Recent research has shown that environmental conditions in classrooms, and namely daylighting conditions, can influence students health, well-being and performance. In the last years several studies, dealing with the effects of environmental conditions in classrooms in the learning process, have been published (Winterbottom, & Wilkins, 2009; Barret, Zhang, Moffat, & Kobbacy, 2013). The daylight factor (DF) is the most used parameter in the characterization and quantification of daylight in buildings. The DF at a point of a plane inside a room is defined as the ratio (expressed as a percentage) between the daylight illuminance at that point in the interior of the room and the simultaneous exterior horizontal global illuminance due to a hemisphere of a sky of known or assumed luminance distribution (usually, a CIE overcast sky luminance distribution is considered). The DF reflects the effectiveness of daylight penetration in a particular room or space. The exterior daylight conditions may vary, but the DF remains constant, since the interior illuminances change proportionally to the simultaneous changes in the exterior daylight conditions (Santos, 2006).