Working with reports and grouping is complicated but if you know how to do that, you should be able to modify your sql query to something like
select computer_name, left(computer_name,2) as building
Then, building would be a separate column that you could group on?
Sorry for the late response.
Thank You for this. This is exactly what was needed. Looking back it seems so simple, Adding this additional column then grouping by it gave what I was looking for.