Two common materials used in today's greenhouses to get around the problems that we would have with glass is to use a polycarbonate. And the polycarbonate has certain advantages. One, it's very resistant to damage by snow, hail, wind and other features. And typically if you look at it, you can build in between it, an air channel. The air channel acts to help as a heat barrier so you tend to get less heat loss. This is a standard 2-layer polycarbonate sheet. The greenhouse we are in right now is actually a 3-sheet polycarbonate greenhouse so it has an even higher R factor. Very easily constructed at home is a lexan greenhouse which is made by corrugated lexan. And the corrugated lexan is very easy because it can be cut with an ordinary pair of house scissors.