Pocket Curtains Would Flannel And Cotton Material Make Good Thermal Curtains?

Would flannel and cotton material make good thermal curtains? - pocket curtains

Decorative cotton flannel I want to make clear curtain rod, but I am afraid I lose my time - the intention is to make the room warmer in the winter of this book?

Should I many layers and each layer is just as good work?

(The flannel is closer to the inner window. Side Cotton faces playing with colors and theme of the room.)