Illuminance and Daylight Distribution Assessment for Learners’ Comfort and Safety in One-Side-Window Oriented Classroom Building
Natural light as source of illumination in different environmental settings has the highest degree of acceptability as it offers many qualitative strengths and quantitative advantages. The visual functions effects of light are expected since the illumination from a particular light conforms to relevant standard for glare-free and visual conveniences. The present research work measured classroom environment illuminance and light distributions in a one-side-window oriented classroom building for visual comfort and glare. The quantitative measurement of illumination of the inside and outside of the classrooms was done using lux digital meter of high precision wide measurement range of 1 - 1200,000 lux with an accuracy of ±4% ±10 digits (<10000 lux); ±5% ± 10 digits (> 10000 lux). The resolution was set to 1 lux and measuring ranges of 2000/20000/200000 Lux. The measurement was taken according to the school timetable, three times each day at six different points; five points in the classroom (at the front right (FR), back right (BR), front left (FL) and back left (BL) corners, and at the centre (C)), and one outside the classroom (taken along the passageway by the various classrooms’ entrances). The time of data collection were during the assembly/breakfast period (7:50 – 8:30 am), the recess period (11:50 am – 12:20 pm) and short break before afternoon prep (2:20 – 2:30 pm) from March through December, 2016. These periods were chosen to avoid the distraction of the teaching-learning process in the school. Assessment of operational safety for illuminance and daylight distribution of various assessed classrooms were carried out on the basis of Useful Daylight Illuminances (UDI). The result obtained showed significant illumination variation on either side of the classrooms with much effects of under-lit on the un-windowed side and glare potentials on the side close to the windows. It, therefore, demands that for uniformly distributed illumination with glare-free and visual comfort classroom environment, the daylight entrance should be from two or more directions.