Water Heater Energy Efficiency

Energy efficiency

Water heating is the second largest user of energy in your home after space heating. It pays to use hot water wisely.

  • Energy Factor (EF) rates the overall energy efficiency of water heaters. The higher the EF rating, the greater the efficiency, which means lower on-going operating costs.
  • Typical new residential natural gas heaters have an EF of 0.6 to 0.8 EF. Only the most efficient water heaters qualify for the ENERGY STAR® label.
  • For a list of current water heaters and EF ratings, go to the Natural Resources Canada website.

Storage tank

  • Energy-efficient features are electronic ignition, higher insulation levels, and advanced venting systems. 
  • ENERGY STAR certified tank systems have an EF of 0.67 or better.


  • Tankless systems deliver an endless supply of hot water at an efficiency rate of 80 per cent or higher.
  • The ENERGY STAR level for tankless systems is 0.82 or higher.

Combination water and space heating systems

  • The energy efficiency depends on the boiler selected. A high-efficiency boiler is needed to deliver energy savings.

Cost-saving tips

It pays to use hot water more efficiently. Here are some simple tips to reduce water heating costs.