Starting from 2005, the energy certification of buildings definitively becomes part of the Italian legislation. In fact, the energy classes were created to classify the energy performance of houses and apartments on the basis of functional and structural parameters that scientifically determine the use of electricity.

Classification takes place on the basis of the letters of the alphabet, on a scale that classifies consumption in increasing order, starting from class A4, up to G, for a total of 10 classes.

The energy classification therefore serves to establish how much a building consumes, or rather, to assess what impact it has on the environment in terms of consumption.

To this end, the purpose of the legislator, which placesthe obligation of energy certification only to some categories, is to reduce energy waste, to reduce consumption and to encourage both the citizen and the market for new technologies to adopt and propose alternative solutions with low environmental impact.

Energy certification of buildings is an evaluation procedure whose main purpose is to promote the improvement of the energy performance of buildings. In fact, the energy certification provides both a section for the thermal insulation class and a section relating to the quality of high energy efficiency systems.

As if this were not enough, in many Italian regions it is expected that each real estate announcement must clearly report the energy class of the property for sale. The purpose of these provisions is essentially to make the buyers of a building aware of the real energy consumption.


The energy classes are ten and to each is assigned a score ranging from 1 for the least efficient to 10 for the most efficient based on specific ranges of energy values, or consumption range.
In the following table we have summarized the minimum and maximum values of each class and the score assigned to them.

(the abbreviation EP indicates the energy performance index).


The calculation of the energy class is not simple. First of all, specific skills and professional and recognized evaluation skills are needed. In fact, a new professional figure associated with this field was born. In this regard, the energy certifier takes care of carrying out the energy diagnosis of a property in order to quantify the energy consumption of the building in standard conditions of use and climate depending on the climatic zone.

The energy certifier issues the APE, Energy Performance Certificate, which contains all the characteristics of a building from an energy point of view including the Energy Class to which the property belongs. The document must be drawn up in compliance with the guidelines issued with the ministerial decree of 26 June 2009 or with the regional directives if existing.

Much will depend on the materials used in the structure, on the dimensions and fixtures, on the use of renewable energy sources, on the climatic zone or on the improvements and optimizations that one is willing to do if it is an evaluation of a new construction.

However, it is necessary not to rely on any certifiers. The true energy certifier must in fact have adequate training in order to operate in accordance with the law. So choose only certifiers recognized, that have valid certificate.

The low consumption not only translates into energy savings for the homeowner, but also into a lowering of the state’s energy bill and a reduction in environmental pollution, an aspect which has been neglected for too long.


The energy certification can only be issued by persons authorized by law and only after an inspection in the building being assessed. The document is valid for 10 years and must contain various data including:

  • first of all, the global energy performance which includes, through the respective indices, total primary energy and non-renewable primary energy;
  • the energy class, calculated through the global energy performance index and expressed in non-renewable primary energy;
  • the energy quality of the building based on the thermal performance indices for cooling and heating;
  • carbon dioxide emissions;
  • The exported energy;
  • proposals for improving the energy efficiency of the building;
  • information on incentives and other facilities for improving the building’s energy performance;
  • finally, the data of the professional who carried out the inspection, the date and the type of software used for the evaluation.

The energy classes are no longer 8, but 10: starting from A4, the best, then gradually descending with A3, A2, A, B, C, D, E, F, G, the worst.


Before going into the analysis of the individual energy classes, let’s make a brief introduction about the meaning of “energy efficiency”. Today, this expression is very fashionable, but often it is used without knowing exactly what you are talking about.

Therefore, the energy efficiency of a building is defined as the ability that that particular system has to exploit the energy that is supplied to it and that serves to meet its daily needs in the best possible way.

An efficient home is a home that consumes little and this, evidently, has direct and significant repercussions on ordinary management costs.

The so-called redevelopment interventions, aimed at improving the energy efficiency of a building, are thus very useful for cutting consumption and bills, especially those of gas and electricity. In addition, it is essential to receive the energetic certification for your home.

The energy efficiency of a building can be improved by working on those factors that cause energy loss; on some of them it is obviously impossible to intervene, but on others it is certainly possible to act.

