• Dimensioning floor-heating (Power calculations)


    When calculating the heat requirement for a floor heating installation you use the same method of calculating as for other heat sources. In average, well insulated houses with a ceiling height of 2.4 – 2.7m and with double-glazed windows an adequate heating is usually obtained, even during cold winter days, with an installed power of 70-100 W/m² floor surface. The exact heat requirement is depending on the geographic location.

  • Required power in Watt/m² (Guiding principles)

    Type of room

    Lowest outdoor temperature
    -20°C -30°C -40°C

    Living rooms (except bathrooms)

    60 – 90 80 – 110 90 – 120

    Halls and entrances

    70 – 120 90 – 130 100 – 140

    Bath- and shower rooms

    90 – 140 100 – 150 110 – 150


    70 – 90 90 – 110

    Offices and shops

    90 – 100 110 –

    Floor temperature

    The maximum over temperature compared to the air temperature that the floor can take (Tgö) is calculated as per below:

    Tgö = 0,07 x installed power/m².

    Example: Installed power 80 W/m²
    Tgö = 5,6 °C.

    Studies and experience show that temperatures up to 28°C the floor feels pleasant. With floor heating the temperature should not exceed 28°C.

    Higher temperatures can be allowed in places where people stay only a short while, for example in bathrooms.

    Floor coverings

    Most types of flooring materials can be used if the power installed does not exceed 100W/m². When in doubt please consult the supplier of the floor material.

    It is not advisable to put an insulated carpet on floor heating, as this carpet has heating insulating qualities.