Updated on 05.09.11

How We Cut Our Energy Bill By an Average of 30 Percent

Trent Hamm

It’s simple.

We opened our windows in all seasons. Yep, even the winter.

For the past year, every time the temperature outside is between 50 F and 85 F, we simply just open up the windows and turn off both the internal heating and cooling. A sampling of year-over-year comparisons across all seasons shows that this policy saves us an average of 30% all year round (about 10% in winter, about 20% in summer, and about 40% in spring and fall).

Not only that, our house smells fresh, simply because fresh air is regularly blowing through every room in the house. Air freshener is a product you buy? Really?

I’ll address a few of the specific points that I’m sure you’ll have.

You opened up windows in the winter? Not all winter, of course, but during several different spells, we opened up windows in our home on the brief warmer spells that would come a few times a month. We left our windows open all day for several periods in January, for example.

Yes, this often cooled our house down a bit, but the house never got as cool as it was outside. It was comfortable in our house all day long if you wore a light long-sleeved shirt. The savings from not running the heat at any point during those days far more than made up for the heat loss.

Not only that, when the temperature would begin to drop outside and it became noticeably cooler inside, we just set the thermostat to a few degrees warmer than it currently was, since, after all, we were quite comfortable with that temperature. Our indoor temperature usually hovered around 62 to 64 F in the winter.

This ended up saving us about 10% off of the bills during the winter.

Why only 40% during the spring and fall? We largely just opened the windows and turned off the heating and cooling during the days in the spring and fall. However, we would still close the windows at night if we expected the temperatures to drop too much, as we have young children at home who tend to kick their covers off and get very cold.

If we expected the temperature to drop below 48 to 50 F at night, we would close the windows and turn on the heat at a low level during the night to keep the family warm.

And the summer? We opened the windows all the time, even at night, unless the temperature started to reach the upper 80s, in which case we’d close the windows and start the cooling. Again, we’d often keep the temperature at the upper level of what we were comfortable with, usually the upper 70s.

This sounds uncomfortable… What I’ve found is that the more time you spend outside, the wider the range of comfortable temperatures becomes for you. For example, if I spend a lot of the winter inside (which I typically do), the early spring can often leave me feeling uncomfortable with temperatures much outside a narrow range.

However, the more time I spend outside, the more that range widens. I get used to the variety of temperatures that being outside gives me, with the varying temperatures between shade and sunlight and the changes in temperature throughout the day.

This is advantageous in another way. Many outdoor activities are inexpensive or free. Going on walks. Going to the park with my children. Coaching youth soccer. Planting our garden. Playing games in the yard with the children.

So, not only are outdoor activities a great way for me to spend time frugally, they also help me enjoy a greater variety of indoor temperatures, which reduces my use of the furnace and the air conditioner, which reduces my energy bill and extends the life of those devices.

The end result? We’re saving about $50 per month (on average) on reduced energy bills simply because we’re spending more time outside and leaving the windows open much more often. That, my friends, is frugality at work.

Loading Disqus Comments ...
Loading Facebook Comments ...
  1. ckstevenson says:


    Don’t know your region’s weather well, but do you have pollen at all? I live in the DC area, and would love to have the windows open more during the spring/summer/early fall but the pollen is intense. It can quickly put a layer of yellow pollen over every item in my house in a day.

    Anyone have ideas on how to prevent this?

  2. Kathryn says:

    Glad this works for you. Our weather is much colder here. Just woke up to to half an inch of snow. Our house is older and not well insulated. We keep the thermostat set at 53F most of the time, raise it to 62-64 for a few hours in the evening if we’re watching TV. Bundling up and using blankets if we are sitting is our frugal tip. Our summertime highs seem to be what you record for spring/fall. Of course, cooling the house isn’t an issue. A few times in the summer, upstairs we run a fan.

    Good ideas, but they don’t work across the board.

    BTW, we are in Southern California, but at near 7,000 ft elevation.

  3. valleycat1 says:

    We don’t have central air or heat at home [so essentially we live this way all the time], but at the office I continue to be surprised at how many people think that if they’re too hot or too cold, they need to crank the thermostat really high or really low (I’m talking 50 if they’re hot, 80 if they’re cold), instead of tweaking it just enough to get the cool or warm air to cycle on. Or, even better, bring a sweater or have a small fan if you don’t like the temp the office is set at.

    I would like to have central air at home in the spring, as I’m allergic to just about anything that blooms in our ag area & I spend a month or more in abject misery.

  4. Kacie says:

    In our apartment, the windows are so terribly leaky that we seal them and put plastic over them in the winter. It helps a LOT with drafts, and I think that it didn’t get warm enough here to open windows this winter, anyway.

  5. ryan says:

    Leaving the windows open all day might not be safe if everyone is at work/school during the day. Even if you live in a good area, this can be a problem.

