ASHRAE Journal - April 2020 - 48

2020

ASHRAE TECHNOLOGY AWARD CASE STUDIES

quite robust, with tiers of hanging vines draping down
through multiple canyon levels.

Energy Efﬁciency
Energy Systems
Early in design, the University's Planning Design and
Construction Department (PD&C) made it explicitly
clear that simple operation, proven technology, low
annual maintenance, and long-term durability were to
be equally prioritized with high energy efﬁciency. The
design process involved integration of feedback from
a broad section of the University's planning, engineering, and operations groups' knowledge base. Designing
and detailing the building envelope and shade ﬁns,
landscaped balconies, and unusual building systems
involved a high level of collaboration among the architect, engineer, and contractor team. Certainty that the
aggressive energy-use targets required to reach LEED
Platinum would actually be achieved was established
through implementation of whole-building commissioning and an energy measurement and veriﬁcation
(M&V) program, originally intended to run through
the ﬁrst two full years of operation, but which is still in
operation, thanks to the efforts of PD&C (Figure 3).
A simpliﬁed list of energy-efﬁcient technologies
includes the following.

Building Design and Envelope
* Passive conditioning of primary building circulation;
* Solar shade ﬁns; and
* Deep, high thermal mass, overhanging balconies
store nighttime coolness.

HVAC
* Dedicated outside air units serving chilled-beam
and underﬂoor displacement ﬂoors 2-5; single duct VAV
with reheat ﬂoor 1;
* Occupancy control of outside air ventilation and
room temperature set point; and
* Ventilation relief under balcony overhangs and
large ceiling fans.

Electrical
* Lighting control, including vacancy sensing, daylighting, task lighting;
* High-efﬁciency lighting ﬁxtures;
* Separated metering of house, HVAC, lighting panels;
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ASHRAE JOURNAL

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APRI L 2020

FIGURE 1 Aerial perspective of building model, including roof-mounted DOAS.

* Submetering of HVAC, lighting, plug loads; and
* Preparation for rooftop solar PV above green roof
("agrivoltaics") (Figure 2).
Energy modeling began early in the project.
Design was targeted to exceed ANSI/ASHRAE/IESNA
Standard 90.1-2007 by 30%. Use of a hydronic loop
with overhead chilled beams on the perimeter,
along with low static underﬂoor displacement ventilation in the central open ofﬁces and conference
rooms, and stand-alone four-pipe fan-coil systems
for the larger pod areas, yielded signiﬁcant fanpower savings over an all-air baseline alternative,
since water has a higher heat-transfer capacity over
air. These savings are seen in fan horsepower savings. While the proposed building consumed slightly
higher overall cooling energy than the baseline, the
total cooling system yielded energy savings.
Some difﬁculties in modeling HVAC systems, as
conﬁgured for this building, were experienced.
These were discussed with the software vendor
to construct workarounds, and were then vetted,
extensively, with the LEED reviewer. A comparison
showing annual energy consumption for the ANSI/
ASHRAE/IESNA Standard 90.1 baseline compared
to the design model and year 2017 M&V results is
shown in Table 2.
Results show a signiﬁcant variance between the
modeled versus actual projection for heating (Figure
4). Some of this can be attributed to overestimated
lighting and internal loads in the model, which
drove the power and, thus, the cooling loads lower.
More heat than modeled was certainly needed in

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ASHRAE Journal - April 2020

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