Retrofit

Building Owner

Hongkong Land Limited

Supply and return chilled water temperature differential control with zone control valve

Conversion to demand fresh air control system coupling with exhaust air system

Using electronically commutated (EC) plug fan in AHU / PAU / CRAC

Building/Project Name

One & Two Exchange Square

Systems

HVAC - Waterside Air Conditioning System
HVAC - Airside Air Conditioning System
Building Automation /Management System

Building Types

Commercial - Office

Description of the building:

Grade A Commercial Buildings for a prestigious, globally oriented, 24-hour business complex.
52 levels for One Exchange Square and 51 levels for Two Exchange Square comprising of offices, retail, and F&B outlets.
Fully air-conditioned with water-cooled central chilled water system and primary and secondary chilled water pumping system.
Air handling unit (AHU) and Fan-coil units (FCU) for offices, retail, and F&B outlets with pre-treated fresh air.

Retrofitted initiative:

EC Plug Fans:

Replace the existing AHUs with belt-driven centrifugal fans to EC Plug Fans. Apart from a more effective motor comparing with the old AC motor, EC Plug Fans also enhance system efficiency as it does not require belt and pulley for operation. With BMS control for the new AHU, if one of the EC Plug Fans malfunctions, the other EC Plug Fans can pick up the required flow or provide partial flow by maintaining a static pressure set point and preventing the single point failure of centrifugal fan motors, fan bearings, pulleys etc.
Energy Valve:

Replace the existing control valve in chilled water return pipe with Energy Valve. The Energy Valve consists of ‘Delta-T Manager’ Control - when cooling load is met and the chilled water delta-T is lower than the design value, the Energy Valve will further be closed to reduce water flow for achieving energy saving.
IEQ Monitoring:

Install the CO₂ sensors and PM sensors to monitor the indoor air quality. When the CO₂ /PM level is too high in the environment, the fresh air supply can be increased. Alternatively, the fresh air supply can be reduced if the CO2/PM is constantly at low level.

Observed benefits other than energy saving:

Reduced maintenance resources in operations, future retro-commissioning and water re-balancing when adding/removing AHUs..
More information for AHU monitoring and reporting as both EC Plug Fans and Energy Valve provide high level interface for connecting to Building Management System (BMS).
Provide resilience with multiple modular fans to replace single centrifugal fan in traditional AHUs.
Provide better indoor air quality monitoring and control.

General observations of the retrofitting project:

AHU retrofit requires suspension of AC supply to tenant. To avoid nuisance to tenants, the replacement of AHU was done in 60-hours during the weekend.
Advanced work such as conduit and wiring works can be arranged weeks before actual replacement to shorten the AC suspension time.
Some AHU rooms are located inside tenant area; comprehensive protection works are done with reference to tenant’s comments. No complaints received.
A few models of EC Plug Fan were selected to reduce the parts provision and storage.
Overall a well justified project with good outcomes with tangible and non-tangible benefits.

Other information:

Cost		Saving
Total cost:	HKD 25 million for supply and installation of 130 nos. of EC Plug Fan AHU / PAU and energy valve only (2019)	Savings/year breakdown:	HKD 1 million (Average Energy Saving) HKD 2.2 million (Average Maintenance Cost Saving) Note: More than 30% saving of water volume of some AHU / PAU obtained from position to flow control + dT Manager after applying the function of Energy Valve.
		Payback:	Around 7.8 years (Around 5-15% direct saving in air side. The indirect saving in water side was achieved by lowering the demand after installation of energy valve)
Name of the consultant and contractor
Consultant: J. Roger Preston Ltd. Contractor: The Jardine Engineering Corp., Ltd.

Supply and return chilled water temperature differential control with zone control valve

Conversion to demand fresh air control system coupling with exhaust air system

Using electronically commutated (EC) plug fan in AHU / PAU / CRAC

Building Owner

Hongkong Land Limited

Building/Project Name

One & Two Exchange Square

Systems

HVAC - Waterside Air Conditioning System
HVAC - Airside Air Conditioning System
Building Automation /Management System

Building Types

Commercial - Office

Description of the building:

Grade A Commercial Buildings for a prestigious, globally oriented, 24-hour business complex.
52 levels for One Exchange Square and 51 levels for Two Exchange Square comprising of offices, retail, and F&B outlets.
Fully air-conditioned with water-cooled central chilled water system and primary and secondary chilled water pumping system.
Air handling unit (AHU) and Fan-coil units (FCU) for offices, retail, and F&B outlets with pre-treated fresh air.

Retrofitted initiative:

EC Plug Fans:

Replace the existing AHUs with belt-driven centrifugal fans to EC Plug Fans. Apart from a more effective motor comparing with the old AC motor, EC Plug Fans also enhance system efficiency as it does not require belt and pulley for operation. With BMS control for the new AHU, if one of the EC Plug Fans malfunctions, the other EC Plug Fans can pick up the required flow or provide partial flow by maintaining a static pressure set point and preventing the single point failure of centrifugal fan motors, fan bearings, pulleys etc.
Energy Valve:

Replace the existing control valve in chilled water return pipe with Energy Valve. The Energy Valve consists of ‘Delta-T Manager’ Control - when cooling load is met and the chilled water delta-T is lower than the design value, the Energy Valve will further be closed to reduce water flow for achieving energy saving.
IEQ Monitoring:

Install the CO₂ sensors and PM sensors to monitor the indoor air quality. When the CO₂ /PM level is too high in the environment, the fresh air supply can be increased. Alternatively, the fresh air supply can be reduced if the CO2/PM is constantly at low level.

Observed benefits other than energy saving:

Reduced maintenance resources in operations, future retro-commissioning and water re-balancing when adding/removing AHUs..
More information for AHU monitoring and reporting as both EC Plug Fans and Energy Valve provide high level interface for connecting to Building Management System (BMS).
Provide resilience with multiple modular fans to replace single centrifugal fan in traditional AHUs.
Provide better indoor air quality monitoring and control.

General observations of the retrofitting project:

AHU retrofit requires suspension of AC supply to tenant. To avoid nuisance to tenants, the replacement of AHU was done in 60-hours during the weekend.
Advanced work such as conduit and wiring works can be arranged weeks before actual replacement to shorten the AC suspension time.
Some AHU rooms are located inside tenant area; comprehensive protection works are done with reference to tenant’s comments. No complaints received.
A few models of EC Plug Fan were selected to reduce the parts provision and storage.
Overall a well justified project with good outcomes with tangible and non-tangible benefits.

Other information:

Cost		Saving
Total cost:	HKD 25 million for supply and installation of 130 nos. of EC Plug Fan AHU / PAU and energy valve only (2019)	Savings/year breakdown:	HKD 1 million (Average Energy Saving) HKD 2.2 million (Average Maintenance Cost Saving) Note: More than 30% saving of water volume of some AHU / PAU obtained from position to flow control + dT Manager after applying the function of Energy Valve.
		Payback:	Around 7.8 years (Around 5-15% direct saving in air side. The indirect saving in water side was achieved by lowering the demand after installation of energy valve)
Name of the consultant and contractor
Consultant: J. Roger Preston Ltd. Contractor: The Jardine Engineering Corp., Ltd.

Supply and return chilled water temperature differential control with zone control valve

Conversion to demand fresh air control system coupling with exhaust air system

Using electronically commutated (EC) plug fan in AHU / PAU / CRAC