ASHRAE Journal - June 2019 - 61

SECOND PLACE | 2019 ASHRAE TECHNOLOGY AWARD CASE STUDIES

Marine Way, Intuit's new 185,000 ft2 (17 187 m2) headquarters building in Mountain View, Calif., houses ofﬁce
and conference space for the Silicon Valley technology
ﬁrm. The combination of creative low ﬁrst cost and low
energy mechanical systems, an intelligent façade shading system, and a solar photovoltaic system has resulted
in a unique space with a small environmental footprint.
Energy Efﬁciency

Energy efﬁciency was a primary
focus of the design. To that end, a
rigorous conceptual design-phase
efﬁciency charrette was held with
all the project's stakeholders,
including the owner, facilities personnel, architect, engineers and
future occupants. The goal of the
charrette was to brainstorm how
the building's form and façade
could contribute to energy efﬁciency and occupant satisfaction
without sacriﬁcing the desired
aesthetic.
The design team chose a fritted
curtainwall system that incorporates an automated shading system.
The shading system controls each
curtainwall bay independently, in
response to real-time sky conditions, to maximize daylighting
harvesting while always preventing
glare and direct solar beam onto the
occupants of the open ofﬁce.
This automated shading system was estimated to reduce the
annual utility costs of the building
by approximately 2%, compared to
manually operated window shades.
The building's mechanical design
incorporates an underﬂoor air distribution (UFAD) system. The team,
having substantial experience with
Steve Gross, P.E., is an associate, senior energy analyst,
Hormoz Janssens, P.E., is a managing principal, and Shawn
MacLean, P.E. is a principal at Interface Engineering, San
Francisco.

UFAD systems, decided to alter the
traditional system design by decoupling interior loads and building
ventilation from perimeter heating
and cooling loads by incorporating
a perimeter overhead radiant panel
system (Figure 1). In the open ofﬁce
spaces, this allowed all the typical fan powered boxes, ductwork,
and reheat to be eliminated. This
approach also eliminated concerns
of distribution losses that are a typical complaint of UFAD systems at
the perimeter.
The UFAD system allows an
elevated supply air temperature of 62°F (17°C) to be used,
which in turn allows an elevated
chilled water temperature of
52°F (11°C) to be used (versus the
traditional 55°F and 44°F (13°C
and 6.7°C), respectively). These
milder temperatures result in an
extremely high chiller efﬁciency
of 0.50 kW/ton (0.14 kW/kW) at
design conditions and a NPLV
of 0.3 kW/ton (0.09 kW/kW). It
also allows the integrated waterside economizer to function for
approximately 1,500 additional
hours, and the airside economizer
to function for an additional 2,700
hours per year.
The mechanical design also eliminates reheat by using the perimeter
radiant panel system, which is provided heating hot water from a 95%
efﬁcient condensing boiler plant.

J U N E 2 0 19

ashrae.org

ASHRAE JOURNAL

http://www.ashrae.org

ASHRAE Journal - June 2019

Table of Contents for the Digital Edition of ASHRAE Journal - June 2019