Abstract

Highly glazed building façades are increasingly popular in contemporary architecture, and as a result, new solar control technologies incorporated into advanced fenestration products are moving towards improved daylighting performance and more effective control of solar heat gain. Integrating advanced fenestration products into a building's façade design is considered as an effective way to conserve energy in commercial buildings. An advanced fenestration product, known as VisionControl®, integrates controllable aluminum louvers between two panes of glass, and is currently available on the market. This study starts by redesigning the VisionControl® window to reduce its overall thickness in order to enable its applications in commercial curtain walls and retrofit projects. The three-section façade concept is widely used in the commercial curtain wall industry as it provides view and daylight while controlling solar heat gain. This thesis presents a mathematical daylighting model developed based on a three-section curtain wall façade with the newly designed VisionControl® window installed on both the top and middle sections. The model represents separately the two window sections so that the middle and top section louvers can be independently controlled to maximize daylight transmission in the room while avoiding glare. This model is capable of estimating the workplane illuminance with the consideration of several important design parameters, such as building location, façade orientation, control strategy and window materials. Two experiments were conducted for this study. The visible transmittance of the newly designed VisionControl® window was measured in the first experiment. A custom-built testing device was designed to obtain accurate visible transmittance results with the consideration of different solar profile angles and louver tilt angles. Another experiment was conducted with a small scale office model to validate the mathematical daylighting model. Experimental results were compared with model-calculated results under three representative sky conditions. This comparison confirmed that the daylighting model can be utilized to estimate workplane illuminance with the newly designed VisionControl window with reasonable accuracy.