Influence of scale on the daylighting system evaluation in physical models: Experimental method based on objective and subjective measurements

The daylight evaluation in architectural spaces can be carried out using several tools and methods of investigation and analysis. However, many types of research have proven the usefulness of the scale models to evaluate daylighting system performances in buildings. Several scales of a physical model have been used varying between (1:50) and real scale (1:1), and no comparative study has been done to evaluate the effect of the model size in daylighting assessment. The objective of this investigation is to make a comparison between two different scales of a physical model: the first one is a model with a scale of (1:12) while the second is with the scale of (1: 4), aiming to study the scale effects on daylight perception with models equipped with a daylighting system under very high exterior illuminance levels. The methodology of this study consists in collecting simultaneously the measurement of the exterior and interior illuminance level (lux) and subjective evaluations from a questionnaire survey with the two scale models (1:4 and 1:12) under real sky conditions. A correlation between collected data has been explored. Comparing the measurement results, it is obvious that the quantity of light that penetrates the test models (1:4 and 1:12) was the same. The results are with a range of ±1.6%. Moreover, survey results show that the participants’ perceptions regarding satisfaction, light distribution and glare questions differ with the scale of the physical 3D model. The subjects felt more satisfied with the luminous atmosphere with the physical model of (1:4) compared with the model of (1:12)