Design Brief - 40 Ventilation System A proposal has been made to modify the lab room 1.43 in building G09 at Griffith University to include a 3 m high horizontal ceiling. This requires a re-design of the ventilation and airconditioning system (see Figs. 1, 2). Your task is to propose a new layout for the supply air and return air ducting for the room, select an appropriate number of diffusers and their locations, decide appropriate flow rates for supply air (SA) and return air (RA), calculate all volume flow rates of air in every part of your system and determine the pressure drop across the fan in the AHU for your proposed design condition. There is no requirement to make use of existing ductwork.