The luminance value at the window is about 5500 cd /m2. The luminance values for the various variants are given in figure 2. The dark line gives the measurements for the empty window, thus the reference values. With a luminance value of 40 cd/m2 on the wall, this amounts to a luminance ratio of 5500 / 40 = 140, which is much too high. From the light grey lines in figure 2 one can conclude that absorption is not a good way to reduce the contrast ratio between the window and the wall. Luckily, however, from the dark grey lines in figure 2 it can be concluded that reflection and the combination of reflection and absorption is a way to increase the amount of light on the wall next to the window opening, thus decreasing the luminance ratio between the window and the wall to a minimum luminance ratio of 40 for the translucent foil 1 cm in front of the window.