Testing bulb brightness gets a bit tricky. In addition to measuring color temperature and color rendering scores, our spectrometer can take luminosity readings from a given light -- but those readings are easily skewed by things like viewing angle and distance. To get numbers you can rely on, you need something called an integrating sphere.
An integrating sphere is really just a big, hollow ball with a special, reflective coating on the inside. You place the bulb in the middle with the spectrometer peeking in. With a "baffle" between the light and the spectrometer blocking a direct, inaccurate reading, the spectrometer will instead read the luminosity of the light that's bouncing around inside the sphere. If calibrated correctly, this should give you an accurate read of how many lumens a given light source gives off.
Of course, integrating spheres like the ones used by Energy Star and UL are terribly, terribly expensive. So, in lieu of buying one, we built our own.
This wasn't a quick undertaking -- we researched our options for months, speaking with various industry experts to get the best sense of how to pull it off. Finally, led by intrepid technical editors Jared Hannah and Steve Conaway, we started putting the thing together.
The result is a gigantic and hollow styrofoam sphere with a few carefully-applied coats of special, reflective paint on the inside. We're still working to calibrate it as precisely as possible, but have already seen results that look to be within roughly a 1 percent margin of error.
Looking at the 100W replacement LEDs we tested, Philips actually scored the lowest in our sphere, with a score that fell just shy of the 1,620 lumen spec from Energy Star. All four of the other bulbs we tested came in at least slightly higher, a result that lines up with what we see when we compare the bulbs side by side.
That isn't necessarily a bad result -- anything over 1,600 lumens is perfectly adequate at the 100W replacement level. However, it does undercut the notion that Philips' bulb offers extra brightness over the competition.
Something else I took a close look at was how these bulbs performed with dimmer switches. Though many bulbs are listed as "dimmable," some won't dim down as low as others. You also might encounter flicker and buzz due to electromagnetic interference from the dimming mechanism., the Philips bulb was a clear standout, making it easy to recommend for anyone who likes the light dialed down low.
The 100W version of the Philips LED is equally impressive, with zero flicker, zero buzz, and a minimum lumen output that's slightly lower than GE or Cree. However, GE and Cree's LEDs still did well. Unlike their 60W counterparts, neither one flickered or buzzed on any of the switches we tested them with. That makes Philips' dimming performance less of an important factor.
The Philips 100W Equivalent LED is a good bulb with solid across-the-board specs. It's bright, it's efficient, it's dimmable, it's omnidirectional, and it comes with a respectable 5-year warranty. At a price of $22, you could certainly do a lot worse.
The problem is that there's some very good competition in this class, including a very efficient GE bulb and a Cree LED that breaks the $20 price barrier. Both of those cheaper options keep up with the Philips LED at every turn, and surpass it in a few key spots, including the ever-important length of warranty. The Philips 100W Equivalent LED is good, but you can do better if you shop around.