Natural gas, propane, or oil water heaters must have an energy factor EF of at least 0. Photovoltaic systems must provide electricity for the residence, and must meet applicable fire and electrical code requirement. The conservation credit depends on the estimated lifetime fuel savings, expressed in gallons of gasoline. Central air conditioners, heat pumps, ground-source heat pumps, furnaces, boilers, water heaters, and heat pump water heaters. Fuel cells for homes are not yet commercially available. Guidance for auto manufacturers is available from IRS.

There is no credit for other kinds of electric water heaters. Details of some criteria will be determined by the relevant federal agencies. The fuel economy credit depends on the improvement of the fuel economy over the baseline. This is about 20 percent more efficient than the current federal standard. For tax purposes, save your receipt and the Manufacturer's Certification Statement.

Energy-efficient refrigerators, clothes washers, and dishwashers. The system must be certified by the Solar Rating and Certification Corporation SRCC. The credit is not available for expenses for swimming pools or hot tubs. This is more than twice as efficient as the current federal standard. Only some tankless water heaters currently reach this efficiency level. For insulation to qualify, its primary purpose must be to insulate. Insulation, windows, skylights, and other building envelope improvements. Fuel savings are calculated as 120,000 miles divided by baseline mpg minus 120,000 miles divided by vehicle mpg. In addition, windows, doors, insulation, and roofs must be expected to last at least five years a two-year warranty is sufficient to demonstrate this.