Interesting finding in our bldg. Our lobby is 30'x40" and not heated. It is of course warmer than outside in the winter, but people comment how cool it gets if they stop to chat with our doorman or linger for any reason. A door off the lobby goes to the back where our trash areas, laundry and bldg system rooms are. We recently emptied all the back rooms and had our exterminator locate and seal all holes, then the whole area was painted. There were a lot of holes and a few major fissures in boiler and oil tank room walls.

The purpose was pest control and long overdue maintenance but we're noticing how much warmer the lobby is. The walls and floors are marble so the lobby is cool even before temps really start dropping but the difference is already very noticeable.

Proof that sealing holes, etc. is a worthwhile effort. Our lobby is pleasantly warmer. As I said, it isn't heated but if it were, I'm sure the work we did would be saving us money on heating it.