Heating and cooling costs the average homeowner about $1,000 a year - nearly half the home's total energy bill. If your central air conditioning unit is more than 12 years old, replacing it with an ENERGY STAR qualified model could cut your cooling costs by 30%.

A 95% furnace will use 95% of the available heat to heat your home, as an example if you buy a $1 of natural gas, 95% is used to heat your home and 5% of the natural gas is vented outdoors. Many older gas furnaces are only 60% efficient. The other 40% is vented outdoors. You can see that a new high-efficiency furnace will require much less fuel to heat your home. 

Replacing an 8 SEER system (12+ years old) with an Ultra Efficient 20 SEER cooling system can provide up to a 60% reduction in that system's electrical consumption. A variable-speed indoor blower unit will increase the efficiency rating of the system, as well.