Hi. I have 6 hens, three of them are under 6 months and the other three are 1 year or older. They have a pretty warm house it seems, but I'm wondering if theres another way that I can keep them extra warm during the winters cold weather. Besides using just hay. They stay in their house all day, and only come out to eat and peck around for 5-10min, then they go back in. Is there a way that I can insulate the outdoor pen with some sort of plastic? Maybe the stuff they use for greenhouses? Thanks.