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10 Questions to Ask Before A Lighting Upgrade

FacilitiesNet

When considering a lighting upgrade, the first impulse is to retrofit the existing installation by replacing lamps and ballasts, or even replacing existing fixtures with new ones. But often this is not the best long-term solution. There are many circumstances where a retrofit is a poor investment and results in throwing good money after bad. Retrofits are also subject to "cream skimming," where the proposed solutions target the easiest savings with the lowest first cost. It is easy to increase efficiency and decrease consumption — the challenge is to provide acceptable lighting quality and designs that retain their savings over the long run.

True value can come from redesign. Redesign includes assessing the qualitative aspects of the design and exploring potential improvements to lighting quality while saving energy.

Qualitative features include glare control, contrast, color rendering, visual comfort and other elements that have an impact on work performance, retail sales, and health and well-being of the employees, occupants and visitors of buildings. Light levels are seldom the most important element of quality.

In fact, the desire to maintain or increase the quantity of light on the task surface often results in designs where the luminaires re-direct more light downward. The resulting effect is less light on walls and faces, significantly reducing lighting quality. More efficient lamps and ballasts are unlikely to improve lighting quality, even if the quantity of light is increased. The greater brightness of energy efficient lamps like T5 fluorescent and LEDs are likely to increase glare.

The first question facility managers should ask when considering a lighting upgrade is, "What is the purpose of the lighting?" The answer is so much more complex than, "To see the task." In an office, lighting contributes to long-term satisfaction with the work environment and overall work performance.

Important questions include: Would you want to spend eight hours in this space? Is the electric light balanced with the daylight; is there enough variation and stimulation without harsh shadows and distracting hot spots? Can the performance of multiple tasks be accomplished free of glare and with light levels that can be controlled by the individual? Are face-to-face discussions enhanced by flattering lighting that enables facial expressions to be clearly read?

These are not minor issues. Energy savings without quality will inevitably backfire. If the quality of light in a space is poor, occupants tend to "self-medicate" — take more sick days, work less effectively, bring in their own (inefficient) desk lamps, or disable an improperly calibrated control system. These can have a negative impact on energy savings, causing "bounce-back" as energy consumption starts to creep up after a retrofit.

Here are 10 other questions facility managers should ask in evaluating a lighting redesign versus a retrofit.

1. What are the goals for the upgrade?

While energy savings or reduced re-lamping might be the impetus for an upgrade, laying out all the desired benefits may lead to a different solution. Lighting upgrades could improve the lighting quality, increase the effectiveness of the light, improve sales, increase safety, improve flexibility and controllability, justify rent increases, provide marketing opportunities for branding, provide maintenance feedback data, respond to codes and local laws, etc.

2. What is the quality of the existing lighting?

Most often, the original lighting was specified for a generic function, with calculations based on "empty rooms" and standard assumptions. It was also specified for a luminaire with specific distribution and cutoff characteristics. Lighting comfort may never have been a consideration in the initial design. Take a critical look at what currently exists. A design which gives poor quality of light now is unlikely to give better quality if lamps and ballasts are changed.

3. What is an acceptable quantity of light?

It is not all about footcandles on the desk. In offices, lower light levels that are uniformly distributed are more valuable than higher light levels that are uneven. In retail, the reverse may be true. Footcandles that light all the room surfaces are as important as those lighting the task surface.

Know the difference between maintained and initial luminance. Beware of service providers who use a light meter reading of the existing system (maintained luminance) as the benchmark, and then promise to provide equivalent light levels in the retrofitted design (initial luminance). The existing design may have distributed light widely to all the room surfaces, and the illumination level may have been based on lamps that were burning for 4 or 5 years. The service provider then replaces the system with fewer lamps, ballasts and maybe retrofit reflectors that direct light straight down, to achieve the same illumination level. The facility manager is unhappy because the room surfaces look darker, the luminaires are harsher, and the light levels will begin to degrade from the initial level. The Illuminating Engineering Society of North America recommends light levels, but also provides valuable qualitative criteria. Don't stop at footcandles just because they are the most easily quantified. Quantity cannot replace quality; if a space is poorly lighted, increasing the quantity of light won't help, and may even make the bad situations (high contrast, glare, shadows) worse.

4. What do your eyes tell you?

Mock-up the proposed options, with six to 12 luminaires. The expense of a mock-up is well worth its value in evaluating either retrofit or redesign options. It's best to have the mockups in a separate space (or spaces) so that there is not a direct comparison with the existing. The rooms should have identical furniture and finishes, and it should be possible to judge the effect of the proposed light on walls and other vertical surfaces. Evaluate the overall appearance of the space, distribution, high contrast versus uniformity, shadows, harsh patterns, natural color, appearance of faces and objects, glare or distraction from a variety of viewing positions, then measure illumination levels at multiple points throughout the room and on faces and vertical surfaces.

