By letting the electronics remember for you, it automatically saves energy. Furnace ductwork joints sealed with low toxic mastic. Ducts lose air at each joint like a hole in a bucket. Duct tape dries out in a few years and loses its sealing ability. Mastic stays flexible for much longer assuring that heat gets to where it is supposed to go.
Sealed ducts are also safer keeping combustion gasses from entering the living space.
Insulate hot and cold water pipes 3 feet from the hot water heater. By keeping water hot 24 hours a day, some heat is lost all the time. Insulating the pipes reduces the heat loss and helps provide hot water faster in far away sinks and showers. Rough-in gas for clothes dryer. Energy saving features in dishwashers save not only electricity but reduce water consumption as well.