Comparison between optic and energetic performances of close diffusers and drilled plates

Modern luminaries use different systems in order to diffuse light, avoiding glare. The most frequently used materials are opal glass or translucent plastic as these materials exhibit the maximum degree of light scatter with the minimum amount of absorption. These materials, which are suitable for industrial applications, are not always appreciated for architectural purposes. An interesting alternative is represented by sand-blasted glass, fabrics, drilled plates with different hole shapes and dimensions. The choice of the diffuser involves different performances connected to the following aspects: Luminance of the surface, luminaire efficiency, infrared and ultraviolet transmission. In particular in this paper we are interested to solutions that guarantee high transparency for light together with a low transmission of ultraviolet radiations and a good diffusive behaviour. That is in order to select solutions for applications in which comfort for people and conservation of materials are important. With regard to discontinuous materials, such as drilled plates, a particular attention has been dedicated to study the effect of hole shapes and dimensions on the diffuser performances. The test apparatus is composed by a dark room, 1 floodlight and numerous samples of close diffusers and drilled plates.