Table HC4-12a. Air Conditioning by West Census Region, 

 Million U.S. Households, 2001

Air Conditioning

Characteristics

RSE Column Factor:

Total

U.S.

West Census Region

RSE

Row

Factors

Total

Census Division

Mountain Pacific

0.4 1.2 1.7 1.4

Households With Electric

Air-Conditioning Equipment ...................... 82.9 10.7 3.4 7.2 7.1

 Air Conditioners Not Used ........................... 2.1 1.1 0.2 0.9 15.5

Households Using Electric

Air-Conditioning1 ........................................ 80.8 9.6 3.2 6.3 7.2

Type of Electric Air-Conditioning Used

 Central Air-Conditioning2 ............................ 57.5 7.1 2.6 4.5 8.5

 Without a Heat Pump ................................ 46.2 5.2 1.8 3.4 11.2

 With a Heat Pump ..................................... 11.3 1.8 0.7 1.1 10.9

 Room Air-Conditioning ................................ 23.3 2.5 0.6 1.9 10.1

 1 Unit ......................................................... 12.8 2.0 0.5 1.5 11.6

 2 Units ....................................................... 7.5 0.4 Q 0.3 17.4

 3 or More Units .......................................... 3.0 Q Q Q 27.6

Number of Rooms AirConditioned in Summer 2001

 One or Two .................................................. 12.3 1.9 0.5 1.4 11.2

 Three ........................................................... 9.2 1.4 0.2 1.1 22.5

 Four ............................................................ 12.0 1.8 0.8 1.0 15.9

 Five or More ................................................ 47.3 4.5 1.7 2.8 8.2

Percentage of Rooms

Air-Conditioned

 100% ........................................................... 58.8 6.4 2.3 4.1 7.8

 50% to 99% ................................................. 12.1 1.7 0.5 1.3 18.6

 25% to 49% ................................................. 6.4 0.9 0.3 0.6 19.7

 1% to 24% ................................................... 3.5 0.5 Q 0.4 20.4

Large Tree(s) that

Shade the Home

 Yes .............................................................. 41.5 4.6 1.4 3.2 7.4

 No ................................................................ 39.3 5.0 1.8 3.1 11.2

Central Air-Conditioner Age

(excludes systems for more than one

housing unit)

 Less than 2 Years ....................................... 6.1 0.6 0.3 0.3 16.8

 2 to 4 Years ................................................. 10.1 1.5 0.7 0.7 14.6

 5 to 9 Years ................................................. 15.4 1.3 0.5 0.8 14.0

 10 to 19 Years ............................................. 15.0 2.0 0.4 1.5 13.9

 20 Years or More ......................................... 5.7 0.9 0.3 0.6 23.1

 Don’t Know .................................................. 3.7 0.6 0.2 0.4 22.9

Central Air-Conditioning Use

 Only a Few Times ....................................... 16.8 3.9 0.7 3.2 14.1

 Quite a Bit .................................................... 12.1 1.4 0.6 0.8 15.7

 All Summer .................................................. 28.4 1.7 1.3 0.4 12.9

See footnotes at end of table.

Energy Information Administration

2001 Residential Energy Consumption Survey: Housing Characteristics Tables
Table HC4-12a. Air Conditioning by West Census Region, 

 Million U.S. Households, 2001 (Continued)

Air Conditioning

Characteristics

RSE Column Factor:

Total

U.S.

West Census Region

RSE

Row

Factors

Total

Census Division

Mountain Pacific

0.4 1.2 1.7 1.4

Pays for Electricity for Central

Air-Conditioning

 Yes .............................................................. 55.5 6.8 2.4 4.4 8.3

 No ................................................................ 2.0 0.2 0.2 Q 33.9

Age of Most-Used Room Air Conditioner

 Less than 2 Years ....................................... 3.1 0.3 Q 0.2 20.4

 2 to 4 Years ................................................. 5.3 0.5 Q 0.5 18.5

 5 to 9 Years ................................................. 6.4 0.5 Q 0.3 16.2

 10 or 19 Years ............................................. 4.3 0.5 0.2 0.3 22.7

 20 or More Years ......................................... 2.0 0.4 Q 0.3 26.9

 Don’t Know .................................................. 2.2 0.4 Q 0.3 29.9

Room Air-Conditioning Use

 Only a Few Times ....................................... 13.6 1.8 0.4 1.4 12.3

 Quite a Bit .................................................... 5.0 0.5 0.2 0.3 22.9

 All Summer .................................................. 4.7 0.2 Q Q 26.9

Pays for Electricity for Room

Air-Conditioning

 Yes .............................................................. 21.9 2.4 0.6 1.8 10.2

 No ................................................................ 1.5 Q Q Q 53.5

1 The number of households, where the end use is electric air-conditioning, does not include households that did not use their equipment (2.1 million). It does

include the small number of households where the fuel for central air-conditioning equipment was something other than electricity; those households were treated as

if the fuel was electricity. 2 The 2001 RECS reported 800,000 households having both central air-conditioning and room/wall air-conditioners, with 600,000 households using both central

air-conditioning and 200,000 households using only room/wall air-conditioners. These room/wall air-conditioners are not included in the count of 23.3 million

households using room/wall air-conditioners. Note: This applies to all occurrences of central air-conditioning.

Q = Data withheld either because the Relative Standard Error (RSE) was greater than 50 percent or fewer than 10 households were sampled.

Notes: • To obtain the RSE percentage for any table cell, multiply the corresponding column and row factors. • Because of rounding, data may not sum to totals. 

• See "Glossary" for definition of terms used in this report.

Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A, B, C of the 2001 Residential Energy Consumption Survey.

Energy Information Administration

2001 Residential Energy Consumption Survey: Housing Characteristics Tables