Discounted cash flow · documented assumptions
Life-cycle Cost Present-value Worksheet
Discount signed, explicitly timed costs and credits over an agreed study period. Recurring categories may escalate independently. Currency is a label only—this worksheet performs no exchange-rate conversion and makes no investment recommendation.
Cash-flow equations
| コンポーネント | Equation | Timing |
|---|---|---|
| Single future flow | PV(Fk) = Fk/(1+r)k | Year k |
| Recurring category j | PVj = Σq=0…n−1 Cj,first(1+gj)q/(1+r)q+δ | δ=1 end-of-year; δ=0 beginning-of-year |
| End flow | PVend = En/(1+r)n | Positive cost or negative residual credit |
| Total LCC | LCC = A₀ + I₀ + ΣPVj + PV(Fk) + PVend | All at common base date |
| End-year EAC | EAC = LCC / Σt=1…n(1+r)−t | Equivalent uniform end-of-year amount |
Positive numbers are costs; negative numbers are credits or income included in the agreed scope. Summation uses compensated arithmetic. No default discount or escalation rate is supplied.
Price basis and timing
Constant-currency analysis uses a real discount rate and real/differential escalation rates. Current-currency analysis uses a nominal discount rate and nominal escalation rates. Mixing nominal cash flows with a real rate—or the reverse—distorts present value. Recurring input is the first payment at the selected timing; escalation is applied between successive payments.
Primary methodology sources
NIST Handbook 135e2025, August 2025, supersedes the 2022 edition and explains LCC methodology, assumptions, timing, present-value factors, escalation, residual value and uncertainty for FEMP facility projects. Its general economic method is also useful outside that regulatory scope. The handbook’s published examples include $1,000 at the end of year 5 discounted at 3% → $862.61, and a $100 base-date annual cost escalated 2% before each of five end-year payments at 3% → PV $485.62 (equivalent in this worksheet to a first payment of $102 followed by 2% escalation).
について DOE FEMP BLCC page states that Handbook 135 was updated in 2025 and current discount/energy escalation data come from the Annual Supplement/EERC; this worksheet does not invent a universal rate. IEC 60300-3-3:2017, edition 3 is Valid with stability date 2027 and gives a general life-cycle-costing application guide across applications, particularly dependability costs. ISO 15686-5:2017, edition 2 is Published, confirmed 2024, specifically for buildings and constructed assets; it is not a universal equipment-rate table.
Why former presets and percentages were removed
The old page assumed constant end-year costs without saying so, rejected residual credits, truncated fractional study periods with parseInt, offered context-free 3–8% rates and equipment cost-share percentages, and changed currency symbols without exchange conversion. Its simple constant-annuity formula was mathematically valid only under those hidden assumptions. Presets, URL parameters, local history, universal pump/motor percentages and automatic efficiency recommendations were removed.
Exact clauses, regulated discount rates and mandatory study-period rules depend on jurisdiction and project scope. Where a licensed standard or rule governs the decision, verify it directly; otherwise record the method as a general engineering cash-flow model.
