The diagram illustrates the process of heat lost and energy wasted in a house because of air getting into and out of the house.
Overall, it is clear that the heat is lost everywhere in the house. Warm air exits on the rooftop, while cold air enters mainly through doors, walls, and windows.
On the one hand, air escapes at the top of the house through the attic hatch, a small cover of the attic. Also, heat is lost through the bathroom fan vent, recessed lights, and chase. Warm air rises; thus, it often leaks out on the roof.
While warm air goes out from the top, cold air usually leaks into the house from the bottom. Some enters through doors and windows, while some comes in through electrical outlets, dryer vents, kitchen fan vents, crawl space, and outdoor faucets.