Bertrand Windows and Doors

Thermal transmittance coefficient – Expert advice

We are slowly entering the winter period. For many of us, this means weekends with Kamil Stoch, but colder days also bring us less enthusiastic moments, such as high heating bills. Where to look for savings? Leaky windows result in a loss of 25 to 45% of thermal energy. Such high heat losses translate into much higher expenses for heating the apartment. That is why, when purchasing windows, it is worth paying special attention to the thermal transmittance coefficient (abbreviated as UIn).

What does the window's thermal transmittance coefficient tell us?

The unit of the U-factorIn is W/(m2K). The coefficient tells us how much energy (measured in Watts) penetrates through a window with an area of 1 m2 at a temperature difference of 1 K inside and outside the building. The lower the coefficient value, the less thermal energy the window transmits. When can we talk about energy-saving windows? For passive construction the maximum value of the coefficient was determined at the U levelIn< 0.8 W/(m2K). In our climate, it is recommended to install windows with a thermal insulation parameter not higher than 0.9 W/(m2K). Therefore, it is worth choosing a window with a U-valueIn  will meet energy-saving standards.

How does the construction of a window affect its thermal insulation?

The impact on the window's thermal insulation index is as complex as the structure of the window itself. The indicator informs us about the heat transfer through the entire window, but we must remember that influence on the U parameterIn have all window elements:

  • Window profile (the U index indicates the thermal insulation of the profilesf)
  • Glazing unit (U indexg)
  • Type of glazing frame (Psi coefficient)

Let's remember that when choosing energy-saving window we must choose a complete window. Window manufacturers often boast of a low U-valueg. This is intentional because the glass provides better thermal insulation. That's why it's the U-factorIn  given for the reference window (window dimensions 1230 x 1480 mm) is the most important information for the buyer. A profile adapted to passive construction, triple glazing and a warm spacer will translate into: real savings on heating your apartment.

A warm montage completes the work

There is one more issue that completes the work of energy-saving joinery. This assembly complies with the so-called standards. warm installation. Remember that even the most energy-efficient window installed incorrectly deprives the entire structure of its thermal insulation properties. Thermal bridges that may form around the window will completely eliminate the high thermal transmittance of the structure. Therefore, window installation should be entrusted to a professional installation team that follows the rules warm installation.

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