The location is Kansas City, Missouri, USA, 39 deg.
I have compadre who wants to build a greenhouse on the south side of her metal garage building 8-6"(2.4m ) high and 32'(7.3m) long. With a 2' (60cm) path down the length there could be 120 sqft (11sq m) growing space.
She will use it to propagate native perennials, grasses, sedges, shrubs and trees. Also want to grow some vegetables over winter. She is planning a workshop around the project to help other urban growers learn important skills.
We talked about using steel pipe and poly film like a conventional hoop house. We discussed the pros and cons of poly film and it's huge carbon footprint. Sadly there are few choice. Low end; glass - highest poly film. The life expectancy of film is 4-6 years, glass 30+ years. We decided to explore the middle of this range with polycarbonate panels 90% light transmission, 12+ year’s life.
In greenhouse design the amount of framing on the sun facing surface is important. The framing will block sunlight and reduce the amount of light the plants receive. Using 1 1/2" pipe like a hoop house minimizes this loss. We are doing a preliminary design with 2x 4 framing. To make up for this loss we will paint the exposed surfaces of our frame member bright shinny white.
