The ability to accurately and concisely describe the performance of complex fenestration systems (CFS) is essential to their effective implementation into the building industry. CFS are a diverse category of daylighting technologies that manipulate the light that is permitted to enter a building space. The variety and degree of dynamics that exist in the range of such technologies require a robust and flexible set of metrics that can communicate performance simply and informatively. This paper presents an approach for processing their detailed optical properties - expressed as Bi-Directional Transmission Functions (BTDF) - into a comprehensible set of metrics that can convey useful information about a system’s adherence to visual comfort and energy-efficiency objectives. These metrics can then inform non-technical members of the building industry about the performance capabilities of a façade. This paper describes the novel method by which performance is evaluated, accounting for spatial and temporal variation in environmental condition.