Beat The Heat: DIY Window Sun Shade

(UPDATED:  Data added to show effectiveness and video assembly!)

It’s now July and depending on where you live you may be feeling the heat of summer.  In my small corner or the northern hemisphere, we recently had temperatures spike into the 90’s(°F) all week when high 70’s and 80’s are historically average.  When my air conditioners started to struggle to keep our poorly insulated apartment cool I decided it was time to devise ways I could reduce the temperatures and energy use inside.

Inspiration: Car Sun Shade

We have an extra car sun shade lying around which got me thinking.  If you can use one of these for a car, surely it can be used in building with similar results.  As I wasn’t planning on using it again, I quickly cut it up and taped it to the size of one of our windows.  This seemed like it would work great, the only problem is I have one of them and still had another window to cover.  I then decided to see if I could construct my own version.  I ended up doing the following to make my own sun shade replacement.

Homemade Sun Shade Tutorial

Tools Required:

You only need a few tools to make these yourself:

    • Box Cutter or Sharp Scissors/Knife
    • Tape – Strong tape such as packaging tape or duct tape.
    • Cardboard  or any other sturdy backing, I used old cardboard from the back of a big-box store brand 6 drawer dresser that we dismantled for its usable pieces to save space.  I suggest reusing anything you can that fits the bill.  No need to buy the backing and its always good to recycle.
    • Aluminum Foil – To reflect the light and thus heat.


Update 2016/7/7 – Now in video format. This video shows me scoring the edges (after including them in the measurements) to create flanges to keep it a single window without other attachment methods. The key to this is to tape the edges when slightly folded to add strength and shape.

Step 1: Size The Window

Using your cardboard, measure the size of your material to the window you wish to cover and remove any excess.  I used only my eyes to size the window, but you can also measure exactly if you would like.

Size Backing To Window
Using your eyes or a measuring tool, find the proper dimensions for the backing.

 Step 2: Assemble The Base

Cut and tape together additional pieces of backing to fit the size of your window.  Ensure to tape the seams well enough that they do not bend or fold easily.  If required, use some form of support, yard sticks, popsicle sticks, whatever you have around to help firm up the board.

Assemble The Back Part 1
Adding additional cardboard to get the vertical height required. Use tape to secure any and all new pieces.

Cut any additional size pieces required.  Again, I only used my eyes to get the correct final width.

Sizing Additional Peices
Sizing additional pieces to fully fit the window.

An easy way to remove the excess for this step is to cut straight lines from the edges starting with the shortest to reduce the length and number of cuts.

Cutting the short side of the excess from the previous photo skips a long vertical cut.
Cutting the short side of the excess from the previous photo skips a long vertical cut.
Cutting Additional Excess
With the majority of extra cut off, this will be a nice short cut.
Full Back
After cutting to size, tape the additional pieces to the back.

After cutting to size, be sure to tape all the pieces securely together and that they do not bend or fold easily.

Step 3: Cover In Foil

This step is as straight forward as it sounds.  Roll out foil to cover the surface to face out the window.  Leave a little extra on the edges to wrap over and secure with tape.  Assuming multiple pieces are needed, tape down each one after placing to ensure they won’t move.  For maximum efficiency, be sure to keep the shiny side facing out to reflect more light.

Cover With Foil
Cover the front with foil, leaving excess to fold over the sides. Use tape to secure each piece before moving to the next section.

After covering the front completely, flip it over to secure the folded edges.

Completed Back
Once the foil edges are taped, your shade is complete.  Although you could cover the rough edges at this stage if you want to.

Step 4:  Attach To Window

Use a safe non-damaging method to attach the sun shade to the window.  Our apartment windows are metal framed, so I just taped the cardboard directly to them using duct tape.  For wooden or plastic frames, it may be best to use a different method such as 3M Command Strips to ensure you don’t damage the window.

UPDATE 2016/07/16: It may be best to wedge in or tack up as the previous duct tape method resulted in melting and falling off when exposed to high heat. I have since made newer lighter versions that lean against the blinds inset to avoid having them hold in place. A cheap tension rod top and bottom would also hold them in place although are a few dollars a piece.

Attached To Window
Attach to the window to complete the installation. My window frames are metal so I am taping directly to them. If your’s are wood, consider tacking it in place or any other method to minimize risk of damage to the window.

Step 5:  Cover

Once completed and secured in the window, you will probably want to cover the back to make it visually pleasing.  I simply drew the blinds over mine, however you could decorate it with photos, use it as an impromptu cork board(if its thick enough), or hang a poster on it to cover any rough edges.

Covered Window
Once installed, cover the shade to make it more appealing.

With these sun shades, it should help reflect a good amount of sunlight and thus heat, out of your home.  I plan to make another 1-2 of these so each window that has an air conditioner has its window covered.  I decided to place these shades in the windows with the air conditioners so I can still open the others for air when the temperature is nice.

Update:  Proof Of Effectiveness

Since posting this article I have recorded some  data to back up the claims made in this article.  At the end of July, we had another heat wave with temperatures hitting the 90’s(°F).  One room did not have a sun shade while two others did.  The rooms with sunshades stayed cool with the AC units able to keep it a comfortable 72°F while the room without one (which was also not facing the hot afternoon sun) was hovering around 77°F with the AC unable to keep up.  So there you have it, this sunshade helps keep your rooms/home cooled by at least 5°F making the difference from overworking the AC to letting it function as intended.  This will definitely help you stay cool during the warmest days of the year.

Questions?  Comments?  Thoughts?  Leave them in the comment section below!

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