Glass in Building - Calculation of Steady-State U Values (Thermal Transmittance) of Multiple Glazing
|Publication Date:||1 January 1994|
|ICS Code (Glass in building):||81.040.20|
This International Standard applies to glass, coated glass and materials opaque in the far infrared wavelengths. It gives the fundamental rules for calculating the thermal transmittance, U I), in the glazing central area, The combined edge effects due to the thermal bridge of a glazing unit spacer and of the window frame are not included.
These rules are intended to enable the heat loss through glazing in a building to be estimated from the glazing U values and, together with heat losses through the opaque elements of the building, are used to determine the capacity of the heating or cooling plant.
In addition, U values for other purposes can be calculated using the same procedure, in particular for predicting:
a) conduction gains in summer;
b) condensation on glazing surfaces;
c) seasonal heat loss through glazing in determining overall energy use in buildings;
d) contribution of absorbed heat in determining the solar factor.
The rules have been made as simple as possible consistent with accuracy.