U-value (W/m2K)

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The thermal transmittance (U-value) or heat transfer coefficient is an international standard to measure the heat transferred through the building envelope. Expressed in Watts per square metre-kelvin, it indicates the insulation capacity of a building element. While a lower U-value indicates a good insulation of the building element, it is useful to know the losses of heat in winter and the inputs in summer.

The national regulations limit the U-value depending on the climatic areas and the solar orientation of the house.

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