5. Are you keeping the long view?

The greatest cost in office buildings is employee salaries. If the lighting causes a distraction that affects less than 1 percent of an occupant's productivity, then all of the savings from reduced energy consumption has been lost. For a facility manager, repeated complaints are costly and have an impact on retaining and renting facilities. Using simple payback as the criterion is shortsighted, if, for a few dollars more, savings can continue to accrue for years to come. Use reputable manufacturers with a good track record of research and development, independent photometric tests, and good service.

6. What other opportunities are available with redesign?

There are a number of energy saving strategies that can be employed when not restrained by existing luminaire locations. For example, a single "building standard" luminaire is not really appropriate for all spaces. If it works for an open office, it may under light private offices and over light circulation or public spaces, using more energy than the codes allow. Spacing the luminaires wider than recommended, to reduce connected load, often leads to high contrast or harsh shadows. Redesign provides the opportunity to redirect light to the walls and ceiling, and to install luminaires that are right for each job — low-wattage corridor lights, or dedicated wall-washers, for example.

Redesign of the interior space layouts can make the entire project more energy efficient. For example, placing open plan offices on the window wall will result in significant savings from daylight harvesting controls. By tailoring the light in support areas and reducing light levels in circulation or lounges, the lighting in work areas will appear brighter by contrast. If the height of cubicle partitions or open plan furniture is reduced, a space utilizes the light more efficiently, and with fewer shadows and better quality, resulting in a lower connected load.

7. What energy conservation measure yields the greatest value?

One low-cost way to improve energy efficiency is to improve the reflective characteristics of the ceiling, walls and furniture. Overall lighting efficiencies can be increased 20 to 50 percent in some spaces. Consider replacing hung ceilings with new, 90 percent reflective ceiling tiles. For even less cost, repainting the walls a lighter color has significant benefits, reducing light loss by absorption, improving efficiency, reducing shadows and high contrast and improving lighting quality. This is the most cost-effective measure a facility manager or owner can make. Recommended light reflectance values are 90 percent for ceilings, 70 percent for walls and furnishings, and 30 percent for floors. Avoid shiny or glossy finishes. A matte or eggshell finish gives the most uniform reflection, and appears the brightest.

8. What are the daylighting opportunities in existing buildings?

The most effective daylighting comes from the highest portion of a window. Many existing buildings were initially designed with high windows and high ceilings, when daylighting was considered the primary source of lighting. But often renovations have resulted in hung ceilings that extend to the window wall, obstructing the window's most desirable portion.

A lighting redesign could include re-thinking the ceiling at the perimeter. Is it possible to relocate HVAC ducts or raise the ceiling to its highest possible level for the first 10 to 15 feet from the window wall? This not only improves lighting quality, but will also increase the rentability of spaces. In addition, if the area at the top is optimized, daylight penetrates deeper into the interior, making daylight harvesting controls more viable.

Energy is only saved if electric lighting is reduced, and that requires controls that are user-friendly and properly commissioned. Daylight quality and glare controls can be enhanced by films, interior light shelves, window treatment, and automated blinds.

9. How can lighting controls provide greater savings?

Studies have shown improvements in employee satisfaction when they have control of their local lighting. Wireless light controls are currently most appropriate for all-fluorescent installations. Beware of the lure of combination sensors — the ideal location of an occupancy sensor rarely overlaps with that of a daylight sensor. Digital addressable lighting interface (DALI) controls not only reduce energy consumption and wiring costs, and enable future flexibility in zoning, but have the added benefit of providing the facility manager with feedback about consumption and equipment failures. But these capabilities are only worth the investment if they will, in fact, be fully used. Finally, lighting controls will only save energy if they are properly designed and calibrated so that they do not distract or annoy the occupants.

10. Are new technologies in their proper place?

There is a strong desire for the magic bullet, pill or technology to solve a problem. Don't fall into the trap of focusing on a product or technical solution before taking the necessary steps to assess the real design need. Independent advice is valuable on this topic. All of the pitfalls and myths about LED lighting would fill an article much longer than this, but the same caution applies to all products. Let the design lead to the technology, not the reverse. Many of the most successful energy savings techniques, and the first ones to consider, are "passive" measures, like room reflectances, proper placement of luminaires, selection of the appropriate light distribution, lighting the room surfaces, layout of furniture and circulation, daylighting, and tailoring the lighting approach for the space type. Excitement over a manufactured product is understandable, but it should never be the starting point for a redesign or retrofit.

In summary, before automatically moving ahead with a retrofit lighting project, take the time and care to evaluate the options and the long-term benefits. More time spent on the design side is likely to result in a luminous environment that is both energy efficient and truly effective for its intended purpose.