Wow, that's amazing. There has to be a better way!

What about those plastic strips used in supermarkets to prevent cold air from leaving a refrigerated room? It looks like most of the opening isn't needed for the plan to exit... could insulated strips hanging from the top prevent most of the hot air from escaping while the door is open?
 

Hey Amit - The plastic strips are a good idea in grocery stores, and they work well enough for cart-sized pieces about two to four feet in width. But for an aircraft with a 50 to 80 foot wing-span, vertically hanging strips would have a hard time getting clearance.

I racked my brain for a while, too, trying to think of a better way. Hangars are big construction money!
 

What about the strong air-blowers, again found in grocery store entrances/exits? Would it cost less to create enough air-pressure near the entrance to keep the heat in while the plane is moving in or out?
 

Or what about plastic/insulated strips about a few feet apart each that can retract individually? 2-3 feet inside the hanger, you'd have IR sensors bouncing from the ceiling of the hanger to the floor. Based on what they saw coming (like those infra-red distance meters you can buy at the hardware store) they would retract the insulated strip to accommodate. So at any given moment, the opening of the hanger would only be as big as needed to allow whatever was exiting to do so. (You could do the same for entering with sensors on the outside.)

It's a little complicated, but if every opening costs $10K, it may be worth it!