| 2000 | 2017 | 2018 | ||
|---|---|---|---|---|
| Total Single Detached Heating System Stock (thousands) | 733.7 | 1,038.1 | 1,054.4 | |
Heating System Stock by Heating System Type (thousands) | ||||
| Heating Oil – Normal Efficiency | 3.6 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 1.3 | 7.0 | 7.2 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 328.2 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 320.8 | 445.7 | 421.2 | |
| Natural Gas – High Efficiency | 37.5 | 488.7 | 527.4 | |
| Electric | 11.4 | 41.7 | 42.0 | |
| Heat Pump | 13.5 | 33.0 | 34.1 | |
| Other1 | 10.6 | 11.8 | 11.9 | |
| Wood | 0.5 | 0.0 | 0.0 | |
Dual Systems | ||||
| Wood/Electric | 0.9 | 1.5 | 1.5 | |
| Wood/Heating Oil | 3.1 | 4.9 | 5.0 | |
| Natural Gas/Electric | 2.1 | 3.9 | 4.0 | |
| Heating Oil/Electric | 0.1 | 0.1 | 0.1 | |
Shares (%) | ||||
| Heating Oil – Normal Efficiency | 0.5 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 0.2 | 0.7 | 0.7 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 44.7 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 43.7 | 42.9 | 39.9 | |
| Natural Gas – High Efficiency | 5.1 | 47.1 | 50.0 | |
| Electric | 1.6 | 4.0 | 4.0 | |
| Heat Pump | 1.8 | 3.2 | 3.2 | |
| Other1 | 1.4 | 1.1 | 1.1 | |
| Wood | 0.1 | 0.0 | 0.0 | |
Dual Systems | ||||
| Wood/Electric | 0.1 | 0.1 | 0.1 | |
| Wood/Heating Oil | 0.4 | 0.5 | 0.5 | |
| Natural Gas/Electric | 0.3 | 0.4 | 0.4 | |
| Heating Oil/Electric | 0.0 | 0.0 | 0.0 | |