Has anyone experimented with passive cooling techniques on their home?

HearthForYou Posts: 52 ✭✭✭
edited October 2020 in Building Projects

I'm moving into a home where utility bills seem high despite measures to reduce usage. So....I'm seeing it as an opportunity to get creative on reducing the need for electricity and gas. Since we're in summer, I'd like to tackle cooling first. Besides opening windows at night and closing them early to keep the cool air in, has anyone tried anything else that doesn't require much or any electricity?

Best Answers


  • seeker.nancy - Central Texas
    seeker.nancy - Central Texas Posts: 795 ✭✭✭✭

    I am definitely interested! Our AC went out Thurs., right as we went into a heat advisory. Our heat indexes are between 105 and 110F. They keep adding a day on every day. It now stretches through until Monday at 8P. We can't get someone out here until Mon. afternoon to fix it. Its like a sauna in the house, positively sweltering. It doesn't cool off outside until about 10PM and its hot by 9AM. We have a lot of fans but even still it stays between 85 and 92 in the house. Since I'm melting I cannot keep a coherent thought in my head so I won't post much lol.

  • The absolute best thing you can start with is a ceiling fan if the design of your house will allow for one. Obviously you need a higher ceiling. A good ceiling fan will save you hundreds of dollars every year. It keeps your house cooler in summer and warmer in winter. It is the cheapest and most effective step you can take on this journey.

    BUT THERE IS ONE IMPORTANT SECRET OR IT WILL NOT WORK!!! You have to change the direction of the fan so that it blows cold air down in the summer and warm air down in the winter. You do this with a simple hidden switch that exists on every fan. There are many websites that tell you how to do this. Here is one of them: https://www.southernliving.com/home/ceiling-fan-direction

    Make sure you know how to do this for your fan, and put it on your calendar twice a year so you don't forget. Good luck!

  • Also, if you want to get into other aspects of passive cooling and heating, one of the best books on the subject I've found is "Moveable Insulation" by Langdon. It is a serious book for contractors and heating installers, but a determined DIY'er can follow the plans as well.

    It is available from Amazon and other online sellers, but I bought mine from Steven Harris's "Knowledge Publications". He is an engineer who makes sure the books he sells are all the best in their relative fields. There are three other books that he recommends in this area: http://www.knowledgepublications.com/heating_and_cooling_your_home.htm

  • Melinda
    Melinda Posts: 123 ✭✭✭

    Following this thread.

  • Jens the Beekeeper
    Jens the Beekeeper Posts: 651 admin

    As @Paradox and @jodienancarrow pointed out one of the best options if you are stuck with the house as is 😉 is to create shade by planting in front of the sun side. But this is not only for the shade the plants will evaporate water during the day and cool oft he area even more.

    If you can't plant the next best thing are blinds on the outside to prevent the sun from getting in the room in the first place. The light will turn into heat when co tacting the surface so it will get warmer with indoor shade options.

    Another option wpuld be to build a lean to greenhouse as it will capture the light and warmth but the actual house will Sta cooler.

  • Sheila
    Sheila Posts: 108 ✭✭✭

    Fans with buckets of ice or cold water in front of them help with cooling. If you want to help drop temps at night thin wet cloth over your openings work if you can keep them wet - we have done the ends in long planters as cotton will readily wick up moisture. Shades on the outside of the windows are excellent as are planting on the west and south sides. If you do annuals they will die back in the winter so you will have your sunshine and if you do a perennial make sure it loses it's leaves and is not an aggressive clinger (ruins and pops siding off!) or rampant invader (never get rid of the sucker - looking at you trumpet vine!) The solar room is a great idea as well if you have the room - a great resource is the book Home Solar Gardening by John Pierce - they will help with heating in the winter as well!

  • dipat2005
    dipat2005 Posts: 1,277 ✭✭✭✭

    Wow!! Such great ideas. We used a very large swamp cooler in California on the high desert. We have also used bamboo blinds over the windows with the most sunlight on the outside. I haven't found blackout curtains but I am on the lookout for some. I am unable to use an air conditioner where I live right now so I use cold water on a dish towel and let it hang around my neck and down my shoulders.

