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Introduction to Indirect Lighting “Indirect lighting” has come to represent a family of fixtures in which 90-100% of the light output of the fixture is bounced off of room surfaces before reaching the workplane. It is available in a broad range of configurations, mounting options, materials, shapes, colors and distributions. Typical indirect fixtures include pendant-mounted linear fluorescent, workstation-integrated/mounted, disk-shaped pendant-mounted decorative compact fluorescent, and others. Indirect lighting for open office plans began to grow in popularity with the rapid adoption of computers in the early ’90s. The computers feature a video display terminal (VDT), a vertical workplane and a highly reflective surface. Since lensed recessed fluorescent troffers in the ceiling of many open offices are brighter than the surrounding ceiling space, they can be reflected on the VDT screen. The eye tends to drift towards the brightest spot in our field of view, making these reflections distracting and visually fatiguing. In many cases, veiling reflections from VDT screens can obscure tasks on the screen. In 1992, the Illuminating Engineering Society of North America published RP-24 (RP-1), which offers guidelines designed, in part, to minimize glare on VDT screens. Afterwards, indirect lighting sales began growing 15% per year, showing up in offices, computer classrooms and other environments. Indirect lighting, properly designed and installed, can reduce glare on the screen by reflecting light from ceilings and walls. By 1996, said one manufacturer, indirect lighting began to be considered in 40-50% of projects where visual comfort was an important design goal. As a result, the industry flourished, reducing prices, increasing volume and promoting research and development. One of the most exciting new developments in indirect lighting is the introduction of the T5/HO lamp, which reduces required fixture profiles, increases possible fixture spacing distances, and reducing the number of fixtures required in a space. |
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Linear indirect lighting can be a cost-effective method of improving lighting quality and reducing glare on computer screens. |
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