ASHRAE Journal - July 2019 - 35

2019 ASHRAE TECHNOLOGY AWARD CASE STUDIES

A Wood Trellis Shades SouthFacing Glazing During the
Summer

Polyisocyanurate Insulation
Achieves R-22 Walls and R-40
Roof

Argon-Filled Insulated Glass with
Ceramic Frit Pattern at West
Glazing and Upper Lights at South
and East Glazing

Custom-Variable Volume AirHandling Unit with Total Energy
Recovery Wheel, Fan Arrays and
Demand-Controlled Ventilation
Sequences

95% Efﬁcient
Condensing Boilers

Glazing Quantity is 21% of
Underﬂoor HVAC System LED Lighting and Daylighting
Overall Exterior Wall Area.
Control Throughout Building
Judicious Use of Glass
Provides Daylight and Views
While Mitigating Heat Loss
and Heat Gain
FIGURE 2 Integrated architecture and engineering systems worked together to meet the client's goals.

national average for existing libraries in the CBECS
database.
The building's energy use from July 2017 through
June 2018 resulted in an operational EUI of
48.4 kBtu/ft2·yr (549.7 MJ/m2·yr). This site EUI reﬂects
a large reduction in energy use when compared to the
ASHRAE Standard 90.1-2010 baseline, CBECS baseline
and the SB 2030 baseline.

Indoor Air Quality and Thermal Comfort

The underﬂoor air system improved thermal comfort and indoor air quality. The freshest supply air
is delivered directly to the breathing zone through
ﬂoor-mounted, displacement-type diffusers. The air
is returned at the ceiling level to leverage the natural
buoyancy produced by heat sources and more effectively
remove heat loads and contaminants from the spaces.
Return grilles were integrated into the ceiling through
perforated panels in alignment with the columns of the
building. The perforated return grilles virtually "disappear" into the architecture.
ASHRAE Standard 55-2013 guided the selection of
appropriate displacement-type diffusers for the variety of occupants and activity levels in the building. For
example, the Tech Services department in the library
handles and moves a large quantity of library materials
every day, and the staff is at a higher activity level than
typical ofﬁce staff.
In contrast, the library's study and meeting rooms
typically see low activity from the occupants. In many

of the public library spaces, non-adjustable ﬂoor diffusers were used. However, in the private ofﬁces,
staff conference rooms and break rooms, a mixture
of manually operable and motorized ﬂoor diffusers
responds to the variable load, occupant and activity
levels in the space.
Ventilation rates for the library were calculated
using ASHRAE Standard 62.1-2010's Ventilation Rate
Procedure. The underﬂoor air distribution system and
ﬂoor diffusers have a zone air distribution effectiveness
of 1.0. The building's air-handling unit is ducted with
separate connections for the minimum outdoor air and
economizer outdoor air. The minimum outdoor air ductwork contains an airﬂow measuring station that continuously measures the ventilation airﬂow and provides
an alarm at the building's automation system if it does
not meet setpoint. The active-ﬁeld, polarized media air
cleaners in the AHU offer a MERV 15 performance while
imposing a lower pressure drop on the system when
compared to typical ﬁlter media.
The conference rooms, community room, break
room, and other high-occupancy areas are controlled
with CO2 sensors. These rooms are served by underﬂoor fan powered boxes. During a CO2 alarm, the
boxes are automatically controlled to increase supply air, and the reheat coils prevent the boxes from
overcooling.
The custom air-handling unit is also equipped with
demand-controlled ventilation sequences. The building's outdoor air is reset based on CO2 measurements
J U LY 2 0 19

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ASHRAE Journal - July 2019

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