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 billing schedule be obtained from the utility company serving the
installation. Once it is analyzed to determine what the company is charging
for and why, it is possible to evaluate which changes in procedures and
equipment that will achieve savings. Normally, electric utility companies use
three major elements to bill:
Demand
q
Power Factor
q
Total Energy Used
q
Depending upon specific billing practices, other factors, usually of lesser
impact, add to basic billing charges: fuel adjustment charges, time-of-day
factor, seasonal rate charges, etc.
4.1 Demand. Demand is electrical power measured in kilowatts required by a
specified consumer. Demand is usually metered at specified intervals during
the day.
4.2 Power Factor. Power factor is the ratio of power used to power
supplied. For alternating current, the ratio normally ranges from 0.75 to
0.95.
4.3 Total Energy Used. Electric energy is the amount of electric power used
over a period of time. Multiplying electric power by hours of use equals
total energy used in kilowatt hours.
5. STEAM MANAGEMENT. Steam costs typically rank just below electrical energy
costs. The cost of steam, in recent years, has increased by an order of
magnitude. Its continued escalation provides a powerful incentive to pursue a
steam management program. In 1985, steam costs at naval installations varied
from $8.00 to $16.00 per million British thermal units (MBTU). Leaks in a
steam distribution system are costly. Table 1-1 shows the cost of various
sized leaks in a steam system pressurized to 100 pounds per square inch gauge
(psig) with steam production costs of $10.00 per MBTU. Without adequate steam
metering, it may be difficult to identify and locate areas of waste. Leaks in
overhead steam lines usually can be located as the escaping steam is visible.
However, when insulation is damaged or missing, the heat losses can be
considerable although the cause may not be so obvious. Leaks in underground
steam mains are another problem often difficult to correct. Another common
cause of wasted steam is malfunctioning or incorrectly specified steam traps.
A comprehensive steam trap program may give the highest payback available.
Manufacturers' manuals should be consulted for suggested inspection frequency
and maintenance practices. Additional waste occurs when buildings are
overheated, and the excess heat is vented through windows and doors. Such
losses must be identified and eliminated.
1-2
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