ASHRAE Journal - May 2023 - 57

TECHNICAL FEATURE
VAV sequences and minimum setpoints.
Since the project changes were
primarily controls programming, converting
the system from VAV to full fl ow
and back again was simple for the facility
operators.
Related Code Changes and Opportunities
In California, there have been two
FIGURE 4 Energy savings of Phase 2 and Phase 3, compared to baseline.
Projected Annual Energy Consumption for AHUs (kBtu)
1,000,000
900,000
800,000
700,000
600,000
500,000
400,000
300,000
200,000
100,000
-
34%
50%
code changes since the beginning of
this project related to the future viability
of hospital VAV. In 2019, after the
start of this project, California issued
a supplemental code change allowing
use of Standard 62.1 in administrative
areas of hospitals. In 2021,
California changed the mechanical
code to eliminate return air VAV boxes
for rooms that do not have pressure
relationships.
The fi nal research project report
includes a further recommendation
that California require VAV controls
in hospital zones. This would align
California to ASHRAE Standard
90.1- 2016, where VAV controls are
required in hospitals, and to other
nonresidential zones in California's
Title 24 building energy standards.
The fi nal report recommends
two changes be considered by
ASHRAE/ASHE Standard 170. The
fi rst is to reduce excess ventilation
minimums. Project data shows no
demonstrable air quality benefi t
to ventilation in excess of 2 ach.
As such, code minimums could be
reduced with no measurable effect on air quality.
Second, several noncritical spaces in ASHRAE/
ASHE Standard 170-2017 require positive pressure
(e.g., laundry storage, medication rooms). This is
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Baseline AHU Phase 2 AHU Phase 3 AHU
Projected Annual Energy Consumption for Chilled Water Plant (North Tower Only) (kBtu)
2,000,000
1,800,000
1,600,000
1,400,000
1,200,000
1,000,000
800,000
600,000
400,000
200,000
-
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Baseline Chilled Water
Phase 2 Chilled Water
4,000,000
3,500,000
3,000,000
2,500,000
2,000,000
1,500,000
1,000,000
500,000
-
Baseline Boiler
Phase 3 Boiler
Phase 3 Chilled Water
Projected Annual Energy Consumption for Boiler Energy (kBtu)
30%
36%
29%
22%
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Phase 2 Boiler
Project Conclusions
ostensibly to protect " clean " air in those rooms from
" contaminated " air in neighboring rooms. The project
data showed similar contamination levels in all
spaces. The noncritical positive pressure rooms that
were tested in this project are not, in fact, cleaner than
their neighbors.
Based on air quality data from an operating hospital,
the research concluded that there was no direct or
strong relationship between air quality and ventilation
rates above 2 ach. Minimum ventilation of 2 ach
satisfi ed the air quality needs in all patient spaces.
There was no benefi cial value to increased ventilation,
from 2 ach to 12 ach, toward measurable reductions of
contaminant levels.
Clean and safe indoor air environments achieved
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kBtu
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ASHRAE Journal - May 2023

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