Improved awnings and overhangs for increasing the daylight factor

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Light that enters a room through the windows exist of short wavelength radiation (visible radiation) and out long wavelength radiation (thermal radiation). The visible radiation contributes to the increasing of the daylight factor. The thermal radiation contributes to the increasing of the temperature in the room. In the summer the contribution of the thermal radiation may become so big that the room will be overheated. The cheapest option is to reduce the thermal radiation due making use of shading devices. The disadvantage by making use of shading devices is that it not only reduces the thermal radiation but also reduce the visible radiation. This will decrease the daylight factor inside the room. In this work the shape of the awning and overhang is changed to increase the daylight factor without increase the heating due to thermal radiation. Different geometries are studied and daylight measurements are done with help of a scale model. For south faced windows, there is only a little difference between the daylight factor for a rectangular overhang and the daylight factor for a trapezium overhang. Therefore is there not calculated any more with overhangs for south faced windows. However this difference in daylight factor is bigger for the awnings of an east or west faced window. At the same time the amount of energy transmitted through the window is calculated. The best awning for an east or west faced window in the Dutch climate (latitude 52oN) studies show that it is possible to increase the average daylight factor by approximately 80% while the irradiation increase due to reduced shad...