Data release date: March 2023

Number of 

housing units 

(million)

Total apartment 

unitsa Totalb Heatedc Cooledc Totalb Heated Cooled

All homes 32.18 926 828 629 456 407 310

Census region and division

Northeast 8.24 934 912 517 450 439 249

New England 2.10 968 958 440 431 427 196

Middle Atlantic 6.14 922 896 543 457 444 269

Midwest 6.15 959 940 667 513 503 356

East North Central 4.42 978 958 667 510 500 348

West North Central 1.73 910 895 666 519 511 380

South 10.19 949 800 826 475 400 413

South Atlantic 5.67 996 789 883 511 405 453

East South Central 1.25 916 880 783 507 487 434

West South Central 3.27 880 788 743 407 364 343

West 7.59 860 682 456 399 317 211

Mountain 1.99 899 821 654 433 396 316

Mountain North 0.99 927 897 565 472 457 288

Mountain South 1.00 870 747 743 399 342 340

Pacific 5.60 846 633 385 387 290 176

Census urban/rural classificationd

Urban 31.29 927 827 628 454 405 308

Urbanized area 29.15 927 822 637 449 398 309

Urban cluster 2.14 929 903 510 529 514 291

Rural 0.89 889 843 641 539 511 389

Climate regione

Very cold/Cold 10.52 961 945 584 496 488 301

Mixed-humid 9.75 917 883 668 459 442 334

Mixed-dry/Hot-dry 4.24 830 614 556 358 265 239

Hot-humid 5.62 968 706 846 473 345 413

Marine 2.04 871 737 231 428 362 113

Year of construction

Before 1950 5.44 942 898 485 488 466 251

1950 to 1959 2.01 811 755 436 399 372 215

1960 to 1969 3.53 869 785 535 432 391 266

1970 to 1979 5.56 897 778 597 436 379 291

1980 to 1989 5.03 915 797 651 443 386 315

1990 to 1999 3.50 979 862 734 458 403 343

2000 to 2009 3.89 984 836 778 505 429 400

2010 to 2015 1.78 954 849 807 477 424 403

2016 to 2020 1.43 996 934 836 440 413 369

Fuels used for any use (more than one 

may apply)

Electricity 32.18 926 828 629 456 407 310

Natural gas 17.89 922 847 593 443 407 285

Propanef 0.76 881 787 584 437 391 290

Wood 0.58 1,068 1,056 740 442 437 306

Fuel oil or kerosene 0.98 910 889 442 427 417 207

Table HC10.15 Average square footage of apartment units, 2020

Average square footage 

per housing unit

Average square footage 

per household member
Number of 

housing units 

(million)

Total apartment 

unitsa Totalb Heatedc Cooledc Totalb Heated Cooled

All homes 32.18 926 828 629 456 407 310

Table HC10.15 Average square footage of apartment units, 2020

Average square footage 

per housing unit

Average square footage 

per household member

Main space heating fuel

Natural gas 11.90 944 944 616 463 463 302

Electricity 16.26 918 887 654 461 446 328

Fuel oil or kerosene 0.84 901 901 430 447 447 213

Propane 0.19 788 788 422 422 422 225

Wood Q Q Q Q Q Q Q

Some other fuelg Q Q Q Q Q Q Q

Does not use heating equipment 2.92 909 0 615 408 0 276

Air-conditioning equipment

Uses air-conditioning equipment 27.13 935 842 746 459 413 366

Does not use air-conditioning 

equipment 5.05 877 750 0 438 375 0

Fuel used by main water heater

Natural gas 13.51 919 846 588 444 409 284

Electricity 17.57 933 815 669 469 410 336

Propane 0.30 949 830 630 524 458 348

Fuel oil or kerosene 0.67 891 860 418 396 382 186

Some other fuelg 0.12 905 391 485 301 130 161

Indoor light bulbs used at least 4 

hours a day

0 to 2 14.93 880 763 583 465 403 308

3 to 5 8.80 932 838 626 444 399 298

6 to 9 5.38 952 882 681 441 409 315

10 to 19 2.63 1,073 994 761 472 438 335

20 or more 0.44 1,173 1,164 827 493 489 347

Total number of rooms (excluding 

bathrooms)

