ASHRAE Journal - September 2022 - 47

TECHNICAL FEATURE
energy use but also the impact of the retrofi t in two
modes (with and without DCV) in a compressed schedule
of one year.
The proposed retrofi t is a fraction of the cost of full system
replacement and reduces energy consumption now,
while putting off full system replacement. The necessary
complementary repair of failed equipment that occurs
at the time of retrofi t enables the controls changes to be
effective and readies the equipment for continued service.
The technology demonstration project showed signifi
cant energy savings (24% to 60%) at the AHU across
the fi ve units. And, it was deemed to have negligible
O&M impact and inconsequential impact on comfort.
LCC analysis showed attractive returns for the conventional
units and adequate returns for two of the three
neutral deck units. Conventional units in fairly good
shape with large energy costs and variable occupancy
should be given highest priority. The DCV option showed
merit as it added approximately 5% to the retrofi t cost
and delivered an average 50% increase in NPV. The technology
transfer effort is expected to ease deployment
of the retrofi t and scale savings across the DOD's large
inventory of MZs.
The retrofi t, in some cases, may provide additional
energy savings and performance improvements beyond
those described in this article when replacing older
controls that often are out of calibration or failing/failed
in DOD facilities and exhibit operational faults that are
energy intensive. For example, in one of the demonstration
units, the economizer was not working and did not
take advantage of free cooling in temperate weather.
This failure was repaired prior to initiating the fi eld
demonstration and reduced the baseline energy consumption
of the unit. Further, DOD units often do not
have any equipment scheduling implemented and remedying
this as part of the retrofi t presents a signifi cant
opportunity for energy and cost savings by matching
equipment run times to facility operational hours. These
ancillary improvements would improve the fi nancial
impact of the retrofi t effort.
The currently implemented policy9 that allows military
installations to retain a portion of the energy cost
savings for use on other projects allows the retrofi t to
serve as a partial source of funding for future system
upgrades and makes implementation particularly
attractive.
Acknowledgments
The contributions of the many groups involved with this
effort are much appreciated including Environmental
Security Technology Certifi cation Program, U.S. Army
Corps of Engineers Louisville District, Engineer Research
and Development Center-Construction Engineering
Research Laboratory (ERDC-CERL) demonstration team,
and ERDC-CERL Directorate of Public Works, Fort Bragg
Directorate of Public Works, Versar Inc., Eaton Energy
Solutions, Dewberry Engineers, Johnson Controls Inc.,
Alpha Controls & Services, the University of Illinois
Facilities & Services, Redstone Arsenal Directorate of
Public Works and USACE Engineering Support Center.
References
1. Schwenk, D., J. Bush, B. Clark, C. Mitsingas, S. Wallace. 2017.
" Converting Constant Volume, Multizone Air Handling Systems to
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ESTCP Final Report. Environmental Security Technology
Certifi cation Program.
2. Westervelt, E., C. Battisti, B. Morton, D. Schwenk. 2021.
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Transactions 127(1).
3. Hittle, D., D. Johnson. 1985. " New Control Design Principles
Based on Measured Performance and Energy Analysis of HVAC
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Construction Engineering Research Library.
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Application of Solution Units. " Form 102.20-AG12(307). Johnson
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5. Schrecengost, R. 2019. " AHUs in HVAC system design
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4, pp. 28 - 30. Federal Energy Managers Program (FEMP), DOE.
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8. 2020 ASHRAE Handbook-HVAC Systems and Equipment, Chap 4,
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9. Beehler, A. 2020. " New Army REFoRM Initiative Will Help
Army Installation Retain 50% of Energy Cost Savings. " U.S. Army.
https://www.army.mil/article/241324/new_army_reform_initiative_
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S E P T E M B E R 2 0 2 2 ashrae.o rg ASHRAE JOURNAL
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ASHRAE Journal - September 2022

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