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2008/04: Creating Energy Efficient Lighting Without Getting Ugly – Part 2
Technology 16 years ago No Comments

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contributed by Lisa Barter [interior architect with 3i Design, LLC / lumenologist in the making]

EDITOR’S NOTE: In Part 1 of this series, entertaining author Lisa Barter put the spotlight on daylight, extolling its ability to chase everyone’s blues away while increasing worker productivity, retail sales, and company profits. She went on to energyefficientlighting2.gifilluminate us on the limitations of fluorescents, the original poster child of energy efficient lighting. In this month’s installment, Lisa continues the conservation conversation by explaining the benefits of dimming down (what you’ve already got), lighting up (with some new sources), and mixing it up (for shining results). Warning: If you don’t care about saving your clients money and looking like a genius, then don’t read any further.


You’re Kind Of Dim, And I Mean That in a Good Way

We’re all familiar with dimmable incandescent sources. You probably have a few dimmer switches in your house or apartment. But how many do you notice” Here’s a mind-blower for you: Of the 37 wall switches in the average American house, 2.7 of them are dimmers. What else in your house just has an on-off switch that’s essentially the same technology as nearly 100 years ago” Your washer has cycles; your hair dryer has heat settings; your fans go in two directions. But your lighting” Well, that’s another story.

Since I love statistics, let me throw a few more at you:

If you dim a lamp (bulb) by 10%, you use 10% less electricity and double the lamp life.
If you dim a lamp by 25%, you use 20% less electricity and quadruple the lamp life.
And if you dim a lamp by 50%, you use 40% less electricity and increase the lamp life twentyfold (I don’t know the "–uple" for that one – maybe twentuple”).

So, let’s think about the practical application here. If you are planning on locating a pendant over a table and are considering a compact fluorescent versus an incandescent halogen source, you might think about an 18-watt compact fluorescent with a 12,000-hour lamp life versus a 50-watt PAR lamp with a 3,000-hour lamp life.

But what if nighttime use and ambience are big considerations, and you think the fixture ought to be dimmed to 50% most of the time” Well, you can dim the incandescent fixture with a very simple controller, use nearly the same amount of energy as the fluorescent, get exactly the light quality you want without an expensive dimming ballast, and easily quadruple lamp life, making the lamp lives identical.

If you have a project with a lighting control system built in, make yourself look smart by suggesting that the “full on” version of all the lights be set at 95%. By doing this, you increase the lamp life by half its original value and decrease energy usage, all without a change that the end user will notice.

Remember that halogen sources (like PAR lamps or MR-16 lamps) have longer lamp life because of the combination of gases in these lamps that let the filament burn longer and cleaner. And by using low voltage systems, you get more punch for less energy.

Trying A New Dish

You head to your favorite restaurant and are once again challenged by the same decision you face every time: Order your favorite dish off the menu, which is a tried and true solution, or order something new, like the chef’s special, that may not be as great as your ol’ standby. Or it just might be dynamite!

Incandescent and fluorescent sources are the old standby favorites. But ceramic metal halide and LED sources are like the chef’s special: adventurous, a little risky, but possibly your new favorite.

Ceramic metal halide sources (CMH) are an update of traditional metal halide lamps that consist of an arc tube with gas vapors and electrodes inside of a bulb. They offer great color rendering, long lamp life, and good optical control (they can achieve “punch”, unlike fluorescent sources), all with high efficiency. For instance, you can get the same amount of light out a 39-watt CMH lamp as a 75- or even 90-watt halogen lamp. The best part about new CMH lamps is that they’re offered in the same configurations and sizes as some of our better-known halogen lamps, like PAR lamps.

Like streetlights (which are in the same lamp family), they require a “strike” time, or time for the gases that produce the light to reach their optimal operating temperature. And that same strike time occurs every time the light is turned off and then on again. They’re also not readily dimmable, though ballast manufacturers are working on that. While these make them tough in certain situations, they’re a perfect solution for retail or other “lights on” operations that see constant traffic and don’t require dimming for effective use.

Then there are LEDs, or light-emitting diodes. These little guys deserve another article all of their own, but for now, they are best used in a linear application like in coves or under cabinets and in outdoor applications like step lighting where exact color control isn’t critical. But keep an eye on these. This is where the lighting industry is focusing much of its research, so we’ll be seeing quantum leaps in available technology in this area in the next few years.

Once More, With Enthusiasm!

If you prefer the Cliffs Notes version of your cool online publication’s super-informative articles, this is the part you don’t want to miss.

How the heck are we doing this energy-efficient lighting thing again”

Daylighting, daylighting, daylighting. Bear in mind that doing this right requires mitigating direct light’s inherent glare with overhangs, light shelves, and window shades or blinds, depending on occupancy type, location, and orientation. Controls should be added that integrate with the lighting system so that a pre-determined light level remains consistent depending on the time of day and whether the space is occupied. That means that, as available daylight increases, the control system switches off certain lights, or certain lamps in multi-lamp lights, to maintain the desired light level.

Use fluorescent sources judiciously. These are great for general illumination in spaces that require even overall illumination, but in spaces with longer occupancy, like classrooms and offices, are preferable in a direct/indirect combination instead of direct only.

Remember to add dimmers or control systems and educate your clients that dimming prolongs lamp life and minimizes energy usage. If you are specifying control systems, set the “full on” level at 95%.

Newer technologies, such as ceramic metal halide and LED, are an ideal match for certain applications (like retail for ceramic metal halide, and exterior lighting for LED).  

Mixing It Up

So what’s the magic bullet” There isn’t one. Those who tell you that a one-size-fits-all solution is appropriate are probably selling a product. What’s more important is using what you learn about each of the light sources to determine which one will best serve the function and provide the required aesthetics while consuming the least amount of energy to achieve both. Does that mean that you’ll be using all incandescent sources” Probably not, though you’ll use them (with controls, please!) in areas where you need punch or ambience. Does that mean you’ll be using all fluorescent sources” No, but you’ll use them in places where you need medium to high levels of even illumination, and you’ll use controls to step them down if you’re incorporating daylighting. And how about ceramic metal halide or LED” If the application merits it. The one constant is daylight, and no one has to buy or sell that!

Sound like a lot to handle” Nah, you’re up to it. Just click some of the links in this article and dive right in. Before you know it, you’ll be impressing your clients with your ability to combine energy-efficiency and elegance. Catch me over a cup of coffee and let me know what you’ve learned!