| Value | Category |
|---|---|
| 01 | No fuel used |
| 02 | Utility gas from underground pipes serving neighborhood |
| 03 | Bottled, tank, or liquefied petroleum gas |
| 04 | Electricity |
| 05 | Fuel oil, kerosene, other liquid fuels |
| 06 | Coal or coke |
| 07 | Wood |
| 08 | Solar energy |
| 09 | Other |
| 99 | NIU (not in universe) |