The 'minimum requirements decree': it implements Legislative Decree 192/2005 by defining the methods for calculating the energy performance of buildings and the minimum requirements they must meet. It introduces the reference-building method and the NZEB (nearly zero-energy building) obligation for new construction. Published in Official Gazette no. 162 of 15 July 2015. Its Annexes 1 and 2 were wholly replaced by the Ministerial Decree of 28 October 2025, effective from 3 June 2026: the decree remains the framework, but the values and calculation methods are now read in the new version.
It applies to new buildings and to works on existing ones (major renovations of the first and second level, energy upgrades), grading the requirements according to the type of works. It is accompanied by the twin decrees of 26/06/2015 on technical-report templates and on the EPC (energy performance certificate) guidelines.
The decree does not only set absolute threshold values: it introduces a comparison. For every real building a 'reference building' is constructed, identical in geometry, orientation, use and climate context, but fitted with standard energy parameters set by the decree. The real building complies if its performance is no worse than that of its reference twin. It is a performance-based method, not a simple checklist of thicknesses.
The requirements concern two fronts: the envelope and the systems. On the envelope, the transmittances of the elements, the mean heat-transfer coefficient (H'T) and the summer equivalent solar area (overheating control) are checked. On the systems, efficiencies and the global energy-performance indices (EPgl) are verified, distinguishing renewable from non-renewable energy.
| Front | What is checked |
|---|---|
| Opaque and glazed envelope | thermal transmittances U of the elements |
| Overall behaviour | mean coefficient H'T; equivalent solar area (summer) |
| Systems | efficiencies; EPgl indices (renewable/non-renewable) |
| Renewables | minimum share from renewable sources (coordinated with D.Lgs. 199/2021) |
Since 1 January 2021 every new building (and many major works) must be NZEB: very high energy performance and a need covered to a significant extent by renewable sources, largely on site. The decree traces the transition that D.Lgs. 192/2005 and the EPBD directive had set out, and that the new EPBD (Dir. (UE) 2024/1275) pushes towards the zero-emission building.
This is the decree that translates efficiency goals into design numbers: without the 'minimum requirements', the great frameworks (D.Lgs. 192, EPBD) would remain principles. It is here that the designer finds the yardstick to prove that a building really does consume little.
Where this rule shows up in past architect qualification exams — study the rule, not just the theme.
A virtual building identical to the real one in geometry, orientation and use, but with standard energy parameters set by the decree. The real building complies if it performs no worse than its reference.
NZEB is the nearly zero-energy building: very high performance and large use of renewables. Since 1 January 2021 it is mandatory for all new buildings (since 2019 for new public buildings).
The decree distinguishes major renovations of the first and second level (based on the share of the dispersing surface affected) and energy upgrades, with progressively less extensive requirements.
D.Lgs. 192/2005 is the framework; D.M. 26/06/2015 is the implementing decree that makes its calculation methods and minimum requirements operational. Without the decree, the law would remain a principle.
It is the report certifying compliance with the energy requirements, required by art. 8 of D.Lgs. 192/2005 (heir of Law 10/1991). One of the twin decrees of 26/06/2015 sets its templates.