Book - School of Science and Technology

General principles 411Roof extract unitSilencerSuction box withacoustic liningGrillePart section throughroof over spectatorsgalleryAir discharge spoutswith adjustabledamper bladeFigure 15.2 Upward air distribution in a swimming pool hallIn office applications air movement is more critical and for floor supply systems it isimportant that the air is introduced by using a relatively large number of small outlets, thedesign of these being such as to produce a high induction effect, the supply air mixingquickly with the room air to reduce velocity and temperature differential. A typicalarrangement is shown in Figure 14.23. A floor supply system may be supplemented bydesk outlets fed from the same plenum thus providing desk bound operatives with adegree of control over their micro-climate. Displacement air-conditioning systems, followingthe pattern described in Chapter 14, rely for their operation on minimal mixing ofsupply air with room air and, in consequence, low level side-wall or floor outlets havinglow discharge velocities are selected for this application. With such systems, perimeterheating loads are dealt with conveniently by an independent system.On a scale appropriate to single rooms, experimental work has been reported whichsuggests that for winter use it is possible to introduce warm air via a long slot near floorlevel, as shown in Figure 15.3, and by this means much reduce the temperature gradientwithin the room.* Discharge velocities of up to nearly 12 m/s were used without reports ofdiscomfort from occupants.* Howarth, A. T., Sherratt, A. F. C. and Morton, A. S., `Air movement in an enclosure with a singleheated wall.' JIHVE, 1972, 40, 211.