Life-cycle cost, NPV and payback calculator

What this page is: one calculator that runs in your browser and stores nothing. Sources and limits are on the calculators page; for a linked 42-sheet model use the engineering toolkit.

Life-cycle cost, NPV and paybackFEMP method

About this tool

What it does: Calculates NPV, payback, savings-to-investment ratio and IRR for an efficiency project.

Background: Uses the FEMP and NIST life-cycle cost method.

Benefit: Tells you whether a project pays back before you commit funds.

Initial cost ($)

Annual energy savings, year 1 ($)

Added annual O&M cost ($)

Study period (years)

Real discount rate (%)

DOE FEMP rate for 2025 analyses: 3.0% real (4.5% nominal).

Real energy price escalation (%/yr)

0 is a conservative planning default. FEMP/NIST publish regional indices.

NPV = savings × UPV* − O&M × UPV − initial cost. SIR = PV savings ÷ (initial cost + PV O&M). Real IRR from the same cash flows. Method: NIST IR 85-3273-40 (Annual Supplement to NIST Handbook 135, August 2025) under 10 CFR 436A. Excludes taxes, incentives and replacement costs.

Planning estimate, not engineering design or professional advice. Results depend on your inputs and published factors, and are not a verified inventory, audit, guarantee of savings or net-zero claim. See the terms of use.

Independent planning estimate using published US government factors. Not endorsed by DOE, EPA, NREL or any agency. Not an audit or a verified inventory. See methods.