The trick to using a storage shed as a shop is insulation the the more the better. My last job bought a shed and had it delivered like you see on corner lots all over, we bought some insulation and crammed it in every crook and crevice, used just some osb sheating on the inside, had it wired, framed in for a window ac/heat unit. And over all once it got the temp where it needed it stayed there, the unit would freeze you out if you let it. I think the size was a 10x8 but it did good for my office space for what I did. We even inslated the roof as well. I even went inside with the doors closed and caulked any light I seen to seal it up further before insulation was put in.
Right now I use my garage its drafty as can be, the doors don't seal at all in fact the doors are just two wooden doors and there is major gaps plus they are falling apart. I don't have any issues out of running my tools when its cold, most times when I turn them first on from being so cold I let them run to warm up to get full power then do my work.
