Insulating a metal storage shed (to use as a green house)
 

I have a metal storage shed (~ 10x12') that I plan on converting into a greenhouse to grow orchids and other exotic rainforest/swamp plants. Since these swamp plants grow under the canopy of the rainforest, I only intend on having filtered sunlight coming from the roof.

The problem I have is that the temperature can rise up to 110-115 degrees in the summer. What is the best way to insulate this shed?

Any advice given will be greatly appreciated.

I would use some R board and set up a decent ventilation system for it.