Do you have some rooms that are too hot or too cold? Are there parts of your house that you rarely use? Is it warmer on the second floor than the first floor? Zoning your heating and cooling system could make your house more comfortable and save you money.

Currently, a single thermostat in a central location probably controls the heating and cooling system in your home. It responds to the nearby temperature, so the den at one end of the house might be too cool, while the bedrooms are too warm. Also, a single thermostat doesn't let you keep the empty bedroom area warmer during summer days, while having the kitchen and den, where your family is cooking and watching television, set to a cooler temperature.

Zoning divides your home into zones with similar heating and cooling requirements, with each zone controlled by its own thermostat. When one of these thermostats senses the need for heating or cooling, it sends a signal to a panel that controls dampers in your ductwork. The signal opens the dampers to that particular zone and closes off the air flow to the other zones.

Zoning is often used to set different temperature levels for different floors or for sleeping versus living areas. Because heat rises, the second floor often requires more cooling in the summer and less heating in the winter. In this case, zoning also means that you don't have to make the first floor too cool in order to make the second floor comfortable.

Since you're supplying less heating and cooling to unused areas, it takes less energy to keep your house warm during winter and cool during summer. A properly zoned system, combined with programmable thermostats that automatically adjust the temperatures in the different zones, can be 10 to 20 percent more efficient than a non-zoned system. The savings depend on the size and style of the house and the type of heating and cooling system.

Most older homes can be zoned with fairly simple modifications to the ductwork and the addition of a zoning control panel and wiring for additional thermostats. Heat pump systems can be easily zoned. Because heat pumps are already very efficient, the energy savings may be lower than with less efficient systems.

The best time to add zoning is when you're replacing your heating and cooling equipment, since you may already need to replace or change the ductwork for the new system. It's even easier to set up zoning when you're building a new house.

Another approach is to install separate, independent heating and cooling systems for each area. This can be a useful approach if you are adding on to a house, but if you are installing a new heating and cooling system or building a new house, using one system with zones is usually more economical.

If you have heating and cooling issues that could be solved with zoning, talk with a heating and air conditioning contractor to see whether your home is a good candidate for zoning.

• Multiple levels
• Sprawling design (wings or "ranch" style)
• Room(s) with large expanses of windows
• Large open areas (vaulted ceilings, foyer, atrium, solarium, etc.)
• Room(s) in a finished basement or attic
• Room(s) with exposed concrete floor
• An indoor swimming pool or hot tub

Zoning is recommended if in your lifestyle:

• You do a lot of entertaining
• You're busy in the kitchen, cooking and baking
• You work out of a home office
• You occasionally enjoy activities in a hobby room or play room
• Some family members occupy a room in the attic or basement