Built-in appliances are any household applicance that is not simply a plug-and-play device. Exhaust fans in the kitchen, bathroom, or other areas where proper ventilation is necessary.

In-wall heaters are good examples of built-in appliances, along with ceiling or wall mounted ventilation fans in the bathroom which remove water vaopr after taking a shower which can save your bathroom from an overgrowth of mold, as well as remove unpleasant odors.