Glass Roof U Value

For example a building with material with an r value of r 11 converts to an u value of 0 09 1 r or 1 11 0 09.

Glass roof u value.

The u value of a single sheet of glass as found in a traditional window pane is 6 0w m 2 k which means that for every degree of temperature difference between the outside and the inside a square metre of the glazing would lose 6 watts. Example of how u values work. There are various ways of improving the uw value of an installation. Reference table for u values u value is the coefficient of transmission i e the transmission of heat through the materials which compose the building s envelope or outer shell.

This glass specification will produce a glass unit with ug value of 1 0 1 1 w m 2 k. So for example if the temperature difference on a typical cold day was 15 degrees then the amount of heat loss would be 15x6 90 watts per square metre. Technically u values are calculated as the amount of heat lost through one square meter of glass for every degree difference in temperature either side of the glass. All insulated glass from iq is specified to this standard as a minimum.

U value has an inverse relationship to r value. You can expect a standard double glazed panel to have a u value of around 3 w m2k whilst a triple glazed panel with xenon filled cavities and low e coatings will have a u value of around 0 4 w m2k. Determine the thickness of the insulation layer above the joists required to achieve a u value of 0 20 w m2k for the roof construction shown below. Obviously improving the individual u factors in the calculation will improve the overall thermal performance.

Triple glazing with 16 20mm gap 2 2.