A space audit is a structured review of how office space is actually used versus how it is allocated. Traditional audits sent people with clipboards to count heads at intervals; modern audits pull the same picture continuously from booking, check-in and sensor data.
Audits usually precede a big decision: a lease renewal, a consolidation, a redesign. The recurring finding is a gap between allocated and used space, and that gap, priced at your cost per square metre, is the business case for change.