Glass Roof U Value

It is proposed to use mineral wool insulation between and over the joists with a thermal conductivity of 0 04 w m k.

Glass roof u value.

Obviously improving the individual u factors in the calculation will improve the overall thermal performance. Double glazing with 16 20mm gap 3 0. U value has an inverse relationship to r value. 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.

In descending order these are typical u values for glass. 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. 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.

Triple glazing with 16 20mm gap 2 2. 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. 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. Example of how u values work.

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.