Daylight distribution models are essential for daylighting design and present information in a visual manner that facilitates decision making. With an accurate model, daylight in a space can be distributed in an efficient and comfortable way, so that the need for electric lighting in daytime is reduced. On the other hand, motorized shades can be controlled automatically to better distribute daylight on the work plane and reduce or avoid glare. 
Most of modern buildings, both commercial and high-rise residential, have windows in more than one orientation and have the provision for daylight penetration into space. In this study, a radiosity model for simulating the daylight distribution of a corner office having two windows in various orientations with motorized shades has been developed. The model calculates the illuminance at different locations on the work plane. 
The simulation model based on radiosity theory is verified with measured data under overcast and clear sky conditions with direct and diffuse lighting, and a parametric analysis is carried out for various room shapes and shading devices and façade orientations. The model is implemented in Mathcad and used to predict the illuminance distribution in the room for developing improved control strategies for shade positions and also for design guidelines to select the properties of the shades. Three section façade is considered with the bottom section being opaque (spandrel), the middle viewing section and a top daylighting section. Variable shade transmittance in the middle and top section of the facades is studied, and it is shown that having a higher transmittance in the top section results in improved daylight utilization and a middle section with lower transmittance provide privacy to the building occupants. Specific recommendations are made for shade transmittances for upper and middle part of the façade to maintain occupant privacy with acceptable illuminance in the work-plane.