None of the windows in the back of the van open, and we didn't want to add others, so alternate ventilation was is needed.
The first job we did on the van was cut two holes in the floor at the rear, behind what would become a false back wall. The idea is to have a window in the back wall which can allow air flow through the back doors if they are open, or through the floor vents if they are shut. The air is directed to a combiner vent just under the window. This way we can have the windows 'open' even though from the outside the van looks closed up.
In the ceiling, a Fantastic vent was added which causes through flow.
Air vents built in