Install a programmable thermostat and set it to accurately follow your schedule. For details, follow these
Proper Use Guidelines
Recycle your old mercury switch thermostat when installing a programmable thermostat.
Thermostat Recycling Corporation (TRC)
is a non-profit organization that can help properly dispose of your old thermostat at no cost to you.
Schedule a yearly tune-up of your heating and cooling system with a licensed contractor to keep your system running efficiently and save money.
Find a Licensed Contractor
Change or clean your air filter regularly. Check your filter every month, especially during heavy use months (winter and summer). If the filter looks dirty after a month, change it. At a minimum, change or clean the filter every three months. A dirty filter will slow down air flow and make the system work harder to keep you warm or cool—wasting energy.
Cut heating bills by as much as 10 percent per year by turning your thermostat back 10 to 15 percent for eight hours per day.
Kitchens are particularly vulnerable to excessive warming, especially from the extra heat generated by cooking. Adjust the kitchen vents, if you have them, until the room is comfortable.
Try adjusting upstairs vents in a two-story home to counter the effect of warm air rising from the first floor.
During the summer, adjust the temperature 1°-2°F per week to a higher setting, allowing your body to adjust to the new temperature. Raising the temperature just a couple of degrees can cut your cooling costs by as much as five percent. Start by setting your air conditioner thermostat to 78°F or higher - health permitting - when you're at home.
 
Consider installing high-efficiency natural gas fireplace inserts or freestanding stoves. If your fireplace doesn't have glass doors, consider having a set installed to help keep warm air in the house. NOTE: Fireplaces with glass doors require proper venting.
When not in use, close fireplace dampers, if possible.