2015-03-26 CRI Not The Whole Story

I got another email from Designing With LEDs about removing the fluorescent lights from a bathroom and replacing them with Cree LED lights.  The blog shows the charts from a spectrometer showing the difference between the fluo lights, which are deficient in the red, and the high CRI LED lights which have much better lighting in the red part of the spectrum.

But as it shows, the CRI doesn’t tell the whole story.  Looking at the graphs and the values for each part of the spectrum show more information.   The spectrometry software says the T12 lamps have a CRI of 86, but the R values show that the lamps are very deficient in the red part of the spectrum. I’ve noticed this a lot over the years. People in the offices would get a beautiful bouquet of flowers and the red ones look dull until they are taken outside and viewed in sunlight. But the offices where I worked were relamped with LED lights last year, so this may no longer be a problem. 🙂

One thing they mentioned is that red deficient fluo lights make human skin look pale and ghostly. The bathroom is the last place that one would want to use fluorescent lights.

The MK350 spectrometer was used along with specialized software to determine the CRI (color rendering index). I would like to have one of those setups. I could find out how good the cheap LEDs I buy are. I’ll look online for a price for the setup. I already know that it won’t be cheap!

The blog also talks about wireless dimming and a standard 10 volt interface which is new to me. The high price was mentioned, but this is typical of new ‘bleeding edge’ technology, and the price will fall later as it becomes a commodity.

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