The Other Mike wrote:
Thanks for all the replies, guess I'll give up on the rockwool idea
but it still needs lining out as it's not that easy to fix shelves to
a single metal skin.

Thinking that a green roof might be a reasonably cheap option with
climbers like ivy up the exposed sides. But that still leaves the
doors that face due south and soak up masses of heat.



I think interior insulation is the only way. Ask anyone who's spent time
in a caravan during extreme weather :-)
Given that you want the option to fix shelves, I'd go with battens/
Jablite rather than wool, mainly for ease of installation, but also the
fact that it doesn't hold moisture. I imagine condensation will be an
issue with a metal structure.