Whilst not carrying out an analysis in the risk assessment sense, i have dealt with a pfi school of 2 floors with a central atrium. This area was populated with ceilingless modules on the ground floor for library, meetings etc and as a multi-use area as defined in BB7/100. The first floor balcony had two or three classromms opening onto it, therefore providing a problem for MofE from that area.
The solution was to put in a glazed, fixed downstand covering the balcony, and mechanical extraction from the atrium (natural was a no go due to a lack of inlet air), allowing sufficient time for evacuation into the adjoining 'normally' constructed wings (approx 60 persons max).
Of course, this was provided off the back of smoke calcs, and the calcs did assume a max fire size (can't recall what that was) of total ground floor involvment, without any sprinklers controlling it.
