188 Energy Project Financing: Resources and Strategies for Success
the most common and most energy-saving operations available to many
facilities. The auditor should check to see if any waste heat from the boiler
is being recovered for use in a heat recuperator or for some other use,
such as water heating. If not, this should be noted as a potential ECO.
Specialized Equipment
Most of the remaining equipment encountered during the indus-
trial audit will be highly specialized process production equipment and
machines. This equipment should all be examined, with operational data
noted, as well as hours and periods of use. All heat sources should be
considered carefully as to whether they could be replaced with sources
using waste heat, or whether waste heat could serve as a provider of heat
to another application. Operations where both heating and cooling occur
periodically—such as a plastic extrusion machine—are good candidates
for reclaiming waste heat, or in sharing heat from a machine needing
cooling with another machine needing heat.
Air Compressors
Air compressors should be examined for size, operating pressures,
and type (reciprocating or screw), and whether they use outside cool air
for intake. Large air compressors are typically operated at night when
much smaller units are suffi cient. Also, screw-type air compressors use
a large fraction of their rated power when they are idling, so control
valves should be installed to prevent this loss. Effi ciency is improved
with intake air that is cool, so outside air should be used in most
cases—except in extremely cold temperature areas.
The auditor should determine whether there are signifi cant air leaks
in air hoses, fi ttings, and machines. Air leaks are a major source of energy
loss in many facilities and should be corrected by maintenance action.
Finally, air compressors are a good source of waste heat. Nearly 90% of
the energy used by an air compressor shows up as waste heat, so this is
a large source of low temperature waste heat for heating input air to a
heater or boiler, or for heating hot water for process use.
COMMERCIAL AUDITS
Introduction
Commercial audits span the range from very simple audits for
small offi ces to very complex audits for multi-story offi ce buildings