| 2000 | 2018 | 2019 | 2020 | 2021 | ||
|---|---|---|---|---|---|---|
| Total Single Attached Heating System Stock (thousands) | 167.9 | 255.9 | 260.9 | 266.0 | 272.4 | |
Heating System Stock by Heating System Type (thousands) | ||||||
| Heating Oil – Normal Efficiency | 6.7 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 2.9 | 5.8 | 5.6 | 5.3 | 5.0 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 41.5 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 34.0 | 47.3 | 44.3 | 41.3 | 38.3 | |
| Natural Gas – High Efficiency | 19.5 | 73.7 | 78.1 | 82.7 | 87.9 | |
| Electric | 50.3 | 110.9 | 114.3 | 117.8 | 121.8 | |
| Heat Pump | 3.1 | 7.7 | 8.0 | 8.3 | 8.7 | |
| Other1 | 2.9 | 1.9 | 1.9 | 1.9 | 1.9 | |
| Wood | 5.5 | 6.2 | 6.2 | 6.2 | 6.2 | |
Dual Systems | ||||||
| Wood/Electric | 1.1 | 1.5 | 1.6 | 1.6 | 1.6 | |
| Wood/Heating Oil | 0.1 | 0.2 | 0.2 | 0.2 | 0.2 | |
| Natural Gas/Electric | 0.4 | 0.7 | 0.7 | 0.8 | 0.8 | |
| Heating Oil/Electric | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
Shares (%) | ||||||
| Heating Oil – Normal Efficiency | 4.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Heating Oil – Medium Efficiency | 1.7 | 2.3 | 2.1 | 2.0 | 1.8 | |
| Heating Oil – High Efficiency | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Normal Efficiency | 24.7 | 0.0 | 0.0 | 0.0 | 0.0 | |
| Natural Gas – Medium Efficiency | 20.2 | 18.5 | 17.0 | 15.5 | 14.1 | |
| Natural Gas – High Efficiency | 11.6 | 28.8 | 30.0 | 31.1 | 32.3 | |
| Electric | 29.9 | 43.3 | 43.8 | 44.3 | 44.7 | |
| Heat Pump | 1.8 | 3.0 | 3.1 | 3.1 | 3.2 | |
| Other1 | 1.7 | 0.8 | 0.7 | 0.7 | 0.7 | |
| Wood | 3.3 | 2.4 | 2.4 | 2.3 | 2.3 | |
Dual Systems | ||||||
| Wood/Electric | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | |
| Wood/Heating Oil | 0.1 | 0.1 | 0.1 | 0.1 | 0.1 | |
| Natural Gas/Electric | 0.2 | 0.3 | 0.3 | 0.3 | 0.3 | |
| Heating Oil/Electric | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | |