"the ideal structure is not supposed to exchange air with the outside"

No, the ideal structure should minimize heat loss from air exchange.

I'm not fully up on my air exchange rates, but it's fairly typical for ranges to be in the 4-20 range, that is, the interior air is exchanged with the exterior 4-20x per hour.

In my Thorsten Chlupp references elsewhere you'll find he makes extensive references to heat exchangers which minimize thermal losses. He does this by a twofold process for his Fairbanks, AK, homes: entering air is routed first through the ground where it's heated from very cold ambient temperatures of as low as -40C / -40F to a temperature closer to freezing (~0F). It's then passed through a heat exchange where the exiting warm air transfers much of its heat to the entering cold air.

The purpose of tightly sealed windows and other possibly entry/exit points isn't to eliminate air exchange so much as to control it: you want air entering and exiting through your designated ventilation systems and transferring heat properly, not traversing the envelope arbitrarily.

See:

Chlupp discussing this issue: http://www.greenbuildingadvisor.com/community/forum/general-...

http://www.engineeringtoolbox.com/air-change-rate-room-d_867...