Lennox makes high-efficiency furnaces such as the SLP98V, the EL296E and the ML195 models with annual fuel utilization efficiency ratings of 98.2, 96 and 95 percent respectively. Since these AFUE ratings are between 80 and 98.5 percent, they fall under the Department of Energy's grade for high-efficiency heating products.
Because heating and cooling account for about 48 percent of the energy used in U.S. homes according to the Department of Energy, highly efficient furnaces save their owners many dollars on heating bills. The furnaces are also more environmentally friendly. As of 2015, the highest-performing heating systems on the market have a 98.5 percent AFUE rating, mid-efficient systems rate 80 to 83 percent AFUE, and low-efficiency ones have a rating of 56 to 70 percent.