  6. Riki says:

    Opening the windows in the winter isn’t an option in Canada. However, I live in a climate where people generally don’t have central air conditioning, so turning on a fan and opening the windows in the summer is pretty much status quo. It probably wouldn’t actually occur to me that there would be other options for cooling the house.

    But I don’t understand why you would open the windows in the winter. If you’re talking about saving heating costs, why wouldn’t you just turn the heat down/off? What does opening the windows do? In fact, wouldn’t you be able to maintain lower heating levels for longer if you *don’t* open the windows? Sure, you get fresh air but that has nothing to do with saving on heating costs. Turning down the thermostat saves money regardless of open or closed windows and one can certainly become accustomed to lower temperatures in the house without opening the windows.

  7. Gretchen says:

    “It was comfortable in our house all day long if you wore a light long-sleeved shirt.”

    Some winter days that’s not even true in my house with the heat on.

  8. Gretchen says:

    Which is also to say I don’t understand what the difference between this and just turning the thermostat down would be.

  9. Russ says:

    @Gretchen – agreed. I have a thermostat, and when it’s warm outside the heating won’t come on anyway. Isn’t that the point of having one? To adjust the heating automatically to maintain a temperature range?

  10. jessie says:

    I guess this is the Canadian in me, because where I live, you have to keep the heat on in the winter or the pipes freeze and burst, and you can do serious winter damage. I would be all for opening the windows in summer though… however, my partner and I have an agreement: I get winter heat and he gets summer A/C. Try as I might, I am a miserable, angry person when I’m cold (which is always – I wear long sleeve shirts in summer), and he walks with an open coat in Ontario winter because he overheats so summer months are deadly for him. If you can do it and you’re comfortable – by all means! However, check in with your kids to see how they feel: my dad kept our house at a terribly cold temperature because HE liked it, and the rest of us were just miserable at night.

  11. Jen says:

    We always shut off both heating and cooling in the spring and fall, and open the windows. We also do this as much as possible in the summer, but will turn on the AC if it gets into the mid 80’s in the house. Winter is when our gas and electric bill is highest. We’re just outside of Chicago, and it gets cold here!

    There is no way I would leave my windows open all night though! Especially with young children in the house. I don’t think it’s safe, no matter where you live, unless there is some kind of safety feature that would prevent anyone breaking in.

  12. Johanna says:

    “The savings from not running the heat at any point during those days far more than made up for the heat loss.”

    Try as I might, I can’t figure out what that means.

    It takes a lot more than a light long-sleeved shirt to make me comfortable with an indoor temperature of 62-64 degrees. If I’m outside in those temperatures, I’m fine, because I’m usually walking around or doing something else active. But inside, sitting on the couch reading a book, I’m shivering if I’m not wearing multiple layers of fleece.

    There are some times when opening the windows can help to keep my apartment at a comfortable temperature. In the evening at the end of a warm sunny day, it can sometimes be pleasantly cool outside while it’s still uncomfortably hot inside. But I also don’t see what opening the windows in January is supposed to do, as opposed to just turning down the heat.

  13. lurker carl says:

    “We left our windows open all day for several periods in January, for example.

    Yes, this often cooled our house down a bit, but the house never got as cool as it was outside.”

    Purposely allowing heated indoor air escape to a colder outdoors is not frugal. Would someone please explain how this saves money?

  14. Amanda says:

    I don’t understand the science of it.

    I really appreciate at GRS that the authors write comments back frequently.

  15. CNM says:

    I also don’t understand the open windows in winter. Yes, I have done that for short periods of time to let in fresh air but not because it would save on heating. Never is it 50 or 60 degrees in winter where I live, so the air in my house would always be warmer than that. Why would I let the warm air out by opening a window?

  16. Riki says:

    The only way it could possibly make sense is if the outside temperature rises ABOVE the temperature that Trent maintains in the house. Otherwise, lurker carl is right, Trent is just heating the house and then letting all of that warmth float right out the windows. How likely is it that the temperature gets above 64 degrees in January in the midwest?

    It makes no. sense. at. all.

  17. Josh says:

    Trent are you trying to heat the whole neighborhood?

    If you want the fresh air, go for it, but purposely allowing heat to escape is not conserving energy.

  18. Kathy F says:

    The only way I can make sense of what Trent is trying to say it that people who spend more times outdoors might become better acclimated to colder or warmer temperatures. Also he is not saying he keep windows open all winter, only when the temperature warmed up enough to open them. But I am not sure that save much money. I have often wondered how people lived in very hot or very cold climates, but then I read that the body can acclimate itself to better tolerate the extreme temperatures over time with exposure. If you never subject yourself to anything else besides temps of 70-75 F, then maybe you do suffer more at temps outside that range.

