“I didn’t get much done last week because it was so hot.”

It wasn’t the first time a client said this to me, and I was curious. “Have you considered getting an air conditioner if it’s that bad?”

“No” He replied (let’s call him Philip), “An open window is usually enough. It’s just that the heatwave this week was particularly bad.” When we discussed it a bit more, Philip said it didn’t seem worth the hassle since the AC only really felt necessary for a few weeks during the summer.

So, was Philip right? Is it worth buying an AC as a productivity hack?

How much is your time worth?

Most people don’t think about air conditioners when evaluating their productivity, because it’s not within the normal scope of time management. But if you frame productivity as the careful use of your resources - including time, effort, and money - to accomplish your goals, then an AC is fair game as a productivity hack. The question becomes “is the cost of buying the AC a good deal for the productive time it saves you?”

If you don’t already have an estimate of how much you will spend to save an hour, try estimating it with the tools below. A dollar value is a handy tool when deciding which time savers are a bargain.

This Clearer Thinking tool is convenient for calculating the value of a marginal hour of your time. (A normal work hour may be worth more or less to you, depending on whether you care more about output from focused work hours or work/life balance. The marginal output of an additional hour worked decreases, probably starting somewhere after three to six hours per day. On the other hand, the marginal value of an hour of free time to you starts increasing the more you’ve worked.)

Another way to calculate the value of a marginal hour of work time is to look at what you could earn in a marginal hour as a baseline for how much your time is worth, e.g. tutoring on Wyzant. These estimate how much you would be willing to pay for an hour of your time. If your income is particularly unstable or you have less than 6 months runway, you may want to be more cautious about spending money.

You could also try directly estimating the value you produce in an hour. Since this seems difficult to do for most people, a plausible proxy is how much existing metrics value the impact of your time. 80,000 Hours’ survey found EA org leaders valued their most recent junior hire for 3 years at $1,050,000 (average) and $450,000 (median). Assuming 40 hours a week, 50 weeks a year, that values an hour of junior hire time at $175 and $75, respectively. For a senior hire, they gave $7,400,000 (average) and $3,000,000 (median), which works out to $1,233 and $500 an hour respectively. While these numbers may be overestimating the value, an order of magnitude less would still be $17.5 per hour for a junior person and $120 per hour for a senior person.

What does an AC cost?

Now that you have an estimate of your time, let’s compare the value of an AC to other ways you can buy productive time with money. For these calculations, I’m going to estimate an hour is worth $30 (50 cents a minute). Your personal value for time may be much higher (or lower if you’re cash constrained right now).

Research on the impact of heat on productivity suggests productivity starts decreasing at as low as 22°C (72°F) and decreases by about 2% for every degree Celsius above 24°C (75°F) (Footnote 1). This would imply that at 29°C, it would take about 4 extra hours per week on average to get the same amount done (a 10% reduction in productivity). While exactly where your productivity starts decreasing depends on your gender, it seems almost certain you’re not doing your top work if it’s blazing hot in your office.

Let’s do some quick back of the envelope calculations. Assuming that your productivity is reduced by 20% per week when the temperature is above 35°C (losing 8 hours per week) and you value your time at $30 an hour, that heat caused you to lose $240 worth in one week.

A window or portable AC unit costs around $300 on Amazon (plus up to $20 per week in electricity) and can completely solve the problem (Footnote 2). That buys time at about 35 cents per minute in two weeks of a heatwave. If you have four weeks of heatwaves, your cost per minute saved goes down to 20 cents. After that, the cost of running the AC for an entire week is more than paid for by saving 1 hour.

If you really don’t want to buy an AC, find a place that does have AC and work there during heat waves. You could also try working in the morning and evening, and taking a break during the warmest parts of the day. These ideas accomplish the same productivity benefit for hassle instead of money.

20 cents per minute seems like a pretty good deal on time, given we started out willing to pay 50 cents. Let’s see how it compares to other ways you can buy time.

How much does it cost to buy time other ways?

Paying for a laundry service

A laundry service that picks up your clothes costs $30-$40 a week based on a quick look at two sites, and I’m ballparking that it would save about 30 minutes per week (it’s hard to tell, since it’s in 5-10 minute chunks here and there). So using the laundry service buys time at around $1.17 a minute. Pretty expensive compared to our baseline of 50 cents.

Buying Soylent

Replacing breakfast power smoothies with Soylent. Soylent is $3.25 per bottle ($2.53 if you buy in bulk with Amazon subscribe and save). It takes about 5-10 min and $2 to make a power smoothie with a similar number of calories. So Soylent buys time at about 10-20 cents a minute. So basically, you’re getting an awesome deal on your time by drinking Soylent occasionally. It’s like the Black Friday sale on time.

Eating takeout

I’m estimating $15 to buy a meal and assuming leftovers to be about another meal’s worth for myself. So $7.50 per meal for compared to $2 per meal and 10 minutes (based on 60min spent preparing 6 meals in bulk). So at about $5.50 to save 10min, eating takeout buys time at about 55 cents per minute, almost breaking even. (Note: There are other health considerations that may easily trump the productivity gain, plus taste and variety.)

Hiring a house cleaner

Our house cleaner is $25 an hour, and I estimate she cleans as quickly as I could. So this buys time at about 42 cents per minute, which does a bit better than breaking even. (Avoiding particularly unpleasant hours may be worth more to you than a normal hour, however.)

Taking an Uber

The value of an Uber can vary a lot between rides, but basically it’s worthwhile when you can save two minutes for each extra dollar you spend above what you would have paid for public transit. A recent 30-minute Uber with 3 people cost us $28 ($16 more than the $12 the Bart would have cost), and saved 15 min. Split across 3 people, that works out to 36 cents per minute.

How do those compare?

If you have 4 weeks of heatwave over the lifetime of the AC, the AC is a better deal than anything except Soylent. If you only have two weeks of heatwave, it’s still better than laundry service, takeout, or a housecleaner.

Of course, the math may work out differently for you. It’s likely that there’s significant individual variation in the value for an hour, the details for the above estimates, and how much heat affects you. Your calculations may look significantly different, so feel free to make a copy of my calculations here and adjust for your own inputs.

I expect a lot of the benefit of an AC to come at extreme temperatures, which is where most people report a clearly noticeable difference in productivity. This particularly true if you live in Europe, which is currently experiencing its third heatwave this summer. July’s heatwave broke at least four countries’ heat records with temperatures up to 108 °F.

If you live in a city where the temperature is above 35°C (95°F) for more than two weeks per year and you don’t work in an air-conditioned space, you should probably go buy an AC right now. For more moderate high temperatures, say 26°C (80°F), it seems more likely you’ll be able to cool off with an open window or a fan.

But even if you live in Alaska, you now know what your time is worth. Try looking for other opportunities to buy some time at a bargain.


Footnote 1:


Pg. 527

Workers' health and productivity under occupational heat strain: a systematic review and meta-analysis

“heat stress (defined as wet-bulb globe temperature beyond 22.0 or 24.8°C depending on work intensity”

“11 studies with 8076 workers were included in meta-analysis three. The pooled proportion of individuals showing productivity loss due to occupational heat strain during work in heat stress conditions was 30% (21–39; appendix). In addition to the prevalence of productivity loss, seven studies reported precise changes in productivity as a function of environmental heat stress. These studies suggest an average 2.6% productivity decline (individual study estimates: 0.8%, 1.4%, 1.8%, 2.2%, 2.8%, 4.4%, 5.0%) for every degree increase beyond 24°C WBGT.”


“Economist R. Jisung Park reported that worker productivity declines by 2 percent for every degree Celsius above room temperature”

“Researchers at the London School of Economics found that urban areas also pay a price for high temperatures, even among indoor office workers. They found that in London, a warm year could cost the city’s economy upward of 2.3 billion euros in productivity. Workers make more mistakes and act more slowly as temperatures rise above their optimal range.”


