| 2000 | 2018 | 2019 | 2020 | 2021 | ||
|---|---|---|---|---|---|---|
| Total Single Attached Heating System Stock (thousands) | 22.0 | 36.9 | 37.3 | 37.7 | 38.3 | |
Heating System Stock by Heating System Type (thousands) | ||||||
| Heating Oil – Normal Efficiency | 0.7 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 0.5 | 0.6 | 0.6 | 0.5 | 0.5 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 10.1 | 0.3 | 0.1 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 5.2 | 7.1 | 6.7 | 6.3 | 5.8 | |
| Natural Gas – High Efficiency | 3.9 | 23.7 | 24.6 | 25.3 | 26.2 | |
| Electric | 0.7 | 4.3 | 4.6 | 4.8 | 5.1 | |
| Heat Pump | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Other1 | 0.4 | 0.5 | 0.5 | 0.5 | 0.5 | |
| Wood | 0.4 | 0.2 | 0.2 | 0.2 | 0.2 | |
Dual Systems | ||||||
| Wood/Electric | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Wood/Heating Oil | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas/Electric | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | |
| Heating Oil/Electric | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
Shares (%) | ||||||
| Heating Oil – Normal Efficiency | 3.3 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 2.1 | 1.6 | 1.5 | 1.4 | 1.2 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 46.0 | 0.8 | 0.3 | 0.1 | 0.0 | |
| Natural Gas – Medium Efficiency | 23.4 | 19.3 | 18.0 | 16.6 | 15.2 | |
| Natural Gas – High Efficiency | 17.7 | 64.4 | 65.9 | 67.1 | 68.3 | |
| Electric | 3.3 | 11.7 | 12.3 | 12.8 | 13.3 | |
| Heat Pump | 0.1 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Other1 | 1.7 | 1.3 | 1.3 | 1.3 | 1.3 | |
| Wood | 2.0 | 0.6 | 0.5 | 0.5 | 0.5 | |
Dual Systems | ||||||
| Wood/Electric | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Wood/Heating Oil | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas/Electric | 0.5 | 0.3 | 0.2 | 0.2 | 0.2 | |
| Heating Oil/Electric | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |