76 comments

How Not to use your Air Conditioning

Happy July 18th. It sure is hot these days, isn’t it?

Statistically speaking, a good portion of the continental US and Canada has its hottest average day of the year right around now. So I thought it was a good time to share some thoughts on the modern household’s biggest energy consumer in July – the Air Conditioner.

See, normally I’d assume that we’re all adults and we’re able to decide for ourselves how to run our own appliances. But after being on my current summer vacation for over three weeks and visiting a large number of family and friends throughout the not-overly-hot Great Lakes region, I’ve noticed that most people leave their goddamned air conditioners running 24 hours a day, whether it is warm or cool outside, with their houses at a stupidly low temperature. Yes folks, it has become obvious that America and Canada both need a lesson from Mr. Money Mustache on how to use their Air Conditioners.

I recently measured the power consumption of the central A/C system in my own house. Mine is a “3-ton” (36,000 BTU/hr) system which dates back to about 1998, when my house was built. At the time, it was considered fairly efficient with a seasonal energy efficiency rating (SEER) of 10. Newer units, thanks to EPA rules, are now much better with ratings of 14 and higher – changes the SEER rating translate almost directly into similar percentage decreases in your cooling costs. When in full operation, my system uses 3,000 Watts (3kW) of electricity, about 500 of which is my furnace blower pumping the cool air around the house (and adding its 500 watts of heat back into the cool air stream, by the way).

For those without electrical engineering backgrounds, 3,000 watts is an Absolute Shitload of electricity. It’s enough to run 230 modern light bulbs simultaneously, and it’s equal to having about 15 monster-legged tour-de-France-level cyclists hooked up pumping at race level on bike generators continuously in your basement.

At the national average price for electricity of 12 cents/kWh, my air conditioning system burns 36 cents per hour, or $86 per month if used for 8 hours per day. With a three-month cooling season, this would compound to SEVERAL THOUSAND dollars of wasted electricity every ten years. Yet my TOTAL average electric bill in summer, despite an average daily high temperature of almost 90 degrees in Colorado, is really only about $35. How could this be?

The answer of course is that I have just cut out the waste, without sacrificing any real happiness or comfort.

Here’s how comfort works. Your body generates heat just by being alive. It needs to maintain its internal temperature at around 98 degrees F, and it depends on the skin surface temperature being lower than this to dump extra heat into the surrounding air. Producing sweat helps you cool the body faster, since the sweat sucks up heat as it evaporates. Humid air cannot evaporate your sweat as quickly, which is why it feels hotter. All basic elementary school science, right? This is why the Southeastern United States is a sucky place to be in summer even at 85 degrees F, while the desert states can feel quite comfy and invigorating at that temperature.

Finally, your body becomes more efficient at cooling itself the longer it spends at higher temperatures and humidities. Every summer as I drive from Colorado down into Nebraska and beyond, I break out into a great sweat and need to crank the car A/C. Even at midnight when the temperature drops into the sixties, I still can’t stand the humidity and need to continue the air conditioning. But within two days, I am comfortable with the higher humidity and I enjoy a regular Eastern summer with no difficulty. As July progresses and things get hotter, I am usually visiting a portion of my family with no A/C, so my body continues to adapt. There are a few days when the temperature is so high that I get uncomfortable, but then I spray myself with the garden hose and drink a gallon of water with ice cubes and all is well.

I also take advantage of the natural cycle of the environment. In the US Northeast and Canada, and even more in the Western desert areas, the temperature usually drops at night. So non-A/C users take advantage of this fact to open all their windows, and use large fans (100 watts) to exhaust heat and draw in cool air to chill the entire interior contents of their homes. A 100 watt fan blowing outwards from your highest window is pulling in night air from all other windows that is 10+ degrees cooler than your house. By sucking in thousands of cubic feet of cool air per minute, this fan is doing almost as much cooling as the 3,000 watt air conditioning unit that does the same job during the day time. The Naturally Cool crowd also makes a point of enjoying more outdoor food cooking and clothes drying on hot days, to further reduce indoor heat sources.

This is to be contrasted with the behavior of Air Conditioning addicts, who set their thermostats to a silly temperature below 80 and let that baby run, night or day. They might turn it off at night, but forget to open the windows, so they miss out on the free night-time cooling. I remember staying over at one friend’s house in June and heading out for a midnight errand. It was so cool outside that I needed a sweater. Yet his air conditioner was still running, pumping out the remaining heat from the 90-degree sunny day that had just passed. Meanwhile his body was not bothering adapt to summertime heat and humidity, because his house was always refrigerator-like inside. All of this is completely unnecessary!

The Mustachian Way is to think of Air Conditioning as a pleasant luxury to be used when all other efforts fail. Much like a car. It should be an exciting moment in your household, when every one is drinking their gallon-sized containers of icewater, wearing comfortable and summery outfits of bare feet and tanktops, and the ceiling fan is running, when you proclaim, “God Dammit it is hot today!! Let’s turn on the AIR CONDITIONING!! YEAH!!!!”

Then you run it for an hour or two, and the sun goes behind a tree, and you shut it back off again. And you open the windows that night and run the fan and go on with your lives.

If this sounds like too much hassle to you, grow some Frugality Muscles, punch yourself in the face, and try again. This is my Earth you are messing with, and your own Money Mustache you are burning off in the boiler of your local Coal-fired power plant.

Stay Cool!
love,
Mr. Money Mustache.

  • Alicia July 18, 2011, 9:01 am

    I hate how disconnected I feel when the air is on. I’d rather have fresh hot air than cool recycled air–it seems more summery that way. But there are definitely limits.

    At my house, we made it only one day into this week-long heat wave before we turned on the air. (I live in Chicago.) It was a humid 92 in the house yesterday and only got down to 88 overnight, despite us using the furnace fan and a box fan to move cool air into the house. Plus, I lolled around the entire day, rather than doing 8 hours of lucrative freelance work like I had planned.

    My frugal solution to this mess: start looking at Seattle real estate.

    Reply
  • Matt July 18, 2011, 9:09 am

    I admire your post but don’t think I can do it. Living in Houston this doesn’t seem like an option. Right now the temperature never drops below 80 degrees, even at 4am.