Summaries of studies on temperature and productivity which found “remarkable consistency in point estimates: (at least) -2% per degree C above room temperature.”

Slides 23 and 25


Table 4

This technical report claims hourly work capacity drops by 74-90% when the temperature is 37°C (98.6°F), compared to a baseline of 26°C (78.8°F).

Footnote 2:

Utility costs, likely overestimating the monthly cost since Jeff’s electricity is 3x the national average.

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Great post.

By the way, taken to its logical conclusion —

People don't move to new apartments frequently enough.

If your neighbors suck badly and you can't influence them, or if you live in a place that's badly maintained and the building management won't do anything about it, you really should strongly consider moving.

You tell that to somebody, you're likely to get to get one of the following arguments —

(1) That'd be too expensive (time, money, etc)! Possibly. I didn't say the person should move, or should move immediately. Just said "strongly consider" — aka, run the math and search out options, see if you can be creative, consider doing a temporary solution like crashing with a friend or staying with your parents or finding some subsidized housing for a short period of time to bank cash and then get a better place. If your apartment is causing major lifestyle disruptions/headaches with any sort of frequently, I'm just saying you should strongly consider moving. I feel really strongly people should do this, because there's been two or three times in my life that I moved too slowly, and I'd have been much better off taking a $1000-$3000 + dozens of hours of cost to move apartments, even if additionally a huge hassle even beyond those factors, because my life got hugely obviously better after moving. Just, at least, run an analysis of all the costs and research options and weigh it against expected value. I'm not saying you gotta do it, just you really ought to think about it.

(2) You don't know what it's like to be broke! Ah, the moral argument in favor of not even considering changing a bad situation. This argument is basically, "Don't make me feel bad and don't assert that I can have agency here." This argument is kinda unfortunate, because "hey, dude/dudette, you should really consider moving given how much your living setup sucks and is getting you down" seems pretty reasonable and is usually a pretty friendly argument.

For the record, by the way, that second argument is false in my case — the nickname of one of my first apartments was "The House of Horrors." Windows were partially broken in a ghetto Boston suburb. My bedroom got freezing cold in the winter. Lots of crime in the neighborhood, and regular rowdy behavior from patrons of local boozeries made getting a decent sleep on Friday and Saturday evenings a dice roll most weekends. (A dice roll I usually lost.) Kitchen was full of broken stuff, mold in the refrigerator, ceiling at times leaked water through a lighting fixture which umm, seemed dangerous.

One day I was sleeping in around 10AM and I woke up to hear a chainsaw from inside my own apartment. Like a horror movie — this was when the apartment got its nickname — and found out my landlord had decided to do something about the water-leaking-into-light-fixture problem and got a handy-man to chainsaw my ceiling but didn't think to knock before letting himself in nor check my bedroom, just assuming I was out. So I woke up to a man with a chainsaw in my apartment chainsawing my kitchen ceiling. It wasn't perhaps as dramatic as it sounds in text; nevertheless — somewhat unsettling.

So yeah, actually, I know what it's like to be broke as fuck. Nevertheless — while amusing years later, I ought to have at least strongly considered moving sooner. It seems a bit irrational in retrospect to not strongly consider it sooner. Life got a lot better once I did.

The people around me reason this way a lot, and I think it's for some reason really unintuitive for most people to start doing. This post is clearly written and I like it as an artifact I can point people to, rather than explaining the thing from scratch myself every time.

That first links seems to suggest that only 30% of workers have this drop in productivity. If you're going on only a statistical argument, that means that $240 * 30% chance means about $72 lost. This seems to alter your numbers drastically. This also seems to suggest a high VOI to measuring your productivity and plotting that against heat, to see if you're in the 30%.

