| 2000 | 2001 | 2002 | 2003 | 2004 | 2005 | 2006 | 2007 | 2008 | 2009 | 2010 | 2011 | 2012 | 2013 | 2014 | 2015 | 2016 | 2017 | ||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Total Heating System Stock (thousands) | 934.6 | 942.8 | 952.2 | 964.6 | 978.0 | 989.4 | 1,000.2 | 1,011.4 | 1,023.1 | 1,033.7 | 1,044.5 | 1,055.3 | 1,066.0 | 1,077.1 | 1,085.2 | 1,091.6 | 1,099.0 | 1,105.4 | |
Heating System Stock by Building Type (thousands) | |||||||||||||||||||
| Single Detached | 661.9 | 667.9 | 674.7 | 683.8 | 692.2 | 699.9 | 706.9 | 713.7 | 721.1 | 727.7 | 734.5 | 740.7 | 746.2 | 751.4 | 755.6 | 759.0 | 762.2 | 765.3 | |
| Single Attached | 62.2 | 62.7 | 63.4 | 64.3 | 65.9 | 67.3 | 68.8 | 70.3 | 71.9 | 73.5 | 75.0 | 76.6 | 78.4 | 79.8 | 80.9 | 81.8 | 82.8 | 83.9 | |
| Apartments | 175.0 | 176.3 | 177.8 | 179.6 | 182.6 | 184.5 | 186.5 | 189.0 | 191.3 | 193.5 | 195.7 | 198.3 | 201.5 | 205.9 | 208.5 | 210.5 | 213.4 | 215.4 | |
| Mobile Homes | 35.7 | 36.0 | 36.4 | 36.9 | 37.3 | 37.7 | 38.1 | 38.4 | 38.8 | 39.1 | 39.4 | 39.6 | 39.9 | 40.1 | 40.3 | 40.4 | 40.6 | 40.8 | |
Shares (%) | |||||||||||||||||||
| Single Detached | 70.8 | 70.8 | 70.9 | 70.9 | 70.8 | 70.7 | 70.7 | 70.6 | 70.5 | 70.4 | 70.3 | 70.2 | 70.0 | 69.8 | 69.6 | 69.5 | 69.4 | 69.2 | |
| Single Attached | 6.7 | 6.6 | 6.7 | 6.7 | 6.7 | 6.8 | 6.9 | 6.9 | 7.0 | 7.1 | 7.2 | 7.3 | 7.4 | 7.4 | 7.5 | 7.5 | 7.5 | 7.6 | |
| Apartments | 18.7 | 18.7 | 18.7 | 18.6 | 18.7 | 18.6 | 18.6 | 18.7 | 18.7 | 18.7 | 18.7 | 18.8 | 18.9 | 19.1 | 19.2 | 19.3 | 19.4 | 19.5 | |
| Mobile Homes | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 | 3.8 | 3.7 | 3.7 | 3.7 | 3.7 | 3.7 | 3.7 | |
Heating System Stock by Heating System Type (thousands) | |||||||||||||||||||
| Heating Oil – Normal Efficiency | 158.3 | 141.2 | 123.7 | 107.5 | 93.4 | 78.6 | 65.1 | 52.3 | 40.7 | 27.0 | 17.7 | 13.5 | 11.3 | 9.4 | 6.6 | 5.0 | 3.3 | 1.6 | |
| Heating Oil – Medium Efficiency | 193.8 | 212.7 | 232.5 | 248.0 | 260.4 | 271.0 | 278.7 | 284.2 | 286.8 | 288.0 | 286.8 | 282.9 | 277.7 | 271.5 | 265.0 | 255.3 | 244.2 | 233.6 | |
| 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 | 2.2 | 2.2 | 2.2 | 2.1 | 2.1 | 1.9 | 1.8 | 1.6 | 1.4 | 1.2 | 1.0 | 0.9 | 0.7 | 0.5 | 0.4 | 0.3 | 0.2 | 0.2 | |
| Natural Gas – Medium Efficiency | 5.2 | 5.2 | 5.3 | 5.4 | 5.5 | 5.5 | 5.6 | 5.6 | 5.7 | 5.6 | 5.6 | 5.6 | 5.5 | 5.5 | 5.4 | 5.3 | 5.3 | 5.2 | |
| Natural Gas – High Efficiency | 5.5 | 5.6 | 5.9 | 6.3 | 6.5 | 7.1 | 8.3 | 10.0 | 10.6 | 11.0 | 11.4 | 12.3 | 12.6 | 12.9 | 13.2 | 14.9 | 18.4 | 19.8 | |
| Electric | 340.5 | 345.9 | 350.2 | 358.8 | 370.0 | 382.6 | 397.3 | 412.7 | 431.7 | 455.1 | 478.7 | 500.5 | 522.1 | 544.5 | 564.6 | 582.4 | 600.6 | 617.1 | |
