Funny you mention curtains, our dogs live in a lean too wooden floored potting shed, I slept in it during the winter when we had pups and I have a thick curtain over the door so I can leave the door open a bit for them to get in and out during the day, and it's really good, it's actually very cosy in here room, they are warmer in there than I am inside if the heating is I off, thick curtains are brilliant, I found some hooks you can push into any fabric, I bought a single very thick throw and have that over our lounge door, the good thing is we have very thick stone walls, so heat does sty in, provided you put the heating on, we have rails around the tops of some walls, apparently they were for hanging heavy curtains around the walls, now that's a great idea in my opinion. our bedroom is cold but we both get too hot in bed, but not good if you want to hang around in......I ham going to stay in the kitchen if it gets too cold, then I can do some cooking and eating....