Technology

1998

1990+9%
Low Technology

1990+9%

1990+9%
High Technology

Highest Available Efficiency^a

 Air-Source Heat Pump

2.70

2.70

2.93

3.22

 Natural Gas Chillers and Air Conditioners

3.52

3.52

3.81

4.40

 Heat Pump Water Heater

2.00

2.00

2.50

2.80

 Natural Gas Water Heater

0.91

0.91

0.91

0.91

Average Purchased Efficiency^a

 Electric Space Heating

1.10

1.13

1.13

1.11

 Natural Gas Space Cooling

1.32

1.73

1.62

1.59

 Electric Water Heating

0.95

1.03

1.00

0.98

 Natural Gas Water Heating

0.79

0.82

0.82

0.84

^aThe efficiencies shown (Btu of output divided by Btu of input) generally are seasonal efficiencies or include some measure of losses incurred during normal use.
Source: Office of Integrated Analysis and Forecasting, National Energy Modeling System runs FREEZE09.D080798A, FD09ABV.D080398B, and HITECH09. D080698A.