Or keep only the bedrooms comfortable at night without heating or cooling any other area. Another benefit is the ability to maintain even temperatures throughout the house when heating or cooling the entire house. As the sun rises and sets, different parts of the home warm up at different times of the day. With zoning, temperature changes caused by sun exposure are handled automatically, keeping every zone exactly the temperature you want. Two story homes have their own special needs in addition to the normal things single story homes must contend with.
Heat rises, causing many upstairs areas to be hard to cool or downstairs locations hard to heat.
One way to solve that problem is to have separate air conditioners and furnaces for each level. Although usually an effective measure, you have twice the equipment cost and a much higher operating cost. Zoning can solve two story problems and make the dual system approach obsolete. Zoning has been around for years, mostly in expensive commercial applications. Recent advances in electronics technology have brought down the cost, encouraging manufacturers to produce residential specific systems.