  • naomi.kohlmeier
    naomi.kohlmeier Posts: 380 ✭✭✭
    edited July 2020

    Sorry to hear you are sweltering in the heat. You know those rice bags you can make for heating pads that you pop in the microwave for a few seconds? We keep ours in the freezer and use it as an ice pack, only the rice doesn't get as cold on the skin. Put it around the back of your neck and it stays cold for a good half hour or so. It only takes a couple of hours to get cold again, so you can use it multiple times a day. Or make several and have enough for the whole day/family.

  • Merin Porter
    Merin Porter Posts: 1,026 admin

    Yesterday in SW CO it was 99 degrees, and we don't have a central a/c unit here, so this is what we do:

    Since it still gets significantly cooler at night here, we use an energy-efficient whole-house fan (QuietCool) and run it all night with the windows open partway.

    We have double-paned windows, and use double-cell shades on most of the windows and, in addition, thermal blackout curtains in the bedrooms. We close all the windows when it starts getting warmer during the day, around 10 a.m., and close the shades and curtains to trap as much of the cooler air in the house as possible.

    During the heat of the day, we also run a window unit in the kitchen and use a fan to direct some of that cooler air into the living room. We have an energy-efficient window unit that uses surprisingly little electricity. We also run ceiling fans in rooms we are in. Ceiling fans don't cool the room, per se, but they cool you while you are in the room.

    Then, once it cools off at night, the shades, curtains, and windows open and we turn the whole-house fan on again to draw in the cooler air.

  • Bryce Langebartels
    Bryce Langebartels Posts: 47 ✭✭✭

    So many good ideas! Obviously, insulation is a big factor. When we first moved to our home, I put a substantial amount of insulation in the attic as well as ensured the airflow in the attic was sufficient. I also added a solar powered ventilation fan to the attic to assist in air movement. We also live in the woods which helps immensely. My in-laws have a whole house fan like @Merin Porter mentioned. Depending on what part of the country you're in these can be amazing. They basically provide a breeze throughout the house which makes it feel cooler no matter the temperature. Crack some windows open, turn on the fan and there's a nice breeze. We also use black out curtains in the bedrooms as well as ceiling fans. All of these ideas mentioned are really great! If you can though, make sure you're not dumping heat out your walls and ceiling by making sure you have enough insulation. You can go around and make sure your outlets are all sealed off from air transfer as well (this is probably more important in winter, but still beneficial in summer).

  • Karin
    Karin Posts: 272 ✭✭✭

    @Sheila I have tried the fans with ice water in front or behind and they really do not do the trick. We did buy 2 fans/portable aircons that can have ice put in them, which work better, but then, you have to have electricity to make the ice!!

    As our house got cold in winter and didn't heat up much in summer, we thought it would be a good idea to fully insulate our walls (as well as ceiling and floor) but sadly this has actuallly made it unbearably hot in summer! We don't have good airflow, and it doesn't cool down appreciably at night, so having the windows open is not much help, so are really regretting our decision. But the best thing I did this last summer was put reflective foil car sunshades on the windows on the southwest side, which stopped the sun shining in, and this made a big difference. I love everyone's ideas on using plants to shade windows and especially the catio @Paradox !!

  • HearthForYou
    HearthForYou Posts: 52 ✭✭✭

    @jodieandcarrow Wow, that sounds amazing. Did you design and build your home?

  • HearthForYou
    HearthForYou Posts: 52 ✭✭✭

    @Karin The good news is you have a well insulated home! I hear you on getting too hot in the summer. I had a similar issue with a home that I used a "paint on" insulation. It got way too hot when I cooked indoors in the summer. The rest of the year it did pretty well.

    If you use the principle of convection, I wonder if there's a way you can cool your home. For example, a trombe wall works b/c the difference of hot and cool air creates a current flow. As hot air rises, the cool air is drawn in from the floor area and the hot air pushes out near the ceiling.

    I was imagining two ducts in your home that would allow for a similar flow of air. One duct would enter your home near the floor and connected to a pipe dug into the ground outside that taps into the geothermal temperature. The second duct, would be located near the ceiling that would allow hot air to escape.

    It make me want to research this some more and figure out how that can be done.

  • HearthForYou
    HearthForYou Posts: 52 ✭✭✭

    There are some great ideas here! Thanks for sharing!

    I'm definitely most interested in the ideas that don't need electricity.

