How We Rate Water Heating Technologies

► Ratings are based on averages and estimates for 50 gallon (3 GPM for tankless) ENERGY STAR qualified models.

Environmental Impact

Our Environmental Impact Rating for the Water Heating Technology Category is based on average annual pounds of CO2 emissions. CO2 emissions are calculated according to each technology's average annual energy consumption in kilowatt hours (kWh).

The higher the Environmental Impact Rating, the less-consuming the technology is of energy and therefore the less-emitting it is of CO2.

Consumption

Our Consumption Rating for the Water Heating Technology Category is based on each technology's average Energy Factor. Energy Factor is the ratio of useful energy output from a product to the total amount of energy delivered to the product. The higher the Energy Factor, the more efficient the product.

The higher the Consumption Rating, the higher the Energy Factor is of the water heating technology and the more energy-efficient it is.

Lifecycle Cost

Our Lifecycle Cost Rating for the Water Heating Technology Category is based on the average annual operating costs of the technology, combined with its average purchase price plus installation. Average annual energy cost calculated using the number of kilowatt hours (kWh) the technology consumes on average per year, multiplied by the average national cost of energy (differs depending on energy source, e.g. electricity, natural gas, etc.).

The higher the Lifecycle Cost Rating, the more cost-effective the technology.

Price

Our Price Rating for the Water Heating Technology Category is based on the average purchase price of the unit plus the average cost of installation for the system, including the 2009 Federal tax credit, if applicable. These numbers are estimates based on averages; for accurate pricing, please contact your local water heating contractor.

The higher the Price Rating, the lower the price of the technology.