[750hp]

Some really good points Spook. I'm fitting a roller door on the downwind side of the shed. The roller door won't lead to anywhere, but it will give me natural light to the work bench and it will get that airflow.
A bushfire raging through here would be a wild sight! The back 4 acres is untouched natural and heavily treed bushland, and it all heads up to me - and the shed - on the crest. I have 3x36000 litre water tanks in an emergency, but I'd probably look at plumbing a petrol powered pump into the new tank I'm getting for the shed to keep it close by.