Determining the energy performance of windows requires detailed knowledge of the thermal properties of their different elements. A series of standards & guidelines exist in this area. Thermal properties of the frame can be determined either by detailed 2-D numerical methods or by measurements in accordance to EU standards. Comparing measured & calculated heat transfer coefficients for 2 typical frame profiles with cavities shows considerable differences. This investigation considers 2 typical frame profiles in aluminium & PVC with internal cavities. Heat transfer coefficient is determined by 2-D numerical calculations & measurements. Calculations are performed in Therm (LBNL (2002)) The calculations are performed in accordance with the future EU standards & measurements were performed at 2 German research institutes.
