| 31.12.2013 | 31.12.2012 | |
|---|---|---|
| Guarantees of origin | 16,397 | 16,350 |
| Emissions certificates | 2,593 | 2,141 |
| Emissions certificates held-for-trading | - | 2,614 |
| Gas | 12,061 | 14,539 |
| Material inventories | 9,278 | 9,246 |
| Total | 40,329 | 44,890 |
Inventories consist of material inventories, gas inventories and certificates, and are measured at the lower of acquisition costs and net realisable value. Certificates that are not necessary for own generation needs and which are held for trading purposes are measured at fair value less selling costs. No impairment loss was recognised in the current financial year or in the previous year.