ASHRAE Journal - September 2022 - 60

ASHRAE TECHNOLOGY AWARD CASE STUDIES
introduced via the active chilled beams to provide a zone
air distribution effectiveness of Ez = 1.0.
In the auditorium, ventilation air and cooling supply
are both introduced through an underfl oor air plenum,
using displacement ventilation to cool and ventilate. The
space is served with a high return, providing a zone air
distribution effectiveness of Ez = 1.2.
The project design achieved LEED Credit IEQ 7.1 for thermal
comfort, demonstrating compliance with ASHRAE
Standard 55-2010. Design temperature goals were 75°F
(24°C)/50% RH in summer and 72°F (22°C)/20% RH in
winter. The building is not actively humidifi ed. Clo levels
were assumed to be 0.66 in spring and summer and 0.70
in fall and winter. Metabolic rate in offi ces and conference
rooms was assumed to be 1.1, and 1.0 for classrooms.
Design air speed for all spaces is below 40 fpm (0.2 m/s).
Occupants in offi ce and administrative spaces are also
able to control natural space ventilation through the
operable windows. Windows in spaces without permanent
occupants, such as classrooms, are locked closed.
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A key challenge was physically integrating 21st century
systems within a facility not intended to house them-
and retain as much of the original building architecture
as possible. The building structure was characterized
by low fl oor-to-fl oor heights and an original masonry
system that integrated air supply and relief shafts within
thick corridor walls. A hot deck/cold deck tunnel (split
top/bottom) ran under the ground fl oor central corridor
that fed a series of vertical masonry shafts in corridor
walls that served individual upper spaces. The original
mechanical design was a pneumatically controlled multizone
system distributed in the building's structural
walls.
To build the new systems into Marston Hall, a similar
utility distribution strategy was used. The hot deck/
cold deck tunnel below the ground fl oor hallway was
cleared out to create a walkable service/utility corridor.
A majority of the MEP ducts, pipes and associated
services (which originate from central mechanical
rooms in the basement) are distributed in this lower
level to multiple vertical chase locations throughout
the fl oor plate. This allowed the horizontal distribution
on each occupied fl oor to be minimized and contained
within small zones on each fl oor. It also allowed ceiling
heights to remain higher than if large utilities were
piped and ducted across the fl oor plate on each occupied
level.
The DOAS ventilation system was used to minimize the
ventilation energy load. In addition to energy benefi ts,
providing only the Standard 62.1-2010 required ventilation
rate via the DOAS system also allowed the ventilation
and exhaust duct mains to be as small as possible,
easing routing through the building. However, in some
cases the code-minimum ventilation air provided to
certain zones was not enough to meet the chilled beam
activation minimum airfl ow rate. For this reason, parallel
fan-powered VAV boxes were used on the DOAS
system. Ventilation air is provided via the VAV air valve
through the chilled beams to occupied spaces. When
the chilled beams have a call for cooling, the parallel fan
energizes, boosting the airfl ow to the chilled beams to
the rate required for proper activation and cooling. This
allowed the primary ventilation ducts to remain as small
as possible to ease space constraints.
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ASHRAE Journal - September 2022

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