Table HC9.6 Air Conditioning Characteristics by Climate Zone, 2005

 Million U.S. Housing Units

Total......................................................................... 111.1 10.9 26.1 27.3 24.0 22.8

Do Not Have Cooling Equipment........................... 17.8 3.2 4.7 3.6 5.5 0.9

Have Cooling Equipment........................................ 93.3 7.7 21.4 23.7 18.5 21.9

Use Cooling Equipment......................................... 91.4 7.6 21.0 23.4 17.9 21.7

Have Equipment But Do Not Use it........................ 1.9 Q 0.4 0.4 0.6 0.3

Air-Conditioning Equipment2, 3

Central System...................................................... 65.9 4.8 12.3 15.1 14.9 18.7

Without a Heat Pump......................................... 53.5 4.7 11.5 11.6 12.3 13.6

With a Heat Pump.............................................. 12.3 Q 0.9 3.5 2.7 5.2

Window/Wall Units................................................. 28.9 3.1 9.3 8.8 4.0 3.7

1 Unit................................................................. 14.5 2.1 5.0 3.6 2.4 1.4

2 Units................................................................ 9.1 0.7 2.9 3.3 1.0 1.2

3 or More Units.................................................. 5.4 0.3 1.5 1.9 0.6 1.1

Central Air-Conditioning......................................... 65.9 4.8 12.3 15.1 14.9 18.7

Housing Units Served by

Central Air-Condition Equipment

One Housing Unit............................................... 64.2 4.7 11.9 14.5 14.7 18.3

Two or More Housing Units................................ 1.7 Q 0.4 Q Q 0.4

Do Not Have Central A/C Equipment................. 45.2 6.2 13.7 12.2 9.0 4.1

Number of Rooms Cooled by Central

Air-Conditioning in Summer 2005

None.................................................................. 1.4 Q 0.3 Q 0.6 0.2

1......................................................................... 0.7 N Q Q Q Q

2......................................................................... 2.1 Q 0.5 0.4 0.5 0.5

3......................................................................... 7.5 0.4 1.4 1.3 2.0 2.4

4......................................................................... 7.9 0.4 1.2 1.8 1.9 2.6

5 or More............................................................ 46.3 3.7 8.9 11.2 9.9 12.7

Proportion of Rooms Air-Conditioned

None.................................................................. 1.4 Q 0.3 Q 0.6 0.2

Some, But Not All of the Rooms........................ 8.4 0.7 1.8 1.6 2.4 1.9

All of the Rooms................................................. 56.1 4.0 10.2 13.2 12.0 16.6

Frequency of Central Air-Conditioner Use

Never................................................................. 1.4 Q 0.3 Q 0.6 0.2

Only a Few Times When Needed....................... 11.4 1.7 3.1 2.3 3.5 0.9

Quite a Bit.......................................................... 12.6 1.6 3.3 2.8 2.9 2.0

All Summer........................................................ 40.5 1.4 5.6 9.8 8.0 15.6

Age of Central Air-Conditioner

Used by One Housing Unit

Less than 2 Years.......................................... 9.0 0.7 1.7 2.0 1.9 2.8

2 to 4 Years.................................................... 11.0 0.8 2.2 2.2 2.2 3.7

5 to 9 Years.................................................... 16.3 1.4 3.3 3.4 3.8 4.4

10 to 19 Years................................................ 16.8 1.4 2.9 4.2 4.4 3.9

20 Years or More............................................ 6.5 0.3 0.9 1.7 1.6 2.0

Don't Know..................................................... 4.5 Q 1.0 0.9 0.8 1.5

Climate Zone1

2,000 CDD 

or More

and Less 

than 4,000 

Air Conditioning Characteristics HDD

Less than 2,000 CDD and --

Less than 

4,000 HDD

Greater than 

7,000 HDD

5,500 to 

7,000 HDD

4,000 to 

5,499 HDD

Housing 

Units 

(millions)

Energy Information Administration

2005 Residential Energy Consumption Survey: Preliminary Housing Characteristic Tables
Table HC9.6 Air Conditioning Characteristics by Climate Zone, 2005

 Million U.S. Housing Units

Climate Zone1

2,000 CDD 

or More

and Less 

than 4,000 

Air Conditioning Characteristics HDD

Less than 2,000 CDD and --

Less than 

4,000 HDD

Greater than 

7,000 HDD

5,500 to 

7,000 HDD

4,000 to 

5,499 HDD

Housing 

Units 

(millions)

Used by Two or More Housing Units

Less than 2 Years.......................................... Q Q N N N Q

2 to 4 Years.................................................... Q N N Q N Q

5 to 9 Years.................................................... 0.3 Q Q Q Q N

10 to 19 Years................................................ 0.3 Q Q Q Q Q

20 Years or More............................................ 0.3 N Q Q Q Q

Don't Know..................................................... 0.7 N Q Q Q Q

Household Pays for Electricity

for Central Air-Conditioning

Yes.................................................................... 63.6 4.7 12.0 14.2 14.5 18.2

No...................................................................... 2.3 Q Q 0.9 0.4 0.5

Window/Wall Unit Air-Conditioning....................... 28.9 3.1 9.3 8.8 4.0 3.7

Frequency Most-Used Unit Used

Never................................................................. 0.6 Q Q Q Q Q

Only a Few Times When Needed....................... 12.1 1.5 4.2 3.8 1.7 0.9

Quite a Bit.......................................................... 7.5 1.0 2.6 2.1 0.9 0.9

All Summer........................................................ 8.6 0.4 2.4 2.7 1.3 1.7

Age of Most-Used Unit

Less than 2 Years.............................................. 6.4 0.5 2.1 2.1 1.0 0.8

2 to 4 Years....................................................... 7.8 0.9 2.6 2.3 0.8 1.1

5 to 9 Years....................................................... 7.0 0.7 2.1 2.3 1.0 1.0

10 to 19 Years.................................................... 3.7 0.3 1.2 1.1 0.6 0.5

20 Years or More............................................... 2.1 0.2 0.7 0.5 0.4 Q

Don't Know......................................................... 1.8 0.3 0.6 0.6 0.2 Q

Household Pays for Electricity for

Window/Wall Air-Conditioners

Yes.................................................................... 26.1 2.7 8.5 7.8 3.8 3.2

No...................................................................... 2.2 Q 0.7 0.8 Q 0.3

 1. One of five climatically distinct areas, determined according to the 30-year average (1971-2000) of the annual heating and cooling 

degree-days. A household is assigned to a climate zone according to the 30-year average annual degree-days for an appropriate nearby 

weather station.

 2. In the 2005 RECS 1.5 million housing units reported having both central and window/wall air conditioners.

 3. The number of housing units using air-conditioning includes a small, undetermined number of housing units where the fuel for 

central air-conditioning was some fuel other than electricity; these housing units were treated as if the air-conditioning fuel was electricity.

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

sampled.

 N = No cases in reporting sample.

 Notes: ● Because of rounding, data may not sum to totals. ● See Glossary for definition of terms used in these tables.

 Source: Energy Information Administration, Office of Energy Markets and End Use, Forms EIA-457 A, B, C of the 2005 

Residential Energy Consumption Survey.

Energy Information Administration

2005 Residential Energy Consumption Survey: Preliminary Housing Characteristic Tables