My project has five conference rooms that will not be used frequently. How should I go about calculating the amount of visitors for them, and how should peak visitors be estimated in this case?
It's up to the project team to decide the most accurate way to determine FTE, program so there's no set rule. Usually the client provides an estimate of the total number of visitors for an office based on their planning or programming. You can make an educated guess and verify with the client if that sounds reasonable based on their needs and experience.