Heating and cooling typically account for about half of a home total energy consumption. Understanding HVAC basics helps homeowners make better equipment and thermostat decisions.
Forced-Air Systems
Most residential HVAC systems are forced-air: a central furnace heats air and a blower distributes it through ducts. The system works by circulating air, not by cooling objects directly. An oversized system heats or cools too quickly, then shuts off before the air has fully circulated.
Sizing
An undersized system runs continuously without reaching setpoint. An oversized system short-cycles and wastes energy. Proper sizing uses a Manual J calculation based on insulation, window area, orientation, and climate.
Thermostat Settings
Each degree of heating reduction saves roughly 2-3% on heating bills. Set the thermostat 7-10 degrees lower in winter when asleep or away for at least 8 hours.