    Reply
    • MMM July 18, 2011, 10:44 am

      Yeah, Houston and even Chicago in July all require plenty of air conditioning. I’m not suggesting that people start suffering and sweating it out just to save 40 cents an hour. I’m just speaking out to remind people that when there ARE cool nights, or it IS less than 80 degrees inside or out, to consider turning that sucker off occasionally. Like Houston in November or Chicago later in August, or Colorado this week (highs in the 90s, but lows still in lower 60s).

      Reply
      • Madison July 18, 2011, 1:44 pm

        Very good tips. I used to live in a second floor apartment in Salt Lake City, UT that didn’t have air conditioning. These are all good tips.

        Another tip to cool your place down – turn off and UNPLUG all electronics (except the fridge). Helps a little (computers are the worst for adding heat to a room)

        The other thing I would do when the place just got too hot – I would go to a coffee shop, bookstore, or somewhere you can browse or linger that has air conditioning (free air!)

        Reply
      • Kirsty August 21, 2011, 1:35 pm

        I live in South Africa, in summer the average temperature is over 85 degrees. Yet very few of our houses have AC’s.

        Its amazing what windows, tiled floors, curtains and ceiling fans can do.

        Sure we all complain about the heat, but that’s the best time to spend some time in the shade – outside, best shared with some friends and a barbecue on the side.

        Reply
    • BobTX May 29, 2013, 8:37 am

      It is now a few years later, but I’m new to MMM (although not to what he calls Mustachianism) and reading through the blog from the beginning.

      I just wanted to chime in as a current Houston resident, and native Texan:

      It is perfectly possible to put in action what MMM is discussing above right here in Houston. My wife and I have been doing it for a long time, quite happily, and she’s self-admittedly not even all that tough when it comes to temperature extremes (and on top of that is currently pregnant – seriously, if she can do it, you can do it). Right now at the beginning of the summer, for instance, we’ve only just started to occasionally use the AC to bump extreme temps down at strategic times. The temps here recently have only been in the mid 90’s, but even temps in the hundreds do not require all-day AC use, in our experience, even if you live in one of the most hot/humid cities in the US like Houston. We certainly don’t have any trouble keeping our AC-related electrical expenses under $15-20 per month in the summer. Invest in a $10 box fan, or install ceiling fans, and enjoy the savings. Drink cold water, and take a 2min cold shower if you accidentally get yourself sweaty. Or pay through the nose to refrigerate your whole dwelling – your choice.

      Just wanted to let you and other readers in the South know it can be done quite easily if you learn how.

      Reply
      • GeauxBig November 27, 2013, 12:36 pm

        I live in Southwest Louisiana and I have a hard time wrapping my brain around a $15-20 A/C related bill in the summer months.
        What square footage are you cooling?
        I use programmed thermostats set at 84 degrees and keep ceiling fans on at all times and my bill hovers around $150-180 in summer.
        Granted we have 2880 sq ft living and high ceilings but I hardly ever run the unit unless at night and we open the windows at the faintest hint of a breeze.
        Do you have the foam insulation? SIPS panels?

        Reply
    • Kristy February 16, 2014, 4:42 pm

      that’s 26.6c

      which made me laugh.

      We don’t use air conditioning and this is the annual range for where we live

      http://www.bom.gov.au/climate/averages/tables/cw_014016.shtml

      Reply
  • Geek July 18, 2011, 11:02 am

    @Alicia – seasonal depression is a big issue during 9 months of winter. Seattle Real Estate is far from frugal anyway. I’m in Redmond.

    I have no A/C but in the Pacific NorthWest we pay for our nice 75 degree summers by having long, chilly, damp winters. Not running the heat is a sure way to get mold. I use so much bleach on the tub! But I acclimate quickly to ~60 degrees indoors and wear some sweaters. As a bonus, shiba inus look much cuter if they have thicker winter coats!

    Last summer it got up to ~100 for about a week, and we still had no A/C on the top floor of our apartment. A couple of fans, a lot of water-spritzing, and we were fine. 80 is not a problem (I’m from the Northeast, we have some 85 degree nights too).

    You acclimate.

    Reply
  • Kate July 18, 2011, 11:15 am

    Air Conditioning isn’t a luxury in certain areas. I spend my summers in Washington, DC where A/C is definitely a necessity. The city is hot, this summer we’ve had heat indexes reaching 110 degrees with no sign of cooling in the near future. Not only is it hot, the air quality is terrible. It’s very rare that DC has an AQI rating of Good (green), and it’s commonly in the orange/red territory. Exposing yourself to low quality air that is full of pollutants has health impacts, even for those people who are not part of an at-risk group.

    In many of the older neighborhoods, living in a row house without A/C would be akin to living in a car parked in directly sunlight. The interior temperatures go well beyond the already miserable temperatures outside. When you’re regularly faced with temperatures high in the nineties, A/C isn’t an exciting treat. It’s a way to prevent health issues, heat stroke, and (for people in at-risk groups) death.

    Reply
    • MMM July 18, 2011, 11:25 am

      Come on people. Does Mr. Money Mustache need to do an article on Reading Comprehension? No more talking about how it is too hot where you live to go without A/C. That’s not what the article is about.

      It’s about taking advantage of cool nights and days IF they exist, and also not running your A/C at freakin 72 degrees when all of us, even European descendants, have evolved to be comfortable at temperatures of at least 80. This article is a story of the observed A/C wastefulness on my current vacation through the Great Lakes region.

      Reply
      • Kate July 18, 2011, 11:33 am

        You specifically refer to Air Conditioning (in general, not only in areas with already reasonable temperatures) a “pleasant luxury” that you “run for an hour or two” until it gets dark out. I don’t think it’s unreasonable to point out, with actual examples, that for many people this is entirely not the case.

        If you want to provide financial advice only for people in the Northwest and around the Great Lakes, that’s up to you, but you should make it clear to your readers. Otherwise, your Mustachioed followers in areas where there aren’t cool nights and days will be endangering their health to save a bit of money.