| Heat Pump | 20.0 | 21.1 | 22.2 | 23.4 | 24.6 | 25.8 | 26.9 | 28.0 | 29.2 | 30.3 | 31.4 | 32.2 | 33.1 | 34.0 | 34.8 | 35.6 | 36.4 | 37.4 | |
| Other1 | 10.3 | 10.3 | 10.2 | 11.3 | 12.4 | 13.4 | 14.4 | 15.4 | 16.4 | 17.4 | 17.3 | 17.0 | 16.7 | 16.5 | 16.1 | 15.7 | 15.4 | 15.5 | |
| Wood | 56.4 | 55.0 | 55.1 | 55.5 | 55.6 | 55.2 | 53.3 | 52.0 | 50.5 | 47.2 | 43.8 | 40.3 | 36.8 | 33.3 | 30.7 | 29.1 | 27.7 | 27.1 | |
Dual Systems | |||||||||||||||||||
| Wood/Electric | 72.6 | 73.1 | 73.5 | 74.0 | 74.5 | 74.7 | 74.7 | 74.8 | 74.9 | 75.0 | 74.9 | 74.5 | 74.2 | 74.0 | 73.7 | 73.4 | 73.1 | 73.3 | |
| Wood/Heating Oil | 65.6 | 66.2 | 66.9 | 67.5 | 68.1 | 68.5 | 68.9 | 69.2 | 69.7 | 70.1 | 70.1 | 69.8 | 69.4 | 69.1 | 68.7 | 68.4 | 68.2 | 68.3 | |
| Natural Gas/Electric | 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 | |
| Heating Oil/Electric | 4.3 | 4.4 | 4.6 | 4.7 | 4.9 | 5.0 | 5.2 | 5.3 | 5.4 | 5.6 | 5.7 | 5.8 | 5.9 | 6.0 | 6.1 | 6.2 | 6.3 | 6.4 | |
Shares (%) | |||||||||||||||||||
| Heating Oil – Normal Efficiency | 16.9 | 15.0 | 13.0 | 11.1 | 9.6 | 7.9 | 6.5 | 5.2 | 4.0 | 2.6 | 1.7 | 1.3 | 1.1 | 0.9 | 0.6 | 0.5 | 0.3 | 0.1 | |
| Heating Oil – Medium Efficiency | 20.7 | 22.6 | 24.4 | 25.7 | 26.6 | 27.4 | 27.9 | 28.1 | 28.0 | 27.9 | 27.5 | 26.8 | 26.1 | 25.2 | 24.4 | 23.4 | 22.2 | 21.1 | |
| 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 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.2 | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | |
| Natural Gas – High Efficiency | 0.6 | 0.6 | 0.6 | 0.7 | 0.7 | 0.7 | 0.8 | 1.0 | 1.0 | 1.1 | 1.1 | 1.2 | 1.2 | 1.2 | 1.2 | 1.4 | 1.7 | 1.8 | |
| Electric | 36.4 | 36.7 | 36.8 | 37.2 | 37.8 | 38.7 | 39.7 | 40.8 | 42.2 | 44.0 | 45.8 | 47.4 | 49.0 | 50.5 | 52.0 | 53.4 | 54.7 | 55.8 | |
| Heat Pump | 2.1 | 2.2 | 2.3 | 2.4 | 2.5 | 2.6 | 2.7 | 2.8 | 2.9 | 2.9 | 3.0 | 3.1 | 3.1 | 3.2 | 3.2 | 3.3 | 3.3 | 3.4 | |
| Other1 | 1.1 | 1.1 | 1.1 | 1.2 | 1.3 | 1.4 | 1.4 | 1.5 | 1.6 | 1.7 | 1.7 | 1.6 | 1.6 | 1.5 | 1.5 | 1.4 | 1.4 | 1.4 | |
| Wood | 6.0 | 5.8 | 5.8 | 5.8 | 5.7 | 5.6 | 5.3 | 5.1 | 4.9 | 4.6 | 4.2 | 3.8 | 3.5 | 3.1 | 2.8 | 2.7 | 2.5 | 2.4 | |
Dual Systems | |||||||||||||||||||
| Wood/Electric | 7.8 | 7.8 | 7.7 | 7.7 | 7.6 | 7.5 | 7.5 | 7.4 | 7.3 | 7.3 | 7.2 | 7.1 | 7.0 | 6.9 | 6.8 | 6.7 | 6.7 | 6.6 | |
| Wood/Heating Oil | 7.0 | 7.0 | 7.0 | 7.0 | 7.0 | 6.9 | 6.9 | 6.8 | 6.8 | 6.8 | 6.7 | 6.6 | 6.5 | 6.4 | 6.3 | 6.3 | 6.2 | 6.2 | |
| Natural Gas/Electric | 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 | |
| Heating Oil/Electric | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.5 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | |