03/26/2003

The Ups and Downs of Lighting

Deciding Between Direct and Indirect Lighting

 

Clean, light-colored furniture works best with all lighting systems and maintains a comfortable working environment.

Deciding Which Light is Right

With a clearer understanding of the benefits and drawbacks of direct and indirect light, it may still be difficult to decide which is best for your facility.

Ask yourself the following questions …

What tasks are being performed?

Are many meetings being conducted? Are employees putting lots of little pieces together? Are computers being used every day? Is there lots of heads-down work? “If you have a conference room where there’s a lot of interaction among occupants; if you’re doing a lot of meetings and multimedia kinds of events, you’ll want some direct light. The reason is to help us create highlight and dimensionality. For example, in video-conferencing, it would be nice to put some downlight in so the camera can pick up dimensionality from the space to transmit to the remote site,” explains Peter Ngai, vice president of product development at Peerless Lighting, Berkeley, CA. In rarely used spaces where little time is spent (corridors, lobbies, etc.), some professionals recommend using direct lighting – especially if plaques, awards, artwork, or other items are being showcased. It also provides a change of scenery and a visual break from the office environment.

What is the height of my ceiling?

Ceiling height plays a factor in this decision. Indirect fixtures are hung anywhere from one-and-a-half to two feet from the ceiling. “If you have a low ceiling, it’s not going to work. You’ve got to have at least seven-and-a-half feet from the floor to the bottom of the fixture,” describes Mary Beth Gotti, manager, GE Lighting Institute, Cleveland, OH. Newer fixtures claim you can snug fixtures up to a foot from the ceiling, and Clark explains that it keeps getting better. Future fixtures will work in ceilings that are eight feet from the floor.

Remember to keep ceiling material and color in mind as well.

What about the lamps?

The lamps are basically the same from one fixture to the next, but Steve Goldmacher, director of corporate communications at Somerset, NJ-based Philips Lighting, explains that not all lamps are interchangeable between direct and indirect fixtures. “If you’re in an area that would use standard fluorescent 2x2 downlighting, I’m sure you can find indirect sources that use the same 2x2 tube. So you could virtually have the same type of light. You may need more of them to reflect than the ones shining down from the ceiling. So, the issue becomes, ‘Is it a one-for-one replacement?’ It may not be,” he says.

He also explains a myth that surrounds lamps in indirect fixtures. “I think people believe you can only get certain indirect lighting with incandescent light bulbs, which is not true. You can get it with fluorescent, you can get it with metal halide, you can get it with almost anything. So people also probably think it’s less energy efficient because you have to use incandescent bulbs, but that’s a fallacy. Because you can use fluorescent or high-intensity discharge lamps, you can get very good efficiencies … perhaps even better than ceiling fluorescents, for example.”

Color rendering is another topic that Goldmacher mentions as significant. “Years ago, the dominant type of lamp was called a cool light, but it had terrible color rendering. On a scale of one to 100, it was about a 62 to 64. Now, it doesn’t have to be fluorescent, but [a lamp] needs to have a color rendering index (CRI) something in the 85 range.”

How will my office furniture and configuration affect the decision?

If your office furniture, partitions, and walls are dark-colored, indirect lighting may not be the best option for you; they can absorb the light coming from the ceiling. Clean, light-colored furniture will help maintain a comfortable working environment.

One other tip to keep in mind: Light reaching the employees’ desks will be 15- to 20-percent lower if furniture partitions are taller than five feet four inches. Furniture-mounted overhead storage bins also reduce light levels. With direct lighting, office configuration has to be taken into consideration. If employees sit directly under or to the side of the fixtures, they may experience glare and discomfort. Employees seated farther away from fixtures may not receive enough light necessary to complete their tasks contentedly.

Want a way to determine whether or not lighting levels are too high? Stand in the area you’re wondering about and hold your hand over your eyebrows like a baseball cap. If you feel your facial muscles relax as a result, your lighting is too bright.

How can I meet everyone’s

lighting needs?


Pleasing everyone may not always be possible. If employees complain about not enough light, provide adjustable, non-glare task lights to compensate for lighting deficiencies. If employees complain of too much light, keep those using computers away from direct luminaires and locate those doing hands-on work closer to the fixtures.

“When you use an instrument to measure the brightness for parabolic downlight, it will be the brightness of a bare lamp. That brightness can be as high as, from T8, 9,000 candela per square meter to over 27,000 for a T5HO lamp. But for indirect, if you use the system correctly, the brightness of the ceiling that the light shines on [is what is measured] and is probably no more than 200 candela per square meter,” Ngai clarifies.

Can I make direct lighting more comfortable?

Lenses and louvers can cover the lamps so only their outline is visible. Direct fixtures can also be located so employees can look up and don’t have to see the lamp.

