I expect a number of us have seen the domes of the Eden project, they are geodetic tubular domes with the in fill being inflated transparent plastic pillows. The plastic is a transparent ETFE, similar to fluon non stick stuff.
I don't know how available this is but it strikes me the see through panes used by wind surfers for sails might suit my purpose which is to provide a temporay transparent insulating roof for a small quadrangle in the middle of my daughter's flat. Its only 2.4m by 2m but as there are glass patio type windows on three sides, adjacent to living space, in winter it loses a lot of heat.
So I'm just considering the possibility of making this 2 by 2.4 pillow, anchoring it at each corner and inflating it in situ, It will still let rain past but should create a greenhouse of relatively still air in the quadrangle.
But where to buy suitably strong plastic, being on the coast there may be a gull problem?
AJH