The energy label is already established as a tool of excellence for supporting consumers in choosing efficient products at the time of purchase.

However, the European energy label is limited to energy-consuming products, such as lamps, appliances, ovens, etc., leaving out other products that also have an indirect impact on energy consumption in a home.


CLASSE+ energy labeling is an initiative by ADENE – Portuguese Energy Agency, especially for building components that do not have a European energy label, such as windows, insulation, paints and elevators. Thus, manufacturing companies can, on a voluntary basis, classify these products on an energy scale similar to that of household appliances. This process is accompanied by the training of installer technicians recognized by CERTIF – Association for Certification.

The first product classified under this system was windows. In practice, a CLASSE + labeled window is a product whose energy performance has been properly rated on a scale from A + to F, in addition to indicating the level of comfort that the window can provide.

More efficient windows mean greater energy savings, better soundproofing and greater thermal insulation. Therefore, the right choice is very important in small interventions, rehabilitation or improvement works in existing buildings.

The choice for efficient windwos

The replacement of an ordinary window, of simple glass and without thermal cut, by a window with CLASSE + label with classification “A +” can mean a reduction of, at least, 55% in the energy losses associated with that element. Depending on the quantity, dimensions and characteristics of the windows in the property, as well as the form and frequency with which you cool your home, the amount of electricity, gas or other fuel you will save will vary and the positive impact this will have on your energy bill monthly.

By using the information provided by the CLASSE + energy label for the choice of efficient windows you get to know and can compare, in a clear and simple way, the energy, thermal and acoustic performance of windows, and thus select the efficient window that can give you the best comfort to housing.

When requesting proposals from companies, you must demand that they submit budgets with the simulation of the CLASSE + energy label, in order to be able to compare the various proposals. At the end of the work, you must always confirm that you are given the energy labels for the installed windows and that the energy class is in accordance with what was proposed and agreed between the parties.



Using the CLASSE + energy label as a reference for choosing efficient windows can bring you different benefits, including reducing your energy bill, as you will spend less energy to keep your home comfortable. To this they add health benefits associated with the improvement of the thermal comfort of the house, as well as an appreciation of the property itself. All together and in the end, there are many euros in the wallet that help offset the investment made in more efficient windows.
In a simple way, it can be considered that by having a more efficient and comfortable home (efficient CLASS + windows, well insulated walls and roofs), a typical Portuguese family can save between € 250 and € 1000 per year if they choose efficient solutions for the surroundings of your home.

Class A+|Class A|Class B|Classe C|Class D|Class E|Class F


The main companies in the market have already joined CLASSE + and can be found in the directory available on the portal.

You can also find in CLASSE + a list of professionals certified as Efficient Window Installers by CERTIF who have experience and training to ensure that installing the window allows you to obtain the maximum energy efficiency and comfort that the solution can provide you.


There are several incentives available today or on a recurring basis that allow you to support the exchange of windows and where the use of the CLASSE + energy label as proof of the efficiency of the window is a mandatory requirement. In these incentives it is also valued or suggested that the installation of the windows be done by a professional “Installer of Efficient Windows CLASSE +” certified by CERTIF – Association for the Certification.

One of these incentives is the Casa Eficiente 2020 program, which provides loans on favorable terms for operations that promote the improvement of the environmental performance of private housing buildings, with a special focus on energy and water efficiency. Intervention in the glazed surroundings is one of the eligible operations, and the energy efficiency of the installed windows is evidenced by the presentation of the energy label.

Another example is the  Fundo de Eficiência Energética (FEE), which provides non-refundable support for the installation of efficient windows with CLASS + energy label. In this incentive system, applications whose work is carried out with the participation of an efficient CLASSE + window installer recognized by CERTIF are valued.

In the CLASSE+ portal you can get more information about energy label, as well as information about efficient windows in the guide for Efficient Windows made available by ADENE in the collection “10 ENERGY EFFICIENCY SOLUTIONS” for buildings.

See also our tip on Efficient Windows.

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