Almost half of American households use natural gas and propane-fired furnaces to heat their homes. This accounts for about 40 percent of energy used in our nation’s homes. Despite this high energy usage, furnace efficiency standards for gas furnaces have remained the same for the past 20 years.
In 1992, the U.S. Department of Energy enacted furnace efficiency standards for all gas furnaces produced after 1992. The minimum annual fuel utilization efficiency (AFUE) was set at 78 percent. That rating meant that furnaces had to be at least 78 percent efficient – every 100 units of energy used must produce a minimum of 78 units of heat.
Over the last 20 years, the AFUE rating has been challenged at various junctures. Energy conservation advocates strongly believe that minimum AFUE ratings should be higher than 78-80 percent. Since gas furnaces are among home appliances that consume the highest amounts of energy, many people think higher furnace efficiency standards are necessary.
In 2007, the U.S. Department of Energy proposed an increase in current AFUE ratings to 80 percent, effective in 2015. However, many gas furnace models currently on the market already meet or exceed 80 percent AFUE ratings. In 2009, another proposal suggested setting furnace efficiency standards based on regional standards according to climate. The U.S. Department of Energy agreed to set AFUE ratings at 90 percent for colder Northern states and 80 percent for the Southern tier of states. These new standards were supposed to go into effect in May 2013, but a federal court decision scuttled the new rules, and the minimum standards remain at 78 percent AFUE to this day.
Industry groups had blocked the higher standards, raising concerns that they could only be met with condensing furnaces, which would require expensive retrofits for homeowners upgrading from standard-efficiency models. Condensing furnaces reuse part of the heat that is usually vented to outside air. For this reason, they are more energy efficient than non-condensing furnaces, but they do require a different type of venting system.
Today, proposed AFUE minimums remain under review. It could take several more years before gas furnaces receive updated furnace efficiency standards.
For more information on gas furnaces and fuel efficiency, contact us at Paschal Heat, Air & Geothermal, serving the home comfort needs of northwest Arkansas for 45 years.
Our goal is to help educate our customers in Springdale, Arkansas about energy and home comfort issues (specific to HVAC systems). For more information about furnace efficiency standards and other HVAC topics, download our free Home Comfort Resource guide.
Image courtesy of Shutterstock