For example, it is possible to isolate surfaces that are exposed to colder environments as well as to intervene by isolating and improving the quality of the fixtures or roof; the replacement of doors and windows can in fact lead to considerable cuts in the energy bill.


But how are the energy classes of the houses divided?

Here are some useful pointers.


Energy class A is divided into classes A1 ,A2, A3 and A4.

It represents excellence in terms of energy efficiency and environmental protection.

A class A house is an energy-impact house which corresponds almost to zero.

There is only very minimal waste.

It also obeys the anti-seismic regulations, has a thermal insulation coat, uses a heating system with high efficiency.

Management costs are negligible and the living comfort inside the individual rooms is really optimal.


The B classes are those of low consumption and sustainable.

The houses of this type haveundergone redevelopment interventions, have undergone work on the outside, have been object of joinery replacement.

In a class B house, consumption is limited and comfort is really good: in short, all in all, you can’t really complain.


Energy class C characterizes all those properties that have some main characteristics.

First of all there are thermostatic valves on all the radiators.

They have a condensing boiler and insulation of the attic.

It could be said that, a bit like school voting, a class C building, from an energy point of view, still deserves sufficiency, nothing more and nothing less!

There are no exceptional performances, but not even big problems, so, if you want, you can do something to improve, but on balance you can be satisfied.


The energy class D indicates those homes that were built relatively recently, about 15 years ago.

Often these houses have undergone requalification.

With class D we begin to fall below sufficiency and therefore it is good to think of implementing some intervention, albeit minimal, that will improve the situation, increasing comfort inside the home and limiting waste and expenses.


Among the buildings built between the 70s and the 90s the most widespread energy class is E.

They are homes that have a methane gas boiler, even if the build quality of these properties is not particularly high.

Starting from class E, up to class G, is always good to ask yourself some questions about your home and what it would be like desirable to do to make it more efficient, because undoubtedly in these cases it is possible and necessary to do better.

A house in class E is not a problem only in terms of expense, because it has fairly substantial consumption, but above all it is the little comforting sensation that those who live live a penalizingoperation.


They indicate buildings where theheating systems are obsolete.

Many of the buildings dating back to the late 70s, inizio anni ’80, especially if they have not been subjected to any type of intervention, fall into this class, for which all that is said with respect to previous one.

They may also have old fixtures and a insulation of walls and floors not very adequate.


Energy class G indicatesthe least efficient class compared to all the others.

This class includes the old masonry buildings that have not undergone insulation and that have not a heating system.

most of the properties in the italian territory, falls into this category. Exactly for this reason, elsewhere we will dwell extensively on this phantom and so demonized class G, especially in order to understand how to turn it into something better.


Now, you will naturally be led to believe that, from a point of view of energy efficiency, a house in class A4 is the top, but attention you must immediately change your mind. In the near future we will all find ourselves thinking exclusively to so-called buildings nZEB, initials that literally translates to “nearly Zero Energy Building”, namely buildings with almost zero energy.

An house nZEB is a very high energy performance system, so much to be characterized from an energy requirement so low as to result practically nil. This is possible not only because consumption is minimal, but also because they are almost completely satisfied with the exploitation of renewables.

Few know it, but the D.Lgs 192/2005,then modified following the European Directive 31/2013 UE, through the D.L. 63 of June 4 2013, establishes that in our country, all new buildings starting from 1 January 2021 they will have to be implemented in the nZEB mode, while as regards public buildings, the obligation has already been released, starting from 31 December 2018.


Energy certification is nothing more than a procedure performed by a professional technician who evaluates the energy consumption of a house or building to maintain certain environmental conditions inside.

In practice, the consumption in Kilowatts is calculated in one hour per square meter of the structure. This assessment, together with other checks and data, determines the APE, i.e. the Energy Performance Certificate of the house or building. These results, then, will make the structure fall within certain energy classes.

However, there are many factors that can affect the determination of the final evaluation of the energy efficiency of a structure and its inclusion within a particular class rather than another.

