You often see on these house programs about how having bi fold doors which open right up to "let the outside in".
They look great but are they really that practical?
Just seeing Smowballs post about flys made me think. In this hot weather you would be inundated with the blighters surely if you have them open.
And what about foxes, squirrels, mice, next doors cat? If you have the back of your house open like that then surely by the end of the day you would have a house full of uninvited guests.
Think of all the dust and dirt, too. I keep my bathroom window open (it is impossible for anyone to break in through it) and I'm always surprised by how quickly the dust accumulates - lots of seed heads, petals and so on in the summer and grit all year round.
In this weather - you'd be letting the heat in, too. South facing windows closed and curtains shut until dusk here.
We have 10 ft of Bi-folds between Kitchen-diner and Patio, never had a problem' You get Flies in with an open door or window, as for foxes, squirrels, mice, next doors cat, we have two Staffie sized rescue dogs who don't miss a trick, so it just doesn't happen.
I very much doubt that the average fly, cat or squirrel can tell the difference between posh new 'accordion' doors (like these https://s-media-cache-ak0.pinimg.com/originals/46/da/7f/46da7fcd9d84b47c4f8fc51d1a9c55ac.jpg ) and the conservatory doors, etc, which people have been leaving wide open in the summer for decades. Simply opening a window can be enough to invite hundreds of flies in!
I do have the sliding patio doors open quite a bit and have often seen foxes and squirrels looking in and I have just managed to see them off in time,
I think they are a bit more cautious looking in a door but if the whole back of the house was open they might not realise they were not still outside till it was too late.