Appendix B 345
The EMS can record energy use with its trending capability. How-
ever, most EMSs record “change of value” (COV) event recordings that
are not directly used for calculating energy savings without tracking
time intervals between individual COV events (Claridge et al. 1993,
Heinerneier and Akbari 1993). It is possible to tighten COV limits in
order to force the trending towards more regular intervals, but this can
overload systems which are not designed for such data densities. Great
care should be exercised to:
- control access and/or changes to the EMS trend log from which
the energy data are extracted. - develop post-processing routines for changing the EMS COV data
into time series data for performing an analysis. - get from the EMS supplier:
— NIST traceable calibrations of all sensors,— evidence that proprietary algorithms for counting and/or
totaling pulses, Bras, and kWh data are accurate. (Currently,
there are no industry standards for performing this analysis
(Sparks et al. 1992), and— commitment that there is adequate processing and storage ca-
pacity to handle trending data while supporting the system’s
control functions.Chapter 6
Definitions and References
6.1 DEFINITIONS
Baseline Adjustments—The non-routine adjustments (Chapter 3.4) aris-
ing during the post-retrofit period that cannot be anticipated and which
require custom engineering analysis (see Chapter 4.8).