I am taking a rather cautious, slow approach to replacing and upgrading my lighting. I did the same thing with CFL bulbs, and as a result found out for myself how quickly they fail when installed “upside down” in recessed cans and track lights, and how frequent on/off cycles kills them. This is now well documented, of course, but several years ago, when we were all being told to scrap our incandescent bulbs, most people seemed oblivious to these problems.
My first step was to attack my kitchen track lighting which probably accounts for almost half the lighting usage in my house. I have fourteen PAR20 halogens in track fixtures, plus three traditional 75W BR30 bulbs in cans. Close to 1,000 watts, and these are on at least three hours a day. Most lighting in my house is controlled with a central computer, triggered by motion sensors, so the lights are turned on and off as people enter and leave the room. Thus, the lights cycle on & off a LOT, and instant on is mandatory.
My search for the “perfect” 50W halogen PAR20 replacement led me to the Sylvania 78748 bulb. You can read about it here, and also read my review (it is under the same user name as my name in this forum):
Sylvania PAR20 LED
As I note in my review at that site, this bulb is actually brighter than the halogen bulbs, but it is quite a bit cooler in color temperature than its 3000K rating would suggest. I actually did a color measurement (you can measure color temperature by taking a photo of a white card in RAW mode, and then correcting the color in the Photoshop RAW import dialog: Photoshop reads out the color temperature in that dialog) and found these results: the Halogens measure at 2900K; the Sylvania measures at 3150K and the TCP bulb that I purchased later measures 2850K.
The TCP bulb:
TCP LED9E2692027KFL LED 9 Watt PAR20 40 Degree Flood Light
has more even illumination, and is almost the exact brightness as the halogens, but the CRI is lower. This gives the light a slightly “less pleasing” quality. Incandescent bulbs have a CRI of 100, meaning they put out equal amounts of every color in the visible spectrum. By contrast, LED bulbs only emit discrete color bands within the visible spectrum. Those bands still combine together to produce white light, but the missing colors make you interpret what you see in slightly different ways.
The best way to describe CRI is that the average of the numbers 1, 5, & 9 is 5; the average of 1, 2, 3, 4, 5, 6, 7, 8, & 9 is also 5. If the two sets of numbers each represented the discrete colors in the spectrum of a light source, the second set would have a higher CRI. The “missing” colors in any LED bulb’s “white” light is why you may have had the feeling that you are not quite perceiving or seeing things as clearly when something is lit by an LED bulb.
So, for me, I have not quite made up my mind between these two bulbs. The Sylvania is more expensive ($38) compared to the TCP ($26); the Sylvania is brighter than the halogen; the TCP is the same brightness; the Sylvania hass more pleasing color than the TCP, but is bluer than the halogen; the TCP has more even illumination, and the beam spread is much closer to the narrow flood spread in my halogen bulbs.
I am not quite yet ready to replace all my halogen bulbs, but these two bulbs are very close to being the right choice.