Retrotec USACE - Manual (Page 369)

I1
Appendix I
Rules of Thumb for Utility System ECMs
Rules of thumb for ECMs are intended to provide energy professionals and
part-time practitioners with guidelines by which to identify and evaluate the
potential of ECMs. The rules of thumb are shortcut methods, factors, typical
percentage results, and formulas to calculate energy system ECO performance
and to quantitatively analyze and estimate economics of savings and installed
cost.
I.1 Energy Management and Economics
1.1 Plant energy audits: Initiate formal plant energy audits by trained audit
teams that identify ECMs that can reduce the facility’s purchased energy
cost (PEC) by 15–25% over a 1- to 3-year period with typical paybacks
under 2 years.
1.2 Unit energy costs: Develop incremental, variable-only, unit energy costs
as a cost basis of savings (CBoS) to value ECOs savings on a variable cost
basis.
1.3 One line balances (OLBs): Develop one line balances for steam, elec-
tricity, and compressed air with an accuracy of ±20%. OLBs are used
to identify savings opportunities in their respective utility system and to
assist in providing a basis for quantities and cost saved.
1.4 Strategic energy plan: Implement a formal Strategic Energy Plan (SEP)
with additional annual savings of 2–4% of annual PEC.
Energy performance index (EPI): Develop and track an overall energy per-
formance index (kBtu (kWh)/unit product) as a regression model to monitor
program performance. Generally saves up to 0.5% of the PEC.
Plant utility indices: Establish and track plant utility indices as effi ciency
guidelines to save up to 1% of the annual PEC.
Savings resulting from accountability, accounting, troubleshooting, project
verifi cation, and overall feedback on the fi nancial contribution from the EM
program.
Optimize water treatment: Optimize water treatment performance to save
2–5% of the annual cost of water treatment.
Shut it off: Shut off energy to facility systems when not needed. Typically
saves more than 1% of the annual PEC.