ASHRAE Journal - March 2022 - 32

ASHRAE AWARD OF ENGINEERING EXCELLENCE
FIGURE 2 Typical floor sectional detail.
FIGURE 3 HVAC&R energy consumption data.
Structural
Seismic
Braces Without
Fireproof
Covering
Multifunctional
Maintenance
Balcony
Double EA Slits
To Ensure Exhaust
Performance of
TWU
EA
AC Drain
Gutter
EA
Snow Melting
Heater
management (LCEM) simulation tool. The tool,
developed in Japan, can calculate energy consumption
in partial-load operation by refl ecting the operating
characteristics of heat source equipment, such as
partial load and outdoor temperature characteristics
at different times of the day. It was estimated by this
simulation that the preferential operation of the
electric heat source during the daytime and operation
of heat dissipation from the heat storage tank during
off-peak hours was very effi cient and enhanced the
system COP per day by about 2%. Therefore, these
results are refl ected in the actual operation.
4. The TWU's exhausting indoor air operation improved
the effi ciency by approximately 30% compared to the
outdoor air circulation operation of a standard unit.
5. Compared to energy consumption data of commercial
buildings, the actual primary energy for the HVAC&R
systems showed an annual energy-savings effect of
about 46% (Figure 3). In summer, the reduction is
about 55%, and it's about 65% during the intermediate
seasons. In the winter, however, gas consumption for
32
ASHRAE JOURNAL ashrae.o rg M A R C H 2 0 2 2
AC Drain
SA
Offi ce
Two-Sided Support Wide
Glazing Ensures a
Dynamic View
SA
Through-Wall Unit (TWU)
Improved By Exhausting
Indoor Air
RA EA
Return Air from Baseboard
Of Perimeter Enclosure
Indoor Air Quality (IAQ) and Thermal Comfort
Ventilation & IAQ: Conditioned air is supplied
to the offi ce by AHUs, and indoor air is exhausted
by TWUs installed in the perimeter. The maximum
amount of outdoor air (OA) introduced is 6 m3/h·m2
(0.33 ft3/min·ft2). During the intermediate seasons,
the AHU increases the fresh air volume for free cooling
from the central control, and the TWU operates
in exhaust mode. The fresh air introduced from the
AHU is exhausted from the outdoor fan of the TWUs.
The maximum amount of OA introduced is 12 m3/h·m2
(0.67 ft3/min·ft2) (4.5 air changes per hour). The air
exchange effi ciency was 0.90, which is higher than the
standard value of 0.5 for normal mixed air conditioning
(in the case of supply air and return air from the ceiling).
Regardless of the wind direction and speed, it was
confi rmed that the unidirectional fresh airfl ow from
interior to perimeter contributes to exhaust indoor contaminant
effi ciency .
Thermal Sensation: During the operation phase,
fi eld measurements and post-occupancy surveys were
conducted in each season. In both summer and winter,
about 80% of the respondents voted either neutral or on
the cool/warm side, respectively. In addition, regardless
of the season, more than 80% of the respondents felt
comfortable regarding indoor airfl ow. The indoor wind
speed was less than 0.25 m/s (49.2 fpm), which is within
the range of the recommended summer wind speed
with no detection of drafts. The predicted mean vote
fresh air load treatment is large, and the reduction rate
is about 30%.
RA
120
100
80
60
40
20
Measured Value
Energy Consumption Statistics in Japan
46% Reduction Throughout the Year
Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug
Statistics are based on DECC (Database for Energy Consumption of Commercial
Buildings). This is the largest database in Japan with about 45,000 data.
2022
4.3 m (14.1 ft)
740
Ceiling Height = 2.8 m (9.18 ft)
Primary Energy Consumption (MJ/m2)
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ASHRAE Journal - March 2022

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