Short for British Thermal Unit, the BTU is the standard metric for the measurement of heat energy. Adding or removing the right amount of BTUs of heat is the essence of all-season indoor comfort. The gas burner in your furnace adds BTUs to warm your house in winter.
In summer, the evaporator coil inside your air conditioner removes BTUs from indoor air to keep you cool. The raw number of BTUs a furnace adds or an air conditioner extracts is known as the unit’s capacity.
BTUs also figure prominently in the calculation of heating and A/C efficiency ratings. These important specs — Annual Fuel Utilization Efficiency (AFUE) for furnaces and Seasonal Energy Efficiency Ratio (SEER) for air conditioners — tell you how much heat or coolness, respectively, you can expect in relation to a given amount of natural gas or electricity consumption. This information, included on the yellow EnergyGuide sticker, empowers you to comparison shop for a unit that provides optimum BTU capacity at lowest monthly operating cost. Here’s how BTUs are incorporated in the equation that produces efficiency ratings.
- Annual Fuel Utilization Efficiency expresses the BTUs of furnace heat that actually contribute to warming your house versus the amount which are lost in the combustion process as hot gases exhausted up the vent pipe. For a furnace that meets the current minimum standard AFUE of 80, this means 80% of the BTUs generated are usable heat while 20% are lost. High-efficiency furnaces incorporate a secondary heat exchanger to recover BTUs from exhaust gases and offer AFUE ratings of 90% or better.
- Seasonal Energy Efficiency Ratio is a numeral that represents the relationship between the number of BTUs an air conditioner extracts from the air and the kilowatt hours of electricity consumed by the unit during that same time span. The higher the SEER rating, the more energy-efficient the A/C. Currently, the minimum SEER is 13. However, high-efficiency units are available that deliver SEER efficiency above 20.
On the job in Terre Haute since 1922, the experts at Paitson Bros. can tell you more about how the BTU impacts household comfort and efficiency.
Our goal is to help educate our customers in Terre Haute, Indiana about energy and home comfort issues (specific to HVAC systems). For more information about BTUs and other HVAC topics, download our free Home Comfort Guide or call us at 812-645-6859.
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One Comment
Thanks for the information. This will come in handy when explaining to my customers what btu is all about.