Appendix B 319
3.4.2 Option B: Retrofit Isolation
The savings determination techniques of Option B are identical to
those of Option A except that no stipulations are allowed under Option
B. In other words, full measurement is required.
Short term or continuous metering may be used under Option
B. Continuous metering provides greater certainty in reported savings
and more data about equipment operation. These data can be used to
improve or optimize the operation of the equipment on a real-time basis,
thereby improving the benefit of the retrofit itself. Results from several
studies have shown five to fifteen percent annual energy savings can
be achieved through careful use of continuous data logging (Claridge
et al. 1994, 1996; Haberl et al. 1995).
Option B involves full measurement of the impact of the ECM.
Therefore there is less need to verify the potential to perform than in
Option A. The suggested installation verifications of Chapter 3.4.1.3 may
be relaxed by eliminating ongoing re-inspections after the commission-
ing inspection.
The savings created by most types of ECMs can be determined
with Option B. However, the degree of difficulty and costs associated
with verification increases proportionately as metering complexity in-
creases. Option B methods will generally be more difficult and costly
than Option A. However Option B may produce less uncertain results
where load and savings patterns are variable. Additional costs may be
justifiable if a contractor is responsible for all aspects of ECM effective-
ness.
ASHRAE’s Guideline 14P is expected to provide technical details
on a similar method (ASHRAE 2000).
3.4.2.1 Option B: Best Applications
Option B is best applied where:
- the performance of only the systems affected by the ECM is of
concern, either due to the responsibilities assigned to the parties
in a performance contract or due to the savings of the ECM being
too small to be detected in the time available using Option C. - interactive effects between ECMs or with other facility equipment
can be measured or assumed to be immaterial. - isolation of the ECM from the rest of the facility may avoid pos-