We usually don’t spend too much time thinking about our AC systems. We just want them, and expect them, to work. And when the AC fails, we don’t think much about the repair or replacement other than the fact that it needs to be repaired or replaced ASAP.

According to the U.S. Census Bureau, approximately three million HVAC units require repair or replacement each year, meaning homeowners will be faced with big ticket decisions that affect their indoor comfort and energy costs for the next 15 or so years. But not all cold air is the same. Understanding the following four terms can help save money and increase your comfort level.

SEER – Seasonal Energy Efficiency Ratio is a measure of system efficiency, which translates to how much it costs to operate. The higher the number, the more efficient the system. A SEER rating of 16 or higher with stepped capacity modulation is considered high efficiency and could save you over $400 per year versus an older lower efficiency system.

Variable Speed – modulated systems with variable speed compressors can continuously vary the amount of energy used as the demand for cooling goes up or down. This helps keep temperatures stable throughout a cooling cycle. These systems are much more energy efficient and also provide superior humidity control throughout the home, possibly saving you more than $800 per year over what you might be paying now to cool your home with an older model.

Humidity – We hear the term all the time, but indoor humidity can cause many problems. Too much humidity in the air causes you to feel warmer, meaning it costs you more to run your AC unit longer. By selecting a thermostat with a humidity control feature, this could save you up to $300 per year and will also increase comfort in the home if you live in a humid area of the country.

Heat Pump – Heat pump systems have long been popular in warmer climates, but improvements in technology and performance are making them increasingly viable options in more northern climates. A heat pump is an air conditioner that can also be used to warm a home in the winter. A high-efficiency heat pump system which moves heat into the home instead of generating heat can be an incredibly efficient and cost-saving solution to replace conventional gas or oil burning furnaces, resulting in estimate annual savings of $700 versus what you might be paying today to heat with an older conventional furnace.

Knowing these four HVAC terms can help save you hundreds on the cost of running your AC system. So don’t wait! Start educating yourself now so that the next time you see your contractor, you know the right questions to ask. Don’t forget to check out our other helpful tips as you prepare your HVAC system for the coming heating or cooling season.