Our 3-season sunroom, as shown in the first photo, has a window wall of single-glazed glass. Since we wanted to extend the use of the room into the winter, one key goal was to reduce the heat loss through these windows. I ultimately came up with a plan to make the Insulating Window Covers discussed here, which are shown fully in place in the second photo. As the third photo indicates, since they are held in place by hook & loop tape (I used a non-Velcro brand because of cost), they can be partially opened at the top to let in some light (or let out some heat into the room on a sunny day), or at the bottom (because the cats like to look out). It's like gathering up a Roman shade using the hook & loop tape to hold the sides.
In researching the project I came across a 5-layer insulating material manufactured by a firm called The Warm Company, warmcompany.com, which looked like the right stuff for the job. It's called Warm Window®, and I'll just refer to it here as WW. I bought mine - 10 yds. - at a local JoAnn's. (BTW, I have no association whatsoever with the company other than having bought and used their product.) On their website they have written instructions for making a straightforward insulated shade using WW (click on "Instructions," then "The Basic Shade") plus a video (click Video, "Warm Window Basic Shade"). These instructions are good, and formed the basis for my project. However, there are some places where additional information would have been useful, and my project - in terms of the sizes of the windows I was covering - was much larger than the one they discuss, and this affected, in particular, the mechanism to secure the covers in place.
The patterned fabric - 11 yds. - which is what you see in the room, was purchased from Hancock's of Paducah (KY). I refer to it here as the "decor fabric."
Step 1: Measure, Mark and Cut
The old adage, "measure twice, cut once" applies here as elsewhere in crafts (and life in general). I would add, if unsure always give yourself extra material. You can always cut it smaller. but not larger. So measure your window(s) and include in your measurement the additional length and width necessary for mounting your covering on the window. The WW instructions, Steps 1 and 2, cover this well. In my project I was covering three windows and a door, side by side, with identically sized covers, so my planning and measurements took this into account.
As indicated in Step 2 of the WW instructions, the WW fabric will be cut to the size of the finished shade. So lay out your material and mark it to cut. Be sure your sides are parallel and are square to one another at the corners. If your project is large, use a dry wall square if available (first photo, above). The "tubes" in the multilayered WW fabric run up-and-down the fabric, not across, and are seamed every 4". The fabric is 52" wide (not 45" or 60" as stated in the WW instructions I viewed). This means that if your window is taller than 4' you will need to join to sections of the WW fabric together to make longer panels. My finished WW length was about 80".
Step 2 of the WW instructions includes piecing instructions, but I found the illustration confusing. Basically you cut two sections of WW fabric near the seam lines; place them face to face with the seam lines aligned, and pin them them together; then sew them together along the seam line (definitely use a walking foot); and trim to ¼". See second through sixth photos, above. While the WW instructions include a "No-Sew Method," I found it extremely difficult to get enough heat from my iron to penetrate the multiple fused fabric layers for the bondable material to work well. (The WW video shows a very powerful steam iron in use.) I recommend sewing everything, and won't discuss the No-Sew Method further here. The WW instructions cover it for each step, if you are interested.
As in indicated in the WW instructions, the decor fabric is cut wider and longer than the WW material. You will be sewing the window cover with the front sides of the material facing each other, and then reversing it as a tube, so extra decor material in the width dimension is necessary to make this work. WW suggests adding 2 ½" to the width; I experimented and added 3 ½" and used slightly wider seams. I recommend experimenting first with just small lengths of the fabrics to see how they work out when sewn and reversed. For the length dimension I added 12" rather than the 9" WW suggests, and then trimmed off the excess for the bottom hem when I got to that point (see next section)..
Step 2: Join the Decor Fabric and the WW Fabric
See Step 3 of the WW instructions. Lay the WW fabric on the table with the interior side facing up and lay the decor fabric on top of it, good face down. The decor fabric should extend an inch above the top of the WW material. Pin the sides of the decor fabric to the sides of the WW fabric, with a ½" seam allowance on each side (I used ¾" here). The decor fabric will be "loose" across the WW fabric because it was cut wider. Then sew the side seams.
The photos above show this process. I used the ironing board as a support/carrier for the large amount of fabric which had to be handled, and took the cover off to reduce friction. The technique worked very well. You can see from the fifth photo, after the "tube" has been turned right-side-out, and the seams pressed, the result comes out well.
I followed the WW instructions for the top and bottom hems. Note: With respect to the bottom hem, as noted above I had left more fabric than called for in the WW instructions. This insured that I did not run short in turning up the bottom hem, which covers a full panel of the WW fabric and must be sewn onto the fused seam. When I got to that point I trimmed off the excess decor fabric before turning the hem. Once the top and bottom hems are done and the cover pressed, it is time to install it.
Step 3: Install Your Cover on the Window
I ran into more problems here than in making the covers. Step 4 of the WW instructions provides a Sewing Method and a No-Sewing Method for installing hook-and-loop tape ("HLT") to hang the cover. Both utilize 1" sew-on HLT. Either probably works fine. So of course I decided to go a somewhat different route. Sewing all that tape through the thick cover materials looked like a daunting and thankless task. And rather than use the fusible tape suggested by WW for the non-sew method, I decided to try some self-stick HLT instead. My theory was that this should do the same job on the covers and would also be the easiest and least visible method of fastening the tape to the window frame parts.
So I mounted the HLT around one of the windows and around one of the covers and put the cover in place. The HLT worked fine to hold the cover in place, but when I pulled on the cover to reposition it - which is a frequent and common usage - the HLT would often start to pull off the cover. What to do? Back to the sewing machine, sewed the HLT onto the cover - very difficult because of the sticky backing of the HLT, which gummed up the needle, which needed repeated cleaning. I finished one cover this way, but it was too difficult and frustrating a task to do the others.
I ultimately found some slim (⅛") screw-together fasteners at JoAnn's, which I installed at about one foot intervals around the periphery of the covers to fasten the HLT firmly to the cover materials. See photo above. They look pretty good, and seem to do a good job of keeping the HLT in place on the covers if I take reasonable care in pulling it back. I also have run staples through the HLT into the window frames at some locations (mainly corners) where the tape tended to pull loose as well; I guess that was to be expected, and they do not impact the appearance when the covers are not in place.
So my recommendation is to follow WW's directions in this area. They were a lot smarter than I was.
Bottom line - this is a challenging project if you have large windows to cover, but it can be done. And it can look pretty good, if I do say so myself.