Appendix B 317
- The significance of the error introduced by possible variations
between the stipulated and true values of parameters. This un-
certainty is controlled through careful review of the ECM design,
careful inspection of its implementation after installation and pe-
riodically thereafter. - The variability in the measured parameters, if less than continu-
ous measurement is employed. This uncertainty can be minimized
through periodic measurements made frequently enough at the
outset of the project to adequately characterize the variability. - The degree to which the measured sample represents all compo-
nents of an ECM
Savings uncertainty under Option A is generally inversely pro-
portional to the complexity of the ECM and variability of operations
in both the baseyear and post-retrofit period. Thus, the savings from
a simple lighting retrofit may typically be more accurately determined
with Option A than the savings from a chiller retrofit, since lighting
stipulations may have less uncertainty.
3.4.1.7 Option A: Cost
Savings determinations under Option A can be less costly than
under other Options, since the cost of deriving a stipulation may be
less than the cost of making measurements. However in some situa-
tions where stipulation is the only possible route, the derivation of a
good stipulation may require more cost than direct measurement. Cost
of retrofit isolation should consider all elements: proper meter installa-
tion, commissioning and maintenance, proper stipulation analysis, and
the ongoing cost to read and record data.
Portable meters may be used so that their costs can be shared
with other objectives. However, meters which are permanently installed
maybe useful in the facility to provide feedback to operating staff or
automated control equipment for optimization of systems or billing of
special users.
Savings determination cost is driven by the complexity of the ECM
and the number of energy flows crossing the boundary of the ECM or
retrofit isolation.
Cost is also driven by the frequency of measurement, whether