10. Air Conditioning and Ventilation Systems
10.1 Introduction
Overall strategy :
G/F - A/C room with chilled water pumps
4/F & below - Air handling unit ( i.e. all air system ) for gallery & lecture rooms
5/F & above - Fancoil system ( i.e. air/water system ) for offices easier control over individual offices, to turn off fancoils if the occupants are out.
Roof - 2 sets of chiller
On each floor - Owing to limited floor area, there is no fresh air handling unit is put inside the meter room with computer control, i.e. DDC - digital direct control
For the air handling unit system, it receives fresh air from the primary air handling units. It also draws in air from the room via return air duct ( RAD ) through supply air duct ( SAD ), the cooled air goes to gallery. SAD supplies air to chillers air boots with higher air velocity. Air boots then supply air to the room through difusers.
Since water cooled chillers will require higher initial expenses and for larger scale building. Also it is a regulation imposed by the water authority to use only sea water ( i.e. not portable water ) for the cooling purpose for air conditioning system. Air cooled water chillers are used.
Fresh air is drawn through primary air handling unit cooled by chilled water ( 4 - 6 oC in coil temperature cooled by air-cooled chiller on the roof ) and is blown through primary air duct ( PAD ) or pre-treated air duct to fancoils of each office. Condensate drain is collected to rain water drainage pipe. In order to stop the smell and foul air migration, there is a water seal trap in the pipe. Flexible conduits are used in the false ceiling void for easier connection since there are so many fittings inside this void.
For the exhaust system, the exhaust air will have two ways to go:
Through these two ways, the lavatories will gain better ventilation. This accomplishes the required and changes for the A/C room and the toilets.
All the A/C ducts were made on site using galvanized iron sheets. The curve connection of these air ducts aer folded by a machine called "seam-forming machine" on site.
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