(These bulbs are stated to be 220 Volt bulbs but with the “lit” one running at 110 Volts)
Well, just back from buying some more 100 W bulbs before they become black market drug dealer specials. California is going first into this long dark green night, so I’m at the tip of the spear on this in the USA. (Those of you in Australia and the UK and the rest of the EU seem to already “be there”…)
I’ve commented before that bulbs in my dimmers seem to last a very long time. Now I’m going to put some numbers on it.
At Lowe’s, they had a very interesting “bulk box” of 24 bulbs for $10. I bought it. These are Sylvania 100W 130 V bulbs. Note that in America the standard for wall voltage is 120 Vac…
They are ‘dual placarded’ for energy consumption.
120 Volts 130 1700 Lumens 1290 100 Watts 88 750 Hrs Life 1875
So here we get an interesting metric. Reducing the voltage by 10 Vac gives about a 2.5 x lifetime extension.
Most of the time I like about a 60 W to 75 W bulb on full bright for a room (we have white walls, so this works well. With dark walls or furnishings it takes much more). A 67 W “GE Save Energy” bulb makes 1015 lumens at 67 Watts with a 750 hour life. That’s a decent baseline for what I want. The cheapo Phillips 57 w bulb from China ( 19 cents each in the bulk 16 pack at Home Depot ) makes 780 lumens and lasts 1000 hours per the box.
So, IFF I put one of these 130 V 100 W bulbs in my dimmer and run it at about the same output of lumens, in that 1000 ish range, I’m likely to get well over 2000 hours of life from it. I’d guess it’s about a “triple” on the typical hours of a bulb on full power. (Though for some fixtures it will be even longer… The bedroom incandescent is usually run very low so as not to disturb others. When we want a lot of light there, we click on the two CFL bulbs in lamps… so that incandescent has not been replaced in a couple of years, at least.)
That estimate assumes life is roughly linear with delta lumens, but that’s not a ‘for sure’ thing. I probably ought to search for more data on that question, but for now, this is ‘good enough’.
I made an interesting spread sheet out of the data from the bulb packages. I’m not sure all these fields have “utility” or meaning… but what caught my eye was the Lumen-hours / Watt rating field. This is the lumens output multiplied by the hours lifetime divided by the Watts rating consumed at that lifetime. You consume Lumens over a period of hours, so Lumen-hours is what you want.
The 130Vac bulb, dimmed with 120Vac, gives the most Lumen-hours / Watt rating consumed of any of these bulbs by a factor of about 2 to 3. It also has the largest Hr-Watts per Lumen number. (These are reciprocal on Watts and Lumens. So that hr-W/lumen is a kind of ‘total power consumed’ for a given lumen rating while the Lumen-hours / Watt is something of a ‘how much light life do I get for a power rating’ consumption be damned.) While Lumens / Watt is the straight efficiency without weighting for bulb lifetime value.
Lumens Watts L/W Hrs Hr-W/L L/Hr L-hr/W Syl 130V 1700 100 17.0 750 44.1 2.27 12750 1290 88 14.7 1875 127.9 0.69 27486 GE 67 ES 1015 67 15.1 750 49.5 1.35 11362 GE 90 ES LL 1450 90 16.1 1000 62.1 1.45 16111 Ph 57 780 57 13.7 1000 73.1 0.78 13684 Ph 95 1550 95 16.3 750 46.0 2.07 12237
I note in passing that the Lumens / Watt of the Philips 57 is worse than that of the 130 V run on 120 Vac, but without the great life extension. The GE Long Life 90 seems like the best deal for a non-dimmer use as it has a reasonably long life but with very good Lumens / Watt as well.
Not a real surprise there. The better bulbs last longer while doing a better more efficient job and cost more. FWIW, the GE Reveal bulbs have better color, but at the expense of lifetime and power consumption. Their Lum/Watt is only 12.6 while the Lumen-Hours / Watt is a dismal 9450. It looks like there is a clearly inverse relationship between good looking color and a long lifetime of service.
Dimmers are good at extending bulb life. Anything that reduces the voltage a little would also work, such as putting a diode in the circuit and cutting out 1/2 the wave form. A 25% reduction in lumens output results in a 2.5 Times lifetime extension (though at the cost of some efficiency – roughly 14% less light per Watt).
If you are interested in stretching your stock of incandescent bulbs as long as possible after they are banned, you need to put in dimmers and use larger wattage bulbs run at a lower power setting. This can easily triple bulb life. Lucky for me, I already have the dimmers in place. I want the incandescents largely because they work well with dimmers and CFLs are crap in them.
I’ll be trying a 150 Watt bulb in my dimmer to see just how yellow / red the color becomes ;-)
Visiting Lowe’s and finding those 130 V bulbs is “worth it”. Buying some of the “rugged duty” 20,000 hour bulbs and putting them on dimmers would likely result in a reddish light that would last longer than you will live ;-) h/t to George in https://chiefio.wordpress.com/2010/12/22/curly-bulbs/#comment-10329.
It pays to buy and store the better longer life bulbs.
So what this says to me is that in a misguided attempt to force me to use less energy I am being pushed into a position of consuming far more energy in order to maximize the life of what will now become a ‘scarce good’. All perfectly in keeping with what economics would predict about scarce goods, but not the goal of the Greens.