The diagram below shows how heat is lost and energy wasted in a house because of air getting into and out of the house.
A process of the air circulation in a house when the heat is lost and the fresh water gets into spaces in the house is illustrated in the diagram. At the first glance, it can be seen that the heat comes out from the home through the ceiling while air from outside gets into the home by a door as the main entrance and some ventilations.
According to the diagram, the heat losing process happens because there is air circulation in the home. Air leaks into the home through several ways. The biggest is from the door and window as the main entrance. Also, kitchen fan vent and dryer vent supply a plenty of air into spaces in the room. Other places, a small quantity is from electricity outlet and outdoor faucet in the crawl space.
Furthermore, heat air releases out home from various places on the ceiling. The first, hot air exits from the rooms through attic hatch. The second, in different places, heat evaporates out home passing the recessed lights in several rooms. Eventually, bathroom fan vent and plumbing stack vent are other media which are passed through by heat air to go out from the home.