The Energy Star / CFL Efficiency Myth

If you still want incandescents:

Newcandescents

First posted on 02-01-07:

For years the Federal Energy Star program has perpetuated the myth that if you buy appliances (or any electrical device) for the home that uses less energy, you'll see proportional savings in your monthly power bill. This is rarely the case.

Other eco-writers do similar simplistic math to calculate savings in money, energy, and carbon. A recent example is Charles Fishman's September 2006 article in Fast Company magazine about WalMart's CFL project, "How Many Lightbulbs Does it Take to Change the World?".

The claim is made that if a single light bulb using 45 watts less is placed in 100 million homes, 6.57 billion Kilo-Watt-Hours will be saved. The fact is, unless you are cooling your house, there is often ZERO savings. Charles focused on the bulb, but forgot about the home. His entire premise is based on a false assumption. The savings are grossly exaggerated for most homes.

"Wasted" energy takes the form of heat. And this heat helps keep you warm, if only just a small amount. For most of America, for much of the year, that 45 watts will be automatically added back in by the home heating system to maintain the same level of comfort. If the home is heated with electricity, the savings in dollars, energy and carbon production is literally ZERO.

The only time energy is actually saved is when the air conditioning is running or you have the windows open to cool the house. With the air conditioning on, the savings can even be a little greater than 45 watts, but for most of America, that's a small part of the year. What are the savings for the rest of the year?

ZERO!

If you are not cooling your home, EVERY light bulb and appliance is 100% efficient.

Here's why...

The second law of thermodynamics demonstrates that "wasted" energy tends to disperse evenly. And if this "wasted" energy is in your house, it simply keeps you warm. More importantly, it keeps your normal heat source from turning on. Let's see how it plays out in a real home and why saving energy by turning off the lights is mostly an illusion.

If you have a home in the northern latitudes which is electrically heated much of the year, you are a net consumer of heat. And the nice thing about heat is that It doesn't matter where it comes from. And that's the key.

Take a light bulb that's only 10% efficient. That means 90% of its energy is converted directly to heat. So what happens to that heat? It spreads out through your house and slightly delays your normal heating system from clicking on.

And what about the 10% of the energy in the form of visible light? Virtually all of it strikes objects in the house. It too is converted to heat. The ONLY ineffectiveness of a light bulb in a northern home in the winter is the light that escapes through the windows, which is a VERY small amount. Even THAT can be stopped with curtains making ANY light bulb 100% effective at producing heat. Here's how Wiki explains it... Efficiency versus Effectiveness.

Why do I qualify this with northern homes and winter? Because if you have to open the windows to be comfortable, you lose the advantage. And if you have to turn on the air conditioning, this "effectiveness" actually becomes a small liability. So those of you in Florida and south Texas... never mind.

It's all about heat, where it moves and how we store it. But for most of America, much of the year, energy efficiency is very much an illusion. Effectiveness rules the day because we actually USE that "inefficient" heat.

And if your windows are closed but your heat is NOT turned on? Or not turned on until later at night? Those appliances are still 100% effective. That's because they are helping keep the house warm. They are one reason your electric heat hasn't come on yet. If that heat doesn't come from one source, it has to come from another.

But what if you're a bit on the warm side in the late afternoon but you haven't opened the windows? Again, it doesn't matter. This thermal inertia will delay heating later on. As long as you don't have to cool your house, everything is 100% effective. Let's take a couple more examples.

Electric blanket - 100% effective. If you turn it off, the electric wallboard heating will kick up 100 watts to compensate: net cost of blanket electricity for the same comfort level - zero.

TV, DVD & computer - Left on all the time? No problem, as long as the air conditioning doesn't kick on.

Hair dryer - 100% effective (and only used for short periods anyway), so get every hair in place.

Electric toothbrush - Yep. Even its charger is a perfect machine in this context.

Refrigerator - 100% effective. This is one of my favorites. What does a refrigerator do? That's right. It compresses gas to pump heat from the inside to the outside of the icebox. Where does that heat go? It heats the kitchen! Even the compressor is 100% effective! Once again, it saves energy that might come from electric heat.

Why do I keep referring to electric heat instead of oil or gas? That's because in the past gas has been far cheaper than electricity per BTU. This made electrical devices a little less "effective" (and a little more expensive) in producing that "wasted" heat. Unfortunately, cheap gas is history (update - well, it was in 2007). The cost of oil and gas heating now approaches that of electricity (at least during the price spikes which are likely to be more common in the future). So for many, there's no big difference. Leaving your TV on is almost as cost effective as buying natural gas.

Another even more significant exception is if you warm your house with a heat pump. Heat pumps with a good source are three times more effective than electrical resistance heat so two-thirds of the stated saving ARE real. CFL and Energy Star DO represent significant saving in this case even though one-third of the savings is still an illusion. Your mileage may vary but it will always be less than claimed by these "expert" sources.

With electrical resistance heat, this "effectiveness" creates the strange situation where you could turn EVERYTHING in the house OFF (except for the electric heat) and set in the dark for a winter month with no entertainment or hot food - and your power bill would be EXACTLY same. Try it sometime. You'll see.

This also means you could go out and buy the most efficient light bulbs you could find and all new Energy Star appliances; STILL, the power bill would be EXACTLY the same. So enjoy your gadgets and think twice before spending extra for "efficiency". Spend your money where it counts.

And where might that be? If there's little advantage to "efficient" appliances, how can we save energy and money? That's another blog post but start by taking a look at the heat leaving your home through the walls or down the drain as hot water. Those two are your biggest loses.

Heat and air conditioning use 50% of home energy. Better insulation and sealing can save up to 25% of your energy cost for the typical home. But make sure the house still has reasonable ventilation - especially in radon areas. And hot water is about 13% of your energy use, so again, use it carefully. It's not effective to heat up the sewer drains.

Which brings up one important exception to this "effectiveness" rule - the clothes dryer. It blows it's heat outside and also brings in cold air - you lose. It's a good reason to get a clothesline. Or use the dryer sparingly.

And if you still want to buy some of those CFL bulbs, put them outside. That's one place where ALL the savings count.

There you have it. Now you can sleep better (and warmer) knowing your heat isn't as "wasted" as you thought.

OK. If you still want to know how much of that 65.7 KWH you would save by buying that bulb, multiply it by the ratio of cooling days over days in a year (365.25). The extra air conditioning load will be offset by less probable need for light in the summer. For me in Reno, Nevada that extra efficiency can be used about a quarter of the time (in the summer) which is probably about average for America. This makes WalMart's claim overstated by four times - you decide if that bulb still makes sense.

But why would Fast Company, WalMart and Energy Star not point this out? Simple. It would make the story less exciting, WalMart would sell fewer light bulbs and... and... and I don't know WHAT'S wrong with the Federal government.

So from now on, don't let some slick magazine make you think a new light bulb will solve all your problems; don't expect WalMart to always save you money. And finally, don't expect the government to set them both straight. When you hear about efficiency, think also about effectiveness.

And quit worrying about your household appliances. They are almost perfect machines much of the year. No matter what their efficiency rating. Please leave a comment if I've missed something.

11-30-11 - The best counterpoint to my post that I've seen so far:

The Math Changes on Bulbs - Wall Street Journal

03-12-12 Ready for $50 Light Bulbs?