I Fell for Their Data

I fell for a stupid article and turned off my home PC last night. The article says that Americans who leave computers on overnight are wasting $2.8 billion on energy costs per year.

It ignores the cost of turning computers off — and having to turn them on again the next morning. Let’s say that process takes five minutes per day, and one does it 250 days per year. That’s 1,250 minutes, or more than 20 hours per person per year.

Assume the average computer user’s wage is $21 per hour, and take the old estimate that time is valued at one-third of the wage. So each person’s time per year turning his/her computer off and on is worth 20 x $7 = $140. I’m being conservative and assuming only 50 million U.S. computer users. That gives a cost of turning computers off/on of 50,000,000 x $140 = $7 billion, which is 2.5 times the alleged savings from turning computers off. Even if people’s time were valued at only $3 per hour (less than half the minimum wage), leaving computers on would still make sense.

This story is yet another example of environmental savings uber alles — that saving $1 in environmental damage is worth much greater costs incurred along other dimensions. These stories assume explicitly — or, more usually, implicitly — that people’s time has no value.

But time has value because it has an opportunity cost. Stories like this and exhortations for environmental do-goodism hurt the environmental movement, because in the end, people realize that heeding these exhortations would actually waste resources (even though some, like me, take a day to catch on!).


Well, that's silly, and your tone suggests a bias. The time needed to turn a computer off is almost nothing. Why should I mind getting coffee while my computer starts up? The fact is, I do not mind because I value the savings in electricity, pollution, and dollars, and I don't feel that my time getting coffee is at all wasted. Can your limited economic model account for me?


It takes me maybe a minute to turn on my computer; about 10 seconds to turn it off.


Do you really sit and stare at your computer while it turns on and do nothing else? Also, restarting your computer is inevitable since continuous use without flushing out the ram will decrease your productivity inevitably - so you might as well start fresh each day.

Turn off your computer when you leave. When you plan to start work, go turn it on, then make coffee, tidy up, or do any of the other countless tasks you will be doing later while your computer is running and you are not working.


You're counting that time as wasted, which is not. I usually come into my office, turn on my computer (takes about 5 seconds) and then go get water for coffee; by the time I'm done preparing coffee, my computer is on. Again, while my computer turns off, I'm preparing my things to go, so the net 'waste' is about 10 seconds :)


Weren't you the same one who says we should drive instead of walk because of the calories of milk we might consume on account of walking, thus raising our carbon footprint?

This is, as the first post suggested, silly. Your opportunity cost is not as high as you suggest. high. Besides, you could turn your computer on, then do something else while that is happening.


Actually you can set up your computer to turn off and wake up in the morning. Mine does as a signal that it is bed time and to save power


I have to agree with Lucy; I never sit around for 2.5 minutes staring at my computer screen waiting for it to boot up in the morning, and another 2.5 minutes to shut down at night. In the morning, I'm off getting coffee or clearing off my desk, or doing any number of other morning routines in my office. At night, I simply tell my computer to shut down, and it does it with no further intervention; I don't need to sit and wait for the process to complete.
Environmentalism has nothing to do with it; it's a cost-saving measure for my company, just like turning off my office lights at lunch, and when I go home at night.


I expect more than this from the freakonomics blog. This is inherently unscientific.

First, the assumption that it takes 5 minutes to turn a computer on and off per day is suspect. It takes my computer at home about 1 minute to boot up and 0 minutes to shut down (considering I can just select shut down and press the monitor button.)

Second, the assumption that people would spend that time otherwise waiting for their computer to boot up working on their computer is probably the most suspect assumption. Because people don't do anything else in the morning? No one ever gets coffee? People dont pick up anything after getting in the office? No phone messages?

This is a blatantly political post that really has no actual backing in any sort of scientific analysis.


I'm sorry but your response is simply an arguement that the poor have a greater obligation to environmentalism then you because 'your' time is so valuable.

5min is just a strawman agrument to make your point.

If you were refering to a laptop you would think it was crazy to leave it on because the battery would be drained.

Like free street parking the cost of electrons though the wall is greatly subsidized and your calculations obsure the real cost of energy consumption without any work output.

What is the opprotunity cost of energy used without work being done?

I'm sorry is your time to valuable?


