Found this article in Countryside and thought that I would pass it on to you.
Solar heat streaming through windows on a winter day feels great, but those same windows can let a lot of heat escape on cold nights, unless you insulate them. I made thermal nighttime insulated shades for my 34" x 76" windows.
They provide the "one-way valve" to heat flow. I used "Reflectix"--a double bubble pack, with Mylar facing on both sides. It is available at most home centers. Using simple rollers to roll them up during the day, each winter morning I just pull a cord to raise them, and pull them down at night. They slide in grooves in the window molding to make for an efficient seal.
I used spray adhesive to cover the inside surface of the Reflectix with muslin, an inexpensive strong cloth available anywhere material is sold. Covering the Mylar with cloth probably reduces its ability to reflect radiant heat somewhat, but the improved looks are worth the tradeoff, in my opinion. No sewing is involved, and the shades cost me about $15 for each of my windows, about 15 years ago. The only maintenance I have done in that time is to replace the hardware. The usual lightweight roller shade hardware only lasts for a few years. Maybe you can find a source for stronger hardware. If you do please let me know: I have taken to making my own.
There are no horizontal battens. The Reflectix just looks that way after it's roiled up and down a few times. It does look good. After a decade or so of sliding up and down in the wood grooves, the edges of the shade wear somewhat, so I just folded a strip of white duct tape along both edges. This also helps to make a good seal. I cut a small piece of the Reflectix to attach to the top, it hangs down so that its lower edge rides on the shade as it makes the corner around the smaller roller. I originally had adhered cloth to the outside of the shade, but sunlight eventually caused the adhesive to let go. I now leave the outside uncovered Reflectix. It shows little signs of deteriorating after more than 15 years in place. It is reflective enough that it helps to keep the space between the shade and glazing from overheating if you leave the shade down when it's sunny, but I try to not do that. The "tracks" are just strips of poplar I cut from my property, air dried, and planed--any 3/4" wood will do. I made mine do double duty as stop strips for the glazing and dadoed grooves in them for the shade tracks. I attached a 3/4" x 3/4" dadoed piece to the bottom of the shade to give me a handle to pull the shade down with, and to help it seal at the bottom. The rock on the cord is to keep the rolled up shade rolled tightly (any weight will work). The stone just fits in with my stone house decor. I'm glad to help; ask if you have any further questions.
Bubble wrap is a great idea; should trap a lot of air. It's cheap, too. I know they sell it at Office Depot and Staples. I think I'd leave the muslin off it in winter, though, so light could get through.
Soapy water sprayed on the window will 'affix' bubble wrap to the window glass, too.
I love the roll up shade directions. Right now I have hemmed blanket pieces on spring rods (top and bottom). During the day, I just take the bottom rod and place it right below the top rod. It gives me half the window open for sunlight. Maybe one day I'll get to the point of being able to make some curtains to cover the rods. Sigh, still living in a construction zone...
Be kinder than necessary, for everyone you meet is fighting some kind of battle.
The roll up method did not work with the insulated quilted foil I bought to insulate with , so I ended up putting lovely heavy corduroy bedspreads up as curtains . They were cheaper than any heavy lined curtains. They are also super easy to take down as my curtain rings have clips on them. The quilted foil insulation went in the attic.