Design Criteria - Air Conditioning System
Outdoor Design Conditions Summer 33.5 ºCDB, 25.0 ºCWB
Indoor Design Temperature 22.5ºC +/- 1.5 ºC
Internal loads Occupancy - 1 person per 10 m2
Lighting and equipment load - 35W per m2
Fresh air supply 6.4 L/s per person
Zoning (typical floor) Six (6) interior zones
Seven (7) perimeter zones:
North, East, South-East, South,
South-West and two North West zones
Air circulation rate (averaged) 7.0L/s per m2
9.3 air changes per hour
Supplementary condenser water 40 mm dia valved take offs on each floor
Internal Loads/Office Areas
People: 1 per 10m2 of NLA for office floors
Lights: 15 W/m2
Outside Air: 10.5 per person
Power: 15 W/m2
Systems
Office Air Conditioning - General Description
Air Handling System
The office floors are air conditioned by a central air distribution system. The air handling units serving Low Rise are located on level 1 and the air handling units serving High Rise are located in the roof plant room.
There are seven (7) air handling units in each plant room:
Five (5) constant volume units are feeding perimeter "skin" system and providing cooling and heating as required. Two (2) variable air volume units are serving both center and perimeter zones providing cooling only.
Conditioned air is distributed to the floors via insulated vertical masonry and sheet metal risers with branch connections on each floor. Fire dampers are fitted at each duct take-off to prevent spread of fire from one floor to another.
The air distribution on the floor is by means of sheet metal and flexible ducts and the ceiling mounted air boots located over 20mm slots. Variable Air Volume boxes forming part of VAV systems modulate air flows to both perimeter and center zones.
The return air is drawn to the masonry risers via ceiling void. The risers double as smoke exhaust risers in the event of fire.
Fresh air is delivered to the occupied spaces via variable air volume systems only.
The air handling systems are designed to operate in an outside air economy mode, taking advantage of favorable ambient conditions to cool the interior.
Tenant Condenser Water System
A secondary condenser water loop operates 24 x 7 and serves all floors. This can be used by tenants to connect water cooled packaged air conditioning plant to serve high heat load areas such as server rooms, conference rooms and meeting rooms. A closed circuit condenser water loop with 40mm dia take offs on each floor is provided for the tenant supplementary packaged units and for the water cooled packaged units serving Ground Floor tenancies.
The overall capacity of the system is 600kW, the average allowance of condenser water per floor is 0.7L/s (9Wr per m2) and the maximum water intake on any selected floor is 1.8L/s.
The system operates at 37.6ºC / 32.0 º C temperature ranges.
Supplementary Ventilation Systems
Mechanical ventilation systems include:
Toilet exhaust systems
Tenant kitchen exhaust system
Car park and loading dock exhaust.
Service rooms ventilation systems
Smoke Control Systems
The smoke management system in the building comprises purge type smoke exhaust systems (four axial fans located on the roof) and stair pressurisation systems for all stairs in the building (six axial fans in total).