ASHRAE Journal - September 2022 - 59

FIRST PLACE | 2022 ASHRAE TECHNOLOGY AWARD CASE STUDIES
ing to be the minimum required by
ASHRAE Standard 62.1-2010. With
the amount of ventilation air minimized,
the peak heating and cooling
loads associated with the ventilation
air were then further reduced by
energy recovery wheels in the DOAS
air-handling unit. Fan-powered VAV
boxes were used for meeting the
chilled beam's minimum activation
air when the minimum ventilation
rate did not.
3. Ventilation air reheat and dehumidifi
cation was accommodated by
using a desiccant dehumidifi cation
and energy recovery wheel in the
DOAS unit. No steam energy is used
for reheating ventilation air.
4. Ventilation air supply to the
auditorium is controlled by CO2
sensing.
5. Hydronic heating and cooling
via active chilled beams and perimeter
convectors were used in a
majority of the building to minimize
air-based heating and cooling. Underfl
oor air distribution for cooling
and ventilation was used in the auditorium,
which has higher ceilings
than practical for chilled beams.
6. Lighting power density was
27% less than the allowed ASHRAE
Standard 90.1-2007 baseline per
LEED v2009. Design lighting power
density was 0.86 W/ft2 (9.3 W/m2).
The ASHRAE Standard 90.1-2007
allowable was 1.19 W/ft2 (12.8 W/ft2).
Lighting is also controlled by vacancy
sensors in classrooms and
offi ce spaces.
The average building EUI was
146 kBtu/ft2·yr (1658 MJ/m2·yr) for
the two years prior to renovation.
LEED energy modeling analysis
showed the renovated building
would consume approximately
53 kBtu/ft2·yr (602 MJ/m2·yr), a
64% reduction compared to prerenovation.
The modeled energy
use was a 33.5% reduction over the
ASHRAE Standard 90.1-2007 allowable
86 kBtu/ft2·yr (977 MJ/m2·yr)-
and $38,850/yr less energy cost than
what Standard 90.1-2007 would
allow. Actual use data shows the
building operated at 71 kBtu/ft2·yr
(807 MJ/m2·yr) the fi rst year.
ISU and the design team executed
the LEED M&V analysis credit to
determine causes of the higherthan-anticipated
energy consumption.
The most notable of multiple
issues was a DOAS unit steam valve
commanded open 100% at all times.
This negated energy recovery benefi
ts, used unnecessary steam and
caused increased chilled water use.
Correcting this issue saves as much
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as $24,000 a year in energy cost;
updated energy modeling based on
actual use and occupancy showed
the building operating within 10% of
the updated modeled EUI.
Indoor Air Quality
The building is mechanically ventilated
throughout via the DOAS.
This type of direct ventilation system
removes any doubt each space
is receiving the ASHRAE Standard
62.1-2010 required outside air. The
unit supplies 10,000 cfm (4719 L/s)
of outdoor air fi ltered to MERV 13, an
average of 0.16 cfm/ft2 (0.81 L/s·m2)
over the entire building. Air is
supplied directly to each space at
the ASHRAE Standard 62.1-2010
required fl ow rate, at least. In
offi ce and classrooms, the air is
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ASHRAE Journal - September 2022

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