        Reply
        • MMM July 18, 2011, 11:53 am

          Well, I appreciate the help and I apologize for the MMM character getting a little over-the-top in his first response to you ;-)

          What I wrote, even in that paragraph, as that A/C is “a pleasant luxury to be used when all other efforts fail.”. In your Washington DC rowhouses, all other efforts have definitely failed, so the A/C is great to use.

          Also, are you sure that air conditioning significantly improves air quality? According to the EPA’s publication “Improving indoor air quality”, circulating plenty of outdoor air into your house to avoid a buildup of stale air improves your quality. But a window or even central A/C may not do so, unless it is fitted with a fine enough filter to pull out things like airborne soot particulates.

          Overall, if you live in a city with air pollution high enough to cause statistically significant health problems even in otherwise healthy people, I still have to recommend moving away, and then starting a lifetime habit of voting for politicians who care about reducing pollution. If we could reduce the 75-90% of car driving people do in cities that is unnecessary, that would pretty much solve the problem immediately.

          Reply
          • Kate July 18, 2011, 5:50 pm

            I think circulating a lot of out door air through your home is effective only if the outdoor air is clean. The recommendations when under an air quality advisory always state that residents should limit their time outdoors, so I have to imagine the experts in charge of making these warnings believe the indoor air really is better.

            Also, I know all the talk about death may have sounded exaggerated and some comments have indicated that they really believe A/C is a luxury for all people. However, a major study run in 1980 – 1985 concluded that people with A/C have mortality rate 42% lower than people who don’t have A/C. A study conducted during a Portuguese heat wave in 2003 concluded similarly, indicating that A/C in hospitals was responsible for a 40% decrease in mortality among patients. So, having A/C and using it when temperatures are dangerously high can really be a matter of life and death.

            Reply
            • dan cain November 8, 2013, 1:01 pm

              I know this is way late and probably no one will read this but I’m making my way thru from newest to oldest post.

              I live in DC, in a rowhome built 100+ years ago and this summer I had a pregnant wife and a 2 year old. We do not have central air but use window units (cheap version of a zoned system!). I’d say we close all the windows and run all five window units (the equivalent of central AC) probably 20-30% of the time from June to August.

              I grew up in Philly which is only slightly less hot and we grew up without central air and only one unit in my mom and dad’s room. The kids sleep on the floor only on the hottest nights…it was a treat, not a luxury.

              I think the case is being overstated a bit, I think AC (especially central AC) falls below luxury but above necessity in DC…it is probably only necessary about a dozen nights a year.

              Reply
            • Adrian M February 11, 2014, 7:02 am

              Kate, I have to ask this question. Why do you live in an area that has such terrible air quality? A good job is not an excuse when it comes to your health. Even if you’re making more money than a surrounding area, the increase in health and electricity costs doesn’t sound like it’s worth it.

              Reply
      • Alicia July 18, 2011, 9:30 pm

        I got your meaning just fine, thanks. :) A huge swath of the country is getting smothered with a triple-digit heat index all this week. You’ve got to admit, this post’s timing is more ironic than anything else.

        Reply
      • Scott November 29, 2012, 8:14 pm

        The truth is that wherever you live, air conditioning is a luxury. People have lived for centuries in the Deep South without it and fared reasonably well. Sure there are a lot more people in the south now that we have it, but it wasn’t an uninhabited wasteland before the invention of AC.

        Having said that, I have been living on the gulf coast for 5 years and I use A/C probably more than I should. However I lived without it for one of those years and it is tolerable, but far from ideal. I almost never use it in my car unless I’m on a long road trip.

        Reply
    • Marcia @Frugal Healthy Simple July 18, 2011, 12:21 pm

      I lived in DC for five years. I always had AC, but I had a few friends who didn’t! Some of the older buildings/houses don’t have it.

      Reply
  • joan July 18, 2011, 11:48 am

    Finally, somebody who shares my A/C values! I am tired of people who are so climate-controlled that they wear shoes and sweaters inside in July and don’t realize their windows have latches that actually make them open. I own exactly three fans–two of which are < 10" in diameter–that help circulate air from outside.

    For me, it's not so much a frugality aspect as it is about comfort. Being born and raised in Southern Nevada, I just prefer a warmer environment. My A/C operates perfectly, yet rarely runs. When it becomes miserably hot, I'll turn it on.

    I'm also enrolled in my local electric company's SmartAC program, where they control my thermostat on hot days. During peak times, it runs 15 minutes per hour, which still keeps the house comfortable during heat waves.

    Reply
  • Marcia @Frugal Healthy Simple July 18, 2011, 12:26 pm

    I am going to admit first off that I live in coastal So Cal, where A/C is not a necessity and most homes don’t have it. Ours does, but that’s because the previous owner painted all the windows shut and installed AC (and smoked like a chimney).

    Our AC comes on pretty rarely – generally when the outside temp hits 100 (though it did come on last night for some reason). We open the windows and turn on fans when it’s cooler outside. The only limitation we have is the neighborhood skunks, which force the closure right around dusk. :(

    We also have dark curtains on the front south-facing window. Open them in the winter and close them in the summer. Really helps a lot.

    Reply
  • DavidG July 18, 2011, 12:51 pm

    Great post MMM!

    My mom’s house is an older one without central air. Most of the time she runs an attic fan at night, but there is a window unit for those times the South Carolina heat is fierce. My 5-year-old modern construction tinker-toy house is designed to only be run with an HVAC; no parallel windows for proper airflow, only one ceiling fan (we’re adding to this), and not taking to account southern exposure for proper heating and cooling. I can’t wait to sell this deathtrap before all the shiny plaster starts coming off the walls and it sinks back in the ground.

    Reply
    • MMM July 18, 2011, 9:21 pm

      Thanks David! Nice example – not many people these days would believe that it’s possible to live in SC without a Walmart-sized air conditioner.

      I also enjoy your scorn of modern suburban construction. You’re totally right – thankfully the strict nationwide building codes these days ensure unprecedented structural integrity, but they still allow builders to totally ignore the natural environment and climate when building a house. I mean, shit, where I live, there is enough sunshine to and day-to-night temperature variation to eliminate most or all fossil-fuel heating and cooling requirements with proper windows and ventilation. But instead everyone keeps building box-with-pinhole-windows-facing-whatever-way-the-street-happens-to-face houses. It costs a few grand less to build the house this way, which is promptly eaten up within the first few years’ worth of higher utility bills! My own house is about to change to address this in a couple months – the topic of an upcoming article!

