Retrofit Cashflow Calculator

Formula Used

• Net project cost = Retrofit cost − Upfront incentive/rebate.
• Tax credit value = (Retrofit cost × Eligible cost %) × Tax credit %.
• Monthly loan payment = r×PV / (1 − (1+r)⁻ⁿ), where r=APR/12 and n=term×12.
• Escalated savings in year y = Year1 savings × (1 + escalation)^y−1.
• Net cashflow = Savings − O&M cost − Loan payment + One-time items + Tax credit + Residual value.
• Cumulative cashflow = prior cumulative + net cashflow.
• Discounted cashflow = Net / (1 + discount rate)^y; NPV is the sum across years.
• IRR is the rate where NPV equals zero (solved by bisection when possible).

How to Use This Calculator

1. Enter the retrofit cost and any upfront incentives or rebates.
2. Fill in year 1 savings and any added annual O&M expenses.
3. Choose cash purchase or loan financing and set loan terms.
4. Select an analysis period and discount rate for NPV.
5. Click Calculate cashflow to view results above the form.
6. Use Download CSV or Download PDF for reports.

Cashflow timeline and sign conventions

Year 0 captures upfront spending and immediate incentives. Negative values mean cash out, while positive values mean cash in. A retrofit costing 25,000 with a 2,500 rebate starts at -22,500 before credit timing. If a 10% credit applies to 100% of cost, the credit equals 2,500 and can be modeled in year 0 or year 1. Use the start year only for labeling and reporting.

Savings drivers and escalation

Annual savings combine energy, demand, and maintenance impacts. For example, 4,200 energy + 600 demand + 300 maintenance equals 5,100 in year 1. If savings escalate 2.5% yearly, year 5 savings become 5,100×1.025^4 ≈ 5,633, and year 15 becomes ≈ 6,885. Track added O&M cost separately; a 150 yearly cost escalating 2% becomes ≈ 204 by year 15.

Financing impact on early years

Loan terms shift cash strain from year 0 into annual payments. With 15% down on a 22,500 net cost, the upfront is 3,375 plus any unrolled fees. Financing 19,125 at 7.5% for 7 years produces a payment near 287 per month, or about 3,444 yearly. Comparing net cashflow under cash versus loan helps estimate working-capital requirements and covenant pressure.

NPV, IRR, and discount rate selection

NPV discounts each year’s net cashflow by (1+discount)^year. At a 6% discount rate, 1,000 received in year 10 is worth about 558 today, so higher rates penalize long paybacks. IRR is the break-even rate where NPV equals zero; compare it to your hurdle rate, debt cost, or weighted average cost of capital. Use consistent rates across projects to rank fairly.

Decision checkpoints and reporting

Use three tests together: positive NPV, acceptable payback, and IRR above your benchmark. Many portfolios screen for payback under 8–10 years, then prioritize projects with higher NPV per dollar invested. Add one-time events to reflect reality, such as a 3,000 replacement in year 8 or a residual value at the end of year 15. Export CSV for audit trails and PDF for stakeholder summaries.

FAQs

What does “Year 0” include?

Year 0 includes upfront project spending, the rebate reduction, any down payment or fees, and optional upfront tax credit timing. It usually produces the largest negative cashflow.

Why can payback show “Not reached”?

If cumulative cashflow never becomes positive within the chosen analysis period, payback is not reached. Increase the analysis years, adjust savings assumptions, or revise costs and incentives to test scenarios.

How is the tax credit applied here?

The credit is calculated as: retrofit cost × eligible cost percent × credit rate. You can model it in Year 0 or Year 1 to reflect when the benefit is received.

What discount rate should I use?

Use a rate consistent with your capital hurdle, financing cost, or portfolio standard. Many organizations test 5%–10% and run sensitivity, because NPV is highly dependent on the discount rate.

Why is IRR sometimes not available?

IRR requires at least one sign change in the cashflow series and a solvable root. If cashflows stay negative or multiple sign changes create ambiguity, the calculator may not be able to bracket a stable IRR.

Can I model a mid-life replacement?

Yes. Enter a replacement cost and the year it occurs. The calculator subtracts that one-time expense in the selected year, which can change payback, NPV, and IRR materially.