Many years ago I kept a pair of golden pheasants in an aviary approx 20x8x6ft high it had a couple of iron sheets on the roof one end & straw bales for the pheasants to nest & hide in, there were a couple of pole pearches under the roof. When I had a racer with a cold etc I used to put them in there, within a few weeks they were fine again and actually gleaming, just fed on mixed chicken corn. I think todays lofts (mine included) are constructed with the fancier in mind, they are for our comfort & pride & also we think we are doing the best for the birds. As for ventilation you dont need any in an old hands loft the birds live in the fresh air !!. When you think about it whilst bird watching at a reserve---who is the one in the hide ?. Yes if I didnt care about being laughed at by the tiled roof boys it would be an old hands loft for me !!