ASHRAE Journal - October 2020 - 42

2020

ASHRAE TECHNOLOGY AWARD CASE STUDIES

PHOTO 2 Data center. 1) Rear return to economizers hidden behind metal closure
access doors; 2) hot ceiling plenum return non-ducted-all openings to ceiling are
sealed from "cold aisle"; 3) hot air containment chimney; 4) entire room is a "cold
aisle," maintained at 67°F from air discharged off the top of the AHUs; 5) computer room air handling units-N + 2 with full economizer (160 tons net capacity).

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systems to signiﬁcantly reduce direct solar gain and
facilitate implementation of the DV system for patient
rooms. Direct sunlit areas of the ﬂoor where DV is used
were limited to a maximum of 5% of the total ﬂoor area.
Daylighting. The use of daylighting has been optimized to maximize natural light, access to views, and
mitigate energy consumption in many areas of the hospital. Patient rooms and corridors are designed to mitigate direct solar gain, while leveraging daylighting and
access to views. Other areas, such as the post-anesthetic
care unit, use skylights to access natural light, minimizing lighting energy use and facilitating a connection to
the outdoors.

Other Energy-Efﬁciency Strategies

Data Center. In a departure from traditional facilities,
the hospital's data center (Photo 2) is positioned on the
roof (rather than in the basement). The relocation of the
data center resulted in a dramatic reduction of building
chilled water energy and allows the system to use cold
nighttime outdoor air, as opposed to air-conditioned air,
for much of the year.
Economizers are incorporated into the computer room
AHUs directly from exterior walls. A combined return
plenum is above the ceiling; each data cabinet's hot air
discharge is captured through a hot "chimney," which
is sent up into the plenum. When the outside air temperature is less than the return air temperature of the
plenum, the plenum air is relieved using three large

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plenum relief fans. This technique, combined with the
high temperature discharge of the IT cabinets (87°F
[31°C]), allows use of the economizer cycle for up to
6,400 hours per year.
Energy Recovery. Heat and cooling recovery was used
for 100% outdoor air systems in the ACU patient bed
tower, minimizing air distribution into that tower.
Renewable Energy. All electrical energy provided to
the building is from renewable sources. This includes a
small amount of power produced on site (wind power
and photovoltaic), with the remainder of the power from
the City of Palo Alto. The latter is from 100% renewable
sources.
Heating and Hot Water Energy. Eighty-eight percent
of the building's heating and domestic hot water energy
is provided from the campus central energy facilities'
waste heat reclamation.

Indoor Air Quality/Indoor Environmental Quality
Displacement ventilation has been shown to be as
effective as or more effective than standard dilution
distribution systems for control of particulates in the
patient environment. In 2007 the project's engineering ﬁrm led a collaborative study on alternate distribution systems ("Healthcare Ventilation Research
Collaborative: Displacement Ventilation Research, Phase
II Summary Report," tinyurl.com/y3mqou9m). This
study was the basis for the design of Packard Children's;
the team incorporated the report ﬁndings and recommendations to maximize the ventilation effectiveness
and particulate control for patient rooms (Figure 2).
The design complies with and exceeds Facility
Guidelines Institute (FGI)-prescribed Standard 170 for
outdoor air and ﬁltration levels and complies with all
requirements of Table 4A of the California Mechanical
Code (CMC). This compliance is more restrictive and
stringent than ASHRAE Standard 62.1-2010. The study
showed DV at 4 ach is 30% to 50% more effective than
standard overhead distribution at 6 ach. Figure 2 shows
visually overhead ventilation tracer gas particulate modeling, which shows dispersion of particulate throughout
the room vs. Figure 3, which shows particulate modeling
for DV, and particulate is captured at the top of the room
and removed. The use of DV was tailored so the design
could provide the beneﬁts of DV while still complying
with the 2007 CMC requirements under which the building was permitted. DV is now a much more recognized

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ASHRAE Journal - October 2020

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