The U value of a frame, called Uf value, indicates the heat transfer through the area of the frame and is based on DIN EN ISO 10077-2.

The heat transfer is expressed in watts per square meter and Kelvin. The Uf value of a frame profile is determined automatically in WINISO®. The glass structure is replaced by a calibration panel. After the calculation a scalable frame and the result appear in the view. The sides of the frame can be moved manually. This changes the calculated Uf value.