1 or 2 4.33 632 560 448 407 361 289

3 7.57 765 658 497 446 384 290

4 10.02 900 804 603 434 388 291

5 6.30 1,066 970 744 463 422 323

6 2.64 1,297 1,162 968 533 477 397

7 0.65 1,367 1,279 832 486 455 296

8 0.31 1,567 1,430 929 592 540 351

9 or more 0.36 2,059 2,028 1,193 551 542 319

Number of bedrooms

0 1.68 565 490 396 338 293 237

1 12.38 751 675 486 523 470 338

2 14.56 1,010 890 710 444 391 312

3 2.98 1,283 1,190 867 412 382 278

4 0.37 1,620 1,478 1,067 389 355 257

5 or more 0.19 2,087 2,057 1,142 520 512 285

Adequacy of insulation

Well insulated 6.81 946 850 682 496 445 358

Adequately insulated 16.63 931 832 642 466 416 321

Poorly insulated 6.85 918 840 591 425 389 274

No insulation 1.88 839 668 454 365 290 197
Number of 

housing units 

(million)

Total apartment 

unitsa Totalb Heatedc Cooledc Totalb Heated Cooled

All homes 32.18 926 828 629 456 407 310

Table HC10.15 Average square footage of apartment units, 2020

Average square footage 

per housing unit

Average square footage 

per household member

Type of glass in windows

Single-pane glass 15.79 884 773 590 446 390 297

Double-pane glass 16.05 965 880 667 464 423 320

Triple-pane glass 0.34 1,001 901 638 542 488 345

Number of household members

1 member 14.47 850 770 566 850 770 566

2 members 9.82 956 846 683 478 423 342

3 members 3.54 984 893 629 328 298 210

4 members 2.58 1,015 898 668 254 225 167

5 members 1.04 1,133 976 784 227 195 157

6 or more members 0.71 1,133 948 793 159 133 111

2020 annual household income

Less than $5,000 2.27 839 734 492 344 302 202

$5,000 to $9,999 2.14 829 748 502 433 390 262

$10,000 to $19,999 4.22 845 768 492 445 405 259

$20,000 to $39,999 7.76 908 819 635 457 413 320

$40,000 to $59,999 5.27 924 810 649 463 406 325

$60,000 to $99,999 5.62 942 860 646 466 425 319

$100,000 to $149,999 2.59 1,024 902 754 473 416 348

$150,000 or more 2.31 1,168 1,010 882 555 480 419

Ownership of housing unith

Owned 4.32 1,191 1,040 888 609 532 454

Rented 27.86 885 795 589 433 389 288

Data source: U.S. Energy Information Administration, Office of Energy Demand and Integrated Statistics, Form EIA-457A of the 2020 Residential Energy Consumption Survey

Notes: Because of rounding, data may not sum to totals. See RECS Terminology for the definitions of terms used in these tables. 

a Total apartment units includes all primary occupied housing units in apartment buildings in the 50 states and the District of Columbia. Vacant housing units, seasonal units, second 

homes, military houses, and group quarters are excluded.

b Total square footage includes all basements, finished or conditioned (heated or cooled) areas of attics, and conditioned garage space that is attached to the home. Unconditioned 

and unfinished areas in attics and attached garages are excluded. The square footage of the home is based on respondent reports. Previous RECS cycles calculated square footage 

based on interviewer measurements. For households that did not report an exact square footage estimate, the square footage of the home was imputed based on a reported 

square footage range and/or characteristics of the home. See 2020 RECS Square Footage Methodology for full details about data collection and processing.

c

 When calculating average heated and cooled square footage, all housing units are considered, including those that are not heated or cooled. 

d Housing units are classified using criteria created by the U.S. Census Bureau based on 2010 Census data. Urbanized areas are densely settled groupings of blocks or tracts with 

50,000 or more people, while urban clusters have at least 2,500 but less than 50,000 people. All other areas are rural.

e The Building America program, sponsored by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE), created these climate regions. We 

combined climate regions for this publication. The Subarctic region is included with data for Very-cold/Cold .

f Households that use propane only for outdoor grilling are excluded from the RECS estimate of households using propane. 

g Some other fuel includes coal and district steam.

h Rented includes households that occupy their primary housing unit without paying rent. 

