Should I cancel / alter office hours for committee meetings? My contract requires that I maintain a certain number of office hours a week where I am available to meet with students.  In practice this time is rarely entirely taken up by student meetings however.  

Recently I have joined some relatively large university committees that (not surprisingly) have a hard time arranging meeting times. I have historically indicated that I am unavailable to meet during my office hours but I am not sure if this is the appropriate position to take.

The solutions that I see are:


Consider this time booked and unavailable.
Consider this time flexible and reschedule office hours as needed (this would likely be somewhat frequent and could also just create more downstream conflicts).
Cancel the office hours as conflicts arise. 


What is the appropriate way to deal with responsibilities that conflict with office hours?
My feeling is that it is fine to cancel or reschedule office hours when other responsibilities conflict, provided:


You announce it to students several days in advance;
You tell students that you  are happy to meet them at another time, if they make an appointment.