Putting up a greenhouse in my yard helped me get why we fuss over air gaps in insulation. | Insulation Installers - Freelance Forum - The Community for Independent Professionals
My old neighbor in Phoenix used a plastic shed for seedlings and it would hit 100 degrees inside by 10 AM. It really shows how any clear container, like @logan_anderson40 said, becomes a heat trap. You see the same thing with cars left in the sun, the heat just builds and has nowhere to go. It makes you notice how bad regular insulation is in a lot of cheap builds. That thin plastic teaches a harsh lesson about temperature control real fast.