Choosing the Right Light: Page 2 of 2

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Inside this Article

Choosing the Right Light
Choosing the Right Light
Color rendering index (CRI)
Color rendering index (CRI) is a measurement of a light source’s accuracy in rendering various colors that it illuminates.
Incandescent bulb
Used judiciously, newer, more efficient incandescent bulbs can still serve a purpose in residential lighting schemes.
Halogen bulb
Halogen bulbs are made for many fixture types, are more efficient than standard incandescents, and are readily dimmable, providing added energy savings.
Halogen bulb
Halogen bulbs are made for many fixture types, are more efficient than standard incandescents, and are readily dimmable, providing added energy savings.
Halogen bulbs
Halogen bulbs are made for many fixture types, are more efficient than standard incandescents, and are readily dimmable, providing added energy savings.
Fluorescent lighting
Electronic ballasts and better color rendering have improved high-efficiency fluorescent lighting.
Compact fluorescent lamps (CFLs)
Though they are almost as ubiquitous as incandescents, CFLs aren’t the best choice for every application.
CFL variations
CFLs now come in many sizes, shapes, and fixture types, but continue to have variation in quality and performance.
LEDs are now being made to fit traditional fixtures
Today’s LEDs are now being made to fit traditional fixtures.
LED variations
New LEDs come in many shapes and sizes for various fixtures and applications.
Recessed fixtures for LEDs
LEDs work well in recessed fixtures due to their inherent directional light.
LEDs
Task lighting is a perfect application for LEDs.
Motion sensor switch
Motion sensor switches can make up for bad habits and unaware energy hogs.
Task lighting can provide ample illumination
Well-placed, specific-purpose task lighting can often provide ample illumination, spillover for safe navigation, and a pleasant lighting aesthetic.
Choosing the Right Light
Color rendering index (CRI)
Incandescent bulb
Halogen bulb
Halogen bulb
Halogen bulbs
Fluorescent lighting
Compact fluorescent lamps (CFLs)
CFL variations
LEDs are now being made to fit traditional fixtures
LED variations
Recessed fixtures for LEDs
LEDs
Motion sensor switch
Task lighting can provide ample illumination

Light Right

Hang a bare lightbulb in a room and turn it on. You’ll see that a large portion of the light shines on the ceiling, where it’s only useful to your local spiders or to make stick-on stars glow. Very little shines where you need it. Now put a reflector behind the lamp, and your useful light levels have increased with no increase in energy use, and your spiders are out of luck. Your great-grandmother probably knew all about this, too—kerosene and gas lamps back in the day didn’t produce much light. But by positioning the lamps at strategic locations and placing reflectors behind each, she could maximize the useful illumination. In more modern homes, lighting fixtures serve the same purpose, redirecting light to where it’s needed most, but different lamp technologies cast light in a variety of patterns and intensities, called “candela distribution.”

“Lumens measure light emitted in all directions,”says Rea. “Candelas measure light emitted in a specific direction. With the lumens per watt standard, we completely misrepresent any situation where we are not lighting the entire room, such as with undercabinet lighting for kitchen counters.”<

Your great-grandmother probably would not have approved of much indirect lighting, either. Valance, cove, and soffit lighting can create ambiance, but also waste a portion of your lighting energy budget. If you have the luxury of building a new home or remodeling an old one, you can plan ahead and consider the optimum locations for your fixtures. Do you really need to brightly light up your entire home office (ambient lighting), or would your energy be better spent on illuminating just your desk and other work surfaces (task lighting)? Consider your kitchen—it doesn’t take much light to navigate around a room without tripping, but you certainly want bright, high-quality light focused on the cutting board. The spillover from task lights may be enough to safely illuminate pathways. Avoid wiring lighting circuits that put more than one fixture on a switch, as you can end up lighting areas that do not need it.

At the hardware store, don’t just fill up your shopping cart with a pile of energy-efficient lamps. Quality of light, brightness, candela distribution, and color temperature vary significantly between manufacturers and models, even when the lamps show similar specifications on the package. Instead, buy a variety of single lamps and try them in different rooms and fixtures until you find what you like.

Rea also cautions against relying too much on “equivalency ratings” printed on CFL and LED lamp packaging that claim, for example, a particular 26-watt CFL makes as much light as a traditional 100-watt incandescent. “Don’t believe it,” Rea says, “Such ratings are based on industry standard test methods that often do not reflect how the products are actually used in the home. Consumers need to try different lamps themselves, and find what works best for them.”

Stick with the major lamp manufacturers. This used to be just the “big three”—Philips, Sylvania, and General Electric—but in recent years several other manufacturers have entered the market (see “Access”). However, avoid imported lamps that are not UL-listed or Energy Star-rated; some are so shoddily made that they pose a fire hazard.

Make sure the lamp you are interested in purchasing is compatible with the fixture in which you want to put it, and with any dimmers that will be involved. Write down brand names, model numbers, and manufacturer websites so you can research options on the Internet, and do your homework before you call.

“Lamp manufacturer technical support departments are used to working with large-volume buyers such as big-box stores, not directly with individual consumers,” Rea says, “but if you can make your questions very specific, most will be happy to help educate you about their products via phone or email. However, vague questions about ‘light quality’ and so forth won’t often receive a detailed response.

