Security grilles and burglar bars are covered by Title 24 , Section 1008.1.3.5 of Part 9 and Title 19, Section 4.1 et. al. The main point to remember is that any of these devices placed on windows need to be of a break-away type to allow emergency egress from the inside. There are some limitations in the event that you have multiple exits, windows and the like. The break-away portion must be on the inside of the window for occupants to access it while thy are in the classroom/room. We have seen many instances where the safety release is located on the exterior of the building, which typically does not meet the code requirements.