Fenestration Systems as Luminaires of Varying Candle Power Distribution

When designing a fenestration system, it is often required to determine its luminous performance, that is the way it allows daylight to enter the space and contribute to the required illumination levels. This can be achieved either through use of scale models or through computer simulation. Each approach has advantages and disadvantages.

On one hand, scale models allow the simulation of the luminous performance of any fenestration system, including consideration of outdoors and indoors parameters, such as exterior and interior obstructions, space geometries and surfaces reflectance. However, the construction of scale models is time consuming and expensive. Parametric studies require the use of many models, or a sophisticated, changeable one. Moreover, the use of scale models requires appropriate luminous source(s) to simulate the light from the sun, sky and ground, dictating testing under real or simulated sky conditions, which introduces additional limiting issues: real sky conditions are beyond the designers control and simulated ones require highly sophisticated and expensive facilities.