      Reply
  • linda July 18, 2011, 3:16 pm

    We’ve been keeping the AC to absolute minimum but are having trouble getting everything done due to the discomfort of excessive heat warning type weather for past few weeks with no relief in sight.

    We’re getting stir crazy, feel trapped in the house, have gone out for meals that we’d normally cook at home just to get out a bit. Most of our usual spending free activities are outdoors-which is just not tolerable at this point. Any ideas that might work in small town MO.

    Reply
  • Chris July 18, 2011, 4:05 pm

    Get used to it MMM. Reading comprehension is at an all time low! Not only this, but interpreting information and translating it into something for your own use is even lower! Common sense is not common.

    Reply
  • Executioner July 18, 2011, 4:35 pm

    For most of human history, air conditioning was not only a luxury but a fantasy — it has existed for a mere ~100 years and been commonplace for only about half of that time. My ancestors lived in Texas for generations without A/C and not only survived the long hot summers but somehow thrived.

    The great Egyptian pyramids (built in blazing desert sun) were completed without A/C.

    The US Civil War (fought largely in the South) was waged without A/C.

    The US transcontinental railroad, the Suez canal, the great wall of China, the architecture of ancient Greece and Rome — all completed (somehow) without air conditioning.

    Vast areas of the tropical world today, in desert and humid zones (from South America to Africa to Southeast Asia) are heavily populated and still very sparsely air-conditioned.

    The human body is capable of adapting to a much wider range of temperatures and conditions than most in the modern world are willing to admit (or even imagine).

    I will concede that a lot of modern construction assumes that A/C will be installed (and used) and therefore does not include sensible design features (such as those described by DavidG in an earlier comment) which would make it more comfortable to live without air conditioning.

    However, it’s still a luxury.

    Reply
    • MMM July 18, 2011, 6:17 pm

      Very Nice, Mr. Executioner! Thank you for reminding our naysayers that Mr. Money Mustache’s advice is actually on the LUXURY side of frugality! I am allowing you to use your air conditioning, people! Jacob from ERE would never do this! Take my gifts and be thankful.

      Still, I am glad the article generated such lively discussion. Perhaps we are all Hot and Bothered this week.

      Just for the record, in Colorado I turn my own A/C on if the interior temperature reaches about 28 Celsius / 82 Fahrenheit. On a day that is 100F outside, this usually happens at 4-5PM. At temps below 90, it never happens.

      So in the worst case I’ve only got 1-2 hours before the outside air is cooler than 82 anyway, when the whole house can open up in a great gush of nice wind and the night time cycle can begin anew. (I know, I know, I am lucky to live in the West :-))

      Reply
  • Amy July 18, 2011, 8:36 pm

    I would love to not use so much air conditioning, but I have really bad allergies. Opening a window to let cool air in would allow the allergens and humidity in and make me want to jump off a bridge just so I wouldn’t feel so crappy. We try to keep the air temperature as high as we can though. Usually it is 25 degrees C during the day and turn it to 22 degrees C at night.

    Reply
  • Kathy P. July 19, 2011, 5:12 am

    Exactly how I do it – AC is something to be turned on only when necessary. Like now, when we’re near 90 with dewpoints in the upper 70s. I really despise that kind of weather so I’m grateful to have the AC.

    My neighbor, on the other hand…she has a small window unit that I can hear whenever I go to my small “barn” (on the edge of my property), mostly to get out the lawnmower. She runs that AC unit apparently 24/7 from May through September, even when it’s in the 60s outside. I am so glad I don’t have to pay her National Grid bill!

    One of my plans for the future is to create some kind of trellis/pergola over my front windows (which face south) in order to grow some kind of deciduous vine like grapes or hardy kiwi. My roof overhang isn’t deep enough to block all the direct solar gain in the summer, but of course I want that in the winter. I have window shades inside, but they darken the room and still, the heat gets in. The idea is to block the heat from the outside. Someday…

    Reply
  • Mark July 19, 2011, 8:58 am

    Thank you so much for pointing out that the body adapts. If you expose yourself to the heat, you will eventually not notice it anymore.

    We are supposidly in record breaking humidity levels and temps right now but I wouldn’t know it was “record” breaking unless I watched the news. I never run my A/C ever and I am actually barely even running my one fan that I own. And, I am not even uncomfortable.

    The thing about an A/C is that you have no idea what is going on with the air. I would much rather crack the window open at night and get surprised by a chilling breeze coming in. That feels so much better than A/C.

    Furthermore, you get this phenomenon of people wearing sweaters to work in the summer (cause the air in the building is so cold) and wearing tank tops in the winter cause the heat is soo hot! hahahahahha.

    i love you Triple M.

    Reply
    • MMM July 20, 2011, 7:28 am

      Thanks Mark, I love you too, Man.

      Reply
  • Kari July 19, 2011, 9:30 am

    We are currently building a home in humid, hot east Texas (it’s been over 100 here for the last 25 days) and I have to say there’s a big difference between our current garage apartment and the new house with foam insulation and low-e windows. The new house is almost bearable, even though it doesn’t have electricity yet. I’m not saying I won’t be running the air conditioner next summer, but I’m looking forward to a much more efficient usage of it.

    Reply
  • Kevin M July 19, 2011, 10:46 am

    Good thoughts, MMM. Can I come up to Canada with you next summer? Highs at 100 or above all week here in St. Louis.

    It is nice to go out and warm up for a little while after getting off work, where the A/C runs almost constantly. I wonder how many office buildings run their A/C all night just to keep it a constant 72 degrees for when the cube farmers arrive in the morning.

    Reply
  • Heidi July 20, 2011, 6:46 pm

    Cold baths at night before bed go a long ways for those of us without the cool nights. We gave in on Sunday and ran the A/C. Our kids slept really well for the first time in weeks so we’ve kept running it each night for 2 hrs. My husband falls in line with ERE more so I am quite thankful for the gift of this awesome A/C post.

