thermal conversion curtains cheap easy no-waste

It is very easy, and probably much cheaper, to add a thermal backing to an existing curtain. The backing can be transfered if the curtain at a later date has to be replaced.

I bought some admittedly very good thermal curtains to cover two windows for a total of $214. I felt warm just looking at them, but I could have put thermal backing on the existing curtains for just $36 including some tape, thread, hooks and two or three hours of inexpert sewing. See further.