The Directive provides for a compulsory energy performance certification document, which certifies the quantity of energy required by the building for the air conditioning/heating of the internal environments: heating, cooling, production of hot water, ventilation… 

Certification was identified as the most effective instrument to promote the reduction of energy consumption in the building industry, to spread the culture of energy saving and to introduce the associated mechanisms (benefits and discounts on charges, government incentives and tax exemptions, third-party financing, etc.).

Energy certification – which in the future will be presented in the stages of construction, buying and selling, or rental of a building – must become a culture and not a formality. 

Certifying, for designers will become an indicator of the quality of the project, for companies an occasion to highlight the quality of the ''building'' product, for users a comparative guarantee for decisions of efficient and economic management, for public administrations a concrete occasion for planning the sustainable development of the territory.

The decree expressly indicates public building as a benchmark model of behaviour: buildings occupied by public authorities, and more generally open to the public, must show an exemplary approach to the environment and to controlled energy consumption, becoming subject to regular reviews of the certification.

In particular public buildings (unlike private ones) will be obliged to exhibit certificates in a visible place, exhibiting an energy plate showing the heating needs of the building shell.

The combination of energy saving and environmental impact (consuming less to pollute less but also to rationalize the exploitation of energy resources) highlights in terms of eco-sustainability the culture of external insulation: rendering as ''public'' conscience.