A nearby college includes a building, surrounded by an outdoor arcade, at street level. At one point, the warm internal air is expelled, which is natural, they perform continuous circulation. A nice spot, on a cold night!
However, I wonder, is there any hazard in breathing that air? Is it chemically processed somehow, contaminated? And, isn't it inefficient? The outgoing air ought to pass through a heat exchanger, to warm the incoming air. Isn't that wasted energy?