This project was made 12 years ago, and has worked very well, The role up curtain is made up of two layers of space blankets and then the inside curtain. We needed to wind it up so we can get heat in the winter, and lower it in the summer and at night to keep the heat out and in the winter to keep the heat in. We use to burn 3 cord of wood a year. now we burn less that 2, This is the first in the series of solar projects we have done, and they all add up. We live 20 miles north of Saint John N.B. and at the time of this writing it was -6 F this morning and is now only 12 F. so it does work.
Give it a try