Fixed air loss in Heat Loss calculation

I just want to check what the Fixed Air loss is considering when running a Heat Loss calculation in Load Calcs.

Fixed air @ 17C enters a room with 21C set point at 40.5 L/s.

(40.5 x 1.23 x 4) = 199W fixed air loss

However my room calc is coming out at 348W.

Could anyone let me know what other things are considered in this Fixed Air loss?