Home Energy | Three-Scenario Cost Model

Home_Energy_Scenario_Model.xlsx — an editable 12-month electricity cost model with three scenarios. Every figure is labelled simulated; the file states on the Read Me sheet that costs and savings do not represent real conditions.

Sheets

• Read Me — purpose, the simulated-data warning, sheet guide, how to use it, the calculation rules and the model's limits.
• Parameters — all assumptions in yellow editable cells: base monthly consumption (800 kWh), January unit price ($0.28/kWh), 3.0% annual price escalation, each scenario's consumption change (−12% habits, −28% upgrades) and one-off investment ($3,600), plus the 12 monthly seasonal factors. Input validation limits, freeze panes and a live check block (factors average 1.00, annual kWh and cost reconcile) are included.
• Monthly Model — 12 rows × 3 scenarios: seasonal factor, unit price (compounded monthly from the January base), consumption and monthly cost per scenario, monthly savings vs baseline, and totals. Filterable, print titles repeat.
• Annual Summary — annual consumption and cost per scenario, difference vs baseline in $ and %, investment, net first-year benefit, simple payback, a key-figures block, and two native charts (monthly cost lines, annual cost bars).
• Cumulative Savings — running bill savings and running net benefit after the investment for both scenarios, the payback month, and a third native chart.

Simulated results with the default assumptions

The upgrade case does not break even inside the 12-month year, so the cumulative sheet reports "Beyond 12 months" — that is the arithmetic of the assumed 28% saving against a $3,600 outlay, not an error.

Checks run on the saved file

• All 241 formulas were recalculated independently from the workbook's own formulas (a separate formula engine, not the stored values): 241 compared, 0 mismatches, 0 missing.
• Data-only read-back matched the Python model cell by cell, including the three Parameters self-checks reading "OK".
• Structure verified: 5 sheets, 3 charts pointing at the correct ranges, 3 data validations, filters, freeze panes and print areas; zip package integrity clean.
• Layout audited deterministically (column widths vs text length, wrapped-line heights, merged ranges, chart anchors): 0 fit problems after two fixes.

Limit to note: no spreadsheet renderer (LibreOffice) is installed in this environment, so I could not produce a pixel rendering of the sheets. Fit was verified by the deterministic width/height audit above rather than by visual inspection; if you open it and want any column widened or a chart resized, tell me which sheet.

Changing any yellow cell on Parameters recalculates consumption, prices, costs, differences, cumulative savings, payback and all three charts.