    Reply
  • Joan July 20, 2011, 6:52 pm

    We live in Phoenix. When the kids are at camp or school (we start school late July/early Aug), we turn the A/C off, even when it’s over 100 out. Our house is well insulated and it goes up to about 89-90 inside, which is fine for us. We set the temp at about 80 when the kids get home around 4. Unfortunately, it doesn’t cool down much in the evenings.

    It takes a while for the temp to go up inside the house, and when it feels unbearable, we splash on some water or go to the library. It’s kind of a fun challenge for my husband and I to figure out how to stay cool without A/C. (we are easily amused)

    Reply
  • Travoid July 21, 2011, 2:25 pm

    Sorry Kevin M, it’s hotter than that right now in Canada where MMM is. Right now with Humidex, it’s feeling like 120 degrees, 100 before the humidity! Balls hot. I’m probably one of the houses he visited that he found too cold, but I usually have mine set at about 78, which means it often doesn’t come on at night time. Ceiling fans are great at tricking your body into thinking that it is much cooler than it really is. I also have some extra body weight, so I’m like an oven most of the time, so I like it cooler when I sleep.

    Reply
  • rosarugosa July 22, 2011, 4:13 pm

    You would be proud of us, MMM. We have no a/c at all. We have an old window unit sitting in the basement, but it hasn’t been used in at least 15 years. Don’t know or care if it even works or not (should probably get rid of it). We live in MA., so I’m sure it would be different if we lived in FL or AL, but there are really so few days that are intolerably hot, that we never felt a/c was worth the investment. It reached about 104 degrees today, so we just took our cues from the cats, relaxing and staying hydrated. Seriously, this weather teaches us to slow down and enjoy the gazebo and the hammock and eating popsicles in front of the fan. And I remind myself that I’ll feel nostalgic about this weather in January :)

    Reply
  • Lisa July 24, 2011, 1:23 pm

    Just read Laura Ingalls’ journal, imagine riding in a covered wagon across America in temperatures of 106, 107, 108. Nobody died.

    My home is set up for CAC but hubby and I use window units, only when we need them. Why cool the whole house when you are only in one place at a time?

    Reply
    • Steve July 26, 2011, 10:24 am

      They reckon on around a 5% death rate on that trail. Going by a published accounts isn’t a very good way to knowing how perilous it is as the person has to be alive after to publish.

      Reply
  • Lisa Marrin July 26, 2011, 8:51 am

    Oh and my mom lived in a four story walk up in a tenement in Brooklyn in the fifties. No AC. No one died there either.

    Reply
  • Jenny July 26, 2011, 11:25 am

    We installed A/C this year, for many reasons, and I do love having an inside place to retreat to! Our basement is shut off on the A/C, so we save $ that way, and we keep it at a comfortably high temperature (although we do have a kid in a body cast, so we have to allow for that), and we have fans running in the main rooms and ceiling fans in the bedrooms, and at night, doors and windows open. It helps! Before this we had no A/C at all and I’ve never had A/C here in CO until now, and we used our basement for cooling and air circulation. Now we do the same, but we have it to use on the hottest days, which is awesome, I admit.

    Reply
  • jDeppen July 27, 2011, 10:27 pm

    Don’t cook inside the house on hot days (bake in your car):
    http://www.ghettoredhot.com/funny-ghetto-photos/

    Reply
  • Claire July 28, 2011, 11:17 am

    Man I love your blog posts. This one in particular has me chuckling. :) I’m soon-to-be moving into an apartment with no A/C and am seriously looking forward to the dog days of summer and a cold lemonade. (Not to mention the much smaller electric bill).
    Keep up the awesome posts!

    Reply
  • BC February 13, 2012, 6:43 pm

    Thanks for getting technical and not dumbing down your articles. I, too have measured the watt consumption of many A/C systems I have had in my homes over the years. 3000 watts is actually a very low number. I currently have a 4 ton unit that is 18 seer and it pulls 4500 watts (which I thought was good.) I have had some dinosaur systems from the early 90’s that pulled 9-10K watts!

    Reply
  • MZ April 9, 2012, 6:45 am

    A couple questions about saving money on AC:
    1. What about medications that have to be kept at around room temperature? Most of them have to be stored between 60-78 degrees F.
    2. What can people with severe seasonal/outdoor allergies do to get that extra cooling? People like us cannot have windows open without suffering heavily from the pollen/grasses/mold that are everywhere.
    3. You didn’t mention window units – does it help to have AC only in one room at a time, or are they less efficient than central air?

    Reply
    • Mr. Money Mustache April 9, 2012, 9:01 am

      Hmm.. the special medical cases are a bit outside of the scope of the group I was poking fun of with this article – the able-bodied young people who keep their house at 76 or cooler in the summer just because that’s how they’ve always done it. But here’s what I might do to meet special needs:
      – keep the medicine in a cooler part of the house or a tiny fridge of some sort set barely below room temperature.
      – use a filter on the air-intake to my house so I can still draw in outdoor air and exhaust it through the roof or an upper window at night.

      Window units are definitely a great idea – modern ones are efficient, cheap to buy, and use much less power than a central unit, and you can cool only the room you are spending time in (your office if you work from home, for example). But they can be ugly, so I’ve been known to install small wall-mounted mini-split units in rooms that need special cooling permanently. In Northern or high desert areas, the window unit works well, since it’s only needed for a month or two of the year anyway.

      Reply
      • MZ April 17, 2012, 4:27 pm

        Thank you for the tips! Do you know where I could find one of these air filters and/or where one would install them? The point is moot for now, because I live in ancient barracks from the 40s that the University provides us, so we only have a window unit in our bedroom. Pretty decent for East Coast weather, but probably wouldn’t survive in St. Louis where I grew up!

        Reply
    • JaneMD April 17, 2012, 12:34 pm

      I’ll answer the medical question. Very few medications MUST be kept at room temperature 60-70 degrees. Almost all can tolerate a mid 80s temperature. Gel caps are less tolerable of higher temps because they melt, but most of the warnings are so that you don’t leave them in your 130 degree car for several days.

