Monday, February 27, 2012

Helpful Household Hints: Lighting

I heard something about eliminating light bulbs?  They're going to outlaw light bulbs?

Nope.  That got overturned in Congress late last year.  Looks like the light bulb as we grew up with it is still safe...for the moment.

Why ban it?  It works, right?

Sure it works, but it doesn't work very well.  Ask yourself the question: what do you want the light bulb to do?

I want it to make light.  I turn it on, it lights up.

How does it do that?

Um...never really thought about it.

It gets hot.  It gets so hot it glows, not just red-hot but white-hot.  That's how it works.

And that's why it's so darned hot?

Exactly.  But what if you could have the light without the heat?

What about it?  Would that be better?

Sure.  About three-fourths of the energy emitted by a light bulb is heat, not light.  What that means is your light bulb is only about 25% efficient at making electricity into light.  That heat is wasted potential, and of course in summertime that means your AC has to work to remove the heat.  Using electricity to remove waste heat generated by using other electricity: that's terrible.

We can do better than that.  A compact fluorescent lamp - CF for short - gives off about the same amount of light, but only needs 30% of the electricity.  Where you need 100 watts of power to make a bright light with an old-fashioned, hot incandescent bulb, you can get the same light from a CF lamp that uses only 30 watts of power.  CF lamps get warm, but nowhere near as hot as an incandescent.  That 70 watts you don't use doesn't have to get thrown back outside, either.

That's a big savings.  Why would anyone ever buy the old bulbs, then?

They don't understand the savings.  The CF bulb costs way more than a conventional bulb to purchase up front, but it costs way less to use the CF bulb.  Look at the chart:

  Incandescent CF
per lamp cost $0.18 $2.24
lamp life (hours) 1,000 10,000
lamps per 10,000 hrs 10 1
lamp cost per 10,000 hrs $1.86 $2.24
  Advantage: Incandescent
  Savings:  38 cents
watts 60 14
kilowatt-hr per 10,000 600 140
Assume $0.12/kilowatt-hr - varies locally    
$ per 10,000 $72 $16.80
  Advantage: CF
  Savings:  $55.20

10,000 hours worth of incandescent bulbs costs only $1.86, whereas 10,000 hours worth of CF bulbs costs $2.24.  You save 38 cents.  Of course, in that time you also replace the incandescent bulb ten times.  The CF lamp just keeps going.  That isn't the part that people see, though.  What they see is that a 16-pack of incandescent bulbs costs less than $3.00, while a four-pack of CF lamps is $9.00.  That's short-sighted.  The four-pack of CF lamps represents 2.5 times as many hours of light as the 16-pack of incandescents.

But let's level the playing field.  Compare 10,000 hours of incandescent light to 10,000 hours of CF.  In that same amount of time, the incandescent bulbs burn through $72.00 worth of electricity, and the CF lamp uses less than $17.00 worth.  You spend a little more for the lamp, but you spend a lot less keeping it lit. that's where the savings lie.  And every lamp you replace with a CF gives the same kind of savings for every minute it's lit.

If it's so great, why doesn't the CF go absolutely everywhere?

Because it's not perfect for everything.  CF lamps don't like being cold, so you don't replace the bulb in the refrigerator with a CF.  They don't do well being switched on and off all the time, either.  Neither do incandescent bulbs, for that matter.  For either of these applications, you might do better with the LED.

I've seen those in the store.  Pretty expensive.  Are they that much better than the CF lamps?

No.  In fact, they're not quite as good.

Then why even bother?

Because they're getting better.  When CFs were brand new and still $30 for a single bulb, I bought a couple.  It cost a lot but somebody's got to take the plunge and see whether it's worth the trouble.  It is, and CFs are here to stay...and now that lots of people are buying them, the price has plummeted.  LEDs are still new and not quite up to par with CFs, but they're getting better all the time.  Soon we'll see LED lamps that are even more efficient than CF lamps.  And as more people buy them, their price will come down, too.

LED lamps function just fine when cold.  Switch them on and off all day long, it doesn't affect them at all.  And where a CF lamp might last 10,000 hours, the LED could easily go 50,000 hours.  They really do keep going and going.  You could put an LED lamp in your refrigerator and never replace it again, even if you keep the fridge for the rest of your life.

When CFs were new and expensive, commentators recommended putting them in fixtures that were hard to get to, so the convenience of not having to do that difficult replacement would offset the higher price.  Well, LEDs are even more convenient and again, if you have a fixture that's a real bear to change, maybe that's where your LEDs should go first.

I have a bunch of LED floodlights in some ceiling fixtures...a ceiling that is 35 feet high!  I have to rent a telescoping lift to get to these fixtures.  But with a 50,000-hour life, I may not have to change those lamps again until 2020.  That makes the high cost a whole lot easier to swallow, since renting the lift is $200 and I used to have to do it every year.  As far as those ceiling fixtures go, the energy savings is a bonus, I really wanted to avoid having to rent that lift.  This way I dodge $1600 worth of lift rental.  That's a savings no matter how you slice it, in spite of the light bulbs costing $40 each.

So it all really just comes down to money, doesn't it?

Doesn't everything?  You can buy cheap but buy over and over, or you can buy expensive and not have to buy again for a long time.  Savings right now vs. savings over the long run.  These can be kind of subtle and you have to sit down and do a little math to see where and how the savings add up...and they do add up.

Plus it saves on air conditioning...

Exactly!  You're seeing how the effects can snowball.  Not having to rent a lift for eight years is going to save me a lot more than the $600 cost of the LED lamps.  It's way more expensive than $8.00 for regular bulbs, but the bulbs aren't where the savings lie.  Look at all the costs associated with lighting and that's how you see where there are places to trim costs.

But there will always be a place for the wasteful old incandescent bulb.  There's one place where nothing else will do.

Really?  Where's that?

In the oven.  LEDs can't handle heat; CFs don't handle it well either.  But the old-fashioned, one-step-up-from-fire incandescent does its thing by getting hot.  Heat is what it does best, like being the heating element inside the old Easy Bake Oven.  In fact, the hotter the oven is, the better and more efficient the incandescent bulb becomes.

That's it for today.

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