ASHRAE Journal - April 2021 - 67

FIRST PLACE | 2021 ASHRAE TECHNOLOGY AWARD CASE STUDIES

with possible diagnoses, prioritized based on estimated
energy and comfort impacts.
Detailed commissioning was critical to ensure the new
sequences were programmed correctly and that the system performed as designed. The intimate project knowledge and understanding of the control system design
intent was leveraged by having the lead design engineer
also serve as the commissioning authority. Functional
performance tests were used to exercise systems through
an array of simulated conditions designed to conﬁrm that
individual pieces of equipment and associated BAS control work properly to meet the design intent.
After all functional tests were successfully completed,
four weeks of trend data was accumulated and analyzed
to ensure that sequences of operation were programmed
correctly and that control loops were stable and controlling properly within an acceptable range. Working
together, the commissioning authority and the contractors resolved all operational issues logged throughout
the commissioning phase, and new trend data was
reviewed as conﬁrmation.
After successful completion of the project, an AFDD
and building analytics platform were installed and
used to identify additional operational issues found
during the one-year warranty period. The commissioning software automatically generated monthly
reports with action items for the contractor to address
and remains installed for continuous monitoringbased commissioning for facilities staff. Action items
are prioritized using estimated energy cost impact,
while providing a description of operational faults and
possible diagnoses.
Comprehensive operations and maintenance (O&M)
manuals were provided to the owner, and an eight-hour
training session was held for the entire facilities staff. The
training session provided the facilities staff with the critical
understanding of the design intent, operational features,
and tools available to them to ensure consistent, optimized
performance. The training session was recorded and distributed to the facilities staff for future reference.

Cost Effectiveness
The initial project scope included replacement of all
air-handling and terminal units. However, the results of
the pre-retroﬁt investigation indicated that most existing operational issues with the terminal units could be
resolved by upgrading the controls and that the terminal

units could largely be reused and upgraded on a caseby-case basis. This ﬁnding drastically reduced the overall project cost, as it removed the replacement of nearly
350 VAV boxes from the project scope.
The total project cost of $7.3 million included engineering design, replacement AHUs, BAS and mechanical contractor scope as well as general contractor management
fees. The existing AHUs were 25 years old and beyond
their expected service life. A like-for-like replacement of
the AHUs would not have achieved nearly the same energy
savings, as the bulk of the energy savings are associated
with the zonal upgrade to DDC and Guideline 36-2018
high-performance sequences of operation. With a BAS
ﬁnal implementation cost of $1.7 million and annual
energy savings of $192,000, the project would have been
cost-effective as a stand-alone energy-efﬁciency project
with a simple payback of 8.9 years.

Environmental Impact
This project reduced the building environmental
impact by achieving signiﬁcant energy-efﬁciency
improvements, with associated reductions in pollution and fossil fuel consumption. More critically, this
project serves as a crucial demonstration of the importance of HVAC controls and a cost-effective approach
to signiﬁcantly reduce building energy use in existing
buildings. In particular, the reduction of heating energy
use by more than 55% is an illustration of the potential to cost-effectively realize massive decarbonization
in the existing building stock. The reduced building
energy consumption allowed for a larger percentage
of total electricity use to come from the large on-site
photovoltaic system, reducing the use of grid-supplied
electricity, which is largely supplied by nonrenewable
energy sources.

Conclusions
The medical ofﬁce building is an energy-efﬁcient building, which uses ASHRAE Guideline 36-2018 to demonstrate signiﬁcant energy savings in existing buildings with
an upgrade of existing building automation system and
upgrade of zonal controls from pneumatic to DDC.

References

1. Taylor, S. 2014. " Select & control economizer dampers in VAV
systems. " ASHRAE Journal 56(11).
2. Taylor, S., et al. 2012. " Dual maximum VAV box control logic. "
ASHRAE Journal 54(12).
APRI L 2021

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ASHRAE Journal - April 2021

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