      Reply
      • MZ April 17, 2012, 4:25 pm

        Thank you all for the advice! I’m curious – most of my medications are nasal sprays (for the allergies), and the warning labels say not above 78 degrees F. Do these fall into the “very few medications” for which the warnings actually apply?
        The point is moot really since I live in University Housing barracks built in the 40s and we only have a window unit in our bedroom, but still I am curious.

        Reply
        • JaneMD April 19, 2012, 9:29 pm

          I truthfully find that a bit bizarre to be ‘under 78′ degrees. You see, if you carry it in your pocket,its going to be hotter than 78 degrees. I assume they mean room temperature and feel anything above 80 degrees is over room temp.

          Also, if you bought it over the counter at walmart, it was transported to Walmart in a non-temperature controlled truck. I doubt any otc nasal spray would be so heat senstive.

          If you get it from a prescription, you can ask the pharmacist. Don’t be surprised if they roll their eyes. Again, the majority of warnings are related to keeping people from doing the extremes.

          On either extreme you can change the form and potency of the medication. Most medications are formulated to hang out a ‘room’ temp – your freezer and your sauna-car aren’t considered room temp.

          Reply
  • Jeremiah J.K. May 19, 2012, 1:30 am

    Great article. This reminds me of a time when I had the opportunity to visit Brazil. Even though I was staying with very wealthy folks at the time, the only place that they used AC was in their bedrooms at night. This really minimised the amount of energy they used, and made sure they used it only when it mattered the most.

    Reply
  • PeteyP July 16, 2012, 7:27 pm

    As it doesn’t seem to have been mentioned yet, I’d like to add a bit of engineering know-how about how air conditioners work, which everyone should know (perhaps everyone knows already?)

    The Long Version: Air conditioners, just like refrigerators, have a measure of efficiency called the ‘coefficient of performance’ (CoP). This CoP is proportional to the room’s temperature divided by the difference between inside and outside (the units are in Kelvin, so you have to add 273 to the degrees Celsius). In other words, if you halve the difference between inside and outside temperatures then you approximately double your CoP. But why do we care about CoP? Because the CoP means “how many watts of cooling are we getting for each watt of electricity input?”. If it’s 40 degrees out and you’re cooling to 20 degrees, then by putting the thermostat up to 30 degrees you get twice as much cooling per unit of electricity… but you also (obviously) need less cooling in total. You get a double whammy – you not only use less cooling energy, but that cooling energy comes cheaper. So turning up your thermostat on the aircon gives you exponential savings.

    The Short Version: Every degree you turn up your air conditioner, your air conditioner works more efficiently, so you get a double saving – you use less, and what you do use comes cheaper.

    Together with MMM’s philosophy of getting accustomed to the temperature, and the conclusion is clear – slowly sneak up the temperature on your aircon!

    Reply
  • Qwerty October 23, 2012, 7:58 pm

    Maybe I haven’t gotten there yet, but I’d love to see a post on how to effectively use your furnace when you live somewhere like northern Ontario, and the temperature routinely drops to -30 C, talk about cool nights!

    Reply
  • GrowaMo November 6, 2012, 4:24 am

    Don’t you guys in the States have evaporative coolers? Particularly in the dry states evap cooling rocks! Particularly the ducted version, which has one giant fan on the top of your roof, sucking in air through water-soaked filters which cools the air and pumping it into your every room via ducts in the ceiling!
    Here in Australia the summer gets up to high 30’s (celcius, whatever that is in Fahrenheit) and I can cool the house to a very comfortable 25 degrees: the nice airflow makes you feel even cooler.
    And, btw, all this with the windows open (needed to let the moist air out), so no shouting to the kids to keep the door closed because the hot air will enter the house!
    My neighbour installed it last year, all-in for about $8,000, you’d lay out more for A/C and the fan at the top uses only a fraction of the energy of an airconditioner.

    Reply
    • Kira July 14, 2014, 2:06 pm

      Evap doesn’t seem to be that common. We had both evap and a/c in the house I grew up in (Phoenix), but none of the houses I’ve lived in since had it. I definitely preferred the feel of evap (except for during monsoon season when the humidity went crazy high).

      Reply
  • Mark December 13, 2012, 2:41 pm

    This does ignore my first summer in St. Louis. We had a 10 day period where the COLDEST temperature (even at night) was 89 degrees. I usually set the A/C around 80 and it still cost me a ton. Luckily I have a small apartment, so not as much as it would an entire house. I’ve made up for it by only turning on my heat for a few days so far this year (I got sick and set a luxurious 65 during recovery).

    Reply
  • Joe C January 5, 2013, 6:49 pm

    As a native of western NY, I spent the entire summer in FL in 2012 as part of an internship. Talk about HEAT! The house I lived in (a shared set-up in which I had little control over the conditions) was kept at 72 degrees constantly throughout the summer. Suffering as I was, I still thought this was a little excessive. Sometimes I was so cool in the house I had to put layers on, even though it was steaming hot outside. It was weird. I don’t plan on going back to FL anytime soon.

    Reply
  • Dana Macarthur May 20, 2013, 10:25 am

    I live in Ogden Utah, and yes it dose get HOT here in the summer.But for many years I lived without a/c and the one thing I would suggest is getting room darkening curtains.When the sun starts to hit my house, I close the curtains and I am able to keep my place cooler for longer.Also they are great for winter time use as these curtains will help keep the heat inside when I am running my furnance. Also if you live in a dry climate, consider getting a swamp cooler instead of a a/c unit. Swamp coolers are cheaper to operate.And one other trick I have used is placing my feet in a bucket of cool water.For some reason that helps me.I know this is a blog about saving money, but I strongly suggest spending the cash to get room darkening curtains or shades.It will pay for itself.And (so far) in my experience the curtains I got have lasted me 10+years and are still in great shape!

    Reply
  • Tracy July 16, 2013, 10:21 am

    I will also say that a dehumidifier does wonders. We have a house dehumidifier and run that during the day for an hour or two when the temps climb to the 90s. It feels almost as awesome.

    That, plus a well timed cold shower (or two) will get me through the day very well.

