| Value | Category | 
|---|---|
| 1 | Central heating - monthly expenses | 
| 2 | Heating on electricity | 
| 3 | Heating on solid fuels (coal, fire wood)-last heating season | 
| 4 | Heating on gas-last heating season | 
| 5 | Liquid fuels (heating/crude oil)-last heating season | 
| 9999998 | REFUSAL | 
| 9999999 | DONTKNOW | 
| Sysmiss |