The Therm C 1050 ES from Bosch increases efficiency rating by 2% bringing the energy factor up to 0.94.

Bosch Thermotechnology North America has announced an efficiency increase of 2% to its Therm C 1050 ES tankless water heater, increasing its total energy factor (EF) to 0.94 overall. EF, as defined by the U.S. Department of Energy, is a measurement based on the amount of hot water produced per unit of fuel consumed over a typical day. The higher the number, the lower is the energy usage, hence greater unit efficiency.