  19. Sam says:

    Just thought I would chime in that ASHRAE (AMerican Society of Heating Refrigeration and Air Conditioing Engineers), the people who design heating and cooling systems and came up with human thermal comfort zones have plenty of research showing that when one uses “Natural Ventilation”(as opposed to mechanical, compressor based) that people have a wider range of comfort temperatures, a significantly wider range. Also people in extreme climates, during extreme months (Arizona in the summer, Wisconsin in the winter) typically have a tighter comfort range due to being accustomed to the tighter temperature ranges of living in conditioned space.

    Last but certainly not least-Riki, what Trent is suggesting is basically using his operable windows as an economizer. This is a typical attachment used in commercial AC and heating units where a thermostat opens a damper to let in fresh air when the air outside the building is cooler than the inside temperature in the summer (due to all of the computers, children running around, stove etc.) and warmer than the inside air in the winter (inside could be colder because the window overhangs prevent sunlight from entering etc.) This is a very common practice and quite energy efficient.

  20. stannius says:

    If I had to guess the logic here, it would be that Trent and his family open the windows to get themselves used to it being cold inside, so that it seems positively warm on those days when the windows are closed and the heat is set to 62.

  21. Rebecca says:

    We live in WI and our furnace works hard to keep the house at 62 in the winter. For that to be comfortable, everyone is in flannel lined jeans, socks plus slippers, a tee shirt under a long sleeved shirt under a fleece hoodie and sometimes a hat or fingerless gloves. And I am a person who prefers to be sightly cold. We do sometimes turn the heat off and open the windows briefly for some fresh air when the temp gets up over 40, usually march or so, but we that isn’t for cost savings, just to air out the house.

  22. Marinda says:

    There are over six months were I can live with open windows, 24/7.
    Fall, some of winter and spring over mild temps and because my windows can NOT be pulled up higher by someone on the outside, I feel relatively safe. In the evening, when it’s cool the unfortunate thing is I hear what goes on next door and if they only knew, they would take the arguments inside. But for long periods of time, not even the central fan runs. For a four bedroom home, during those months, our bills are under 100 dollars, easy. Best thing we ever did was replace the windows

  23. Rachael says:

    I live in Michigan and we occasionally have days in January that reach 60. I also open all of my windows on those days to air out the house and take advantage of the decent weather as it only lasts 48 hours max. It is not uncommon in Michigan to have a 70+ degree day in Dec/January and 3 feet of snow the next.

  24. JS says:

    I live in southern Arizona, where the summer lows are rarely below 85, and that’s only from about midnight to just after sunrise. The only time we open our windows in the summer is during the period around a thunderstorm where the temperature drops. The summer is just something you get used to around here. We run fans, keep the thermostat at 80-90 degrees, pay a little extra each month on our electric bills the rest of the year, try to use heat-generating appliances only at night and remind ourselves that we have 8 months of heavenly weather coming and that, hey, at least it’s a dry heat :)

    I do think there is something to be said for conditioning yourself to the weather. When I started my current job, I had a long walk to/from the bus stop. After doing that walk in 100-115 degree heat regularly, the heat didn’t bother me so much when I was out and about. Now I carpool a few days a week, so every year when it starts getting in the 90s, I’ll go outside for a walk during the day, or grab my resistance band and do a strength workout outside. The summers are still insanely hot, but these efforts make them more tolerable.

  25. EngineerMom says:

    Riki – In the Twin Cities in Minnesota (Trent lives in Iowa), it is fairly common to get a few warm days periodically (4 or so in Oct and Nov, 1 or 2 in Dec with the temp above 55F) up until about December. January and Februrary are cold (that’s when the Twin Cities gets its below-zero weather), but then in March you start to see the temperature start to bump up again.

    So yes, it is very likely and makes a lot of sense to open the windows on those few days. Trent is not talking about keeping the windows open all winter – he was very clear about that. What he IS talking about is taking advantage of those mild days to both air out the house and help his body readjust to winter-type temperatures, so when he does have to close up for those -20F days, keeping the thermostat at 60F feels comfortable, not freezing.

    People think the Midwest is this giant icebox in the winter. I lived in Grand Forks, ND for 5 years, and even up there you occasionally get above-40F days up until December. They’re not common, and snow before Thanksgiving is pretty much the norm, but it’s not like the entire area between the Rockies and the East Coast is locked in snow and ice for 6 months!

  26. EngineerMom says:

    I’d open our windows more, but the pollen really gets to my husband. There’s a narrow band of time between the last frost and the spring pollen, then again between the first frost and when the temperature drops too far when we can keep the windows open without DH having trouble sleeping due to coughing, itchy eyes, and sneezing.

    And yes, he takes meds – the effect I’m describing is what “breaks through” the medication on especially bad pollen days (windy, warm but not hot – basically the days best for opening windows!)

