Law 15/2014, of September 16, which has been in force since October 17, 204, establishes the energy efficiency principles and requirements for the acquisition of goods, services and buildings by the Public Administrations that belong to the State Public Sector. Through it, article 6 of Directive 2012/27/EU of the European Parliament and the Council, of October 25, 2012, on energy efficiency, was incorporated into Spanish law. Consequently, the Public Administrations that belong to the State Public Sector shall only be able to acquire goods, services and buildings that have a high level of energy efficiency to the extent that it is coherent with profitability, financial viability and sustainability. In what concerns the acquisition or leasing of buildings for administrative purposes, it is disposed that the minimum required energy qualification shall be class C for the energy demand indicators of heating, refrigeration and consumption of primary nonrenewable energy. To this effect, the energy efficiency of a building shall be certified through energy efficiency certificates regulated by Royal Decree 235/2013, of April 5, whereby the basic procedure for energy efficiency certification of buildings was approved. Notwithstanding the above, upon the acquisition of a package of products to which a delegated act adopted in virtue of Directive 2010/30/EU applies as a whole, the Public Administrations may demand that the aggregate energy efficiency should have preference over the energy efficiency of the products in the aforementioned package on an individual basis. The above obligation applies to supply, services and construction contracts resulting in the construction of a building, whenever the costs of said contracts are above the threshold values established in the Public Sector Contract Law in the following cases: construction and concessions of public construction contracts subject to harmonised regulations; supply contracts subject to harmonised regulations; and service contracts subject to harmonised regulations.