Is it (tight-beam?) burning or crushing? Homogenous objects have no special resistance to those damage types.
As for the SM of the lock, I believe it's -5? It can't be much bigger than a padlock.
The windows are SM -2 at the smallest, no bigger than SM -1. A (slim or small) human could crawl through one, in theory (if they had a good entry angle to climb in through).
DR+HP for the window? The lock?
The windows have bars (DR 5 & HP 12 each), the fragile glass is nothing to worry about.
The lock hardware is DR 12 and HP 14.
Making any skill rolls for the attempt?