    To add to the conversation, window shelves on the outside of your solar gaining windows will also help block the sun in the summer allowing you to see out your windows during the day. During the winter, the window shelves allow the winter sun to come through for passive heating and light.

  • HearthForYou
    HearthForYou Posts: 52 ✭✭✭

    @seasparrow32 What a fascinating contraption! Thanks for sharing. This one is a new one to me.

  • frogvalley
    frogvalley Posts: 675 ✭✭✭✭

    Wonderful ideas!

    When we build our house almost 40 years ago, there was basically only passive solar so we aligned it with the rooms we wanted to heat the most facing south. The windows were double pain and we told everybody we had an active solar house because we had to run around to take insulated curtains down in the morning in the winter and put them up at night to keep in the heat and reverse the process in the summer.

    I made mock trombe walls a few years back and they were great for generating heat in the room where I installed them. Basically, there are two five foot long by two foot wide windows facing east. I painted two four foot by two foot pieces of metal black and screwed them inside the windows, leaving six inches at the top and bottom. The cooler air went in the bottom and warm air exited the top. The overhead fan pushed the heated air back down into the room. It was just a six month experiment which we considered successful, cost effective and easily removable.

    I've alway wanted to cool the house with snow after watching some documentary on how they do it in Sweden. Can't wait to try it - put snow in a pit, refrigerator or under the house (insulated of course) and use the melt to cool the house. Bet you could use ice cubes.

    Another heating experiment waiting in the wings is uses a huge compost pile which contains a coil inside that provides warm air to the house.

    I read about Japanese houses using composting in the walls to provide heat. Can't find the article, but I'm going design something like it and to give it a go this winter.

  • RustBeltCowgirl
    RustBeltCowgirl Posts: 1,403 ✭✭✭✭✭

    Will definitely be checking out some of these ideas.

  • marcy_northlightsfarm
    marcy_northlightsfarm Posts: 103 ✭✭✭

    I also open windows at night. There is one window that is at the top of the stairs that I put a big fan in front of which blows out. This pulls air in all the other open windows and cools off the whole house. Every window is closed in the morning to keep the house cool. Our house is surrounded by trees except the east side. We used to get too much heat in the summer through two windows in the kitchen. I used to put a towel across each window every morning to keep the heat out. I didn't want curtains to hide the lovely woodwork. Then I planted a tree outside. I think the variety is Sunburst Locust. It has very fine leaves so it doesnt block the warmth of the sun when you still want it in early spring. As it grew I trimed the branches up real high so it also doesn't block our view either. It's a fine shade tree now after about 12 years.

  • HearthForYou
    HearthForYou Posts: 52 ✭✭✭
    edited September 2020

    @frogvalley Great ideas for passive heating. I'm wondering what kind of metal you used for your mock trombe walls. I love that idea.

    I'd also love to try the compost pile with the coil inside of it. Jean Paine lived off of that kind of heat with his wife. Check out Jean Paine Method:

    video: https://www.youtube.com/watch?v=JHRvwNJRNag

    video using Paine's method for 500 showers: https://www.youtube.com/watch?v=-Jm-c9B2_ew

    Here's a great article on him and his method: https://www.permaculturenews.org/2011/12/15/the-jean-pain-way/

  • solarnoon.aspen
    solarnoon.aspen Posts: 219 ✭✭✭
    edited September 2020

    When we built our house, we decided to try an air temperature moderating idea. We used a 4" PVC tube. It started above ground outside of the house, traveled for 100' at 48" below the surface, and emerged inside through the floor of our pantry. Because the temperature of the soil that deep is always the same temperature, so is the air as it comes into the pantry after traveling so far. Which means in the summer, it is cooler than outside air and in the winter it is warmer than outside air. The air always seems to be coming in - you can feel the gentle breeze as it enters the pantry. In the winter, it is drawn in every time we light the fire, turn on a bathroom fan or stove fan.

  • solarnoon.aspen
    solarnoon.aspen Posts: 219 ✭✭✭

    The other thing that we are very pleased we did, was to build our house with straw bales. In the hot 30+ degree summers, we are never overheated. If we come inside to sit for a breather on a hot day, we usually find it necessary to put on a long-sleeved shirt to keep warm. I realize it is all relative to the outside temps and that bodies get accustomed to heat when outside, but our inside is relatively so cool inside that we have to keep warm if we stay there too long. lol