ASHRAE Journal - April 2021 - 66

2021

ASHRAE TECHNOLOGY AWARD CASE STUDIES

bringing in excess outdoor air during the vast majority of operating hours to take full advantage of the mild
climate. Building schedules have been adjusted to
begin providing minimum ventilation one hour prior to
scheduled occupancy to meet the preoccupancy ventilation requirements of Title 24.
New zone controls limit discharge air temperature in
heating mode, consistent with Standard 62.1-2016, to help
maintain high air distribution effectiveness. Thermal
comfort is improved by using demand-based resets, which
drive the system to respond to " request " signals from each
zone for additional cooling or airﬂow. These resets actively
maximize energy efﬁciency while ensuring thermal comfort is maintained in the most demanding zones.
While there is no active humidity control, the mild
coastal climate maintains space relative humidity
between 20% and 70% all the time and between 40%
and 60% most of the time. Space temperatures are
maintained between 70°F and 75°F (21°C and 24°C).
The space conditions coupled with an assumed clothing insulation of 1.0 clo and a metabolic rate of 1.1 met
ensure that all spaces are maintained within the
Standard 55-2017 comfort zone. Occupant surveys were
conducted by the University of California, Berkeley
Center for the Built Environment before and after the
retroﬁt to evaluate the impact of the project on occupant
satisfaction. The surveys showed an increase in occupant satisfaction with their thermal environment. In
addition, space temperatures were measured with data
loggers in a sampling of spaces to objectively evaluate
the improvement in temperature control.
The medical ofﬁce building is connected to an adjacent
hospital building via a corridor. Prior to the retroﬁt, the
buildings experienced over-pressurization and a space
pressure imbalance with a signiﬁcant amount of air being
transferred between buildings, causing a " wind tunnel "
effect in the connecting corridor. These pressurization
issues were resolved by the Guideline 36-2018 building
pressure control sequences. In addition to normal building pressure control, the general surgery area is maintained at a slightly positive pressure relative to the corridor, with individual surgery rooms maintained slightly
negative with respect to the general surgery area.

A Model of Innovation
This project served as part of a California Energy
Commission-funded demonstration project, which aims
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ASHRAE JOURNAL

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to promote and validate the effectiveness of Guideline
36-2018 using demonstration sites such as the medical ofﬁce building, and to transform the BAS market
by streamlining design and installation processes. This
project exempliﬁes the potential of Guideline 36-2018
sequences as a key approach to cost-effectively achieve
signiﬁcant energy savings and large-scale decarbonization in existing buildings (see " Environmental Impact "
section). Following the success of this project, the building owner has standardized on the use of Guideline
36-2018 sequences across its portfolio of buildings
throughout the United States, and the use of Guideline
36 will contribute to the reduction in BAS implementation and commissioning costs. The owner will continue
to promote standardization.

Operation and Maintenance
The engineering staff at the facility was involved in the
design process from the beginning and reviewed bid
documents prior to issuance for conformance with their
facility standards. Due to the heavy fog in the area and
salty air from coastal location, special attention was paid
to limit the potential of corrosion, including using 304SS
cabinet walls in the coil section, coated steel walls in all
other sections, ASTM-rated salt-spray coatings on copper/copper coils and all exposed surfaces.
The supply and relief fans are direct drive for reduced
maintenance. Supply fan arrays were installed with two
VFDs per array to provide redundancy. Manual blank-off
plates, which are more efﬁcient and less expensive than
backdraft dampers, are stored in the AHUs. The operators are alerted by the BAS to slide these over failed supply fans to prevent backﬂow through inoperable fans.
The new BAS front-end facilitates operation and
maintenance through features including graphics for
all major equipment with animations to indicate equipment status and alarms, user-adjustable values for every
setpoint, direct hyperlinks in the graphics to submittals
and sequences of operation, hyperlinks throughout the
graphics to streamline navigation between associated
equipment and summary graphics to provide an overview of all VAVs, AHUs and exhaust fans. The BAS also
includes AFDD, hierarchical alarm suppression and
rogue zone identiﬁcation logic, all of which are featured
in the Guideline 36-2018 sequences used for this project.
The AFDD and analytics platforms provide automatic
alerts to engineering staff of potential equipment issues

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ASHRAE Journal - April 2021

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