|
Building Owner
|
PCCW-HKT Telephone Limited
| | Building/Project Name |
Ngau Tau Kok Engineering Centre
| |
Systems |
HVAC - Airside Air Conditioning System
Building Automation /Management System
| |
Building Types |
Commercial - Office
Commercial - Data Centre / Server Room
|
Description of the building:
|
|
- A 10-storey building with offices, a 24 hours call centre and canteen.
- Fully air-conditioned with water cooled central chilled water system & constant speed pumps.
- Water cooled central chiller water system controlled by Building Monitoring System round the clock.
- Air Handling Unit and Fan Coil Unit for offices, call centre and canteen with pre-treated fresh air.
Retrofitted initiative:
- Converted the fresh air supply system to demand control ventilation.
- Fresh air supply on every floor is controlled by the indoor carbon dioxide level instead of fixed amount of fresh air intake.
- Building Management System is engaged to control the amount of fresh air intake in each floor.
- Speed of fresh air fan is controlled by the static air pressure level at the supply air duct.
- Free Cooling Mode will be activated to allow 100% of fresh air intake while ambient temperature is under 20℃ by Building Management System.
Observed benefits other than energy saving:
- Improved cooling capacity in each floor and reduced complaint for poor indoor air temperature.
- Improved indoor air quality and Nil complaint for insufficient fresh air.
General observations of the retrofitting project:
- Fresh air supply system retrofit has not affected the users in general.
- Standard retrofitting initiatives with proven technologies and straight forward.
- Retrofit requires shut down of fresh air supply temporarily. Some disturbance to tenants but manageable.
- Overall a well justified project with good outcomes with tangible and non-tangible benefit.
Other information:
- Conceptual Drawing indicating the changes
| Before Renovation |
After Renovation |
 |
 |
- Conceptual Diagram indicating the Control Logic
 |
Ambient Temp:
22 to 35℃
PAU water valve:
controlled under PAU set point
Fresh Air damper:
Control under CO2 setpoint |
| |
|
 |
Ambient Temp:
20℃
PAU water valve:
closed
Fresh Air damper:
by-pass CO2 setpoint & fully open |
| |
|
 |
Ambient Temp:
below 20℃
PAU water valve:
closed
Fresh Air damper:
by-pass CO2 setpoint & room temperature control the opening to minimise cooling requirement
|
| Cost |
Saving |
| Total cost: |
HKD 1,200,000 |
Total savings/year: |
170,000 kWh |
| Payback: |
7 years |
| |
|
Conversion of constant-air-volume (CAV) to variable-air-volume (VAV) system
Conversion to radiant cooling technologies (e.g. chilled beam / chilled ceiling) with dedicated air handling system (DAHS)
Enlargement of fresh air inlet and ductwork for free cooling application with low ambient temperature and relative humidity
|
|
|
