314 Energy Project Financing: Resources and Strategies for Success
3.4.1.1 Option A: Isolation Metering
Measurement equipment must be used to isolate the energy use of
the equipment affected by the ECM from the energy use of the rest of
the facility. The isolation metering should reflect the boundary between
equipment which the ECM affects and that which it does not affect. For
example, a lighting load reduction often has a related impact on HVAC
system energy use, but the boundary for measurement may be defined
to encompass only the lighting electricity. However if the boundary of
the savings determination encompasses HVAC effects, measurement
or stipulation will be required for both the lighting and HVAC energy
flows.
Chapter 5 discusses metering issues.
3.4.1.2 Option A: Measurement vs. Stipulation
Some, but not all parameters of energy use may be stipulated un-
der Option A. The decision of which parameters to measure and which
to stipulate should consider the significance of the impact of all such
stipulations on the overall reported savings. The stipulated values and
analysis of their significance should be included in the M&V Plan (See
Chapter 3.2).
Stipulation may be based on historical data, such as recorded op-
erating hours from the baseyear. Wherever a parameter is not measured
in the facility for the baseyear or post-retrofit period it should be treated
as a stipulated value and the impact of possible error in the stipulation
assessed relative to the expected savings.
Engineering estimates or mathematical modeling may be used to
assess the significance of stipulation of any parameter in the reported
savings. For example if a piece of equipment’s operating hours are
considered for stipulation, but may be between 2,100 and 2,300 hours
per year, the estimated savings at 2,100 and 2,300 hours should be com-
puted and the difference evaluated for its significance to the expected
savings. The impact of all such possible stipulations should be totaled
before determining whether sufficient measurement is in place.
The selection of factor(s) to measure may also be considered rela-
tive to the duties of a contractor undertaking some ECM performance
risk. Where a factor is significant to assessing a contractor’s perfor-
mance, it should be measured, while other factors beyond the ESCO’s
control should be considered for stipulation.