Don’t ever invert a conventional direct fixture to aim toward the ceiling as a replacement for an indirect fixture. This will create a “hot spot” on the ceiling directly above the luminaire, causing more computer glare and discoloration of wall surfaces. Dimming controls may be another option.

What about my personal taste?

Some facilities managers like the soft, “home-like” feel that indirect lighting provides. Others prefer the contrast and dimensionality of direct lighting. It’s perfectly okay to take your likes and dislikes into consideration. Make sure you get the input of your building occupants as well.

What about cost?

In earlier years, installation and material costs for indirect fixtures were much more expensive. But today, “manufacturers can show they are very much equivalent or even better,” notes Ngai.

Per fixture, direct lighting may be cheaper in some cases. But Goldmacher recommends facilities managers take this equation into consideration when looking at expenses: “If you think of lighting as being broken down into three parts – lamps, labor, and electricity – the lamps section is only about three percent of the total. Labor is about 11 percent, and electricity is about 80 percent. Lamps and fixtures go in one time. You have to change them occasionally, but that’s really nothing. It’s electricity and maintenance that are the killer costs. What you want to do is find the most efficient product that can handle the task you’re working with and get the best lamp for that system.”

What about a combination of light?

A combination of both direct and indirect is another possible option. “It is okay for you to introduce some downlight components into an indirect lighting system. A combination of both can be good. You just want to be sure you do it appropriately and you do not go overboard. It’s also fine to say, ‘Well, I want to have 100-percent indirect.’ A lot of times, it’s a matter of personal preference as well.” Ngai also explains that for every bit of direct downlight you bring into a space, you take away a certain amount of the “goodness” of the indirect light. He explains it as a trade-off, comparing what you want to have with what you’re willing to give up. “But,” he says, “we should never, in an office space, give up to the point that is going to create a visual glare problem.” His advice when mixing the two: “In order to maintain the overall lighting quality, introduce no more than 40 percent of downlight into the space and at the same time control the brightness of the downlight component to avoid glare.”

Being a facilities manager, chances are you’ve heard a building occupant complain of fatigue, blurry vision, headaches, or back and neck pain. Before you call the doctor, consider your building’s lighting system – it could be to blame. With 68 percent of employees complaining about the lighting in their workspace, facilities managers are constantly being challenged to re-evaluate their current lighting situations.

Most professionals recognize the obvious differences between direct and indirect lighting systems – but there are other benefits, drawbacks, and points to consider before deciding which is best for your particular situation. No single type of fixture is appropriate for every application.

Direct Lighting

Direct lighting luminaires are typically recessed into the ceiling and aim 90 to 100 percent of their light downward from the ceiling onto the worksurface. A small amount of reflection may occur due to light hitting the wall, but the majority of the light hits the space without any reflection. High in popularity, you’ll see this type of lighting in most office spaces today. Many manufacturers provide lenses or louvers to shield the actual lamp from view and cut down on glare. Direct lighting can produce visual “excitement” and create visual variation. In most cases, the fixture cost is less with a direct lighting fixture than an indirect fixture, and installation is easier considering many of today’s traditional grid ceiling systems. Depending on an employee’s task, direct lighting may prove superior.

On the flip side, direct lighting can create an “uneven” environment if fixtures are not spaced properly. It can cause shadows in the space: Employees sitting under the fixture may receive very high levels of light (sometimes even too much), while others seated away from the fixture may receive much less (sometimes too little).

Office furniture must be clean and light-colored in order to reap optimum benefits from the fixtures. Darker-colored furniture or partitions can absorb lighting, making it hard to maintain a good balance of brightness for the user.

Some direct fixtures, like those with plastic lenses, can create glare on computer screens. This can contribute to blurry vision, fatigue, and headaches. Too much overhead light can create direct glare and visual discomfort. Eye fatigue can also result from uncomfortable differences in “visual brightness” in the work environment.

Additionally, cleaning and maintenance can be a hassle with these lighting fixtures. Maintenance workers may have to climb ladders to reach the fixtures; if lenses and louvers aren’t hinged, the piece must be removed and set down before workers can install the new lamps. Lenses and louvers must be cleaned, as well as the interior of the fixture’s housing.

Indirect Lighting

Indirect lighting fixtures are typically suspended from the ceiling on pendants or aircraft cable, and they aim 90 to 100 percent of their light upward. The light hits the ceiling and is reflected back down onto the workspace. Terry Clark, president at Union City, CA-based Finelite Inc., explains that the indirect lighting market is breaking into two segments. “There’s one [segment] that deals with a lot of architectural pizzazz. You’re buying style, you’re buying a brand name … they often offer custom lengths, and perhaps shapes. You pay a substantial premium because these fixtures are hand-crafted, high-margin products. The second, and fastest-growing segment, is for affordable, easy-to-install fixtures made in high volume. These fixtures often can be installed for less than half the cost of the architectural ones. If a customer is being told that indirect lighting is too expensive, they may be looking at the fixtures in the architectural segments instead of high-volume ones, or the contractor may not be aware of how easy the newer-style fixtures are to install,” Clark explains.

