ASHRAE Journal - April 2020 - 52

VFD
VFD

Operations and Maintenance (O&M)

VFD
VFD

CHB

AFMS M
Filter

WTRD

Filter

Cooling
Coil

Return Air
M

WTD

Preheat
Coil

Cooling
Coil

M
Year three of operation has not
CHB Supply
revealed any latent operation and
Fans
WTRD M
maintenance issues, occupant
complaints, or unusual numbers
DV Supply Fans
of HVAC shop calls. The most
M
RA
signiﬁcant issues have related
DV
to faulty metering early on and
a failure of the automatic control of the outside air dampers
FIGURE 5 Dual-tunnel air handler.
due to a stuck damper actuator.
Interestingly, that failure was ﬁrst
picked up in review of monthly M&V data, when a
large variance in monthly building chilled-water
consumption over the previous year was observed.

Cooling
Coil

2020

ASHRAE TECHNOLOGY AWARD CASE STUDIES

NC
M

WTD

M
WTD
NO

NO
HHWR
HHWS
CHWR
CHWS

Cost Effectiveness
Demonstration of the cost-effectiveness of systems
designed for ENR2 was a continual challenge. As one
of the ﬁrst systems of its kind in Southern Arizona,
contractors found it difﬁcult to estimate labor costs.
This may have driven a premium of the upper-ﬂoor
system over the more conventional single-duct
reheat systems installed on the ﬁrst ﬂoor (Table 3).
Although use of chilled beams and UFAD did enable
a 1 ft reduction in the ﬂoor- to-ﬂoor heights, it
was difﬁcult, in the end, to discern any tangible
reduction in general construction cost. The effort
to contain the mechanical budget at under $45/ft2
($484/m2) drove much of the simpliﬁcation to dualtunnel outside air units and the two-pipe, chilledbeam arrangement. Collaboration with the general
contractor and subcontractors to derive a perimeter chilled-beam installation detail that worked
within the overall construction sequence involved
extensive three-dimensional modeling, independent clash detection software and construction of
a mock-up. Yet the ﬁnal cost per square foot based
on the general contractor's schedule of values for
mechanical systems yields a 2.4-year payback over a
conventional VAV with reheat system.

Environmental Impact
A side-by-side comparison of ENR2 building energy
use to other buildings on the University of Arizona
campus with similar occupancy is dramatically low. A
more signiﬁcant impact of this building design is the
52

ASHRAE JOURNAL

ashrae.org

APRI L 2020

ENR2's courtyard attracts a thriving, passively cooled ecosystem.

potential long-term beneﬁt that would be derived
if the project's primary objectives of ensuring interdisciplinary collaboration between environmental,
earth sciences, natural resources and an engaged
student and faculty yields practical results addressing
the causes and effects of climate change. The success
of this building is also due to the Integrated Design
Process (IDP). Lead by the University's Planning,
Design and Construction staff, Design
Architects, Richard + Bauer, the A/E
of record, GLHN, user groups and
the local community worked closely
together to balance the cost, energy,
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space and aesthetic demands.

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ASHRAE Journal - April 2020

Table of Contents for the Digital Edition of ASHRAE Journal - April 2020