Windows energy label

Windows energy label

Window energy label: energy classification of windows to know in advance the impact they will have on the energy needs of the house.

L'energy label of the windowsarrives to allow you to choose good quality fixtures, which do not disperse heat in winter or coolness in summer. It has spread since January 1, 2015, promoted by the Swiss Association of Window and Facade Manufacturers (FFF) and by the Swiss Central Window and Facade Builders (CSFF).

Windows energy label:energy coefficient

L'energy label of the windows it is less intuitive than the classic energy label of household appliances. The energy label of household appliances indicates the average annual consumption recorded for that appliance under standard conditions assigned by means of the energy classes.

For theenergy label of a windowthe subject changes: the plate provides information on the energy quality (efficiency) of the frame in the winter period.

To indicate the efficiency, an energy coefficient U equivalent Uw, eq of a reference window with dimensions equal to 1.55 m x 1.15 m is used (the dimensions include frame and glass).

The equivalent energy coefficient U takes into account not only the heat loss, it also evaluates the usable solar energy gains (theenergy coefficient U equivalent Uw eq, consider the energy balance between energy losses and gains). In this way, the user can evaluate the efficiency of a window also taking into account the heat that it is able to transmit to the home by exploiting the contribution of solar radiation.

Energy label:the energy efficiency classes of the windows

Thewindowsare classified into 7 energy categories on the basis of the equivalent energy coefficient U:Uw, eq.We thus have:

  • Class A windows with aUw, eq <0
  • Class B windows with aUw, eq between 0 and 0.1
  • Energy class C windows with aUw, eq between 0.1 and 0.2
  • Class D windows with aUw, eq between 0.2 and 0.3
  • Windows of class E, with aUw, eq between 0.3 and 0.4
  • Windows of energy class F, with aUw, eq between 0.4 and 0.8
  • Windows of energy class G, with aUw, eq greater than 0.8

Theenergy class A windowsnot only do they allow you to optimize heating consumption, they even manage to gain energy by making the most of solar radiation.

The standard windows interface between class C, D and class E while theenergy class windowsF or G should be replaced or refurbished. Class B windows are a good energy saving solution.

How to read the energy label of windows

In addition toenergy class of belonging, on the label there is other information:

  • Frame size
  • Permeability to water and air
  • Frame value Uf
  • Glass quality
  • Spacer
  • G value

The G value indicates the degree of energy transmission of the glass, ie the amount of solar radiation that is able to pass through the glass. The higher the G-value, the greater the energy gain.

Permeability to air and water indicates the resistance of the window to wind and rain. The higher the category, the higher the quality of the window.

The spacer (Ψg) is the linear thermal transmission coefficient. It is indicated with the symbol Ψg and depends on the material of the frame and the glass. Again, the higher the value, the higher the quality of the window.

The quality of the frame is expressed by the Uf value, the lower this value, the better the window will be (because the less heat is lost).

The Ug coefficient indicates the quality of the glass in terms of thermal transmission. How much heat can glass lose? As with the Uf coefficient, also in this case, the lower this value, the better the window will be. If the value is very high, the window will be subject to heat loss due to cold air currents.

Video: The science of energy and energy efficiency (July 2021).