I hope no one falls for YOUR data! I make no money at home, so turning that PC on/off costs me nothing. In fact, the chime that signals that it's booting up tells my son his bedtime is near, so the act has actual value. At work each morning I badly need the 2-3 minute boot-up time to unpack my bag, tend to the coffee pot, shuffle papers on my desk, etc. And, in a repeat of the time-management benefit of the home PC, knowing that i have only 2-3 minutes before my work PC is ready to deliver the morning dump of junk email forces me to move through my other chores quickly, so again the on/off ritual has a very real efficiency benefit, which I could probably quantify economically if I were sure I were going to live to be 1,000 and could thus spare the time for that. In short, just as dubious studies of the time people "waste" on NCAA office pools suggest that all economic activity must come to a standstill, when in fact the break probably increases productivity, so too does the time "wasted" on turning PCs on/off prove illusory. But the savings in electricity are extremely real, as is the benefit to the global community in not allowing your machine(s) to be hacked, turned into zombie spammers, at least during the off time(s).



I think it would be just as bad to "fall for" this article.
5 minutes is quite the exaggeration. If it takes that long, you certainly are wasting a lot of your time on such a slow computer! Save yourself the "value" of your time and invest in a faster computer with a hibernate feature (aka any computer made since 2000). This allows you to do a quick start-up and shut-down, each taking about 30 seconds.

Scott K

I second what others have said. During the computer shutdown/startup process at work, I'm often busy taking my motorcycle riding gear on and off anyways.

Besides, if you use the hibernate mode in most modern laptops, both the startup and shutdown take very little time.


If you're going to do a complete analysis, you should account for the additional wear and tear on your HD, spinning needlessly all night long. That will certainly hasten the day that it dies and needs to be replaced.


Hibernate, duh. That saves the time consuming part of a reboot (i.e. getting the apps and files you need opened and arranged just the way you like them).

You should do a cleansing reboot once a week or so, especially if you run windows.


I actually do not do much while my computer is booting up or shutting down. As a web developer, it's my primary means of work.

Bruno Gomes

I'm sorry, but saying that people's time is too valuable to waste it turning computers on and off doesn't make sense at all. Are you really trading 5 minutes of "making money" for 5 minutes of sitting by the computer per day?

Even if that all-too-academic thought were true, would you use the money you'd be making to do something for the environment?


I wonder what the cost to global economies will be for relocating the significant percentage of the human population that live within the low-middle estimate of three feet of ocean rise before the end of the century. (See PBS program NATURE - I believe the episode is "extreme Ice".)

Once again, an incomplete argument to justify lazy, insensitive, selfish, and short-sighted decision making. Mr. Hamermesh, can I wonder aloud about whether any of your scholarship was used in the business plans of the financial institutions or oversight agencies that didn't see the current economic crisis coming? The market of the earth's environment will not react as quickly to your personal choices as the stock market - but when it crashes the results will be much worse than the effects this little recession and, at that point, there will be no chance of a government bailout.


I hate to pile on, but this is nonsense.

(1) You don't lose the time while the computer starts up, since you're not doing the starting up. You lose the fraction of a second during which you're required to have your finger on the button.

(2) Energy cost to the consumer is not the same as energy consumption's total cost. We externalize much of that cost to the environment.

(3) If you wanted to argue for a real cost of starting up, you should have mentioned the problem of reconstructing the workspace you had: which programs and windows were open, which sites had you logged into, etc. These take time. The "hibernate" mode still uses energy.

(3.5) A real proposal would be to come up with a way that the state of an OS could be saved for later. Many systems or individual programs have this, but mainstream OSs do not.

(4) A real way to save energy and time? Drink tap-temperature instant coffee. Mmmm...



There is nothing wrong with trying to quantify "green" savings, but at the same time, the dollar savings is not the point.

Then you present a counter-argument based on quantifying your time savings (in which, as others have pointed out, you have made quite a few bad assumptions).

It's as if you have a tree and a pile of coal of equal mass. Which has more value? Well, if you are going to measure the value by "converting" both into energy by burning them, then the coal is of more value. However, the tree has other value such as the fact that it consumes carbon dioxide, produces oxygen, provides shade, acts as a habitat, etc. These don't factor into a simple "to energy" conversion. Your apples-to-oranges green-to-dollar-time-to-dollars conversion is similar. Economists and their oversimplified quantification!

If such a flawed comparison weren't bad enough, it's as if you miscalculated on only one side by a factor of 10. As others have said, most people are still productive during their boot up and shut down time.

As a consultant, I have a bill rate of $200 per hour. That's not some far-fetched opportunity cost; I can actually COLLECT that and put it in the back. I also realize, though, that without a planet, it won't do me any good.

If you are going to be critical of environmentalism, as least provide a more sound analysis.


Mr. Shiny & New

Just use the suspend feature. Doesn't save as much power as hibernate or full shutdown/restart but it does save a lot of power; most of the computer gets powered down. You can even set your computer to suspend automatically after a certain amount of time. A modern computer resumes from suspend in under 10 seconds.