The effect of architectural details on daylight distribution inside a room

Abstract

In Iranian historical architecture one of the most important design criteria is daylight accessibility and quality. To evaluate daylighting conditions in a historical house in Kashan city in Iran, one of its main rooms was examined according to field and simulation studies in the year 2012 and 2014. To evaluate the effects of architectural design details on daylighting conditions of the room, some elements such as balcony, ceiling shape and height, window size and frame, glass size and colour, where changed or eliminated by simulation. The amount and distribution of daylight inside the room was simulated in the morning, noon and afternoon of two sunny days in summer and winter on a horizontal mesh at 80 cm height. The important UDI (useful daylight illumination) levels on different parts of the room were calculated on this height in all months of the year. On a column diagram, the results of this calculation show the percentage of daylight accessibility in a year. The illumination amount and its distribution inside the room show great differences in different architectural detail conditions. The results show that the original condition of the room has a delightful daylighting in comparison to changed configurations. Also it has the best UDI daylight distribution in all seasons and hours. The other result is that with the same sky view and room dimension, changing detail design such as ceiling shape, window height and size, glass details, and so on, has great effect on illumination distribution and light level in different seasons inside the room. Therefore, in some cases, it is possible to modify the daylight condition of a room just by deliberate detail changes in architectural design.