Consumer Interest Inquiring Minds

Inquiring Minds Want to Know: Do you save energy by dimming LED bulbs


I’ve got my Philips Hue light bulb working with my Amazon Alexa. It’s an older 860 lumens bulb. I also have a voltmeter. So I went through different intensities, recording the power draw for each. The results are in the table below.

Level (%)Power (Watts)
0 (off)0.3*
Power draw of LED light bulb at various brightnesses set by Alexa voice command.

So above 60% or so the relationship looks exponential. 50% seems like an outlier.

*Unexpected finding – smartbulbs are vampire devices

I didn’t originally measure the power draw when “off.” You don’t think to do that. Then I gave it some more thought and had an aha moment – the bulb can only be smart if it is always listening for commands. And that, in turn, must create a power draw when off. A quick measurement and sure enough, confirmed. Though very small – 0.3 watts – it is not nothing. A typical single-family home has over a hundred bulbs. If they were all smartbulbs, it would add up… I believe small draw devices – typically those power adapters for cell phones – are called vampire devices.


So we have a very non-linear relationship here. I probably should plot the current draw as well. But, you definitely can save energy by lowering the intensity – quite a lot. But LED bulbs are drawing very little power anyway, so unless you have bunch of them, why bother?

My second conclusion – a finding I didn’t expect – is that even when off these bulbs are consuming a bit of power. It’s not a lot, 0.3 watts, but it’s something to keep in mind when planning your smartbulb deployment. So, large arrays of smartbulbs? Probably not such a smart idea.

Consumer Interest Security

Can you go from Terminal 1 to Terminal 2 in O’Hare without going through the security lines again?


Yes, at least if you walk. Not sure about other transportation options. Count on about 13 minutes for the walk.

Not sure why this information is so hard to find… Sometimes you land at one terminal and have to take a puddle jumper to a regional airport out of another and you’d really like to know is 50 minutes or whatever gonna be enough?

This is probably true for most major airports. It seems for instance that at Newark Liberty you can also move between terminals A, B and C without going through security once again. I thought JFK may have been an exception to this rule, but I’m not sure…