Law 10/91, defines that to improve reducing processes of energy consumption and make better environmental compatibility under the same rendered service and quality of life, the rules of this title favour and stimulate, in accordance with the European Community energy policy, the rational use of energy, the consumptions reduction, the use of renewable resources, a more rapid reduction of the installations, in particularly in sectors with higher energy intensity. From an extract of the Ministerial Decree of April the 2nd ‘98 published in the Official Gazette No. 102, imposes the certification of energy for the fixtures that is a declaration by the manufacturer certifies that the performances of the new window are evaluated by laboratory tests according to technical standards issued by CEN.