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"Marshall's Happy Lights" PDF Print E-mail
Written by Steve Heising   
May 02, 2006 at 12:19 PM
SunWave lamps (known around the lab as Marshall's Happy Lights are specified for new Idaho Energy Lab. The new SunWave F32 T8 Plus, 93 CRI (color rendition index) 5550 K (Kelvin temparature), 15,000 to 30,000 hour rated life are reducing energy consumption, reducing maintence costs, and improving the visual ergomonics for workers at the Idaho National Energy laboratory. These lamps started out in a conference room relamped to improve visual reading performance, and have since spread through out one entire building and are catching on for both retrofit replacements in existing fixtures. They are plan for new building projects as they reduce energy consumption and have lower lifecyle costs.

This new SunWave lamp features a proprietary rare earth phosphor blend, an energy efficient heavy duty cathode, and a slightly larger tube diameter which results in an extra long-life tube with unmatched energy effectiveness. These tubes can be driven from 20 watts to 37.5 watts per tube depending on the characteristics of the ballast. At the rated 32 watts, the high scotopic light content (light seen by the rods in the eye), in combination with 2700 lumens photopic light (seen by lightmeters and the cones in the eye) effectively produces 5400 pupil lumens. In other words, the eye sees the light as twice as bright. This high scotopic factor combined with the energy effective tube and cathode results in decreased energy use, decreased maintenance costs, and ergonomic effects attributable to full spectrum natural daylight. (Please see the daylight studies article.)

5550 Kelvin, the correlated Color Temperature is a North sky, noon-time, daylight color match. The light coming in the skylight or open window is the same bright white color. 5550 K photopic and scotopic light is seen by the rods in the eye as much brighter than the typical 3500 K and 4100 K Super T8's, and in the mid to low range of the 5000 K, 6000 K, and 6500 K "Daylight" or "High Spectrum or Full Spectrum" lamps. Many find 6500 K and up to be too blue. Typical lamps: 2700 K (warm white), 3500 K(white), and 4100 K (cool white) are all quite yellow compared to acutal noon time north sky daylight.

One doesn't buy yellow windows and yellow skylights, why buy yellow lights that don't match the daylight? The SunWave spectral power distribution conforms the to Lighting Research Center proposed definition of "Full Spectrum" as it is spectrally similar to the original Vita-Lite produced by Durotech.

The original Vita-Lite is also the same light source that corresponds with the highest performance in a study with 4th grade students by the Institute for Reseach in Construction IRC in Canada. As the eye sees brightness and color differently from a light meter, (see Sam Berman et. al.) and as Brightness increses depth perception and visual acuity. Also, color perception requires reflected light, if some wavelengths are missing especially, in the blues and violets, there is no light to reflect. You would expect a lower CRI. The 93 CRI for SunWave tubes indicates more wavelengths and a fuller spectrum than delivered by a 5000 or 6500 tube with only an 85 CRI that are commonly available. Daylight has a CRI of 100.

The Idaho National Energy Lab now has over 900 SunWave tubes that have been in service for up to 3 years now with zero defects. The SunWave lamps were originally installed in a conference room that was being used by auditors (to make the room brighter and make reading easier) The light spilling out of the confence room door was noticably whiter and brighter than the light from the hall fixures. Now an entire building has been outfitted with these tubes and the energy costs have dropped 18% below the next lowest alternative. In addition, the maintenance costs have been reduced as the lamps are lasting longer on average and don't need to be replaced as often. Ergomomics, productivity and morale (subjectively reported) has improved.

Around the Idaho Lab, they are not even referred to as SunWave lamps any more. They are known as "Marshall's Happy Lights." Once the staff get past the initial "it is too bright" perception, or about 2 weeks, the new lights seem to make our employees happy, we have less headaches, less eye strain, etc. But they really make the facility mananger happy as there is only one lamp to stock for several applications, there is less maintenance for changing lamps (as they last longer on average), They work with existing T8 ballasts and they use less energy, more than enough to pay for the tubes. So now other buildings are wanting to know when they are going to get to try some of Marshall's happy Lights.

Initially upon installation brightness complaints typically seem to last 2 to 3 weeks (see Sam Berman and Intel test) and then after that the difference seems to be registered in the brain as being ok. Energy managers often see this as and opportunity to reduce energy consumption even further by replacing the ballast with a lower ballast factor. With the SunWave tubes, the brightness at individual fixtures can be increased or decreased at specific fixtures by adjusting the ballast. While there are ballasts available that can be adjucted with a screwdriver, typically, the entire unit is swapped with the appropriate replacement.

So far, the Idaho Energy Labs have been running 900 tubes for 2 to 3 years with zero failures and are running about 18% less energy for lighting than other T8 combinations tested.

Now that really is a "Happy Light".

Last Updated ( May 18, 2006 at 07:45 AM )
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