Picture posting is enabled for all :)
I have just finnished the frame work for my new hot house can post some pictures of how its done if you like
I tried last Winter using arrays of plastic ex-milk containers. These were filled with water and painted black. The idea was that they would absorb heat during the day and radiate it out during the night.I put them in cold frames and on the north wall of a greenhouse.I don't think they made a great deal of difference but will try again this Winter.