8' T12 HO bulbs is the 110 watts.... Watts = heat...
I've got 16 double lamp fixtures --- so that's 32 bulbs cranking out 110 watts each... Which is 3500 watts on 24/7. With the 6" of high density bat for insulation -- and the 5/8" plywood interior walls... I've got more heat than I can use!