Great post, Sarah, sounds like you've given this a LOT of thought. The same idea applies to just about any place/situation...scrounge smart, and use what you can find.
Just curious, what scenario do you picture that's got you held up inside an office building. As a Northern Redneck, unless I was pinned down to the floor, or being held hostage, I'd be trying to get out and away from it. Even in a blizzard, I'd feel better at my Suburban with my kit, than trying to keep warm in a dark, cold, concrete, six story refrigerator.

Seriously, I'd like to hear more, I think I might learn something with this discussion.

Troy