AFUE (Annual Fuel Utilization Efficiency)
The efficiency rating for gas furnaces, boilers, and water heaters — the percentage of fuel energy that becomes useful heat. A 95% AFUE furnace converts 95% of gas energy to heat.
Why It Matters
AFUE helps compare gas vs. heat pump costs. A 95% AFUE furnace converts 0.95 units of gas to heat; a heat pump with COP 3.0 delivers 3.0 units of heat per unit of electricity. Even at higher electricity rates, heat pumps often win.
Related Terms
COP (Coefficient of Performance)
The ratio of heating or cooling output to electrical energy input for a heat pump. A COP of 3.0 means the system produces 3 kWh of heat for every 1 kWh of electricity consumed.
Heat Pump
An efficient HVAC system that transfers heat rather than generating it, providing both heating and cooling. Air-source heat pumps are most common; ground-source (geothermal) are most efficient.