ASHRAE Journal - September 2021 - 68

ASHRAE TECHNOLOGY AWARD CASE STUDIES
IAQ and Thermal Comfort
A superior level of thermal comfort was a goal of
the design, which resulted in a system selection that
not only controls air but also radiant temperature.
Lower airfl ows also reduce the chance of drafts, and
diffusers were selected with an ADPI of greater than
80. The building was designed with the thermal
comfort assumptions found in Table 1 to comply with
ANSI/ASHRAE Standard 55-2010.
Ventilation airfl ow rates were calculated following the
ANSI/ASHRAE 62.1-2007 ventilation rate procedure.
As most systems are DOAS with air supply below space
temperature, the zone air distribution effectiveness is
1.0. The auditorium has a stratifi ed underfl oor air distribution
design with low-velocity displacement supply,
achieving a zone air distribution effectiveness of 1.2; an
airfl ow measuring station was installed on its outdoor
air intake to ensure proper airfl ow is maintained during
all operating conditions, as well as to enable DCV. Floor
diffuser selection and location were carefully analyzed
to ensure thermal comfort was achieved for occupants.
All AHUs are provided with MERV-13 fi nal fi lters. Carbon
dioxide sensors are installed in densely occupied spaces
(including the top row of the auditorium due to stratifi
cation) and they produce an alarm in the BAS when
CO2 levels exceed setpoints. Laboratories and shops are
negatively pressurized to contain pollutants.
Innovation
The use of TABS for radiant heating and cooling is not
common in North America. Design manuals were used
from North America and Europe to help make the project
design go smoothly and give the team confi dence.
As the Design Building used the TABS for both heating
and cooling, a fi nite element analysis (FEA) study took
place to determine the minimum slab surface temperature
required to meet the space loads. The minimum
slab temperature was determined to be 21°C (70°F),
using 18°C (64°F) chilled water. The slab surface temperature
was compared to typical annual weather data
for the city, and it was determined that, on average, the
dew point exceeded 21°C (70°F) only four hours a year.
Nonetheless, mitigation strategies were put in place,
and dew point is monitored throughout the building.
These strategies include increasing airfl ow rate to high
dew-point zones, followed by shutting off water fl ow to
zones, if required. During unoccupied hours, the AHU is
68
ASHRAE JOURNAL ashrae.o rg S E P T E M B E R 2 0 2 1
TABLE 1 Design thermal comfort assumptions.
Assumed Activity Levels
Clothing Thermal Resistance
Dry-Bulb Temperature
Radiant Thermal Control
Humidity
Air Velocity
1.1 met (All Areas Except Workshops)
0.5 clo (Summer), 1.0 clo (Winter)
Summer: 77°F in Radiant Cooled Areas, 75.2°F in
Areas Without Radiant Cooling
Winter: 69.8°F
Designed for 84°F Maximum,
70°F Minimum Floor Temperature
60% Maximum
< 40 fpm
enabled in recirculation mode as required to meet dewpoint
requirements that may result from infi ltration.
Operation and Maintenance
Operation and maintenance personnel were involved
in design presentations throughout the design process,
providing feedback on design improvements to ease
maintenance. The auditorium supply plenum was made
accessible to ease cleaning, and baskets were included
with diffusers to catch items that may fall through the
diffusers. Radiant cooling was discussed to ensure
the appropriate measures were incorporated into the
design. The radiant tubing was placed in the middle of
the 250 mm (10 in.) structural slabs to reduce the chance
of anchors piercing the tubing.
All major mechanical equipment (AHUs, heat pumps
and rainwater cistern) are located indoors to ease maintenance
during harsh weather conditions and increase
equipment life at this coastal location.
The mechanical and electrical systems are also
designed to be used as a teaching aid for engineering
students. Piping systems in mechanical rooms are
color coded according to service, matching the building
automation system (BAS) graphics, allowing students to
more easily understand system operation. Large screen
TVs are located in mechanical rooms, allowing tour
guides to display BAS graphics to students.
Cost-Effectiveness
An economic analysis took place, comparing three
options for the heating system. The baseline was using
the university's district heating plant. A second option
considered was an air-to-water heat pump backed up
by district heating, while the third option was a ground
2021
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ASHRAE Journal - September 2021

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