ASHRAE Journal - June 2022 - 42

Water-Cooled to Water-Cooled
Chiller Replacement Saves Big
BY KIM TANG CHEUK, IR, MEMBER ASHRAE; CLARA TIANQI LIU, PH.D., ASSOCIATE MEMBER ASHRAE;
REGINA Y.Y. WONG, IR, MEMBER ASHRAE; JEREMY C.Y. HO, IR, ASSOCIATE MEMBER ASHRAE; CARY CHAN, PH.D., IR,
JP, MEMBER ASHRAE
A
deep energy retrofi t
of the aged chiller
plant system at the
Queensway Government Offi ces
(QGO) is a good example of Hong
Kong's joint efforts in advancing
net zero with innovative
technologies. Signifi cant energy
savings of 32.8% resulted from
an upgrade of a typical watercooled
to water-cooled chiller
replacement.
Building and Project Information
Located in the Admiralty district
of Hong Kong, the QGO has
a total of 56 fl oors and rises 199 m
(652 m) in height, providing over
665,255 ft2 (15 754 m2) of space
entirely for offi ce use. The QGO
is air conditioned by a central
water-cooled chiller plant with
indirect seawater heat rejection.
In an annual energy review
of the QGO, it was found that,
after more than 25 years of
operation, the energy performance
of existing chillers was
degraded to a very low level
with an average COP of 4.4. As
these existing chillers account
for 70% of electricity use of the
whole chiller plant and constitute
a substantial proportion of
building energy consumption,
ultrahigh-performance chillers
with next-gen technologies and
environmentally friendly HFO
refrigerants were proposed in
this chiller replacement project
to achieve a remarkable increase
in the overall energy effi ciency of
the building.
To avoid signifi cant disruption
of government work, two phases
were scheduled in the process.
During Phase I, one 1,024 ton
(3601 kW) water-cooled chiller
and one 512 ton (1801 kW) chiller
was installed and commissioned
in March 2020. For Phase II, one
1,024 ton (3601 kW) and one 512
ton (1801 kW) chiller were used
as a replacement and put into
full operation by mid-2021.
To further drive sustainability,
safety and reliability in this
chiller plant retrofi tting project,
new innovative and advanced
technologies such as the adoption
of HFO chillers, retrocommissioning
(RCx), advanced
chiller plant modeling, building
information modeling (BIM)
technology, digital controls,
mobile app application and
more were also used to help the
QGO achieve its goal of becoming
a pioneering green government
building in Hong Kong.
Queensway Government Offi ces in Hong Kong.
Methodology
This project mainly uses a
retrocommissioning approach:
an energy audit was conducted
for the existing chiller plant.
With data collection and analysis,
the potential energy-saving
opportunities (ESOs) were identifi
ed for chiller replacement.
Subsequently, energy models
were built to predict energysavings
and to evaluate the economic
benefi t of new chillers.
BIM was also used to visualize
the proposed chiller plant to
minimize clashes and reduce
risks of project delivery failure.
Upon successful installation
and operation of the new chiller
plant, the actual energy savings
were measured and verifi ed
Kim Tang Cheuk, Ir, is the assistant general manager, and Clara Tianqi Liu, Ph.D, is an engineer at Trane Hong Kong. Regina.Y.Y. Wong, Ir, is a senior engineer in the
General Engineering Services Division and Jeremy C.Y. HO, Ir, is an engineer in the Electrical and Mechanical Services Department at Hong Kong S.A.R. Cary Chan,
Ph.D., Ir, JP, is the executive director at the Hong Kong Building Council.
42
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2022 ASHRAE Technology Awards | Honorable Mention

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