If you dig deeper into the first link, you'll find these numbers which indicate that the productivity loss increases as a function of the temperature increase: "In addition to the prevalence of productivity loss, seven studies reported precise changes in productivity as a function of environmental heat stress. These studies suggest an average 2.6% productivity decline (individual study estimates: 0.8%, 1.4%, 1.8%, 2.2%, 2.8%, 4.4%, 5.0%) for every degree increase beyond 24°C WBGT.”

Still, I'm all for running an experiment to check how much your personal productivity responds to temperature! Individual variance might be high here.

Am I reading this wrong? It seems like the meta study is suggestion that the linear productivity decline applies to the 30% of workers who experience a productivity drop due to heat.

I interpreted it as overall average productivity drop, which makes sense since I wouldn't expect most people to report productivity losses at the lower end of this scale (75°F). Rereading it, my interpretation still seems more likely, but it's not totally clear which one the authors meant.

A bonus not mentioned for the AC is that it can radically improve the quality of your sleep (if your sleep is temperature sensitive), which can have pretty major effects on your energy.

Seconded. Sleep is the sine qua non of my productivity, and the first thing that suffers in heat waves.

This is a good reminder for those who haven't thought of it or haven't examined their voices and habits for awhile. But https://www.lesswrong.com/posts/6NvbSwuSAooQxxf7f/beware-of-other-optimizing, and watch out for a rationalist habit to overweight the legible (measurable, calculable) portions of life choices and ignore the hidden and hard-to-quantify.

Consider that Philip may preFer not to have gotten much done on the dimensions he can communicate, and the heat gives him an easy justification. Or that the emotional cost of picking and committing to spend for the unit is higher than the benefit for a week or two.


She mentioned Philip was a client. He's literally paying to be other-optimized. Also, she's citing enough evidence to get around the typical problem of a failure to generalize.

I agree that the time cost of shopping can eat at the calculation. Looking at Wirecutter and Amazon top reviews for ACs can help make a quicker decision for many such purchases.

Disposable plates and flatware are cheap and save significant time.

Your argumetn is sound. For me, it's curious that development economists almost never mention the temperature x productivity relation - except for J. Sachs (who mixes it with other geographical factors) and Nordhaus (who got a Nobel Prize for reasoning about it).

I think the case for an AC is stronger than some of the other ideas, because an AC increases energy as well as time. But even though doing laundry takes time, it doesn't feel to me like it takes a lot of energy and might even increase it (light physical activity through the day=good for productivity?)

Light physical activity through the day is definitely good for living longer and more importantly staying instrumentally rational longer.

This is a core piece of a mental toolkit, being able to quantify life choices like this, and the post explains it well. I think I would like the a version in the book to spend a bit more space helping the reader do the calculation that you do in the Clearer Thinking tool. A lot of the value of the post is in showing how to use the number to make decisions.

I think it's a valuable post, and I expect to vote for it somewhere in the range of +2 to +4.

How much is your time worth if you're retired, a homemaker, a student, or otherwise not working for pay?

For retired and homemaking folks, I think that's really up to them. I don't have a good model for external evaluation. For a student who wants to do impactful things later, I think the calculations are similar. 

Since I can't link to it easily, I'm reposting a FB post by Rob Wiblin on a similar point: 
"There's something kinda funny about how we don't place much value on the time of high school and undergraduate students.

To see that, imagine that person X will very likely be able to do highly valuable work for society and earn a high peak income of say $100 an hour by the time they're 35. As a result they'll work a solid 50-60 hours a week.

But today, as a 19 year old undergraduate, X is only able to earn $15 in hospitality. They also feel they quickly hit declining returns on studying and so, like many undergrads, spend a lot of time goofing off and having fun, because it seems like the opportunity cost of their time is really low.

That's fine as a lifestyle choice, but the whole scenario is also... weird. 

If their career advancement is purely determined by how quickly they learn what they need to learn, and generally become fully-fledged adults, then the true opportunity cost of each hour should be closer to $100 than $20. 

