I had a building with a similar situation. The roller shutter provided a means of escape for an underground loading bay, a gym, and a restaurant /bar. The shutter remained open and manned by a security officer for most of the day and although it was closed at night and weekends, it opened automatically upon activation of the alarm.
The shutter was powered via the mains electrical supply which was backed up by a generator. In addition, a manual over ride facility was provided which consisted of a chain and pulley system. The chain was painted green, and clearly labelled (with a sign on the wall) as to its purpose. This was approved by the local Fire authority and building control officer.
When the shutter was eventually replaced the new one operated in a similar fashion, but was counter balanced so that operating the chain override released a lock and the shutter moved up under the influence of the counter balance.
The building had AFD to L2 standard and sprinklers in the basement areas.