ASHRAE Journal - December 2021 - 47

FIRST PLACE | 2021 ASHRAE TECHNOLOGY AWARD CASE STUDIES
15% with the newly installed variable speed drive and
operation strategies in 2019.
Operation Effi ciency
In 2017 a simulated model of 2PP Offi ce was built using
software developed by Tsinghua University that complies
with ASHRAE Standard 140-2017. The simulation model
facilitated the prediction of future building energy consumption,
helping to evaluate potential energy saving
strategies including equipment replacement and different
chiller plant control strategies. With more information
on the cooling load profi le, the facility management
team can arrange action in a timely manner to enhance
operation effi ciency.
Filter Replacement and Indoor Air Quality
Instead of conducting fi lter replacement regularly, the
fi lter replacement schedule is shifting to an on-demand
basis. As indoor air quality reaches a predefi ned setpoint,
the sensor indicates the fi lter effi ciency has
reached a point of requiring replacement. Continuous
monitoring of the IAQ sensors facilitated the development
of smart facility management, ensuring fi lter
replacement is at the right time without excessive waste.
Cost Effectiveness
Comparing the years before and after the chiller
replacement, i.e., 2015 and 2017, the net energy savings
of the chiller energy consumption is 4,845,922 kWh,
equivalent to $875,212 per year, assuming an electricity
tariff cost of $0.18/kWh. With the chiller replacement
cost at $6,773,802 and net savings of $875,212, the simple
payback of the replacement is 7.7 years.
Apart from the chiller replacement, strategies derived
from retro-commissioning had also enhanced energy
effi ciency of the operation. The optimization of the
chilled water pump operation control and installation
of variable speed drive on the condensing water pumps
had achieved 531,663 kWh reduction in 2019 ($96,042).
The payback period is calculated to be 1.6 years.
Comparing the total chiller plant consumption in
2015 and 2019, the total chiller plant energy saving is
5,836,953 kWh, equivalent to $1,054,417 per year.
Environmental Impact
Numerous energy management opportunities were
implemented, including RCx of waterside and airside
systems, retrofi tting lighting with higher effi ciency
lamps, and installing occupancy and daylight sensors.
Compared to 2015, the electricity consumption was
reduced by 5,836,953 kWh in the 2PP Offi ce and Mall in
2019. Based on the data from our utility provider, 1 kWh
of electricity emitted an equivalent of 0.81 kg of CO2 in
2019. The reduced electricity consumption is estimated
to reduce CO2 emission by more than 4,728 metric tons.
Furthermore, old R-22 chillers (ODP = 0.05, GWP =
1,780) were replaced by new R-123 chillers (ODP = 0.02,
GWP = 76) in 2016, and non-CFC refrigerants are used
in all our HVAC system. The new chillers were chosen
so the refrigerant can be swapped with the newly developed
R-514a (ODP = 0, GWP = 2).
As part of the green procurement strategy, we implemented
guidelines on procurement in accordance
with ISO 14001 Environmental Management Systems,
considering energy effi ciency and the environmental
impact of the chillers and accessories as part of the
evaluation. Various assessments had been conducted at
chiller procurement stage, including life-cycle assessment.
The project cost of the supply and installation of
the chillers, energy cost, maintenance cost and carbon
emission induced had all been incorporated in the lifecycle
assessment to ensure we are sourcing sustainable
products.
The buildings' owners have committed to the ScienceBased
Targets initiative, developed by the United Nations
Global Compact, World Resources Institute, the CDP24
and the World Wide Fund for Nature. Despite the energy
effi ciency improvement measures conducted in the
past few years, strategies will be continuously identifi ed
and implemented in 2PP to progress with the ambitious
Science-Based Targets. By 2025, 2PP will need to reduce
over 34% in carbon emission.
Conclusion
2PP's chiller replacement generated an attractive
energy savings. Retro-commissioning further helped
unleash energy saving potential, and the innovative
chiller plant operation strategy achieved an additional
9% energy saving, leading 2PP to be a more energy effi -
cient, cost effective and environmentally friendly portfolio.
Free tenant energy audits engaged and encouraged
tenants to reduce electricity consumption. In the future,
tenant engagement will be a key driver to reduce the
electricity consumption and carbon emission.
D E C E M B E R 2 0 2 1 ashrae.o rg ASHRAE JOURNAL
47
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ASHRAE Journal - December 2021

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