Not all heating, ventilation and air conditioning (HVAC) equipment is equal. As much as half of the energy used in your home goes to heating and cooling. Making smart decisions about your home's HVAC system can have a big effect on your utility bills – and your comfort. Heating and cooling costs account for nearly half the home's total energy bill. If your central air conditioning unit is more than 10 years old it may be time to replace. Upgrading to an ENERGY STAR certified, high-efficiency model could cut your cooling costs by 30 percent. Although these products can be more expensive to purchase up front, the cost difference can be paid back over time through lower energy bills. Proper maintenance can go a long way in preventing future heating and cooling system problems. Ask your contractor about annual pre-season check-ups. Contractors often get very busy during summer and winter months, so it's a good idea to check the cooling system in the spring and the heating system in the fall. Change your air filter regularly. A clean filter will prevent dust and dirt from building up in the system, which can lead to expensive maintenance and/or early system failure. Check your filter every month, especially during winter and summer months, when use tends to be heavier.