Among the different environmental functions atria perform, this research has focused only on daylighting. The thesis has been presented in two parts. The first part provides the background information, the extent of daylighting research in atria, objective and scope of the research. The environmental role of atria has also been discussed. The second part deals with the research procedure, the description of the scale model used for the study, the conditions under which the study have been conducted, and finally, the conclusions of the study. The effects of changing the reflectivity of the wall and floor surfaces of the atria well on the illumination in the adjacent spaces to atria have been studied. The objective of the thesis was to establish the relative contributions of the changes in the surface reflectance of the wall and the effects of variations in the area of the openings in the wall facade on lighting in the adjacent occupied spaces. The importance of the floor reflectivity in lighting the spaces adjacent to the atria was also determined. Quantitative analysis of daylighting in atria has been conducted using physical scale models under natural overcast skies using daylight factor and well index to normalize the results. Although the thesis has concentrated on daylighting, in reality there are other functions, both social and environmental, that atria are required to perform, and where appropriate, these functions have been acknowledged. It has been established by this research, that the atria well and the spaces adjacent to it are affected by changes in the area of openings in the form of windows in the wall facades of the well. Small variations in higher reflective surfaces on the wall facade produce greater differences in the daylight factors as compared to similar differences in surfaces with lower reflectances. Using high surface reflectance on the floor of the atria well will enhance illumination in the lower levels of the atria. As the area of the (high) reflective surfaces along the edges of the floor is increased, the illumination in the side spaces in the lower levels also increases. The area of floor reflectivity needed for increasing the illumination levels in the side spaces is dependent on the area of openings on the walls at the lower levels. / Applied Science, Faculty of / Architecture and Landscape Architecture (SALA), School of / Graduate