Legislative Decree 199/21: new standards for plant design that contributes to the ecological transition

Legislative Decree 199/21: new standards for plant design that contributes to the ecological transition

Entering into force on 13 June 2022, Decree-Law 199/21 aims to decarbonise the energy system in order to achieve the European sustainability targets set for 2030.

Last November, the new Legislative Decree 199 (on the promotion of the use of energy from renewable sources) was published in the Official Gazette with a number of changes that came into force on 13 June 2022. The decree transposes RED II Directive No. 2018/2001, with the aim of achieving the European objectives of decarbonisation of the energy system by 2030 and full decarbonisation by 2050.

The regulation is part of the implementing provisions of the NRRP (National Recovery and Resilience Plan) and defines the tools, incentives and mechanisms needed to reduce greenhouse gas emissions by at least 55% (by 2030); Italy aims to use a minimum 30% share of energy from renewable sources on gross final consumption.


From 13 June, new buildings and major renovations must be designed in such a way as to ensure, in the GLOBAL ENERGY CALCULATION, systems powered by renewable sources for:

– 60% of expected consumption for domestic hot water production;

– 60 per cent of the sum of planned consumption for domestic hot water production, winter heating and summer air conditioning.


For public buildings, these obligations are raised to 65%.

With regard to the installation of PHOTOVOLTAIC SYSTEMS, Legislative Decree 199 provides for an increase in the electrical power of systems powered by renewable sources that must be mandatorily installed on or within the building or its appurtenances. This electrical power, measured in kW, is calculated according to the following formula: 𝑃 = 𝑘∙𝑆 where:

K= 0.025 for existing buildings (major renovations) and 0.05 for new buildings

S = the floor surface area of the building at ground level, i.e. the projection of the building outline on the ground.

For public buildings, this obligation is increased by 10%.

In essence, for a newly built single-family dwelling, it is a matter of doubling the kW of installed power.

If it is not technically possible to comply with the requirements of the decree, the designer must detail and demonstrate this impossibility in the report required by Legislative Decree 192.

In addition to this, very strict limits on the efficiency of non-renewable energy use will have to be adhered to, so only high-efficiency heat pumps will be used.


The provisions that have just come into force, even if they seem to entail economic and planning challenges, are particularly significant in relation to the positive effects they may have in the long run, both in terms of simplification and speeding up of procedures, providing an incentive for private individuals to invest in the renewables sector.

This regulatory change is a new challenge for DVArea in proposing to its clients an integrated methodological approach to identify the best building-installation system capable of meeting the standards, while also pursuing end-user satisfaction in terms of sustainability and liveability of the building.