R value of curtains

Here is a nice handwaving on the subject. Conclusion: R = 2, which at least isn't nothing.

www.rebresearch.com/blog/the-joy-of-curtains/

Also, the R value of bubble wrap is most likely 1

www.greenbuildingadvisor.com/community/forum/general-questions/19778/bubble-wrap-window-insulation-testing

www.builditsolar.com/Projects/Conservation/bubblewrap.htm