ASHRAE Journal - November 2014 - 27

TECHNICAL FEATURE

remodeled, without an OCx effort in place to maintain
a high level of performance, system performance will
degrade over time.
For an OCx program to be successful, it is imperative that first, the building be properly commissioned.
Whether the building is new or existing, the systems that
serve the building must be operating correctly and efficiently. OCx should be the final phase of either a commissioning event of a new or existing building.
The goal of an OCx program monitors building performance, and identifies degradation as early as possible.
The actual method used to identify degradation varies
widely, from manual site visits, to real-time automated
fault detection and diagnosis (AFDD). Additionally, OCx
provides the building operators with a continuous program which allows them to monitor and adjust building
operating parameters to fine-tune how equipment and
systems operate. The fine-tuning and continuous monitoring of building systems is one of the best-kept secrets
of an OCx program.

Ongoing Commissioning Overview
When a commissioning event is completed for either a
new or existing building, the final phase is ongoing commissioning. OCx is a process that occurs after a building
has successfully been commissioned. To that point, the
OCx process will help identify issues such as the unforeseen need for additional off-season testing, and control
sequences that may require fine-tuning over a wider
range of varying load conditions that were not seen
during the normal commissioning process. Depending
upon the project requirements, the OCx program will
monitor building performance at the necessary level
(component, equipment, subsystem or system).
There are multiple methods to implement an OCx
program. At the most basic level, a scheduled onsite visit
is made to manually review the performance of building systems. This manual process typically includes
reviewing items such as BAS trend data, setpoints and
utility data. Interviews with the facility operations team
are also performed to understand how the systems have
operated, and to help identify potential problem areas
that may require further investigation.
ASHRAE's Performance Measurement Protocols for
Commercial Buildings (PMP) is an excellent resource for
customers who are looking for a cost-effective OCx
program.

The next level of OCx generally includes some type
of remote connection, such as a virtual private network (VPN) of the BAS. This allows the commissioning
engineer to remotely access trends, saving travel time
to distant sites. BAS data may also be imported into
other analysis tools to help identify potential faults
and problem areas. Virtually all BAS vendors today
offer web-based access to a facility control system,
only requiring an internet connection, IP address and
the required passwords to access the control system
real-time. Historical trend data can be viewed and
analyzed.
A cloud-based platform that can provide continuous
automated fault detection & diagnostics (AFDD) takes
technology even further. Fault detection is the recognition of undesirable abnormalities occurring in equipment, systems, spaces, and/or buildings. Fault diagnostics is the isolation of a root cause of a problem. With
AFDD, everything is a question/answer scenario. The
detection and diagnostic process features automated
software that asks a rules-based question, then runs
data control points through algorithms to detect, and
then diagnose faults.
ASHRAE defines ongoing commissioning as: "A
continuation of the Commissioning Process well
into the Occupancy and Operations phase to verify
that a facility continues to meet current and evolving Current Facility Requirement (CFR) (OPR for
new construction). Ongoing commissioning process
activities occur throughout the life of the facility;
some of these will be close to continuous in implementation, and others will be either scheduled or
unscheduled (as needed)."
ASHRAE Guideline 0.2, The Commissioning Process of
Existing Buildings and Assemblies, is expected to be published later this year. The last step of GL 0.2 includes an
ongoing commissioning phase. The main activities in
the OCx Phase of GL 0.2 are:
* Assemble the OCx Team;
* Update the OCx Plan;
* Verify achievement of current facility requirements;
* Investigate unacceptable performance or outcome;
* Implement corrective actions;
* Update systems manual;
* Update facility personnel training;
* Write/deliver OCx report; and
* Obtain owners acceptance.
N OVEM BER 2014

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