ASHRAE Journal - February 2020 - 29

TECHNICAL FEATURE

connected commissioning program such as the
500-plus DOAS sites described here, manufacturers can use operating data from a much larger and
diverse sample of units to determine potential areas
of improvement.
For instance, aggregated data from the connected
commissioning of 500-plus DOAS units was used by
the manufacturer to develop a more robust algorithm
to control the dew point of a space. The same data
allowed for the optimization of night setback periods for humidity control in larger buildings such as
schools. In some cases, these improvements can also
be applied remotely as part of the connected commissioning initiative itself. Other areas in which a
centralized database can be used by manufacturers
involve:

* Based on the operating data, what is the likelihood
that a unit or component will last its expected lifetime?
Table 1 shows data of runtime and unit cycling that could
be used to assess the probability of system component
failures. The maximum recommended activations and
runtime are typically listed by compressor manufacturers when referencing their expected lifetime.

Identiﬁcation of Performance Outliers

Operational Enhancements

* Are there systems that serve very similar applications while exhibiting much different performance
metrics? Why?

* Are there speciﬁc scenarios that cause inefﬁciencies
in logic?
* Can software be used to identify hardware failures?

TABLE 1 Average, maximum observed and maximum recommended compressor

activations and unit runtime (hours) for over 500 DOAS over the course of a year.
METRIC

AVERAGE

UPPER BOUND

MAX REC.

Activations

1,260

3,966

10,000

Runtime

3,440

6,340

6,667

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FEBRUARY 2020

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ASHRAE Journal - February 2020

Table of Contents for the Digital Edition of ASHRAE Journal - February 2020