  27. getagrip says:

    I agree with the first commenter and #26. Being the allergy sufferer and having to use the wipers on many spring mornings to clear the windshield before I drive in for work, opening the windows for a day, even with meds, can mean many nights of suffering.

    Bigger picture though, I also agree that if the outside temp is above the inside temp, there should be no need to “open windows” to get an energy savings, the furnace shouldn’t be kicking on at all in that case (or vice versa for the AC if outside temp is lower than inside temp). No problem with “airing” the house during those times though if that works for you, I just fail to see how that equates to real energy savings, especially if you’re talking one or two days a month.

    Trent’s savings appear to me to come from being willing to tolerate greater temperature swings, either because the house retains heat/coolness and doesn’t really get all that cold/hot for a while after they’ve shut off the heater/AC and openned windows or because they set the temperature lower/higher on their units to begin with (not many folks I know keep the house at 62 deg F in winter and 85 deg F in summer, especially when you have two or more adults living there).

  28. David says:

    None of this works in a humid climate. Humidity makes a bigger difference in comfort than temperature does. It might be 70 degrees outside, but I can’t open the windows and let the 90% humidity in.

  29. kjc says:

    “…(not many folks I know keep the house at 62 deg F in winter and 85 deg F in summer, especially when you have two or more adults living there).”

    Not to mention three small children.

  30. mary m says:

    Pollen kills it for me too. Not only do I have allergies but so hard to clean.

  31. Michele says:

    I’m with all the pollen sufferers. Even on meds, I’m dying right now. Spring sucks and I actually put the air on a couple of days ago.
    Also- once in a while my husband and I will open to windows to let fresh air in a stale house in the winter, but not for long. Seriously, 62? That’s what I turn the heat on AT NIGHT in winter with the electric blankets on! And our house is really well insulated!
    It gets way to cold here in the winter to let all that precious accumulated heat out the window. We had snow three times last week…and it’s May 10th today. And I’m in southern Oregon!

  32. kristine says:

    We have all 3- pollen, humidity, and crime. Very low crime overall- but some random idiot sitting on women with a knife to their throats as they sleep. Police have advised keeping all doors and windows locked, even when home. This of course, does not make the news, overshadowed by the serial killer on our south shore. Single women should never, ever, leave their windows open at night. Period.

    But I agree with opening the windows for acclimation. It adjusts the body’s thermostat, so you need to manipulate the interior temp less.

  33. Allie says:

    So I’m the only one really put off by the snideness in “Air freshener is a product you buy? Really?” Maybe I’m reading it badly and need to re-evaluate, but on first read, that really rubbed me the wrong way. But if no one else is bothered, this might just be my own problem and not an issue with Trent.

  34. Carrie says:

    We open our windows as much as possible once it hits about 70 degress outside. We don’t have central air, and the window units are horribly expensive. We don’t usually turn on AC until the end of summer for about 4 weeks, when the heat index hits around 100 degrees. I have 2 small kids, with one and the way, and we’re just used to living this way. You can get used to it.

    Regarding opening windows in the winter – I live about 4 hours south of Trent. I have occasionally opened windows for very brief periods of time – an hour or less, strictly to get some fresh air in the house, but opening windows causes too much heat loss in our home. Not economical for us to let the heat out of the house, since that’s money going out the windows.

    There are lots of factors that play into whether or not opening windows at various times in the year can be effective – health, safety, the way ones home reacts to heat and cold. It’s different for everyone, but I think the point here is to encourage people to think about options they might not have considered before, and adapt for their own needs.

  35. Katie says:

    You’re definitely not the only one, Allie.

  36. Karen says:

    I can’t do that in hot and humid Houston, Texas.

  37. Tracy says:

    @Allie – I found it really annoying as well, and I don’t even *like* air fresheners

  38. CW says:

    We live in Tehachapi, CA (4,000 ft. elevation) and keep our thermostat set (Fall and Winter) for 58 at night and 62-64 during the day. We wear sweaters in the house if we’re cold before we ever turn on the fireplace or up the thermostat setting. In Summer, we open doors unless it’s 80 deg. inside and then we’ll turn on the A/C, but we also have ceiling fans in every room, and use portable fans to move the air. Sometimes, all you need to be comfortable is air movement.
    Our electric bill this past month was the lowest it’s been since we moved into the house 3 years ago. We’ve been very conscientious about energy usage and it’s beginning to show in a reduced bill.

  39. Stephanie says:

    @Allie—I found that to be an annoying line as well. I just tried to remind myself that Trent is a guy and he probably wouldn’t buy air freshners even if his house really needed them…(as it is my experience that guys seem to care less about this than women do…)

  40. Steve says:

    @Allie – that stuck out to me too (and similar to Tracy, I’m not even big on air fresheners.)

Leave a Reply

Your email address will not be published. Required fields are marked *