When temperatures start to dip below 40, your thoughts turn to keeping cozy and warm in the comfort of your own home. But is your furnace ready to handle the heat? If it's time to replace your furnace, consider the tips in this handy guide:

Talk to an HVAC professional to determine the correct size system you'll need. If the heating unit is too large for your home, it will waste energy by frequently cycling on and off.

Choosing an ENERGY STAR^® qualified system will allow you to save money on energy bills by heating or cooling your home more efficiently.

Here are some common questions you may encounter when shopping for a new heating or cooling system:

What does AFUE mean?

Annual Fuel Utilization Efficiency: Like your car's miles per-gallon rating, a higher AFUE rating means a higher efficiency unit. A furnace's AFUE of 90% means 90% of the fuel is used to heat your home, while the other 10% is wasted in gases vented outside. Choose a higher AFUE to save more energy.

What is a BTU?

BTU stands for British Thermal Unit, the unit of heat energy that's necessary to raise the temperature of one pound of water one degree Fahrenheit, from 58.5 to 59.5. How does this apply to your home? Well, a 10,000 Btu air conditioner can remove 10,000 Btus of heat per hour.

What does EER mean?

The EER, or energy-efficiency ratio of a cooling system, measures how efficiently the system will operate when the outdoor temperature is at a specific level (usually 95F). A higher EER means a higher efficiency. What is the difference between EER and SEER? The SEER (seasonal energy-efficiency ratio) is a measure of air conditioning system's efficiency over an entire cooling season, as opposed to a single outdoor temperature.

What is HSPF?

Heating System Performance Factor: This is the measure of a heat pump's estimated seasonal heating output during spring and fall. Heat pumps with higher HSPFs are more efficient than heat pumps with lower HSPF ratings.