Replacing old, inefficient heating and cooling units with new, more efficient units immediately lowers heating and cooling costs. A programmable thermostat can also reduce energy costs by making heating and cooling schedules more efficient.
Replacing old units can reduce heating and cooling costs by more than 30 percent. Air conditioning units are rated based on their SEER (seasonal energy-efficiency ratio). The higher the SEER, the more efficient the unit is, and the less it costs to run. A combination AC/heat pump costs more, but will provide efficient heating when ambient temperatures are mild (usually about 30 degrees Fahrenheit or more). Programmable thermostats reduce heating and cooling usage by reducing usage while nobody is home. Newer learning thermostats automatically turn the heating or AC off while nobody is home, saving energy.
Replace AC or furnace air filters regularly; clogged filters require your system to work harder to move air, reducing efficiency. Adding window film with 'Low E' filters add insulation to the windows year round, and reduce solar heating during the summer months. Adding insulation to walls and attics also reduces heating and cooling bills. Find and block any air leaks using an infrared thermometer or a stick of incense. Hold burning incense close to a window, outlet, or light switch to detect drafts. Install foam gaskets inside outlets and switch boxes, and use caulk to close gaps in windows.