Garage too hot

I have a double garage "end terrace" , Double door facing east, , north is attached to a next door garage, the other two walls are exposed. Roof is flat, felt The temperature in the garage gets hot during the day, with the sun on the roof and exposed walls. No windows, one uPVC door at rear I would like to cool the garage a bit - mostly just remove hot stale air in exchange for outside "cooler air" if that's practical. I do not want to aircondition the garage and am not terribly worried about temps in the winter just want to get some airflow / air movement. Garage has power