At my old work place we used the following format:
"Type of Machine" - "Building Letter" - "Room Acronymn" - "Computer number"
e.g : WDT-D-APR-02
WDT: Windows DeskTop
D : DeMontfort Building
APR : Art Prep Room
If it was a windows laptop then: WLT,
Apple Laptop : ALT
Apple IPad : AIP
etc
We always tried kept the Room acronymn to 3 letters.
e.g D3 : D03
Principal's Office : POF or PRI
Main Office : MOF