Q. How does the timezone field store the data?
In the Insights Unified Data Model the Building table includes a timezone field that contains, if available, standard timezone names. Those are used, if not already present, to assign offset values to timeseries records, as seen in Time Zone Database (also reprinted in List of tz database time zones).
SELECT "CREATED_TIME", COUNT() FROM PUBLIC.BOOKING_ALL GROUP BY 1 ORDER BY COUNT() DESC LIMIT 100
Where the time values will have a +hh:mm figure.
The timezone for the building is set in Building Location, learn more in Add, Edit, or Delete a Building.