Page 289 - Mechanical Engineers' Handbook (Volume 4)

278 Energy Auditing

to determine the facility’s major energy uses. These data always include utility bills, name-
plate data from the largest energy-using equipment, and operating schedules. The auditor
then makes a survey of the facility. Based on the results of this survey, he or she chooses a
set of energy conservation measures that could be applied in the facility and estimates their
installed cost and the net annual savings that they would provide. Finally, the auditor presents
his or her results to the facility’s management or operators. The audit process can be as
simple as a walkthrough visit followed by a verbal report or as complex as a complete
analysis of all of a facility’s energy using equipment that is documented by a lengthy written
report.
The success of an energy audit is ultimately judged by the resulting net financial return
(value of energy saved less costs of energy saving measures). Since the auditor is rarely in
a position to exercise direct control over operating and maintenance practices or investment
decisions, his or her work can come to naught because of the actions or inaction of others.
Often the auditor’s skills in communication and interpersonal relations are as critical to
obtaining a successful outcome from an energy audit as his or her engineering skills. The
auditor should stress from the outset of his or her work that energy management requires a
sustained effort and that in complex facilities a formal energy management program is usu-
ally needed to obtain the best results. Most of the auditor’s visits to a facility will be spent
in the company of maintenance personnel. These personnel are usually conscientious and
can frequently provide much useful information about the workings of a facility. They will
also be critical to the success of energy conservation measures that involve changes in
operating and maintenance practices. The auditor should treat maintenance personnel with
respect and consideration and should avoid the appearance of ‘‘knowing it all.’’ The auditor
must also often deal with nontechnical managers. These managers are frequently involved
in the decision to establish a formal energy management program and in the allocation of
capital for energy saving investments. The auditor should make an effort to provide clear
explanations of his or her work and recommendations to nontechnical managers and should
be careful to avoid the use of engineering jargon when communicating with them.
While the success of an energy audit may depend in some measure on factors outside
the auditor’s control, a good audit can lead to significant energy savings. Table 1 shows the
percentage of energy saved as a result of implementing energy audit recommendations in
172 nonresidential buildings. The average savings is more than 20%. The results are espe-
cially impressive in light of the fact that most of the energy-saving measures undertaken in
these buildings were relatively inexpensive. The median value for the payback on energy-
saving investments was in the 1- to 2-year range (i.e., the value of the energy savings
exceeded the costs in 1–2 years). An auditor can feel confident in stating that an energy
saving of 20% or more is usually possible in facilities where systematic efforts to conserve
energy have not been undertaken.

2 PERFORMING AN ENERGY AUDIT—ANALYZING ENERGY USE
A systematic approach to energy auditing requires that an analysis of existing energy-using
systems and operating practices be undertaken before efforts are made to identify opportu-
nities for saving energy. In practice, the auditor may shift back and forth from the analysis
of existing energy-use patterns to the identification of energy-saving opportunities several
times in the course of an audit—first doing the most simple analysis and identifying the
most obvious energy-saving opportunities, then performing more complex analyses, and so
on. This strategy may be particularly useful if the audit is to be conducted over a period of