Most quality glass garage doors are constructed with insulated glass to maintain climate control. Even with insulated glass, these types of doors can still be inefficient compared to steel or wood alternatives. The glass door is basically a large floor to ceiling window and, as such, is subject to the same temperature disadvantages. Glass doors can allow a lot of heat to escape and cold to enter. Because of this, the location and contents of the garage should be strong considerations when installing a glass door.