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Ergonomic Office Lighting

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The modern office concept is largely based on flexible layout with computers as standard feature on all work stations. This creates specific demand on lighting to reduce glare from computer screens and to be fluid enough to match the flexibility of workspace.

The contemporary open-plan offices and their need for flexible use of the available space has made fixed lighting concept outdated. The new workspaces need lighting installations that can easily be adjusted individually without incurring major costs. Glare-free light sources that can adapt to daylight, the colour of light to enhance visual comfort and productivity & luminaries that can detect the presence of individuals are also basic requirements. The lamp selection is based on efficacy (lumens per watt), colour temperature, colour rendering index, life and lumen maintenance, availability, switching, dimming capability and cost.

Lighting Design

The requirements of new age work places are being addressed by the latest intelligent light management systems, the advanced lamp technology and varied lighting luminaries with activating light color to provide a motivating working atmosphere. For instance, conventional bright white bulbs that offer high illumination levels but cause eye discomfort or headaches are being replaced by the full spectrum fluorescent lights which are designed to mimic natural light. Similarly, incorporating wall washing to light the perimeter of the open plan office space increases the eye’s adaptation level and the impression of light in the space. General lighting is often provided by ceiling light fixtures with louvers complemented by table lights and floor lamps to intensify /layer the lighting effect. Umesh Rao, Founder & CEO, Vector Projects (I) Pvt. Ltd, an end-to-end interior turnkey solutions company for workspaces explains, “The primary purpose of any office lighting design is to provide sufficient illumination to support the work being done and to provide comfort for those doing the work. For each type of work there is a range of brightness which helps eliminate fatigue and give maximum output in terms of quality and quantity. Based on which, the three main aspects of ergonomic workplace lighting identified are, quality of lighting, correct illumination level and the uniform distribution of light. It is recommended that the ceiling lights should be Category II dark lighters with Paralite P5 louver system in fixtures for better light distribution and cutting down glare. For the passage or work space, the recessed / suspended channel fitting or the strip provides long and uninterrupted light beam. Conversely, for cabins, task lighting is important such as direct / indirect luminaries over the tabletop with some amount of ambient lighting whereas, for meeting and conference rooms the lighting is generally driven by AV requirements. We have experimented with hanging Direct / Indirect luminaries in some projects. These throw up to 80 % of the light on the ceiling which maximizes even distribution of light in the workspace. This also makes the space look bigger as the entire ceiling is lit up.”

As some tasks and workers require more light than others, designers keep the overall light level low that allow workers to supplement it with individually controlled task lights. For instance, illumination on the document should be relatively high, while lighting on the screen should be kept

relatively low. Industry recommended light levels for today’s computerized offices are 40-50 foot-candles and for intensive work such as data entry lighting level requirement is as high as 50-70 foot-candles (provided by task lighting systems).

While natural light at the workplace is important in terms of worker well-being, it also has its “dark side,” particularly for computer workstations. This means, each workstation should display a proper balance between natural and artificial light. Louvers, awnings, canopies and neutral-density film coverings can reduce direct light from windows while, use of task lights avoid shadows. The modern trend in efficient designing practices is towards “localized lighting plus general lighting”. This strategy uses uniform lighting layout for providing the ambient illumination level to the minimum acceptable level and then task lighting using CFLs closer to the working environment for increasing the illumination level at the task to the required level. Common practice is also to provide the controls to the users so that user can operate the localized lighting as per specific requirements. This also helps in lowering the lighting power density.

Also, as reflections and glare can interfere with visual comfort when working at a computer, ceiling suspended, indirect lighting also referred to as “uplighting and wall mounted sconces offer the most suitable solution. Indirect lighting fixtures are preferred over grates and parabolic louvers that can create uneven lighting with shadows. The effects of light and shadows decide the lighting quality as well. Lights placed parallel to the window and the working place help avoid shadows and glare and achieve a balance between natural and artificial light. Rao says, “Selection of direct / indirect fixtures generates reflected light in workspace which has more uniform distribution that helps to avoids glare. In addition, an energy efficient lighting system that utilizes natural and electric sources can provide a comfortable yet energy saving environment for the office. Intelligent use of lighting control systems with daylight sensors will ensure that lighting levels in Interiors are adjusted as per ambient light outside.”

Energy Efficiency

Recently developed energy efficient lighting equipment such as compact fluorescent lamps and “soft-start” electronic ballasts can cut lighting operational costs by 30% to 60% while enhancing lighting quality. Linear fluorescent lamps T5HO lamps work well in general lighting luminaries because the long and diffuse nature of these lamps provides excellent surface lighting and the smaller lamp diameters make for better optical performance. Indirect/direct linear fluorescent pendants and wall-mounted uplights are typical applications for these lamps. An energy efficient substitute for incandescent lamp is the Compact fluorescent lamps (CFL). Due to their small size, CFL lamps can be used in recessed luminaries, wall and ceiling mounted fixtures and even track lighting and task lighting. The diffuse nature of the fluorescent lamp makes the CFL lamp a good choice for downlighting and wall lighting also. Incandescent lamps are still used for accent and specialty lighting, where the warm color, controlled brightness, instant-on, and dimming capabilities of these sources is needed. PAR and low-voltage lamps provide good beam control and if dimmed can also provide a reasonable lamp life.

LED lamps are the newest addition to the list of energy efficient light sources. The key strength of LED lighting is reduced power consumption. When designed properly, an LED circuit can offer 80% efficiency. Since most offices demand high colour fidelity (CRI of 70-90), the white LED available today with CRI (Color Rendering Index) 80 or more are used for the vast majority of workplace applications. For example, Philips LED lighting products LumiStone and DayZone facilitate lighting flexibility and enable maximum energy savings. Commenting on the limitations of LED technology, Rao says, “T5 lamps are the most widely accepted energy efficient products being used in lighting. This is because the ROI for complete LED solutions is still not within the range which would make them affordable for majority of the Clients. LED prices need to come down further and efficiency needs to be better for it to be more viable.”

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