Q = Data withheld because either the relative standard error (RSE) was greater than 50% or fewer than 10 households were in the reporting sample.

N = No households in reporting sample. 
Data release date: March 2023

RSEs for number 

of housing units

Total apartment 

unitsa Totalb Heatedc Cooledc Totalb Heated Cooled

All homes 0.00 0.70 1.04 1.42 1.16 1.54 1.57

Census region and division

Northeast 0.00 1.57 1.70 3.17 2.61 2.58 3.39

New England 0.00 2.22 2.33 4.70 4.05 4.10 5.34

Middle Atlantic 0.00 1.95 2.14 3.70 3.30 3.33 4.25

Midwest 0.00 1.67 1.80 3.54 3.53 3.64 4.26

East North Central 0.00 1.89 2.10 4.12 4.27 4.46 4.88

West North Central 0.00 2.91 3.11 5.35 5.25 5.26 7.78

South 0.00 1.35 2.38 1.83 2.57 3.49 2.54

South Atlantic 0.00 1.77 3.34 2.58 3.08 4.29 3.32

East South Central 0.00 2.44 2.68 4.58 3.45 3.86 4.89

West South Central 0.00 2.51 3.68 3.74 4.58 5.52 5.19

West 0.00 1.14 2.59 3.66 2.74 3.56 4.53

Mountain 0.00 2.69 3.72 5.71 4.37 4.90 6.70

Mountain North 0.00 4.45 4.90 11.06 6.69 7.66 12.22

Mountain South 0.00 2.51 5.55 4.52 6.03 7.02 6.83

Pacific 0.00 1.42 3.41 4.96 2.99 4.34 5.42

Census urban/rural classificationd

Urban 0.30 0.73 1.06 1.49 1.15 1.54 1.61

Urbanized area 0.53 0.77 1.10 1.51 1.20 1.61 1.64

Urban cluster 6.19 2.73 3.03 5.39 5.15 5.65 6.74

Rural 10.45 4.15 5.16 5.38 7.10 8.13 8.14

Climate regione

Very cold/Cold 1.17 1.48 1.56 2.82 2.07 2.11 2.93

Mixed-humid 1.77 1.33 1.49 2.09 2.29 2.37 2.42

Mixed-dry/Hot-dry 3.02 1.49 4.23 4.06 4.09 6.07 5.35

Hot-humid 2.21 2.10 4.42 2.66 3.14 4.84 3.15

Marine 5.72 2.16 3.89 13.00 4.48 5.86 13.70

Year of construction

Before 1950 4.06 2.06 2.44 5.04 3.92 4.14 5.92

1950 to 1959 7.64 2.76 4.12 6.90 6.36 7.96 9.32

1960 to 1969 4.45 1.88 2.90 4.15 3.80 4.44 4.87

1970 to 1979 3.37 1.27 2.48 3.25 2.78 3.73 3.76

1980 to 1989 3.56 1.64 2.52 4.03 3.87 4.33 5.39

1990 to 1999 5.77 2.64 3.40 4.75 4.44 4.69 6.49

2000 to 2009 4.65 2.01 3.14 3.41 3.53 4.65 4.31

2010 to 2015 6.03 2.86 3.74 3.76 6.43 6.98 7.00

2016 to 2020 7.60 3.45 4.06 5.33 6.46 6.64 7.39

Fuels used for any use (more than one 

may apply)

