Insulation Savings Calculator Formula

Understand the math behind the insulation savings calculator. Each variable explained with a worked example.

Use the Insulation Savings Calculator

Formulas Used

Annual Savings

savings = annual_savings

Energy Reduction

savings_pct = efficiency_gain * 100

Payback Period

payback = insulation_cost / annual_savings

10-Year Net Savings

savings_10yr = annual_savings * 10 - insulation_cost

Variables

VariableDescriptionDefault
annual_hvac_costAnnual Heating & Cooling Cost(USD)2000
current_r_valueCurrent R-Value(R)11
new_r_valueNew R-Value(R)38
insulation_costInsulation Upgrade Cost(USD)2500
efficiency_gainDerived value= 1 - current_r_value / new_r_valuecalculated
annual_savingsDerived value= annual_hvac_cost * efficiency_gaincalculated

How It Works

How to Calculate Insulation Savings

Insulation reduces heat transfer, lowering the energy needed for heating and cooling.

Formula

Efficiency Gain = 1 - (Current R-Value / New R-Value)

Annual Savings = HVAC Cost * Efficiency Gain

Recommended R-Values (US)

  • Attic: R-38 to R-60
  • Walls: R-13 to R-21
  • Floors: R-25 to R-30
  • Crawl space: R-25

    • Worked Example

    Upgrade attic insulation from R-11 to R-38 with $2,000/year HVAC costs and $2,500 upgrade cost.

    annual_hvac_cost = 2000current_r_value = 11new_r_value = 38insulation_cost = 2500
    1. 01Efficiency gain: 1 - 11/38 = 1 - 0.289 = 71.1%
    2. 02Annual savings: $2,000 * 0.711 = $1,421
    3. 03Payback: $2,500 / $1,421 = 1.8 years
    4. 0410-year net savings: $1,421 * 10 - $2,500 = $11,710

    Ready to run the numbers?

    Open Insulation Savings Calculator