| 2000 | 2017 | 2018 | ||
|---|---|---|---|---|
| Total Single Detached Heating System Stock (thousands) | 869.2 | 1,001.6 | 1,009.6 | |
Heating System Stock by Heating System Type (thousands) | ||||
| Heating Oil – Normal Efficiency | 15.3 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 14.3 | 33.5 | 33.5 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 212.4 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 156.9 | 202.1 | 189.0 | |
| Natural Gas – High Efficiency | 88.6 | 298.3 | 315.9 | |
| Electric | 242.8 | 270.8 | 271.1 | |
| Heat Pump | 24.8 | 45.4 | 46.7 | |
| Other1 | 14.5 | 14.4 | 14.4 | |
| Wood | 0.0 | 0.0 | 0.0 | |
Dual Systems | ||||
| Wood/Electric | 60.4 | 80.6 | 81.7 | |
| Wood/Heating Oil | 21.1 | 28.3 | 28.7 | |
| Natural Gas/Electric | 12.4 | 18.5 | 18.8 | |
| Heating Oil/Electric | 6.0 | 9.7 | 9.9 | |
Shares (%) | ||||
| Heating Oil – Normal Efficiency | 1.8 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 1.6 | 3.3 | 3.3 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 24.4 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 18.0 | 20.2 | 18.7 | |
| Natural Gas – High Efficiency | 10.2 | 29.8 | 31.3 | |
| Electric | 27.9 | 27.0 | 26.9 | |
| Heat Pump | 2.8 | 4.5 | 4.6 | |
| Other1 | 1.7 | 1.4 | 1.4 | |
| Wood | 0.0 | 0.0 | 0.0 | |
Dual Systems | ||||
| Wood/Electric | 6.9 | 8.0 | 8.1 | |
| Wood/Heating Oil | 2.4 | 2.8 | 2.8 | |
| Natural Gas/Electric | 1.4 | 1.8 | 1.9 | |
| Heating Oil/Electric | 0.7 | 1.0 | 1.0 | |