Electricity 0.00 0.70 1.04 1.42 1.16 1.54 1.57

Natural gas 1.45 0.99 1.30 1.92 1.81 2.08 2.42

Propanef 11.39 5.91 7.23 10.63 11.44 13.23 15.18

Wood 12.98 4.64 5.00 11.11 8.04 8.21 11.83

Fuel oil or kerosene 11.11 3.42 3.79 8.04 7.94 8.52 10.98

RSEs for average square footage 

per housing unit

RSEs for average square footage 

per household member

Relative standard errors (RSEs) for Table HC10.15 Average square footage of apartment units, 2020
RSEs for number 

of housing units

Total apartment 

unitsa Totalb Heatedc Cooledc Totalb Heated Cooled

All homes 0.00 0.70 1.04 1.42 1.16 1.54 1.57

RSEs for average square footage 

per housing unit

RSEs for average square footage 

per household member

Relative standard errors (RSEs) for Table HC10.15 Average square footage of apartment units, 2020

Main space heating fuel

Natural gas 2.12 1.30 1.30 2.70 2.26 2.26 3.10

Electricity 1.57 0.97 1.09 1.88 1.74 1.82 2.30

Fuel oil or kerosene 12.66 3.31 3.31 8.24 8.34 8.34 11.51

Propane 20.22 5.83 5.83 12.45 18.48 18.48 17.87

Wood 38.14 12.12 12.12 54.80 22.84 22.84 49.96

Some other fuelg 100.48 0.00 0.00 0.00 0.00 0.00 0.00

Does not use heating equipment 6.45 2.28 0.00 5.49 5.44 0.00 7.58

Air-conditioning equipment

Uses air-conditioning equipment 0.71 0.84 1.15 1.09 1.34 1.74 1.49

Does not use air-conditioning 

equipment 3.83 1.87 3.22 0.00 3.60 4.35 0.00

Fuel used by main water heater

Natural gas 1.94 1.21 1.64 2.55 1.92 2.26 2.84

Electricity 1.46 0.94 1.34 1.84 1.55 2.02 2.03

Propane 16.86 9.81 12.99 17.49 11.70 17.66 19.73

Fuel oil or kerosene 13.74 4.03 4.65 8.67 9.69 10.59 12.39

Some other fuelg 33.74 9.79 28.64 28.82 8.61 31.27 28.19

Indoor light bulbs used at least 4 

hours a day

0 to 2 2.22 0.92 1.61 1.91 1.88 2.62 2.49

3 to 5 3.20 1.20 1.53 2.69 2.90 3.28 3.66

6 to 9 3.89 1.93 2.21 3.41 3.43 3.81 4.75

10 to 19 6.50 3.38 4.06 5.39 4.67 5.26 6.57

20 or more 19.51 6.98 7.15 11.48 5.97 6.00 10.20

Total number of rooms (excluding 

bathrooms)

1 or 2 5.10 2.17 2.73 3.71 6.05 6.38 6.82

3 2.87 1.11 2.25 2.78 3.13 4.12 3.90

4 2.79 0.81 1.55 2.57 2.23 2.65 3.12

5 3.86 1.09 1.92 2.98 2.74 3.08 3.73

6 6.89 1.75 3.11 3.93 4.60 5.40 5.94

7 14.64 6.45 6.47 12.50 11.28 10.46 15.32

8 17.45 6.27 8.76 16.78 12.45 11.57 20.12

9 or more 15.58 8.43 8.56 17.68 14.97 15.02 19.30

Number of bedrooms

0 9.33 3.90 5.29 7.43 8.91 10.10 11.16

1 2.15 1.03 1.68 1.86 2.06 2.56 2.63

2 1.85 0.85 1.46 1.77 1.84 2.45 2.44

3 5.51 1.63 1.96 5.32 3.38 3.67 5.91

4 17.61 5.57 8.09 12.02 9.69 8.49 13.68

5 or more 23.28 16.47 16.72 35.02 28.23 28.35 37.07

Adequacy of insulation

Well insulated 3.49 1.82 2.77 2.76 2.75 3.55 3.41

Adequately insulated 1.96 0.85 1.25 2.06 1.84 2.27 2.45

Poorly insulated 3.92 1.70 2.33 3.08 2.76 3.20 3.56

No insulation 8.95 3.19 6.20 6.85 6.50 8.41 8.70
RSEs for number 

of housing units

Total apartment 

unitsa Totalb Heatedc Cooledc Totalb Heated Cooled

All homes 0.00 0.70 1.04 1.42 1.16 1.54 1.57

RSEs for average square footage 

per housing unit

RSEs for average square footage 

per household member

Relative standard errors (RSEs) for Table HC10.15 Average square footage of apartment units, 2020

