| Value | Category | 
|---|---|
| 1 | Collective central heating | 
| 2 | Individual central heating based on gas | 
| 3 | Individual central heating based on another fuel (coal, wood, petrol, etc.) | 
| 4 | Stoves (tiled stove using wood, coal, sawdust, etc.) | 
| 5 | Electric heating (accumulative) | 
| 8 | Unknown | 
| 9 | NIU (not in universe) |