A sensitivity analysis on glare detection parameters

Maximizing daylight access while maintaining a glare-free indoor environment is an ongoing challenge for daylighting design. Glare is a discomfort sensation that is produced as a result of greater variation of luminance across the visual field than the one that the eye is adapted to. This type of discomfort sensation is one of the main drivers for building users' interaction with the façcade setting, which consequently can change the building's performance over time. Optimised integration of glare-free daylight solutions thus proves to be crucial for a sustainable building design. The existing methods for glare-free daylighting design rely on analyses on image-based advanced renderings with accurate simulation of light behaviour. These methods are becoming more commonly used for daylighting design using simulated three-dimensional geometrical model of the architectural space and employing tools such as Radaince for rendering the light. As convenient as this approach seems, it has complexities in attempts to define different components of the visual comfort metrics. One of these complexities is detecting the glary image pixels. The existing glare source detection methods consider any image pixel of luminance value that is x-times larger than the average luminance of a visual adaptation region as a potential glare source pixel. The method then searches the image based on a predefined search radius to find and combine all the glary pixels as one glare source. In this method, the value of the threshold multiplier and the search radius are decided intuitively based on the luminous environment of the studied scene. In this study we have made a sensitivity analysis on the threshold and search radius parameters for glare source pixels detection.