ASHRAE Journal - October 2024 - 50

2024 ASHRAE TECHNOLOGY AWARDS CASE STUDY
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technician to master the black box of
controls automation.
Having a full-time staff person dedicated to
the building BAS/EMS has enabled this owner to
effi ciently develop, test, commission, verify and fi netune
the various controls strategies. Additionally, the
full-time BAS controls technician provides hands-on
fi eld assistance to address any necessary calibration
of adjustment of BAS/EMS control components and
to provide continued education and awareness to all
building facilities personnel on what is required to
ensure building systems are operating effi ciently (day,
night, varying space load conditions, etc.).
INDOOR AIR QUALITY & THERMAL COMFORT
The 157 Berkeley Tower maintains an Energy Star
certifi cation, which requires an annual site visit and IAQ
testing. In 2022, the average CO2 concentration of fi ve
randomly tested spaces in Liberty Mutual Tower was
512 ppm, which aids in the owner's health and wellness
objectives for the occupants.
Related controls strategies implemented to optimize
ventilation include:
 Conference center VAV ventilation control with
the installation of motion sensors and additional
CO2 sensors. This included installing open space
type CO2 sensors to maximize the demand control
ventilation strategies for conference rooms and large
collaboration spaces.
 For rooms with fan-powered terminal boxes, the
dampers modulate based on the maximum airfl ow
setting to maintain space CO2 less than maximum
CO2 setpoint.
 Installation of VAV control for chilled beams to
provide required ventilation air based on occupancy
and maintaining CO2 levels below alarm setpoint.
 Restroom ventilation optimization and reduction of
restroom supply air with undercutting of doors prevents
over-cooling when outdoor air is 70°F (21°C) and above.
 Optimized garage ventilation opting for a passive
operation instead of mechanical ventilation. This energy
reduction strategy was identifi ed when the owner saw
that the garage ventilation system (exhaust and supply
fans) was cycling on/off up to 30 times a day by visual
observation and validating via EMS trends. Additional
CO2 sensors were installed throughout the garage with
a time delay control strategy. This has signifi cantly
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reduced the fan's maintenance requirements and
cycling has been reduced to about three times each day
even during the post-COVID return-to-work mode.
INNOVATION
One of the biggest challenges our industry faces is
transforming existing, poor performing buildings into
high-performance, energy effi cient buildings. The
owner has committed to a 50% reduction of Scope 1 and
2 global greenhouse gas (GHG) emissions from 2019
levels by 2030.
To ensure that energy effi cient operation is
maintained as various fl oors undergo renovation, the
owner has developed with input from the design team
a list of required controls strategies to incorporate into
the space fi t out design to ensure a consistent building
systems operation. Having a full-time dedicated
building facilities' energy engineer provides the owner
the capability to beta test new EMS strategies, and
with the data that is recorded, review EMS graphics
feedback and trends occur quickly. Some beta testing
strategies include:
 Enabling a fl oor's VAV terminal boxes one hour after
the fl oor's AHU and fan powered terminal boxes start,
reducing peak demand.
 Ramping AHU fans ramp up to setpoint after
start-up for a set time (30 minutes) to level start-up kW,
reducing building electric peak demand.
 Solar reset for AHU discharge air temperature reset
based on solar intensity by installing solar sensors is
being planned.
To date, their building is operating at an EUI of
35 kBtu/ft2·yr (397.5 MJ/m2·yr), a massive 60% energy
reduction, and $4.5 million in utility savings from
their 2014 baseline. At the same time, their operational
carbon footprint has drastically reduced to 1,600 metric
tons of CO2 equivalent. These reductions have been
achieved through ongoing proactive commissioning
focusing on fi ne-tuning building automation sequences.
The owner also implemented innovative HVAC control
strategies such as optimized ventilation control, solar
reset for AHU discharge air temperature and discretely
staggering start time of HVAC equipment for peak
demand reduction.
COST EFFECTIVENESS
Undoubtedly, saving energy saves on utility costs.
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ASHRAE Journal - October 2024

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