17. Inventories (in millions of euros)December 31, 2016December 31, 2015Maintenance materials120110Projects under construction, unsold517Trade goods1411Total139138Inventories of maintenance materials consist of raw materials and materials for the purpose of production and maintenance of semi-finished and finished products of the maintenance department. In 2016, the write-down of inventories to the net realisable value and recognised as an expense amounted to €11 million (€6 million in 2015). The cumulative impairment, after withdrawals, came to €94 million at the end of 2015 (€95 million in 2015).