You might have heard some of these suggestions on how to conserve energy:

  • Unplug unused appliances
  • Switch to CFC light bulbs
  • Adjust your thermostats & insulate
  • Carpool or buy a car with good mileage

But how much of an impact do these things really have on our energy usage? What really is the number one thing we can do to save the most energy?

I read an interesting book on this topic, “Sustainable Energy – Without the Hot Air”. Author and Cambridge professor David MacKay painstakingly assembles the data that shows where we use our energy. It is surprising that some things we are told to do to conserve energy are really just a drop in the bucket, and that some of the biggest energy hogs are never mentioned.

MacKay looked at the energy usage of the “typical well-off consumer” in the United Kingdom, and came up with the following numbers:

Let’s start the biggest offender. “Stuff” represents the energy required to manufacture all of the crap we buy and use, from iPhones to clothes to cars to furniture. This is the number one energy drain, yet people rarely suggest buying less stuff to save energy!

Next is driving. The chart above assumes you drive 33 miles per day alone, and some of us drive A LOT more than that every day. So, cutting down on driving really does make a difference on your total energy usage. Riding a train uses 1/10 as much energy as driving alone. Riding a bike uses a fraction of that (just because of the food you burn). Carpooling is pretty good, but not as good as riding a train. Hybrid cars are only 30% better than a conventional car. Pure electric cars are pretty good though.

Third is heating/cooling. Again, the conventional advice to adjust your thermostat, insulate your home, etc., is sound. Hopefully, you are already doing that.

The fourth item is flying. Before I saw this chart, I didn’t realize how much energy jet flights used. I mean, a jet carries a lot of people, so the per-person energy usage shouldn’t be that much, right? It turns out that jets use about half the energy per person per mile as driving a car alone does, which is terrible when you consider how far we fly. In addition, this chart assumes 17,600 miles flown per year. Many of us fly much more than that. So, cutting down on flying can actually have the biggest impact on reducing your energy usage. Yet, no one talks about flying less to save energy, even though skipping one trans-Pacific flight can save more energy than not driving your car for a year!

By the way, ships are awful when it comes to energy efficiency per person per mile, about 30% worse than driving alone. Keep that in mind when booking your next cruise.

The next item is food. I can’t think of how to reduce that, other than to buy locally or grow your own.

Transporting stuff takes a lot of energy too, especially since so many of our manufactured items are shipped from China.

“Gadgets” represents the electricity used by appliances and devices like computers. It turns out that unplugging your unused appliances saves less than 1% of this tiny bar. So, you should still unplug unused appliances because it’s easy to do, but don’t pat yourself on the back too much. It’s like bailing out a swimming pool with a Dixie cup. It saves much more energy to use your washer or drier less often.

Let’s also take a look at lighting. The graph represents someone using a mixture of high-efficiency CFC bulbs and some low-efficiency incandescent bulbs, which is probably pretty accurate for most people. Although it is good for us to use CFCs, we shouldn’t be too proud of ourselves in the grand scheme of things. Skipping one jet flight saves many times more energy than shutting off all of your lights completely for a whole year. Still, saving electricity is really a good thing to do, since it is a high-grade form of energy that can’t be stored. Saving electricity will reduce the need to build more power plants, which is a very good thing. So, by all means, keep saving electricity, but keep those other things in mind.

Now, I mentioned that this data is for the average UK resident. The average US resident is probably much worse. I made some ballpark guesses on my own energy consumption. I picked 2011, since that was a peak year of energy usage for me. Here’s what I estimated:

Note the whopping amount of energy I burned on jet flights!

In 2011, one of my biggest travel years, I made two trips to Asia for work, plus many coast-to-coast trips. The energy I used on these jet flights was insane!!!!! Because of that, I used much more energy than the jerk who drives a Humvee (assuming he doesn’t fly much).

With regard to heating/cooling, I am a miser. I made it through a New England winter only using my heater for about a week! But, despite my efforts, my total energy usage was still through the roof due to my air travel.

The other adjustment I made was for national defense. I estimated that the U.S. energy usage for defense was about ten times that of the UK (very rough and probably conservative estimate).

Now, I work from home, so I re-estimated my energy usage for 2012, and it looks a lot better:

My air travel is down, which is better but still not great.

Since I work from home, I hardly drive anymore, and I take the train when I have to go to Boston. I love traveling by train now. When I factor in the cost of gas, parking, and wear and tear on my car, the train is cheaper than driving in my case. For most of my local trips, I ride my bike. I only use my car about twice a week.

I’ve tried to cut down on buying stuff, but a lot of it was unavoidable. My bike got stolen so I bought a new one (I suppose I should have gotten a used one). My car needed tons of new parts including new battery, tire, and cooling system (yet another reason not to drive!!!) So, I can’t really say I spent less on stuff, unfortunately. It is difficult to cut down on stuff, even when I am not extravagant in my purchases!

To sum up, here are the things you can do that have the biggest impact on reducing your energy usage:

  • Buy less stuff! Try to make due with what you have for as long as possible or buy used.
  • Fly less if possible. I know that is hard to do, but if there’s anyway to consolidate trips or whatever, that can have save more energy than not driving or not using any electricity for the whole year! I have been a bad offender in this area.
  • Save energy on heating/cooling by adjusting your thermostat, insulating your home, etc. Wear a sweater at home in the winter.
  • Drive less. Carpool or use public transportation. Riding the train uses 1/10 as much energy as driving a car alone does!! Biking is awesome.
Cities like Boston and Washington D.C. have easily-available bikes to rent all over town!

Now, a word to my friends who don’t believe in “global warming”, or who don’t believe that human activities are responsible for global warming. To you I say, forget about global warming. Think of all of the other reasons why it’s good to save energy:

  • You’ll save money.
  • You’ll give less money to countries in the Middle East who hate us and have oppressive governments with terrible records on human rights. (Take Saudi Arabia, where converting from Islam to Christianity is punishable by death, where being gay is a crime, and where women aren’t allowed to drive a car. I hope this offends everyone reading this in some way!)
  • You’ll have cleaner air
  • We’ll have fewer Exxon Valdez or BP-style oil spill disasters.
  • Oil won’t last forever. When it runs out, things will be very very bad. It might not happen in our lifetime, but it can happen in your childrens’ lifetime.

So, please keep unplugging unused appliances and shutting off lights. But, keep in mind the really big energy-consuming activities that no one ever talks about, like buying stuff and flying!

– Brian

I got the data for the first graph from this book:
David J.C. MacKay. Sustainable Energy – without the hot air. UIT Cambridge, 2008. ISBN 978-09544529-3-3. Availalbe free online from www.withouthotair.com.



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