ASHRAE Journal - September 2023 - 54

FIRST PLACE 2023 ASHRAE TECHNOLOGY AWARDS
dedicated water-to-water heat pump system that can
produce chilled or hot water supplied to a face and
bypass coil, which modulates to maintain a room neutral
leaving air temperature. Using a face and bypass coil
arrangement significantly reduces the amount of energy
required to provide the desired discharge air setpoint by
reducing the amount of air that needs to be cooled and
dehumidified or heated. This air is then blended with
the bypass air stream to achieve a space neutral leaving
air temperature. Blending the air with the bypass air
achieves the desired space neutral temperature. The
system also implements demand-control ventilation
(DCV) by measuring CO2 in each room and adjusting
the amount of ventilation air needed to maintain the
occupied spaces to be below 650 ppm above ambient,
per ASHRAE Standard 62.1-2016. Heat pumps and
ventilation units are also equipped with MERV 13 filters
to reduce airborne particles and virus transmission.
During the pandemic, modifications were made to the
BAS schedule to allow the DOAS units to run two hours
before and after occupancy to increase the effectiveness
of the high efficiency filtration system. Due to the
school's proximity to interstates, industrial sites and
a shipping port, the outdoor air system was designed
with an emergency mode that closes off the outdoor air
intakes if there is a release of hazardous chemicals or
other airborne contaminants. Air intakes are located
at the highest point of the buildings, reducing the
exposure to ground contaminants.
Creating a high-performance learning environment
with optimal thermal comfort for students and teachers
is paramount, and the design team made sure this was
not compromised for energy reduction. All occupied
spaces have adjustable thermostats that allow each space
to maintain temperatures between 68°F (20°C) and 74°F
(23°C) in accordance with ASHRAE Standard 55-2013.
Each thermostat has an override button that allows spaces
to be conditioned during unoccupied hours as needed.
Innovation
Graceland and Holabird were designed with a
decoupled geothermal wellfield system that operates
independently of the heat pump loop system serving
the building. The system is comprised of a set of basemounted
pumps responsible for circulating water
through the geothermal wellfield, and dedicated in-line
circulator pumps serve each water-source heat pump.
54
ASHRAE JOURNAL ashrae.org S E PTEM B ER 2023
CASE STUDY
These inline pumps circulate only as much water as
needed to satisfy that specific piece of equipment
when there is a call for heating or cooling. This allows
the dedicated geothermal wellfield pumps to operate
independently of the building and to circulate only
as much water as is required to maintain the desired
wellfield differential temperature. This load matching
reduces excess pumping energy typically required to
satisfy the minimum flow requirements of the terminal
equipment, while keeping the interior heat pump water
loop at a temperature range that allows the equipment
to operate efficiently.
Most of the time, the wellfield pumps will remain off,
and the heat is captured and transferred internally and
simultaneously between cooling and heating needs
in the building. A primary-secondary header serves
as an air separator allowing the interior and exterior
systems to have different system flows while remaining
hydraulically independent.
Another innovative aspect of the project was the
advanced metering system (AMS), which separates
the building energy components into HVAC, lighting,
kitchen and plug loads for BCPS to monitor where the
energy is going and compare it to the energy model. AMS
allows BCPS to look for anomalies in energy use to guide
building operations toward higher efficiency.
The AMS meters connect to a live, interactive
dashboard that connects learning and real-time energy
data to the built environment where students and
teachers can track building performance, incorporating
sustainability into their curriculum. The customized
dashboard easily converts between English and Spanish.
The dashboards allow the individual schools to be
used as learning labs for the district, students and
community. Rarely are facilities operated by the same
owner, have identical massing, are in the same climate
zone and designed with the same mechanical/electrical/
plumbing systems. By designing them as identical
zero energy/zero operational carbon schools with only
a 180 degree rotation difference, BCPS has a unique
opportunity to be used as learning labs for the school
district and design teams. BCPS can make adjustments
to one building, such as increasing ventilation or
expanding run time on HVAC equipment, for example,
and understand how this affects the performance of the
building.
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ASHRAE Journal - September 2023

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