Turn retrofit costs into clear investment insight now. Model savings, incentives, and maintenance impacts fast. Make better upgrade choices with cashflow clarity today always.
The calculator discounts each year’s net cash flow back to today and adds the initial outlay:
| Scenario | Capex | Incentive | Years | Discount | Year‑1 Net Savings | Residual |
|---|---|---|---|---|---|---|
| Typical retrofit | $25,000 | $2,000 | 15 | 8% | $3,500 | $2,500 |
| High‑savings case | $30,000 | $3,500 | 20 | 7% | $5,000 | $3,000 |
| Conservative case | $18,000 | $1,000 | 12 | 9% | $2,200 | $1,500 |
Retrofit value depends on the size, timing, and stability of annual savings. In the model, year‑1 net savings combine energy savings plus maintenance savings minus extra operating costs. Inflation can grow those dollars over time, while degradation can reduce performance, so the calculator applies both effects before discounting.
Discounting converts future savings into today’s dollars using your discount rate. A positive NPV means the retrofit is expected to create value beyond the required return. When comparing alternatives, the higher NPV generally wins, but you should keep analysis periods and assumptions consistent across options. For organizations, the discount rate may reflect a hurdle rate, weighted cost of capital, or a risk‑adjusted target return.
Simple payback uses undiscounted net cash flows and is easy to explain, but it can ignore late‑life benefits. Discounted payback is stricter because it uses present values. Many projects miss a short payback yet still deliver strong NPV when savings persist for 15–25 years. Use payback as a liquidity check, then rely on NPV to judge total value created.
Upfront incentives reduce the year‑0 net outlay and can materially improve profitability index and payback. Residual value is added in the final year and discounted back to present value. For equipment with resale value, avoided replacement, or transferable warranties, including a realistic residual can change borderline decisions. Document incentive eligibility and timing, because delayed rebates behave more like a later cash flow.
Real savings vary with weather, occupancy, tariffs, and maintenance quality. The sensitivity table shifts savings up and down to show how NPV and payback respond. If NPV stays positive under a conservative shift, the project is more resilient. If it turns negative quickly, focus on cost control, verified savings, or phased upgrades. Pair sensitivity with measurement plans, such as utility bill normalization or submetering, to tighten assumptions over time.
A positive NPV indicates the discounted value of future net savings exceeds the initial net outlay at your chosen discount rate. It suggests the project meets or beats your required return, assuming the inputs reflect realistic costs and savings.
Use a rate that matches your required return or cost of capital. For households, it may reflect alternative investment returns. For organizations, it may be a hurdle rate or WACC, adjusted upward for higher uncertainty.
Payback focuses on how quickly costs are recovered, often ignoring late‑life benefits. NPV counts all discounted cash flows across the full period, so long‑lasting savings and residual value can deliver strong NPV even with longer payback.
Include inflation when utility prices or savings dollars are expected to rise over time. Include degradation when equipment performance declines or savings erode. If uncertain, run sensitivity shifts and compare results with and without these assumptions.
Incentives reduce the year‑0 outlay, typically improving NPV, profitability index, and payback. If a rebate arrives later, model it as a later cash flow instead of an upfront incentive so discounting reflects the timing.
Residual value is the expected value at the end of the analysis period, such as resale proceeds, avoided replacement, or transferable warranty value. The calculator discounts it back to present value and adds it to NPV.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.