Two ways you can do it.
If you're using LDAP in your environment, that information can get pulled from LDAP.if you map Room to something on your AD/OD side that contains the info you're looking for.
In your case though it sounds like users are not actually associated with these Macs (you mentioned lab systems) In that case to bulk update them, you can do it via a shell command in the Run Command section of a policy assigned to a Static or Smart Group.
Do this-
jamf recon -room "Room Name"
THat will plug in whatever you enter for their room.
You can also do this through Casper Remote, assuming you have a group you can select with the Macs in your lab.