Although indirect lighting isn’t used as often as direct lighting, its popularity is increasing in commercial office facilities. It’s proven that employees tend to prefer indirect lighting in the work environment due to the increased visual comfort. “We get thousands of people that come through the Lighting Institute, and [there] we have an office lighting demonstration room. We’ll show them direct lighting systems with lenses and parabolic louvers. Then we’ll show them an indirect lighting system in the same space, and almost without exception, people tend to prefer indirect lighting just because it’s visually very comfortable and gives a very pleasant glow to the space,” notes Mary Beth Gotti, manager, GE Lighting Institute, Cleveland, OH.

The light is shadow-free and evenly distributed; everyone in the space receives the same amount, regardless of where they’re seated. This allows office furniture to be moved and rearranged without having to take the lighting fixture locations into consideration.

“Probably one of the best advantages of indirect lighting is that it does give the illusion of more light,” says Gotti. “As everyone is struggling to get watts-per-square-foot down for their lighting systems, [indirect makes] the space appears brighter than what it is. You probably can get by with a bit less lighting because the quality of lighting is so good. Some of the lowest watts-per-square-foot can be achieved with some of today’s indirect lighting systems.”

Maintenance is also convenient with indirect lighting. Fixtures can sometimes be reached without a ladder. It can be a simple process of removing the bad lamp and replacing it with a good lamp; no pieces need be removed or set down. Surfaces still need to be cleaned, as with direct fixtures.

Common complaints about indirect lighting are that it is “uninteresting” or “gloomy” since it doesn’t create much visual excitement or variation. Emphasis isn’t placed on any certain area, and nothing in particular is accentuated.

To obtain maximum advantage from an indirect system, your building’s ceiling material must be at least 70-percent reflective, or preferably 80-percent or higher reflective. In recent years, ceiling material made with 90-percent reflectance has been made available. Peter Ngai, vice president of product development, Berkeley, CA-based Peerless Lighting, explains that ceilings shouldn’t be made of specular-type materials. “If you have a mirror-finish type of material, that’s not very good for indirect. You actually will be able to see the lamp images in the reflection.”

Ceilings must be light-colored and clean. “If you have a paint color that’s not white, you’ll reflect some of that color down. For example, if you have brown paint and reflect white light up, some of the brown light will come back down. Something will bounce off,” explains Steve Goldmacher, director of corporate communications, Somerset, NJ-based Philips Lighting.

As mentioned with direct fixtures, indirect fixtures also work best if office furniture is clean and light-colored.

Although installation and fixture costs have previously been thought to be higher than direct luminaires, popularity and familiarity are lowering expenses. And fixtures are not only becoming cheaper, they’re becoming easier to install.

Energy Efficiency

Energy efficiency is always an issue when buildings professionals talk about lighting. Both direct and indirect systems have things to keep in mind when contemplating energy usage.

Direct lighting can be an efficient option. Gotti points out that efficient lamp and ballast combinations can be used in these luminaires. The New York City-based Illuminating Engineering Society of North America (IESNA) recommends certain footcandle levels for various tasks (writing, typing, reading, etc.). “To achieve that level with reflected light may require more initial lumen output from the lamps if they have to reflect back before [hitting the required level],” explains Goldmacher. In other words, it may take more actual light output from an indirect fixture to equal the same footcandle level as the light output from a direct fixture.

Indirect fixtures can be an efficient choice as well. Instead of having to feed each light separately, continuous pendant systems require only a single point for an electrical feed. And because of the high intensity and smaller diameter of T5 fluorescent lamps, indirect fixtures can be more efficient and spread farther apart, which lowers watts-per-square-foot. “If you can get your watts-per-square-foot down, the energy savings may more than pay for the difference in going from direct to indirect lighting,” emphasizes Gotti.

To meet the tightest energy codes (approximately eight-tenths of a watt-per-square-foot or lower), Clark estimates a building owner will need at least 15- or 20-percent downlight.

Although no one answer fits every building, think about the lighting system your facility currently has, look at your possible options, and take these points (as well as those in the “Deciding Which Light is Right” section) into consideration during your quest to make your facility its best.

Leah B. Garris (leah.garris@buildings.com) is editorial coordinator at Buildings magazine.

 


Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

Bluebeam® Revu® simplifies digital facilities document management from design review to leveraging as-builts, maintenance manuals and O&Ms submittals.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.


Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

Bluebeam® Revu® simplifies digital facilities document management from design review to leveraging as-builts, maintenance manuals and O&Ms submittals.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.


 
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