The Commission sent a reasoned opinion to the two Member States asking them to notify the Commission of all their transposition measures for the directive, which had to be transposed into national law by 9 July 2012. If the Member States do not comply with their legal obligation within two months, the Commission may decide to refer them to the Court of Justice. Under this directive Member States must establish and apply minimum energy performance requirements for buildings; ensure that the building`s energy performance is certified and carry out regular inspections of heating and air conditioning systems. In addition, the directive requires Member States to ensure that from 2021 onwards all new buildings will be so-called nearly zero-energy buildings.