342 Energy Project Financing: Resources and Strategies for Success
cost options for each project.
For a given savings determination model at a specific site, there
will be an optimal savings determination plan. The method to identify
that Plan includes iterative consideration of sensitivity of the savings
uncertainty to each variable, estimating the cost of metering specified
variables in the model and a criteria for valuing reduced uncertainty
(e.g. risk-adjusting saving per a given formula).
Chapter 5
Measurement Issues
5.1 USING UTILITY METERS
Whole building energy measurements can utilize the same meters
that the local power company uses to bill the owner if they are equipped
or modified to provide an output that can be recorded by the facility’s
monitoring equipment. The “energy/pulse” constant of the pulse trans-
mitter should be calibrated against a known reference such as similar
data recorded by the power company s revenue meter.
5.2 ELECTRIC DEMAND
Electric demand measurement methods vary amongst utilities. The
method used by any sub-meter or modeling routine should replicate
the method the power company uses for the relevant billing meter. For
example, if the local power company is calculating peak demand using a
15 minute “fixed window,” then the recording equipment should be set
to record data every 15 minutes. However if the power company uses
a “sliding window” to record electric demand data, the data recorder
should have sliding window recording capabilities. Such sliding win-
dow capability can be duplicated by recording data on one minute fixed
window intervals and then recreating the sliding 15 minute window
using post-processing software. Most often 15 minute fixed window
measurements will represent sliding 15 minute data reasonably well.
However, care should be taken to ensure that the facility does not con-
tain unusual combinations of equipment that generate high one minute
peak loads which may show up in a sliding window interval and not