11 Inventories

11 Inventories
  31.12.2015 31.12.2014
Guarantees of origin 15,914 12,993
Emissions certificates 2,249 2,896
Gas 3,022 6,733
Material inventories 9,554 9,598
Total 30,739 32,220

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 inventories were held for trading purposes in 2014 and 2015. In the 2015 financial year an impairment loss of TCHF 74 was recognised (previous year: TCHF 774) and TCHF 219 released.