Tropicals & Tender Perennials: HOW FULL IS YOUR GREENHOUSE?, 0 by bwilliams

bwilliams wrote:
Are you using on piece or two pieces of plastic? We use a plastic that usually last us 5 to 8 years. Their are two pieces on top of each other and a small blower that keeps it full of air like a big bubble. This makes a large air space which is the best insulation you can use. If you did not do it you should look into it would save you a ton of heating.

Not sure if you can tell in this pic but both the greenhouses have doubly poly the one on the right has a air space about 1 foot. The greenhouses are heated and it has a hard time melting the snow off they were probably around 75f in the roofs during this pic.