This calculator estimates total insulation R-value from material performance and installed thickness, then compares your result to climate- and assembly-based reference targets. It helps identify where envelope upgrades are most likely to reduce heat loss and improve comfort before larger mechanical investments.

Retrofit Guidance

Prioritize envelope upgrades in areas with largest R-value deficits and high seasonal load. In many homes, attic and upper-envelope improvements offer strong comfort and utility benefits, especially when paired with air sealing.

• Benchmark current insulation by assembly, not whole-home average
• Address air leakage before or alongside insulation top-ups
• Use climate-appropriate targets to avoid under- or over-insulating
• Account for framing thermal bridges in performance expectations
• Validate moisture and condensation control details in retrofits
• Re-estimate utility savings after envelope improvements are complete

Sources & References