Elevator Modernization ROI Calculator

Not through Modernization Cost itself -- Total Annual Savings is computed purely from the three savings percentages applied to current energy, maintenance, and callback costs, with no dependence on Modernization Cost. A higher Modernization Cost only ever lengthens Simple Payback (years), since the same annual savings must now cover a larger upfront investment.

Total Annual Savings sums Current Energy Cost x Energy Savings %, Current Maintenance x Maintenance Savings %, and Current Callback Cost x Callback Reduction % -- three inputs that describe operating costs and expected improvement rates, not the price of the retrofit. Modernization Cost is a separate input used only in Simple Payback, Net Benefit, and ROI, never in the savings calculation itself.

Yes, across the full 1-30 year range -- both Net Benefit and NPV accumulate Total Annual Savings for every additional year in the window (NPV discounted at 5%), and neither term can go negative as years increase since annual savings are non-negative at any input combination the calculator allows.

IRR is solved with a 50-iteration bisection search bounded between -50% and 200% rather than an algebraic formula. When the real internal rate of return falls outside that bracket (extremely poor or extremely good input combinations), the search converges toward whichever boundary is closer rather than reporting a genuine root -- treat a result pinned at either edge as a sign the scenario is outside the method's intended range, not a literal answer.