| 2000 | 2017 | 2018 | ||
|---|---|---|---|---|
| Total Single Attached Heating System Stock (thousands) | 133.7 | 241.8 | 249.1 | |
Heating System Stock by Heating System Type (thousands) | ||||
| Heating Oil – Normal Efficiency | 0.9 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 0.3 | 1.7 | 1.8 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 62.6 | 1.0 | 0.2 | |
| Natural Gas – Medium Efficiency | 57.6 | 91.7 | 87.7 | |
| Natural Gas – High Efficiency | 6.9 | 131.5 | 143.1 | |
| Electric | 2.3 | 10.5 | 10.8 | |
| Heat Pump | 0.5 | 1.5 | 1.6 | |
| Other1 | 1.9 | 2.8 | 2.9 | |
| Wood | 0.4 | 0.6 | 0.7 | |
Dual Systems | ||||
| Wood/Electric | 0.0 | 0.0 | 0.0 | |
| Wood/Heating Oil | 0.0 | 0.0 | 0.0 | |
| Natural Gas/Electric | 0.1 | 0.3 | 0.3 | |
| Heating Oil/Electric | 0.0 | 0.0 | 0.0 | |
Shares (%) | ||||
| Heating Oil – Normal Efficiency | 0.6 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 0.3 | 0.7 | 0.7 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 46.9 | 0.4 | 0.1 | |
| Natural Gas – Medium Efficiency | 43.1 | 37.9 | 35.2 | |
| Natural Gas – High Efficiency | 5.2 | 54.4 | 57.5 | |
| Electric | 1.7 | 4.3 | 4.3 | |
| Heat Pump | 0.4 | 0.6 | 0.7 | |
| Other1 | 1.4 | 1.2 | 1.2 | |
| Wood | 0.3 | 0.3 | 0.3 | |
Dual Systems | ||||
| Wood/Electric | 0.0 | 0.0 | 0.0 | |
| Wood/Heating Oil | 0.0 | 0.0 | 0.0 | |
| Natural Gas/Electric | 0.1 | 0.1 | 0.1 | |
| Heating Oil/Electric | 0.0 | 0.0 | 0.0 | |