    Reply
  • Travis C August 7, 2013, 8:05 pm

    Interesting website name. So I’m in South Florida and electric bill is at $300 in July with the AC set at 78°F day & night. I do have a medical condition that makes me worse in the heat, and feel it is too uncomfortable above 78°. When I have tried 79°, I start sweating whenever I exert any energy by merely just getting out of my sofa chair and rolling over to the bath or the kitchen. I am renting but the owner says it is a 17 SEER unit, so I am still looking for alternatives to save on my bill. The sun facing windows are tinted and have wood blinds on every window, is there anything else I can do to see a reduction without turning off the AC?

    Reply
    • Dave April 10, 2014, 11:51 pm

      Super duper late comment. But, you can build this:

      http://www.youtube.com/watch?v=HxSLbpAwibg

      Its not really an ” air conditioner” more of a “heat exchanger”. The cooling is done by your freezer turning a gallon of water into a gallon of ice. Please note: Your fridge will then put the heat taken to perform this task back into your kitchen, however that is sorta irrelevant if you: a) set your house/apartment thermostat higher and b) use this to spot cool your person.

      It will pump out 50 ish degree air at you for five or so hours, which is pretty damn impressive. The only electricity required (other than your freezer, of course) is a small fan, which could be run off solar. This would also work in a car (provided the fan was a 12v model) that either was too old for A/C, or had a broken one that you didn’t want to fix. Strap it into the passenger seat with bungie cords and let it blow cool air at you.

      Why cool the whole environment, when you can just cool yourself? It doesn’t get more mustachian than that!

      Reply
  • Brooke Albanese August 9, 2013, 7:23 am

    Hells Yeah!!! I have had an on going argument with my boyfriend about unnecessarily running the air conditioner all day and night during the summer months. Mostly on nights that the temperature drops below 60 degrees. It is soooo aggravating! As a kid there were no air conditioners pumping recycled cold air in our faces and spinning the meter around and around. You laid in the warm night air with a standing fan blowing a breeze over your half covered body by a single sheet. Your feet dangling off the bed and the smell of the fresh air.
    My argument is that he won’t let us turn the hot water on . Take hot showers, wash our hands in warm water or wash the towels and under garments in hot water (which is the sanitary thing to do) to save money on thew oil bill. We live in western NY. We need heat more than we need it cold, like it is 9 months of the year!!! UGH!!!
    I say GO FANS!!!

    Reply
  • Don October 6, 2013, 9:25 am

    I just finished this blog post a few minutes ago and as I was reading another MMM post my neighbors air conditioning turned on! I couldn’t believe my ears. I live in the suburbs of Philadelphia, it’s Oct 6th, overcast and 70F!!!!!!!! I’d call this weather almost perfect.

    no way….it just turned on again as I write this……should I politely inform them that their AC is on and that its beautiful outside? I have not used my AC in over a month.

    Reply
  • Jan October 9, 2013, 12:12 am

    I live in the Northeast, and we typically get a handful of days that are unbearably hot, but people here run their air conditioners the minute it hits 70-75%. New neighbors moved in last June, and they have not gone one day without running their air conditioners, no matter what the temperature is. Right now, it is 50 degrees out, and they are running their three air conditioners, and the worst part is, they are so loud. Unfortunately, their house is only 10 feet from mine, and the noise of those running constantly– especially at night when it is quieter and noise is amplified– is really starting to grate on my nerves. On those beautiful nights when it is great to have your windows open, forget it. I have to put my storm windows down because of the noise. Even with the storm windows down, I can easily hear them. It is like living next to a power plant. And the air conditioners, unfortunately, face the the side of my house where I sleep and have an office. At this point, I can only assume they are going to run them right through the winter. I am probably going to end up moving because it is sometimes hard to sleep with that racket. How cold do people need their houses? If it is 50 out and you have your air conditioner on, how cold is your house– 40 degrees? I guess I just don’t get it. I think it’s a complete waste of energy.

    Reply
    • Miichael August 31, 2014, 11:40 pm

      I’m in exactly the same position, and feel exactly the same way. The houses in my neighborhood were built in 1900 to take advantage of the Lake Erie breezes (1/2 mile away)…we have lovely porches in front (which I can'[t enjoy due to AC noise) and sun-porches in back. I am extremely sensitive to heat and a fan in the bedroom window on the very hottest nights is all that’s needed. Neighbors on both side leave their storm windows on all summer to run the central A/C…I’ve also clocked them running at outside temps of 58 degrees. Currently my neighbor’s unit (2 feet from my house) has been running for 5 hours continuously (it’s 69F out). We victims of AC noise need to form an organization.

      Reply
  • Vana October 14, 2013, 7:04 pm

    Would love to be able to do this but it’s 85 degrees at 8pm here Miami. Also I fear Palmetto bugs and they always find their way in. However, I had our attic insulation replaced with R30 a few days before finding ur blog (two weeks ago) and I’m hoping to see a difference in my bill. Also, I will be investing in LED bulbs for the entire 2500 sf home come November thanks to u.

    Reply
  • Ashley November 11, 2013, 4:48 pm

    I’m currently living in San Antonio, TX and the people here are absolutely obsessed with air conditioning. If the sun’s out, the AC is on. If you dont need a heavy jacket when you walk outside, the AC is on. Right now it is a breezy cool evening of 74 degrees and here at the apartment complex. there are three AC motors running outside my window, loud as hell, inhibiting my enjoyment of the night air. I bet you anything these people’s AC’s are set to 72 degrees and they’re just too lazy to step outside and actually get a grip on reality in terms of the weather.

    Reply
  • GeauxBig November 27, 2013, 1:03 pm

    I love this article because I agree about the body adapting to certain temperatures and my wife is a testament to this.
    I went to school in Baton Rouge, La and my first semesters were spent in a dorm with no A/C. Temperatures in the summer ranged from 90-100 with nearly everyday having 90-100% humidity.
    We had two windows in the dorm and had two box fans constantly running.
    One pulled air in and the other we pointed out for circulation.
    We slept in our tighty whities on top of our sheets and when we woke in the morning (especially after long nights of drinking) it looked like a crime scene with a chalk outline on the sheets from us sweating.
    Girls would shun the vortex and friends made excuses to stay elsewhere while in town for football games.
    It has helped with my adapting to the heat and since my wife and I moved in together she slowly adapted as well. Grudgingly at first, especially thru 2 now 3 pregnancies, but now she comments when we visit someone who has the A/C cranked about how cold it is or how much their bill must run.
    I really hate paying utility bills.
    I’ve even researched solar panels but the initial expense is tough to swallow.
    My house needs a serious efficiency overhaul and have been researching people that know more about this in this area.
    Unfortunately, most people in the South are less concerned about these things and have just relied on the ole’ A/C.
    As I’m writing this now we are expecting a hard freeze tonight and I reluctantly agreed to turn the heater on so the wife and kids don’t endure much more pain.
    I love curling up at night in my ski suit with tons of blankets piled high. Reminds me of camping.

