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Efficient windows

Windows are one of the most vulnerable elements in buildings’ surroundings. In winter, heat losses can represent 30% of heating needs.


The efficient windows, due to their characteristics, contribute to the increase of the thermal and acoustic insulation of the buildings, allowing to reduce the energy consumption associated with the air conditioning of the spaces in values ​​in the order of 50%.

The installation of efficient windows allows for greater thermal comfort, reduction of air and water infiltrations and consequent risk of inherent pathologies, as well as saving on the energy bill. These windows can have wooden, PVC or aluminum frames with thermal cut (thermal break) or a combination of them. For glazing, you should consider, at least, a double glass, and you can choose for the gas that separates the two layers of glass, air or a noble gas, for example, argon.

You should consult with the supplier in order to obtain the best options for your home, considering, in addition to the energy performance, other factors, such as the orientation of the windows, climate, construction limitations, durability and other factors to be taken into account.

Janelas convencionais

Uma casa com 5 janelas de correr em alumínio sem corte térmico e vidro simples com uma área de janelas de 9m2 tem um consumo anual estimado de 325€ associado à climatização.

Janelas eficientes

A mesma casa após a instalação de janelas eficientes de abertura oscilo-batente, com corte térmico e vidro duplo terá um consumo anual estimado de 116€.


A substituição das janelas por janelas eficientes de classe A permite reduções anuais no consumo com a climatização até 209€.

Other tips
  1. When choosing windows, pay attention to the acoustic performance. If you live in an urban area or next to a busy road, the higher the value of the window’s acoustic attenuation, the better the sound comfort inside your home will be.
  2. The placement of efficient windows will make your home more watertight and allow you to control drafts making the interior of the home more comfortable. However, it is important not to forget to open the windows regularly to allow the air to renew and prevent condensation.
  3. Follow the recommendations of the window supplier when carrying out maintenance and cleaning. Following these instructions will allow you to maintain the thermal and acoustic performance of the windows for a longer time.
Energy Label

The CLASSE + energy label for windows is a new, easier way for consumers to know which windows are the most efficient with which they can save energy and gain in comfort. All of this using the color scale that is already familiar from “F” to “A +”.

The CLASSE + label also includes other more detailed technical information, namely, the calculation parameters that served to determine the energy performance, in addition to complementary data related to the characteristics of the glass and the window’s acoustic attenuation capacity.

How to read the energy label:

  1. Manufacturer Identification
  3. Energy Class
  4. Comfort level (Summer / Winter))
  5. Window thermal transmission
  6. Technical characteristics of glass
  7. Air permeability class
  8. Sound attenuation
  9. QR Code

See also our article on  energy efficiency classes and the Class+ portal

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