Type of glass in windows

Single-pane glass 1.97 1.16 1.74 1.93 1.99 2.59 2.74

Double-pane glass 1.92 0.95 1.35 2.09 1.93 2.35 2.18

Triple-pane glass 17.72 7.02 9.05 12.11 13.83 16.35 16.36

Number of household members

1 member 1.80 1.24 1.77 2.00 1.24 1.77 2.00

2 members 2.67 1.43 2.09 2.71 1.43 2.09 2.71

3 members 4.73 1.95 2.94 4.47 1.95 2.94 4.47

4 members 6.57 2.44 3.47 5.09 2.44 3.47 5.09

5 members 12.61 4.50 6.74 7.56 4.50 6.74 7.56

6 or more members 13.14 6.32 9.50 11.87 8.07 11.51 12.88

2020 annual household income

Less than $5,000 7.02 2.63 4.25 6.05 5.05 6.22 7.52

$5,000 to $9,999 6.80 3.43 4.36 6.52 6.02 6.11 8.17

$10,000 to $19,999 5.76 2.22 2.41 3.51 5.04 5.31 5.63

$20,000 to $39,999 3.67 1.54 2.19 2.73 2.74 3.09 3.36

$40,000 to $59,999 4.24 1.39 2.52 3.56 2.79 3.46 4.36

$60,000 to $99,999 3.45 1.41 2.10 3.32 2.76 3.64 4.00

$100,000 to $149,999 6.87 2.55 3.68 5.06 4.30 4.17 6.28

$150,000 or more 5.72 3.12 4.50 5.21 4.29 5.19 5.42

Ownership of housing unith

Owned 4.13 2.14 3.29 3.92 3.24 3.90 4.68

Rented 0.64 0.69 1.05 1.38 1.28 1.64 1.71

Data source: U.S. Energy Information Administration, Office of Energy Demand and Integrated Statistics, Form EIA-457A of the 2020 Residential Energy Consumption Survey

Notes: See RECS Terminology for the definitions of terms used in these tables. 

a Total apartment units includes all primary occupied housing units in apartment buildings in the 50 states and the District of Columbia. Vacant housing units, seasonal units, second 

homes, military houses, and group quarters are excluded.

b Total square footage includes all basements, finished or conditioned (heated or cooled) areas of attics, and conditioned garage space that is attached to the home. Unconditioned 

and unfinished areas in attics and attached garages are excluded. The square footage of the home is based on respondent reports. Previous RECS cycles calculated square footage 

based on interviewer measurements. For households that did not report an exact square footage estimate, the square footage of the home was imputed based on a reported 

square footage range and/or characteristics of the home. See 2020 RECS Square Footage Methodology for full details about data collection and processing.

c

 When calculating average heated and cooled square footage, all housing units are considered, including those that are not heated or cooled. 

d Housing units are classified using criteria created by the U.S. Census Bureau based on 2010 Census data. Urbanized areas are densely settled groupings of blocks or tracts with 

50,000 or more people, while urban clusters have at least 2,500 but less than 50,000 people. All other areas are rural.

e The Building America program, sponsored by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE), created these climate regions. We 

combined climate regions for this publication. The Subarctic region is included with data for Very-cold/Cold .

f Households that use propane only for outdoor grilling are excluded from the RECS estimate of households using propane. 

g Some other fuel includes coal and district steam.

h Rented includes households that occupy their primary housing unit without paying rent.