| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total Heating System Stock (thousands) | 448.9 | 451.9 | 454.9 | 458.3 | 462.6 | 467.0 | 471.4 | 476.3 | 481.9 | 487.3 | 492.1 | 497.6 | 502.7 | 509.0 | 514.3 | 519.6 | 525.2 | 530.6 | |
Heating System Stock by Building Type (thousands) | |||||||||||||||||||
| Single Detached | 302.3 | 304.6 | 307.1 | 309.8 | 312.9 | 316.3 | 319.5 | 322.7 | 326.0 | 328.8 | 332.4 | 335.6 | 338.5 | 342.0 | 344.7 | 347.2 | 349.2 | 351.7 | |
| Single Attached | 28.8 | 28.9 | 29.1 | 29.2 | 29.4 | 29.6 | 29.9 | 30.3 | 30.8 | 31.3 | 31.8 | 32.7 | 33.4 | 34.2 | 35.4 | 36.2 | 37.1 | 38.0 | |
| Apartments | 107.7 | 108.2 | 108.5 | 108.9 | 109.8 | 110.5 | 111.4 | 112.5 | 114.2 | 116.2 | 116.8 | 118.2 | 119.5 | 121.3 | 122.8 | 124.8 | 127.4 | 129.3 | |
| Mobile Homes | 10.1 | 10.2 | 10.3 | 10.4 | 10.5 | 10.6 | 10.7 | 10.8 | 10.9 | 11.0 | 11.1 | 11.2 | 11.3 | 11.4 | 11.4 | 11.5 | 11.6 | 11.6 | |
Shares (%) | |||||||||||||||||||
| Single Detached | 67.3 | 67.4 | 67.5 | 67.6 | 67.6 | 67.7 | 67.8 | 67.7 | 67.6 | 67.5 | 67.5 | 67.4 | 67.3 | 67.2 | 67.0 | 66.8 | 66.5 | 66.3 | |
| Single Attached | 6.4 | 6.4 | 6.4 | 6.4 | 6.3 | 6.3 | 6.3 | 6.4 | 6.4 | 6.4 | 6.5 | 6.6 | 6.6 | 6.7 | 6.9 | 7.0 | 7.1 | 7.2 | |
| Apartments | 24.0 | 23.9 | 23.8 | 23.8 | 23.7 | 23.7 | 23.6 | 23.6 | 23.7 | 23.8 | 23.7 | 23.8 | 23.8 | 23.8 | 23.9 | 24.0 | 24.3 | 24.4 | |
| Mobile Homes | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.3 | 2.2 | 2.2 | 2.2 | 2.2 | 2.2 | 2.2 | 2.2 | |
Heating System Stock by Heating System Type (thousands) | |||||||||||||||||||
| Heating Oil – Normal Efficiency | 3.4 | 2.4 | 1.7 | 1.1 | 0.6 | 0.4 | 0.2 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 5.7 | 5.9 | 6.1 | 6.3 | 6.3 | 6.3 | 6.3 | 6.3 | 6.3 | 6.3 | 6.2 | 6.2 | 6.2 | 6.1 | 6.0 | 5.7 | 5.3 | 4.9 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 127.1 | 117.5 | 107.6 | 97.6 | 87.3 | 77.3 | 67.5 | 58.0 | 48.9 | 40.5 | 32.6 | 24.6 | 17.0 | 10.3 | 4.0 | 1.3 | 0.3 | 0.2 | |
| Natural Gas – Medium Efficiency | 73.3 | 78.8 | 83.2 | 87.5 | 90.9 | 93.7 | 96.5 | 99.6 | 100.5 | 101.3 | 100.6 | 99.6 | 98.0 | 95.7 | 92.6 | 88.2 | 82.9 | 77.0 | |
| Natural Gas – High Efficiency | 58.5 | 66.0 | 73.1 | 81.2 | 89.0 | 96.8 | 106.5 | 113.6 | 122.0 | 131.5 | 141.1 | 151.4 | 161.1 | 171.3 | 181.3 | 190.1 | 198.6 | 207.1 | |
| Electric | 138.0 | 138.2 | 140.3 | 140.6 | 144.2 | 148.3 | 150.6 | 155.3 | 160.8 | 164.6 | 168.9 | 173.4 | 177.6 | 182.3 | 186.8 | 190.3 | 193.8 | 196.8 | |
