Directive 2010/31 EU (like the previous Directive 2002/91 EU) establishes that all the states of the Union must establish precise criteria and limits to be respected for the energy efficiency of buildings and of the systems connected to them. This is to limit emissions, which in Europe for 40 # 37 are due to the civil sector. This entails, in addition to greater attention to the energy ef ciency of the new buildings, especially the 26-rsquo; careful requalification The energy certification of the buildings was introduced in Italy in 2005 by Legislative Decree 192 and implemented fully with the 26-rsquo; emanation, in June 2009, of the National Guidelines on the Energy Certification of Buildings (Ministerial Decree of 26 June 2009). The certi cation is intended to inform the end user / buyer of a property about the performance and energy characteristics of the property itself. Therefore, each building and each individual housing unit must carry a ’ ” label” with l’ indication of its energy ef ciency class. Just as it has already happened for household appliances, this certification aims to promote the spread of high quality standards from an energy point of view and allows the end user to make an informed choice. L’ energy performance certificate must be drawn up by an energy professional of the existing building heritage, very often built without any care in this respect. Among the most important innovations introduced by Directive 2010/31 EU l’ the obligation that all buildings built in Europe from 1 January 2021 (1 January 2019 for public buildings) are NEARLY ZERO ENERGY, that is, buildings with a very low energy requirement, significantly covered by renewable sources.