yes, we have a bit of a different climate than you, but still, the air movement is important. I've just seen the interior of the wood shed for the first time in months in daylight and it's terrible - discoloration everywhere on the roof and the start of mould. There is a vent or two, but obviously not enough air movement. Time to fit a fan....outside, the cold kills off the mould before it starts, but inside the warmth, lack of air movement and moistness really gets it going. My garage is around 10-15C most of the time.
- Bret