Furnace efficiency is measured by AFUE, short for Annual Fuel Utilization Efficiency. It’s a simple percentage that gives consumers a basis to compare energy efficiency among similar makes and models of furnaces at a glance. AFUE isn’t the only element that impacts your efficiency and operating costs. Other factors include the airtightness of your home, the amount of insulation, and how many hours a day you typically run the furnace.
Energy Lost And Found
The AFUE rating indicates the percentage of energy consumed in a furnace that actually generates heat. An AFUE 80 rating means 80 percent of the energy contained in the fuel produces heat while 20 percent is lost. The laws of physics dictate that some energy is always lost in the combustion process – usually in the form of hot gases vented up the exhaust duct. However, a higher AFUE percentage means less heat loss and a more energy-efficient furnace.
A New Standard
Federally-mandated AFUE minimums are periodically reviewed and adjusted to reflect advances in furnace technology and increased efficiency consciousness. As of Jan. 1, 2015, the minimum AFUE for furnaces sold in all 50 states will rise from 78 to 80. Furnaces in this range are considered standard efficiency models. To earn the federal Energy Star label, furnaces sold in the South and West including California must be high-efficiency models with ratings of at least 90 percent.
Is Higher Better Everywhere?
High-efficiency units, known as condensing furnaces, recover some of the heat from exhaust gases and provide AFUE ratings above 90 percent. The lower monthly energy costs of a high-efficiency furnace will eventually offset the substantially steeper sticker price of these units. However, in moderate climates such as Fresno with shorter heating seasons and average winter low temperatures in the mid-40s, the payback time may be excessively long. A new standard efficiency AFUE 80 percent furnace may be a better upgrade, particularly when accompanied by measures to increase the efficiency of the home, such as air sealing, weatherstripping and improving insulation.
For more info on using AFUE to evaluate your next furnace upgrade, in Fresno please contact us at Donald P. Dick Air Conditioning.
Our goal is to help educate our customers in the greater Fresno, California area about energy and home comfort issues (specific to HVAC systems). For more information about AFUE ratings and other HVAC topics, download our free Home Comfort Resource guide.
Credit/Copyright Attribution: “mstanley/Shutterstock”