Our Methodology

We don't guess. Our calculator is powered by official climate data and engineering standards.

The Science Behind the Score

The Insulation ROI Calculator uses a deterministic algorithm based on the 2021 International Energy Conservation Code (IECC) and U.S. Department of Energy (DOE) recommendations.

1. Climate Zone Mapping

We map your Zip Code to one of the 8 distinct IECC Climate Zones. A home in Miami (Zone 1) faces completely different thermal dynamics than a home in Minneapolis (Zone 6). Our database ensures you are compared against the correct standard for your specific location.

2. R-Value Calculation

We calculate your current "Thermal Resistance" (R-Value) using standard industry multipliers:

  • Fiberglass Batts: ~R-3.2 per inch
  • Blown-in Cellulose: ~R-3.5 per inch
  • Closed Cell Spray Foam: ~R-6.5 per inch

3. The Efficiency Gap

Your "Efficiency Score" represents how close your current insulation is to the Retrofit Target recommended by Energy Star. We prioritize the Retrofit Target over the New Construction Code because it represents a realistic, high-ROI goal for existing homes without requiring major structural reconstruction.

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