Impact of internal venetian blind openings on daylight in an office space in Serdang, Selangor, Malaysia

Having a daylit space together with view results in a pleasant and productive environment for office employees. A daylit space is a space which utilizes daylight as a basic source of illumination to fulfill user's visual demands and minimizes the electric energy consumption. The daylight evaluation is based on comparing the data gained through field measurement and computer simulation with suggested cut-out variables by the literature. Workplane area in a private office room has been selected as a case study. Eight-day measurement experiment was conducted to investigate the effect of different venetian blind angles using per pixel analyzing tools in an office ro220m under daylight condition in Serdang, Malaysia. The main goal of the study was to explore daylight comfort of a commercially available venetian blind system, its daylight sufficiency and excess (8:00 AM to 5 PM) as well as Glare examination. Recently developed software, analyzing High Dynamic Range Images (HDRI captured by CCD camera), such as radiance based Evalglare and hdrscope help to investigate luminance-based metrics. The main key factors are illuminance and luminance levels, mean and maximum luminance, daylight glare probability (DGP) and luminance ratio of the selected mask regions. The findings show that in this case, office room with south-west window, in morning session, daylight alone is not enough and artificial lighting is necessary to achieve occupants' comfort. Moreover, there are conditions in the afternoon session which have disturbing light and exceed the cut-out variables suggested by the literature as a comfort anticipants. For example, workplane illuminance level exceeds the maximum illuminance 01'2000 Lux for some conditions after 3:00 P.M(figure 4.4). Generally, a rising trend is discovered toward mean window luminance level during the day and the most unpleasant cases occur after 2:00 P.M. Evaluating the scene pixels, 40% of the selected hours (from 9:00 a.m. to 5:00 p.m.) have more than 10% of the scene pixels higher than 2000 cd/m- after I :00 P.M. Surprisingly in no blind condition, there is no extreme case of window It ask ratio due to the lack of the reflection from the slats. Studying the daylight glare probability, there is not any DGP value higher than 0.35 in this experiment It should be considered that this research is done under the specific office location, weather condition, window direction and selected blind system in Selangor, Malaysia. Further research is recommended for different window directions and locations, as well as different blind and glazing systems.

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