As far as we know, and according to validated research, tankless water heaters are about 28% more energy efficient than the conventional tank-style hot water heaters. "According to Energy.gov, “For homes that use 41 gallons or less of hot water daily, demand (or tankless) water heaters can be 24% to 34% more energy-efficient than conventional storage-tank water heaters.” Tankless water heaters (if gas-fired) will save homeowners over $100 annually the longer they remain in service."