When the Olympic was up and sailing they soon found the ventilation was inadequate. Passengers complaining too hot or too cold. Were quite a few changes took place on the build of Titanic.
There is a very good book which covers all the changes to the ventilation and the deck changes too. The book also covers the conspiracy theory's of the two ships been switch too! TITANIC or OLYMPIC WHICH SHIP SANK? By Steve Hall, Bruce Beveridge, Art Braunschweiger and foreword by Mark Chirnside.
In reply to your question, Bastian, the ventilation system (extraction and intake) would have been active whenever the ship was powered up. It would normally run continuously when the ship was carrying passengers.
To piggy back on his answer... As long as at least boiler room 1 was in use the auxillary systems were in use (which makes sense as you would have to vent boiler room1). However fans could be controlled for speed and on or off meaning fans not needed were not used. Also in warm weather or port opening potholes for ventilation was always practiced and most time perfered as venting such a large enclosed space is easier said than done.
Does there exist a Vent Layout plan and vent inventory for RMS Olympic? There's already a vent plan for Titanic but is there one for Olympic? specifically Olympic in 1911.
Why I'm asking for this because I'm working on
modifying CanisD/D.breidis's RMS Olympic shipbucket drawing.by change it to be more accurate. I plan on putting all the differences between it and Titanic, but someof them are the placement and the types of vents because some of the vents from the port side would poke out in the starboard view. Shipbucket drawings are always done from the starboard side..
I'm also asking if there's any plans of Olympic in 1911 as well.