    Reply
  • Deborah January 18, 2014, 3:02 pm

    I am astounded that no-one has mentioned exterior blinds (awnings) or pegolas. When we put awnings on the house, the inside temperatures on hot days reduced significantly. Yes, you need to pull them down in the mornings and up when the sun has gone, and if our house was oriented correctly (as we are in Australia – facing North, – would be South in northern hemisphere) we would just need a pegola or correctly sized eaves. If window glass gets sun on it, it is acting like a solar heater. Curtains and e-glass send some of the heat back outside, but awnings stop the heat from being created. You can even get much of the effect of awnings if you hang a sheet on the outside of your window.

    Our area has just been through a record period of hot days (more days over 35C = 95F than ever recorded here), and we have only had the AC on during the day for 2 days (all our neighbors have had their AC going the entire time). We are not as good as MMM, in that we have been starting the AC at 10am and stopping it at 7pm, but we the temperature has been really shooting up in the mornings, and coming down very slowly at night.

    One problem we are having is that there are over 200 major fires in south eastern Australia at the moment, and the wind last evening started to bring an enormous amount of smoke. There are EPA warnings that more is on the way from the most major fire about 800 km or 500 miles away. This is when we really use the AC.

    Reply
  • Will February 27, 2014, 7:03 am

    I grew up in Middle Ga with parents who did not use the A/C ever. We have 3 solid month of 90+ temps and where just fine. Yes it was hot and yes we sweated but we were just fine. It is funny to think what some folks would do, say 70 years ago, before A/C was around, you’d almost think it was impossible to even live.

    Reply
  • Melissa Wannabe blogger March 11, 2014, 10:09 am

    Ah MMM you make me laugh with your colorful language and continuous recommendations to punch ones self in the face… Soon all the aspiring mustachians will be easy to spot with their black eyes.. I totally agree people are just too dependent or on auto pilot with a lot of things… Cooling and heating is one of them… I went to school in Michigan and I remember walkin into the apt with my roommates in the winter and having my glasses fog up… Hmm I think we have the heater on a bit high…. I mean I shouldn’t have to put on shorts inside… Turn the heat down put on pants and a sweater… It is winter afterall. Still working my way through… Don’t know if I’ll ever catch up

    Reply
  • Samala June 27, 2014, 7:13 pm

    Triple M, your scene of AC celebrations during a dog day of summer made me smile and brought back memories of my childhood in Philly. I always figured everyone grew up that way in the Northeast. I’ve lived in Orlando, FL for eight years now and thrive in the heat. I’m a bit shocked at the responses from the Southern Contingent though.. most seem somewhere between envy of cooler climes’ cash savings or a little defensive.. and nowhere, unless I missed it, did anyone stick up for the Southeast and proudly proclaim: “YES! We love our air conditioners! But in the winter, dear Northern friends, we never have to turn on the heat!” (No joke, eight years of small apartments and townhouses and never even once.)

    Reply
  • Karl July 31, 2014, 9:26 pm

    Cracks me up how so many people run the ac all day and night. I live in the desert in Southern California with summer temps most days over 100 degrees. Here’s what I do every year. First I clean the outside condensor of my ac unit with a garden hose and spray from the inside out (making sure the powers off of course). I also make sure all connections are good no frayed or weak wiring, good contactor and capacitor, and check and tighten/torque the compressor motor. After reassembly and cleaning I then clean the filters inside the house. I do this at least 2 times in the summer to keep the unit perfectly clean and operating at peak efficiency. Now I have ceiling fans in every room in the house so I run them most of the day. I also wear nothing but my underwear all day in the house. I know it might seem funny but it makes a huge difference! Finally when the indoor temp hits 88-90 degrees I’ll turn on the ac at night for maybe a couple hours to get the temp down so I can sleep at night. No need to run the damn thing all day and I only turn it on late in the day so the wife is a little more comfortable when she gets home. Once the temp gets down to 80 or so at night It’s shut off till 4 or 5 the next day. We use fans at night and sleep without covers. Why can’t people just use common sense? Running the ac 24/7 is really a waste and chances are when you really need the ac one super hot day it will probably die because of poor maintenance and overuse. Compressors on most ac units are not supposed to run 24/7. Treat your ac unit as a luxury not as an all the time convenience and you’ll not only save a lot of money but you’ll be surprised how long your ac unit will last!

    Reply
  • Jared September 25, 2014, 6:38 pm

    Oh, you anti-air conditioning freaks crack me up. Here in Alabama I keep my a/c unapologetically set between 68-71 all year around. Granted I bought the nicest, two,stage Carrier heat pump on the market. I do not care about utility bills. Some mornings I have my house so cold my windows are dripping with dew. I love my air conditioner. You guys toughing it out make me laugh. Even on 62 degree days the western sun warms it enough to bump on the air conditioning. When I’m drinking I set it even lower. Who are you air conditioning Nazis– judging your neighbors for running the a/c’s? Enjoy sweating, I guess. It’s currently 69 degrees in my house. I have two spare window units in my garage that serve as emergency backups should the central systems fail for any reason. Have fun saving $50. Buy 3/4 of a tank of gas with it or something. Cry about the climate change lie our government wants you to be afraid of so they can control you.

    Reply
    • Mr. Money Mustache September 25, 2014, 7:31 pm

      Yeah! Thanks Jared.

      Reply
    • Kira September 29, 2014, 6:50 am

      Toughing it out?! I’d need a sweater if the inside of my house was 69 degrees F!

      Reply

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