| Heat Pump | 9.0 | 9.4 | 9.9 | 10.4 | 10.9 | 11.4 | 11.9 | 12.4 | 13.0 | 13.5 | 14.1 | 14.6 | 15.2 | 15.8 | 16.4 | 16.9 | 17.4 | 17.9 | |
| Other1 | 4.4 | 4.3 | 4.3 | 4.3 | 4.3 | 4.2 | 4.1 | 4.0 | 3.8 | 3.6 | 3.4 | 3.3 | 3.1 | 2.9 | 2.8 | 2.6 | 2.5 | 2.3 | |
| Wood | 10.7 | 10.3 | 9.4 | 9.7 | 9.1 | 8.3 | 7.3 | 6.3 | 5.5 | 4.6 | 3.4 | 2.6 | 2.3 | 2.1 | 1.9 | 1.7 | 1.5 | 1.3 | |
Dual Systems | |||||||||||||||||||
| Wood/Electric | 14.9 | 15.1 | 15.3 | 15.5 | 15.7 | 15.9 | 16.1 | 16.3 | 16.5 | 16.7 | 16.8 | 17.0 | 17.2 | 17.3 | 17.5 | 17.6 | 17.7 | 17.8 | |
| Wood/Heating Oil | 2.5 | 2.5 | 2.6 | 2.6 | 2.6 | 2.7 | 2.7 | 2.7 | 2.8 | 2.8 | 2.9 | 2.9 | 2.9 | 3.0 | 3.0 | 3.0 | 3.0 | 3.1 | |
| Natural Gas/Electric | 0.3 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.4 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | |
| Heating Oil/Electric | 1.1 | 1.2 | 1.2 | 1.3 | 1.3 | 1.3 | 1.4 | 1.4 | 1.5 | 1.5 | 1.5 | 1.6 | 1.6 | 1.7 | 1.7 | 1.7 | 1.8 | 1.8 | |
Shares (%) | |||||||||||||||||||
| Heating Oil – Normal Efficiency | 0.8 | 0.5 | 0.4 | 0.2 | 0.1 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 1.3 | 1.3 | 1.3 | 1.4 | 1.4 | 1.3 | 1.3 | 1.3 | 1.3 | 1.3 | 1.3 | 1.3 | 1.2 | 1.2 | 1.2 | 1.1 | 1.0 | 0.9 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 28.3 | 26.0 | 23.6 | 21.3 | 18.9 | 16.5 | 14.3 | 12.2 | 10.1 | 8.3 | 6.6 | 4.9 | 3.4 | 2.0 | 0.8 | 0.3 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 16.3 | 17.4 | 18.3 | 19.1 | 19.6 | 20.1 | 20.5 | 20.9 | 20.9 | 20.8 | 20.4 | 20.0 | 19.5 | 18.8 | 18.0 | 17.0 | 15.8 | 14.5 | |
| Natural Gas – High Efficiency | 13.0 | 14.6 | 16.1 | 17.7 | 19.2 | 20.7 | 22.6 | 23.8 | 25.3 | 27.0 | 28.7 | 30.4 | 32.0 | 33.7 | 35.2 | 36.6 | 37.8 | 39.0 | |
| Electric | 30.7 | 30.6 | 30.8 | 30.7 | 31.2 | 31.8 | 31.9 | 32.6 | 33.4 | 33.8 | 34.3 | 34.8 | 35.3 | 35.8 | 36.3 | 36.6 | 36.9 | 37.1 | |
| Heat Pump | 2.0 | 2.1 | 2.2 | 2.3 | 2.3 | 2.4 | 2.5 | 2.6 | 2.7 | 2.8 | 2.9 | 2.9 | 3.0 | 3.1 | 3.2 | 3.2 | 3.3 | 3.4 | |
| Other1 | 1.0 | 1.0 | 1.0 | 0.9 | 0.9 | 0.9 | 0.9 | 0.8 | 0.8 | 0.7 | 0.7 | 0.7 | 0.6 | 0.6 | 0.5 | 0.5 | 0.5 | 0.4 | |
| Wood | 2.4 | 2.3 | 2.1 | 2.1 | 2.0 | 1.8 | 1.5 | 1.3 | 1.1 | 0.9 | 0.7 | 0.5 | 0.5 | 0.4 | 0.4 | 0.3 | 0.3 | 0.3 | |
Dual Systems | |||||||||||||||||||
| Wood/Electric | 3.3 | 3.3 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | 3.4 | |
| Wood/Heating Oil | 0.5 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | |
| Natural Gas/Electric | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | |
| Heating Oil/Electric | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | 0.3 | |