Occupancy rate is the percentage of available space in use, measured at a point in time or averaged over a period. A floor with 100 desks and 62 people present has 62 percent occupancy at that moment; the same floor might average 40 percent across the week.
Both numbers matter for different decisions. Peak occupancy sizes the office; average occupancy prices the waste. Boards tend to hear the average, employees experience the peak, and good reporting shows both.