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Calculator Methodology

How the Home Energy Savings Estimate Calculator estimate works

Use this to test whether an efficiency upgrade is a comfort decision, a payback decision, or both.

This estimate is for planning. Actual results may change based on local pricing, contracts, title practice, lender disclosures, insurance documents, inspection findings, hidden conditions, timing, and professional review.

Use the calculator Build decision packet

Inputs used

Defaults are planning placeholders, not recommendations.

Current monthly utility bill
Default: 260 $
Expected savings
Default: 18 %
Upgrade cost
Default: 9500 $
Rebates / credits
Default: 1500 $

What is included

  • The visible inputs listed on the calculator page.
  • The assumptions shown below the calculator.
  • A planning estimate based on the calculator family, not a binding quote, contract, appraisal, insurance settlement, title statement, or lender disclosure.
  • Input: Current monthly utility bill.
  • Input: Expected savings.
  • Input: Upgrade cost.
  • Input: Rebates / credits.

What is excluded

  • Final contractor pricing, local permit interpretation, lender underwriting, title-company settlement, insurance claim approval, tax advice, legal advice, or property-specific professional judgment.
  • Every local custom, contract term, hidden condition, inspection finding, market shift, and timing issue.
  • Guaranteed savings, resale value, coverage, approval, or final cash due.
  • Full Manual J design, in-person HVAC diagnosis, roof inspection, structural inspection, code inspection, or contractor warranty review.

What can make the estimate too low

  • Hidden damage, access difficulty, permit/code requirements, disposal, electrical, gas, duct, decking, flashing, ventilation, or warranty scope is not included.
  • The quote is a low base price with change orders likely.
  • Emergency timing reduces quote leverage.

What can make the estimate too high

  • A narrower repair, partial replacement, roof-over, owner-supplied material path, rebate, or scope trim is safe and documented.
  • Access is easier, hidden conditions are absent, or the project is bundled efficiently.
  • A second quote proves the first quote included unnecessary scope.

Assumptions

  • Behavior, weather, utility rates, and equipment sizing can change actual savings.
  • Use bills, not guesses, when possible.

When to verify before acting

  • Before signing a contractor quote, purchase contract, listing agreement, loan document, title document, insurance claim document, or association document.
  • When a result depends on local custom, contract language, code, warranty, hidden conditions, eligibility, or professional judgment.
  • When the result changes whether you repair, replace, sell, buy, claim, finance, or walk away.