344 Energy Project Financing: Resources and Strategies for Success
- establish a maximum acceptable rate of data loss and how it will
be measured. This level should be part of the overall accuracy con-
sideration. The level of data loss may dramatically affect cost. - establish a methodology by which missing or erroneous data will
be interpolated for final analysis. In such cases, baseyear and post-
retrofit models may be used to calculate savings.
5.6 USE OF ENERGY MANAGEMENT SYSTEMS
FOR DATA COLLECTION
The facility energy management system^1 (EMS) can provide much of
the monitoring necessary for data collection. However, the system and
software must be fully specified to provide this extra service as well
as its primary realtime control function. For example, significant use of
trending functions may impair the basic functions of the EMS. Some
parameters to be monitored may not be required for control. These extra
points must be specified in the design documents. Electric power meter-
ing is an example. Trending of small power, lighting and main feed power
consumption may be very useful for high quality savings determination
and operational feedback, but useless for real time control.
Other functions that can easily be incorporated into the software
are automatic recording of changes in set-points.
It is not unusual for many of the trending capabilities required for
verification to be incorporated in an EMS. However adequate hardware
and software capability must be provided since data trending can tie
up computer processing, communication bandwidth and storage.
Facility staff should be properly trained in this use of the EMS so
they too can develop their own trending information for diagnosing sys-
tem problems, providing the system has the capacity for extra trending.
However where a contractor is responsible for some operations controlled
by the system, EMS security arrangements should ensure that persons
can only access functions for which they are competent and authorized.
The EMS design and monitoring team may have a direct read-only
connection into the EMS via a modem link so they can easily inspect
trend data in their office. However possible concerns for virus attacks
and computer security should be addressed in this situation.
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- The terms in italics are defined in Chapter 6.1