The Technical Building Code, hereinafter referred to as TBC, promulgated by Royal Decree 314/2006, 17 March 2006, is the regulatory framework governing the basic quality requirements that must be met by buildings, including their installations, in order to comply with the basic safety and habitability regulations defined by Law 38/1999 (known by the Spanish acronym LOE). The TBC applies to new construction, except for technically simple structures of negligible constructional consequence not designated for residential or public use.The TBC also applies to the extension, modification, alteration or renovation works that are carried out on existing buildings. The Technical Code includes a set of Basic Documents, BD, for complying with the its basic requirements. These documents are to be updated in accordance with technical advancements and social requirements, and shall be approved regularly. Among the various BD is the Basic Energy Saving Document, which aims to obtain a rational use of energy required for buildings, reducing their consumption to sustainable limits, and ensuring that part of this consumption comes from renewable sources of energy, thanks to their design, construction, use and maintenance characteristics. This Basic Document comprises the following sections: HE.1: Limiting energy demand (heating and air conditioning). HE.2: Efficiency of heating/air-conditioning systems. HE.3: Energy efficiency of lighting systems. HE.4: Minimum solar contribution to the hot water supply. HE.5: Minimum photovoltaic contribution to the electrical power supply. The TBE contributes to the transposition of the Directive 2002/91/EC on the energy performance of buildings, in terms of the minimum energy requirements that must be met. In order to comply with the Directive 2010/31/UE on energy efficiency in buildings, amending Directive 2002/91/EC, with regard to the energy efficiency requirements in buildings, the CTE DB-HE Basic Document on energy saving has been updated through the approval of the Order FOM/1635/2013 . This involves an increase in energy efficiency and renewable energies different from the ones mentioned in the above Basic Document, and also introduces a new section: HE.0: limitation of energy consumption. The energy consumption for the fitting-out, if applicable, of buildings or parts of them which, given that they are permanently open for reason of their use, will exclusively be met with energy coming from renewable energies. These demands shall be checked using a calculation procedure pursuant to the specifications established to the purpose. All the above leads to the partial transposition of Directive 2010/31/EU in terms of the energy efficiency requirements in buildings, as provided in its articles 3, 4, 5, 6 & 7, as well as Directive 2009/28/EC, in terms of a demand of some minimum energy levels coming from renewable energies in buildings, as set forth in its article 13. In like manner, the updating of the DB-HE Basic Document on energy saving makes up a first approach to the objective of Directive 2010/31/EU of achieving nearly zero-energy buildings – before 31 December 2010 in all new buildings and before the end of 2018 in new buildings for public use. More recently, the CTE DB- HE (Energy Sving) and HS (Salubrity) have been updated through the Order FOM/588/2017 in accordance with the Directive 2010/31/EU. The modification of the DB-HE according to the Royal Decree 235/2013 in relation to the exclusion from the scope of application related to the section HE.1. In addition, the section HE.0 is enlarged with the introduction of a new term related to the nearly zero-energy buildings.