That's because each extra day of training they do now should bring forward the day they reach their peak productivity by about... a day. Their opportunity cost being low is an illusion stemming from it not yet being tangible and measurable.

If we model career progression as literally just a linear series of steps that take you from zero productivity up to a peak plateau productivity, before then going back down due to the effects of ageing, then the opportunity cost at the outset, before you've learned anything at all is... the productivity at the peak.

Of course many things interfere with this simplified analysis:
• Becoming more productive is partly just a matter of growing older in calendar time, as the brain, body and personality mature.
• Lots and lots of career capital is gained through 'goofing off', following random interests, exploring the world, working on yourself & your mental health, and socialising. People who skip these parts of life often face problem later on. So what looks 'unproductive' will often be as good as or better than formal training.
• If you're on an inflexible path (e.g. becoming a radiologist) there may simply be no way to speed up the rate at which you learn or can start working. You have to go through a series of predetermined steps that suit the average participant, using materials you can't access yourself, and which occur in calendar time no matter what you do.
• People also want to have fun — work and productivity are far from everything.

The main lessons I draw from this are:
• The true opportunity costs of talented young people are higher than they initially appear, maybe much higher.

• When young people can't afford the tools they need to learn most effectively, this is no joke. Rather it's a heartbreaking waste of human capital.

This kind of thing includes: a great laptop, peripherals and desk; ability to commute quickly; a quiet house or room to study in; connection with colleagues to form a study group; a great bed and other things that improve sleep; help with mental and physical health when required; etc. Basically all the stuff that's 'profitable' for 40 year-old professionals who earn a lot and so value every hour of their time.

• Having training systems that allow people to choose to work harder and advance faster are good. At least if they don't eat into valuable informal learning.

• It can be a real waste of society's limited human capital to have high school, undergrad and postgrad students waiting tables to pay the bills, just because they have no collateral with which to borrow against their likely future income." 

I strongly agree with the essence of this post, considering I've spent quite some time recently thinking about the value of my time and trying to somehow put it into reasonable numbers in order to make everyday decisions easier and more well informed.

About a year ago I took the clearerthinking test and ended up with ~32€, which seemed high, and looking back I think it wasn't particularly accurate. I'm thus not a great fan of that test personally and think getting a correct value requires much deeper thought than this small questionnaire prompts you to do (although thinking about the issue at all is of course already useful). One benefit it has though is that it clearly shows the asymmetry in our intuitions (aka loss aversion), so that was very helpful at the time, yet the number that came out provided me with a false sense of certainty.

Thinking through things further these last few days, I revised that value now to very roughly 12€ (varying from around 6€ to 18€ depending on the type of action, although I assume EA work should very likely be rated much higher than that). But just as the earlier value, it still is mostly based on intuitions and inner simulation regarding what price I'd accept for e.g. somebody asking me to simply do nothing at all for a week. So it's still on fairly shaky grounds. Calculating the external value my time has on the world is difficult as so far I'm focusing more on learning and developing than on generating actual output (the latter only making up 1-2 hours per week so far).

One difficulty is that it's not easy to look at the marginal value only, plus the consequences it has on one's behavior could easily shift spending in a way that the marginally value itself changes significantly. If I spend 200€ more per month, money suddenly becomes more scarce and thus valuable. If I reduce my day job work time from 5 to 4 days a week, the same thing happens. So after any major change or decision I have to reevaluate and come up with new numbers.

Despite these difficulties however, thinking deeply about this and reducing one's uncertainty however far possible is certainly time well spent. Thanks for the post!

Good points - these heuristics are much better than nothing, but probably shouldn't be taken at face value without some additional thought.

AC doesn't "completely" solve the problem, because they:

a) Have time-needs for the purchase, installation and maintenance, none of which are included here.
b) Make noise, at least some of us also work less efficiently while subject to noise.