Friday, May 13, 2016

Converting to LED lighting

When we were renovating our house, I thought a lot about lighting.  LED (light emitting diode) lighting is the future, and really, the future is now.  LEDs have been getting more and more efficient, and they've been suitable for primary lighting for some time now.  If you haven't made the move, you need to, because they use less than 20% of the power of incandescent bulbs and the bulbs last a long, long time.

I'll avoid the technical explanation of how LEDs work and just say they're more efficient than traditional incandescent lighting, and even better than florescent lighting.  There are solid consumer products out there, and the prices have been coming down, but there is a lot of junk, too.
If you have can lights, you're going to buy a bunch of  something like these

How do you know if something is good?

Well, that's the trick, isn't it.  Generally speaking, it's hard to tell from the box, and the bulbs aren't really cheap.  I put a lot of time into figuring out what I wanted to do and read a LOT.  The first thing that matters is color temperature, which we is something we're used to hearing about.  Generally speaking, you're probably going to want "warmer" lights, which are more like incandescent lights, around 2700K, in your home, rather than daylight spectrum, which is more like 5900K.  Why?  Nobody's sure, but there's some speculation that it has to do with fire making us feel safe.
So, targeting 2700K seems like an obvious solution, right?  Unfortunately, it's not that simple, because you can achieve a rating of 2700K and still have really terrible light by having lots of peaks in the spectrum.  So what's next?  Color rendering index (CRI) basically tells how close the spectrum is compared to a perfect reference light at a given color temperature.  Basically, you want a high CRI. You didn't have to think about CRI with incandescent bulbs because their nature was to provide high CRI output.  Florescent lights, which we all recognize as harsh, tend to be very narrow spectrum and have low CRIs.  LEDs themselves have similar issues.  Low CRI lights, for instance, or any light with peaky spectrum due to filters, can make it hard to tell certain colors apart.  To get around this, better lights probably mix different colored LEDs to expand their spectrum, and probably use different filters to attenuate different peaks.  That's my speculation, maybe someone can correct me.  The point is, you CAN get LED lights with CRIs over 90, but it tends to cost them some efficiency.

CRI is far from a perfect metric.  CRI is generally measured created by testing the error accross 14 color samples and averaging.  Of course, "white" LEDs tend to have trouble in certain areas, so you'll often see the "R9" component of CRI, a saturated red, referred to specifically.

High R9s are hard

Unfortunately, 14 samples isn't really enough.  There is plenty of spectrum that isn't covered by the samples so you can still have bad light quality with higher CRIs, particularly considering that people can game it by focusing on weak areas like R9.  Also, just averaging the errors isn't a great plan.  This means that really poor performance in one frequency, but perfect in all of the others, would be considered the same as really good but not perfect performance in all frequencies.  Intuitively that's probably not how you'd like to see it done.

A new standard, TM-30-15, attempts to address the issues with CRI.  First off, it uses 99 color samples, which is a significant improvement:
There are then a set of different indices, and graphical representations that can be used to evaluate quality.  It's a much better system.  It's also fair to say that we are not likely to start seeing these references broadly on consumer lighting for some time.  Is only saw TM-30-15 test results on the highest end produts, like those from Soraa (sample datasheet).

Bulbs for Different Applications

I bought a lot of different bulbs for usage all over my house, and I learned too much about light bulbs in the process.  I didn't want to spend a bazillion dollars on light bulbs.  I didn't after a super high end solution, I typically went for a consumer grade solution.  I also didn't go for a lot of custom solutions, but instead utilized traditional standard fixtures with LED bulbs.  The brand I generally selected isn't one of the consumer brands that you're probably used to seeing like Phillips or GE, it's Feit Electric, which you've likely never heard of.

One thing I noticed, and it's really not surprising when you think that there is going to be extra filtering and a mixture of different LEDs to get good quality, is that you will sacrifice some efficiency and some cost to get high CRI.  Several manufacturers make "normal" bulbs along with their "high CRI" bulbs, and the they always use less power and are cheaper.  I think most of what you can find at Home Depot or Lowes is falls under "more efficient, poorer CRI."  That was certainly true when I was shopping, and it still seems to mostly be the case.  You will see a few high CRI products marketed in the most common bulb applications.

6 Inch Can Lighting

We put in a lot of 6" can lights.  A typical light for a 6" can is a BR40, where BR describes the bulb as "Bulged Reflector," and 40 means 40 eighths of an inch in size, or 5", leaving half an inch all around the bulb in the can.  A BR40 will provide distributed light over a broad area.  You can also get more of a spotlight, or a PAR38 bulb, where PAR means Parabolic Aluminized Reflector" and 38 makes the bulb 4.75" in diameter.  A PAR38 bulb will illuminate a narrower area with a higher intensity at the same Wattage.

I used mostly BR40s from FEIT Electric's "Enhance" product line, which is a common theme in my selections, as they claim 94+ CRI and I've been pleased with them.  Unfortunately, another common theme is that there are lots of different bulbs on the market, made at different times.

The bulb I used throughout my house is no longer listed on FEIT's web site.CRI, 100W replacement bulb (19W), model BPCEBR40/DM/LED.  The FEIT web site now says that their 16W BR40/927/LED bulb puts out the same 1065 lumens, but they advertise it as a 75W replacement.  I looked at a few 100W incandescent bulbs and think that 1065 lumens is more in the 100W range, so I'm not sure why their advertising has changed.

I found lots of different item numbers that seem to be various packaging of the same product, or similar product made over a period of time.  The best deal seems to be the 2-packs, but I also found single bulb packaging, and various old versions of these bulbs.  Be careful on pricing, as a lot of the links are bad deals.  The 2-pack was $16, or $8/bulb, or about half what I paid 2 years ago.

Search Amazon for "Feit BR40" and look for their "Enhance" branding.
In our kitchen, I selectively used a PAR38 bulb, and these also work in outdoor security spotlights.  Again,I did a Feit high CRI bulb.  These come as a 3000K bulb, so they're not going to be quite as warm as the BR40s, in addition to their narrower beam, so you want to use them selectively.

Eyeball Lighting and 4" Cans

6" Eyeball bulbs are actaully like a 4" can bulb.  A 4" can takes a BR30, and the spotlight equivilent is a PAR30.  I found Feit PAR30s for our eyeballs.  Again, in a brighter white 3000K temperature.  For 4" cans you're going to want those BR30 bulbs, which are also widely available.

Products referenced in this post:

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