Among these factors, regarding a building, we find for example the floors, the insulation systems, the walls, the roof, the fixtures and the boundaries of its walls. For a home, however, apart the elements mentioned, also its position inside the building tends to influence.

Then there are additional systems that allow you to reduce still energy consumption, like heated floors, condensing boilers or solar panels, which are essential for achieving of the most efficient energy classes, how can that be A4.

All these elements, however, do not insure a perfectly energy efficient home. Indeed, much depends on the heat loss found and, indirectly, also from the construction quality of the structure.

Fortunately, the State favors this type of work, guaranteeing those who carry them out special tax concessions. Specifically, a reimbursement from 50% to 65%, over a period of 10 years, of the expenses incurred for renovations intended to improve the energy efficiency of buildings and homes. All through the annual tax return.


The factors that come into play to determine the energy requirement of a building and consequently the class it belongs to itself are many.

The 10 energy classes depend substantially by the value from the parameter Epgl,nren,namely from the so-called non-renewable global energy performance index of the building, that corresponds to the total energy consumed by the air-conditioned building per square meter of surface every year.

Here then it is important to emphasize how the new energy classes (as well as also previous ones) do not allow to compare buildings directly colors. To compare the performance of different buildings, you will have to read the numeric value of EPgl,nren, not the letter indicating the class of to which it corresponds..

Keep in mind that an APE is made up of several pages and in addition to the property data, of its owner and the certifier who drafted it contains several other information:

  • energy performance indices of all the systems present;
  • the energy sources used;
  • estimated annual energy consumption;
  • the reference values;
  • emissions of CO2;
  • the energy produced and exported from the building;
  • some recommendations for improvement of the building’s energy efficiency;
  • the presence of financial incentives available at the time of the release of the APE;
  • the opportunity to perform further energy diagnoses or any notes.

From this it is clear that in 2017 the 56% of real estate sales involved class G buildings, the worst of all, 24% classes E and F, 13% classes C and D and only 7% of the deeds of sale it concerned houses belonging to the best energy classes, A and B.

At the same time, one in two real estate agents out of all those interviewed believes that the EPA does not have much weight on the final choice of those who are about to buy.



Recent studies show that in Europe about 40% of total energy is used for residential and tertiary use and the only plausible way to lower emissions levels is to bring about an improvement in the energy efficiency of buildings.

Therefore, Legislative Decree number 192 of 2005 takes over which establishes the obligation of energy certification of buildings with the drafting with the issue of an APE Energy Performance Certificate that assigns the energy class to the house.

To understand how we can improve the energy class of a building and consequently start saving on home consumption, first of all it is necessary to find out the factors that cause energy losses.

You can therefore start by requesting a quote from a building renovation company that can perform a survey on the property and advise you on what changes to make to improve the energy class of the property with a consequent reduction in consumption and therefore costs.

A truly effective way to improve the energy class and reduce consumption, making the property acquire a much higher value than before is undoubtedly thanks to the installation of photovoltaic panels that can substantially reduce consumption.

This type of intervention is very convenient because it falls within the Ecobonus which allows you to have a tax deduction of up to 65% on the purchase of photovoltaic panels.


Regarding the incidence of the energy classes on the value of a property, we can say that similar properties but with different energy classes can fluctuate on the sale price which can vary and even reach 30% depending on whether they are in class A or G.

For this reason you should request a survey from a renovation company, at least to realize how much it would cost to improve your property in terms of energy class through targeted interventions, if in the future you will resell the property you may be able to earn several thousand euros always taking into account the tax bonuses extended again this year that allow you to save on restructuring.

It must be said that improving the energy class through a renovation or buying an apartment in class A compared to a class G can bring multiple advantages over time in terms of consumption and real estate value that can extend over time.

Consequently, improving the energy class of a property and requesting a new energy certification can increase the value of the property with enormous advantages in terms of economic investments.


If the article interested you and the topic is important to you because of an imminent renovation aimed at improving the energy class of the home, you can leave a comment at the end of the article!

In addition, if you have doubts and need advice to get personalized advice on how to use this type of intervention and how to receive your energy certification, you can send an email tovaleriadesign@casaomnia.it

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