I live where it gets hot in the summer!
One of the upstairs rooms has 3 enormous west facing windows so the hot afternoon sun bakes this room for several hours each day.
Even though the windows are double paned, the windows, the shades, and the room really heat up by early evening.
We have a swamp cooler, and a ceiling fan in this room, but it’s an uphill battle against that hot sun.
We brain stormed how best to insulate the windows cheaply and came up with several ideas.
We first considered putting cardboard panels in the windows. Because the windows are each 3 feet by 5 feet, we would need a very large refrigerator box to make cardboard panels. I tried for several days to get a refrigerator box, with no luck.
We had already bought a dozen sheets of foam board (poster board that kids use for school projects – they have a thin foam core between paper sheets) at Dollar Tree to attach to the cardboard for extra sturdiness and insulating qualities as well.
Since the cardboard wasn’t available, I decided to proceed with just the poster board.
It took 4 poster boards for each window because they are so large.
Materials.
Foam Poster Boards from the Dollar Store
White Duck Tape (Use the real thing – the Dollar Store duct tape doesn’t stick as well.)
Yardstick
Scissors
Craft Knife
Measure the windows carefully – twice! I almost goofed and made the wrong size.
Figure out the best way to lay out the poster boards to fit the window with a minimum of waste.
I could not cover the window with less than 4 poster boards, which were 20×30. So each window only cost $4 for poster board, and then some duct tape – probably 1/2 roll (for all 3 windows) which costs less than $3.50 a roll at Walmart.
Measure and mark the poster boards to fit your window. I had to cut down the sides of 2 poster boards, and cut a little off the top of 2 of them.
To cut the poster board, I laid it on the coffee table with the smaller area to be cut off hanging over the edge.
I sharpened my craft knife, laid a metal ruler along the marked line, and cut right up against the ruler for the length of the poster board. (If you use this method, make sure your knife will be cutting slightly away from the edge of your coffee table so you don’t damage the table.)
Lay your cut pieces of poster board out on the floor in the configuration needed to fill the window. Push all the inner edges up against each other.
I used boxes and other straight edge items against the sides, top, and bottom to help align the pieces and hold them in place.
Starting at the center joint, I adhered duct tape all the way across. Leave a few inches overhang on each side to fold under and adhere to the bottom, to help hold the boards together.
Gently but firmly, press the duct tape down to be sure it adheres to the poster board.
If you have a brayer, you can use it gently to help adhere the tape to the foam boards. Or use a hard edge, such as a ruler to gently adhere the tape.
To do the lengthwise joints, I started a few inches above the center, then taped all the way down. I left a few inches extra to tuck under the bottom and adhere to the other side.
I gently lifted up the finished piece and slid it under the shade already on the window. Because the foam board is so thin, it fit right under the shade, which will hold it in place.
Almost the instant I put the foam board in place it felt cooler standing next to that window.
I used the piece I cut off my first board as a pattern for how to cut the rest of the pieces. Just lay it along one edge of the board and mark it. If you’re doing more than one window, be sure to use the same pattern piece, or the piece you are cutting off will be getting bigger and bigger, and make your finished piece too small for the rest of the windows.
I lightly wrote “Pattern” on the first piece I cut, that I was using for a pattern.
When I went outside to see how the newly insulated window looked, I could barely find the joint, and then only because I knew it was there and where to look for it.
The window with the insulation looks exactly the same as the other 2 that just have shades.
I left the poster boards in the windows over the winter, too, and they worked well to keep the cold out and the room warmer.
© Noreen Doll
Patty says
Love this idea!!! Will be doing this also. Thanks.
juan galindo says
You can buy larger sheets at home depot, they also have a reflective side and are about 1/2 inch thick.
there is also a foil you can use on the windows and is great for the attic,it comes in rolls and you can find it on the web, just look up radiant barrier. I have the barrier stapled at the attic and has saved me about 30-40 $ a month. You might do this as a business also–I did.
John says
I would suggest using the 4’x8’x1/2” styrofoam panels used in building construction that are used inside the walls, behind the the exterior building siding. These panels are covered on one side by silver foil that works great against the glass in the windows to reflect the sun away. The effect inside the house is dramatic in the summertime in hot climates. I initially cut the panels to cover all the glass windows at the top of my two garage doors for privacy, but the temperature difference in the garage, which faces west in the hot California sun, was remarkable. I then started placing these panels in the west facing windows in the house and these rooms are now much cooler in the summer. The only drawback is that these rooms will be much darker, but not totally dark, so I simply turn on the light if I need to use the room for a period of time.
Ryan says
I love this. But is there a chance it could be a fire hazard in a heat wave?
Coralcee says
I just used kids book cover. It’s called contact adhesive, as it filters light as stain glass does.
I went with yellow, orange, green, blue so I get a great rainbow hue. Stops the house looking like we’re growing pot or obvious shift workers.
Christy says
I read this and tried it. It took 17 boards to cover a triple sliding door that gets the sun all day in the Florida summer. We are in Naples and today it was 99 out with a heat index of 108 and is only mid-July. It will get worse through September. We have the house air and a split unit as well in this room plus tinting film, blackout curtains and drapes in front of those. Needless to say we just cannot get the room to stay cool this time year. I can honestly say this worked! I walked into the room around 11 when the sun is high and I was amazed at the difference. Thank you for the idea! They want 5k for an awning and just not in the budget right now! So for $21.25 I believe we have a solution! My A/C and I thank you!
Crystal Vali says
I’ve been using foam core board for a few years. I love this method!
Ida says
Jon Where do you buy the styrofoam panels?
PAT says
I believe the Styrofoam panels say highly combustible on them. May want to double check that.
Lupe says
Wow! I did this to my friends windows. Keeps it cool and warm in winter.. He likes a dark living space so it worked out great. But such great alternative suggestions. I plan to try them in the other rooms . Thank you .
Gmall says
Foam poster board will warp in the hot direct sun
Denise says
Is there a chance of the window breaking from the intense heat when there is a covering on it?
Suzzanne says
These are great ideas as we are all looking for ways to keep our homes cooler in this Texas heat!
Our electric bills are just out of control in Texas no mater how we try to save!
Thank you all for your great ideas!
walrus says
You should check with the window manufacturer, some double pane insulated windows can lose their insulation value from blocking the glass on one side which builds heat between the panes of glass. Extreme heat causes the seal to fail. This is also why they don’t recommend tint on the glass.
Jennifer says
Do you worry about fire with these cheap boards. I’m doing this now but read they can catch fire and I cannot find a straight answer so I thought I would as you.
Noreen says
I have no idea whether the boards can catch fire. This is the first time I have heard about that. There are many things in one’s home that can catch fire – given the right circumstances.
Noreen says
That’s a good question, and I have no idea. There are so many things to consider, apparently, when one does anything.
Noreen says
The cheap ones come from the Dollar store. Or you can get them at Lowes or Walmart.