Originally Posted by ELY001

Actually it does cost the airline money in terms of fuel. A few years back I was on a UA 772 flight (back then it was CO) b/w PEK and EWR. Sat in 1A in BF. The captain, who was Israeli (I could tell by his accent when he made the announcements), came out of the cockpit and hung out in the galley b/w the 2 BF cabins. I struck up a conversation with him and somehow we started discussing fuel burn and cabin air temps. He explained to me the mechanics behind a/c cabin air circulation, heating, and cooling, and how it increases fuel burn.