ASHRAE Journal - August 2024 - 61

2024 ASHRAE TECHNOLOGY AWARDS CASE STUDY
ENERGY EFFICIENCY
The commissioning team-led implementation of a
true integrated design process for this facility reviewed
each discipline from architectural-, electrical-,
mechanical-, plumbing- and owner-provided
equipment to establish performance criteria for the
whole building (Figure 1). Baseline performance criteria
were established based on ASHRAE/IES Standard 90.12013
and the center's 2012 clinic (baseline clinic) which
was operating at about 55.5 kBtu/ft2·yr (630.3 MJ/m2·yr)
and $1.64/ft2 per year ($17.65/m2 per year) average
from 2017 to 2019. The responsible design disciplines
took the initial 30% improvement for each primary
component of their disciplines and reported back the
approach and the performance they could accomplish.
The roadmap provided each discipline with baseline and
target performance goals and the disciplines reported
back how they approached the targets with their design
results and performance characteristics.
Results were compiled into an energy model for whole
building simulation, which projected energy savings
better than a 50% improvement over the 2012 clinic,
resulting in a projected energy use intensity (EUI) of
24.6 kBtu/ft2·yr (279.4 MJ/m2 per yr) with an expected
energy cost of $0.51/ft2 per year ($5.49/m2 per year).
Baseline energy performance was calibrated to the
baseline clinic using actual utility bills.
INDOOR AIR QUALITY
ASHRAE Standard 62.1-2013 was used to establish
minimum ventilation requirements. Because
construction began at the beginning of the pandemic,
ventilation rates ~25% higher than code-level minimums
were pursued. A custom energy recovery unit was used
for the dedicated outdoor air system (DOAS), using
needle-point bipolar ionization in addition to 2 in.
(51 mm) MERV 10 filtration on the central unit and 2 in.
(51 mm) MERV 8A filtration on the water-to-air GSHPs.
Indirect evaporative cooling and a water-to-air GSHP
were used to temper outdoor air delivery to heat pumps.
INNOVATION
The project incorporates a close coupled GSHP system
with distributed water-to-air GSHPs, uses energy
recovery for ventilation and ties the heat pumps located
in central and cooling-dominant areas into the domestic
water heating system using desuperheaters. The HVAC
systems are simple and effective. Their interaction
allows heat to be moved where it is needed and looks
to the ground loop for additional heat rejection or
absorption when necessary. The central plant is six
pumps total-four injection pumps for the ground heat
exchanger and two distribution pumps for the building
which fits in a 10 ft × 20 ft (3 m × 6 m) mechanical room
on the first floor and includes the domestic water entry.
Fiberglass framed windows were used for their
excellent thermal properties in action with a U-value
of 0.19 and solar heat gain coefficient (SHGC) of 0.21
(SHGC of 0.42 for the north-facing windows). Interior
lighting design accomplished a maximum lighting
power density of 0.42 W/ft2 (4.52 W/m2). The innovation
of this project was the integrated design that came
from the initial vision, measurable practical goals and
documented interdiscipline communication.
COST EFFECTIVENESS
The pursuit of zero energy had to meet the board
vision, the community vision and the business case.
The board was motivated by the New England Journal of
Medicine ( " The Imperative for Climate Action to Protect
Health, " January 17, 2019) and a growing awareness of
health-care facilities lagging in building sustainability.
The community vision was evident in neighborhood
participation in early design charrette's and in Pueblo's
City Council initiative to be powered by 100% renewable
energy by 2035. It was up to the design team and
operations and maintenance to provide a cost-effective
approach for systems and equipment and identify the
order of magnitude savings potential. The contractor
prepared a cost evaluation comparing a current similar
code-compliant facility to this facility and determined
an increased cost of ~6% total or $1.5 million ($23/ft2
[$247.60/m2]) on a $24 million dollar project ($375/ft2
[$4036/m2], 2021), including the 280 kW PV array. The
added cost breakout was 35% for architectural features,
27% for mechanical and 38% for electrical. The PV array
required for the baseline clinic model was 465 kW,
through the integrated design and modeling process it
was reduced to 280 kW. The utility provided a $126,940
design incentive at the end of construction. PCHC also
received $5,839 at the end of the first year to apply to
other facilities utility bills. The total utility cost in 2022
was $26,558 ($0.415/ft2 [$.039/m2·yr]), not including the
$5,839 credit (reduces to $0.324/ft2·yr [$.030/m2·yr]).
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ASHRAE Journal - August 2024

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