ASHRAE Journal - September 2021 - 56

ASHRAE TECHNOLOGY AWARD CASE STUDIES
communication among concerned parties. The fi rst
priority of the owner is usually meeting the budget.
Performance improvement is second, and energy savings
is last. However, Kyoto Station was different. It was
the fi rst project in Japan to apply a full life-cycle commissioning
process from the investigation phase (which
is important for a renovation project) nearly continuously,
through the construction phase and for three
years after completion (functional performance testing
[FPT] and optimization phase). Commissioning meetings
were held once or twice a month for 7.5 years.
This life-cycle approach enhanced opportunities
for open communication to fulfi ll the owner's project
requirements among the project team, and many new
ideas for energy savings were captured. This integrated
process led to the achievement of signifi cant energy savings
on this project. This teamwork-based approach of
the commissioning process was essential for the success
of this project.
The cloud-based building energy management system
(BEMS) has approximately 15,000 measurement points,
which are collected every one minute. Any parties of
the project team can retrieve all data via the internet,
regardless of their location. Accessing data faster than
usual can allow functional performance testing (FPT)
and optimization of central plant operation quickly for
energy savings. For three years following the completion
of this renovation, data checking, machine adjustments,
tuning of building systems and periodic testing
have continued as the FPT and optimization phase.
Commissioning conferences have been held monthly
during this same period to decide on the best practices
for system optimization. The energy savings of the central
plant system continues to improve; the primary
energy consumption was reduced after the completion
from 74 kBtu/ft2·yr (840.4 MJ/m2·yr) in the fi rst year to
68 kBtu/ft2·yr (722.2 MJ/m2·yr) in the third year.
As an example of the FPT and optimization phase,
the effi ciency of the boilers was improved by reducing
combustion gas fl ow during low load and cutting oxygen
concentration in the gas from 6% to 4%. In addition,
the frequency of on/off cycling and associated purge air
loss was reduced. The annual effi ciency of the boiler
changed from 0.71 to 0.74.
Cost-Effectiveness
The replacement of existing equipment would have cost
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$40 million USD. The plant was required to be renovated
soon because the useful life of several machines was
nearly reached. In a standard renovation project, it is economically
diffi cult for the central plant to change from a
steam to hot water system because it requires the replacement
of the secondary system of air-handling units and
fan-coil units. An owner who looks ahead at CO2 emissions,
annual energy use and operational cost at the same
time can make a clear decision to invest in a new, effi cient
system to reduce annual energy consumption. Additional
investment in the energy-saving systems was $33 million.
The reduction in energy cost, including water, was
$5.9 million per year. The simple payback is 5.7 years.
Environmental Impact
Kyoto has a strict target for the reduction of CO2 emissions
generated by building energy use. The aim is a 60%
reduction by 2050 over a 1990 baseline. A typical HVAC
system renovation might achieve a 10% to 15% reduction
in whole-building performance. This radical energy retrofi
t led to a 40.4% reduction of whole-building CO2 emissions
caused by energy consumption. Energy use intensity
(EUI) of the entire building was reduced from 222 to 119
kBtu/ft2/yr (2521 to 1351 MJ/m2/yr), a 46.3% reduction.
Conclusion
A vast glass atrium is located in the center of the Kyoto
Station Building. This complex building includes a
department store, museum, hotel and many restaurants.
The glazed roof reduces direct sunlight and harvests
natural light. This area is open to the outdoors with
no air conditioning and is naturally well ventilated.
Visitors can look at the features of this renovation on
an informational poster in the atrium. This renovation
casts a spotlight on the environmental model city, Kyoto.
The project team worked hard to achieve such a significant
energy reduction with this renovation. This radical
energy retrofi t has made Kyoto station the representative
building in Kyoto, which is the environmental model city
of Japan. Renovation of all air-handling units and fancoil
units is set to be completed in the near future. Kyoto
Station will continue to improve its energy performance.
Bibliography
Yoshida. H., N. Matsushita. 2020, " Heat Source System Renovation
of a Large Complex Building introducing Commissioning. "
Seminar 10 -Cutting-Edge Japanese Technologies SHASE Award for
Renovation Project in 2019. 2020 ASHRAE Winter Conference.
2021
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ASHRAE Journal - September 2021

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