“Don’t be afraid to put the burden back on your local retail store, either,” says Rea. “Ask them if you can compare different lamps in different fixtures right there in the store.”

Consider installing occupancy sensors if family and friends are in the (bad) habit of leaving lights on when rooms are not in use. The sensors present a small phantom load, though it’s usually less than 1 watt.

Access

Author and educator Dan Fink has lived 11 miles off the grid in the northern Colorado mountains since 1991. He teaches about off-grid systems and small wind power, and is the executive director of Buckville Energy Consulting, a NABCEP/IREC/ISPQ-accredited continuing education provider. Dan is the coauthor of Homebrew Wind Power.

Lamp & Fixture Manufacturers:

APRS World • aprsworld.com • DC LED lamp & fixture

Cree • cree.com

Enduralite LED • enduraliteled.com

Feit Electric • feit.com

General Electric • gelighting.com

Lighting Science Group • lsgc.com

Lights of America • lightsofamerica.com

Lutron • lutron.com

Osram Sylvania • sylvania.com

Philips • usa.lighting.philips.com

Seesmart LED • seesmartled.com

Comments (5)

Abhijeet's picture

Dear Sir,

I have designed Solar Day Lamp. The step by step construction details are given at following links:

http://www.instructables.com/id/Sim...

http://www.instructables.com/id/Hig...

Advantages:

1. Very Long Life
2. Zero Maintenance and zero running cost.
3. Easy to make and Very cost effective
4. Fix and forget type design
5. Can act as emergency light during power failure in day time.

Uses:

1. At home, in areas where there is need of light in day time.
2. In the corridors of offices and apartments
3. Basements and Basement car parking areas
4. In offices can be combined with other lights to reduce power consumption.
5. As a school kit for students for teaching Solar PV technology.

So far I have got very good feedback from people where it has been installed.
I feel this will prove to very useful for all.

Thanks
-Abhijeet
Bangalore

David Bangley_2's picture

The spectral distribution of common light sources graph has two errors that should be corrected. First, the red peak beyond 600 nanometers is missing for FL and CFL lights. FL's are heavy in the green area, but do have significant red output. Second, the color wash behind the graph is backwards. The graph reads blue to red from left to right. Longer wavelengths are redder, until you get into infrared that we can't see. That's where the maximum output of the incandescent bulb is headed on the graph.

Ben Root's picture

Hi David,
You are correct about the rainbow color was being reversed in the graph's background. As the article's designer, that was my mistake...I was thinking "Frequency" when the x-axis is clearly marked "Wavelength". As for the spectral distribution of the CFL, I looked at a lot of curves for "typical" CFLs, and while they all had similar shapes (spikes), they also varied a lot in their distribution. Perhaps I picked a poor one to be "indicative". See http://ledmuseum.candlepower.us/led... for the varieties and similarities...a neat site.

EP's picture
EP

I would like to see additional coverage of "quality of light." The article does a good job of identifying the limitations of the 1-dimensional Lumens/watt rating, but could go farther in explaining color temperature and color rendering index. Halogen incandescent lamps can do an excellent job of replicating the color temperature and CRI of sunlight - but they are not very efficient.

So I am continually trying to find more efficient lamps that have a 3500ºK color temperature, and a CRI of 90 or better. These are rare and very expensive lamps typically. One of the biggest disappointments is finding a lamp with good quality of light, paying a fortune for it, and then having it fail after 6 months of use. Both LED and fluorescent-ballasted lamps do not survive in closed fixtures where heat can not escape. I would love to see a lifetime study of quality lamps in typical application fixtures - I doubt anyone is getting more than a few thousand hours (no better than the incandescent lamps). Moreover, I find that the fluorescent lamps (CFL) have a significant shift in output spectral content as they age - maybe you could quantify that in a future article?

Really enjoy the magazine - keep up the good work!

Dan Fink_2's picture

Thanks for your comments, EP.

When I interviewed Dr. Rea, we in fact did discuss CRI. But it, too is very subjective. Rea's research found that 65 to 70 percent of people in their studies preferred light more towards the 'daylight' side of the spectrum than the 'warmer' side . Very-high-CRI lamps are indeed very expensive, and are mostly used in photography, cinematography, and microscopy applications. For more info about CRI (and CCT) , the Wikipedia has a good summary with lots of math:
http://en.wikipedia.org/wiki/Color_...

Personally...I like my lighting towards the warm side of the spectrum, which does not give a high CRI. But it does make my light-brown wood interior walls and ceilings look cozy, and makes my two white and brindle-colored cats' coats look more lustrous.

I also hope that some research institute will undertake a long-term study of lamp life, but with new LED lamps and fixtures entering the market at a furious rate, compared with the estimated lamp life, I think such metrics would quickly become obsolete; by the time the lamp dies (even if it dies young) multiple generations of new and improved-lifespan models will have already replaced that discontinued lamp being tested for lifespan.

I have also noticed the change in CFL spectral distribution with age that you mention. I hope that PEARL will be able to continue their research as lighting and luminaire technology progresses. At the end of the day, though, lighting is still at least 50 percent psychology and phisiology.

Best regards, and keep your lamps trimmed and burning;

DAN FINK

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