Dimming Different Light Sources
When it comes to use with controls, all lamping options have their cons, says our pro, Randall Whitehead, IALD.
I’ve been thinking about halogen and CFL dimming. Dimming CFLs is more difficult and shortens bulb life, and disposal is an issue. LEDs are coming around, but they are not there yet. If I like the look of halogen and need a dimmable option, how can I maximize my energy savings?
There isn’t a clear-cut answer. The bottom line is that all light sources have lamp life and dimming challenges. Fluorescents and LEDs can be dimmable, but require a dimming ballast/driver. Biax and quad lamps need a three-wire dimmer, while GU24 lamps are dimmable with a two-wire dimmer (down to 30 percent for most). These sources also may require an interface in order to work properly with preset dimming systems. I do see that some fixture manufacturers are listing compatible dimmers on their spec sheets. This is a step in the right direction. Halogen is an incandescent source, so it gets yellower as you dim it like all incandescent lamps do. It’s only a “whiter” light when it is operating at full brightness. It has a 3000K color temperature but slips into the 2700K and even warmer range when dimmed. If you like the color of halogen, then LEDs and CFLs offer a 3000K color that doesn’t shift significantly when dimmed. Yes, halogen dims easily, but it has to be operated at full brightness 20 percent of the time in order for the lamp to clean itself out (like a self-cleaning oven). Otherwise, the bulb blackens and burns out prematurely. Because halogen is so bright, most people dim it down and never turn it up to full brightness, shortening the life of an expensive lamp. It is hard to get your clients on a “lamp cleaning” schedule, but here’s a suggestion: If they clean the house on Saturdays, then have them turn the lights on to full brightness for that amount of time. You could have the last button on a preset system set to “full” for those times that they are cleaning, or at the end of a party, like at a bar when lights come up to clear the joint out. (Don’t ask me how I know this.) I am banking on improved LEDs and CFLs for the future of lighting. On my projects, I am specifying LED festoon lamps, replacing halogen festoon lamps. It looks just like halogen in color quality but uses 66 percent less energy and lasts for 30,000 hours. The amount of mercury in a CFL is less than the tip of a ballpoint pen. And if they are recycled properly, there isn’t a problem. As I have mentioned in this column before, there will be a mercury-free lamp (like sugar-free cola) called the ESL. You should be getting your mercury from fish anyway. In this room, I illuminated the pendant from within using three 8W CCFLs. The red chest and the outside of the pendant are highlighted with a pair of LED MR16 lamps. They are yummy and warm like halogen, but much more energy-efficient.
Randall Whitehead, IALD
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Archived CEU Webinar: LED Lighting 304: LEDs for Kitchens and Baths With a Focus on Dimming and Controls
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