Ventilation 

In the days when smoking was permitted in cinemas it was essential to have a effective ventilating system.

The Plenum ventilating system installed at the Empire Cinema Neath was well designed and kept the auditorium fresh and reasonably free from tobacco smoke. 

Fresh air was introduced into the hall through grills near the screen at floor level.   In cold weather the filtered air could be preheated and in cold weather it could be cooled in the fan chambers.   

It was essential to have quiet system not to distract from the sound track.    The was done by using a rotary fan, as shown in the illustration on the right.