Home Insulation R-Value Savings Calculator
ANA›Life Services Authority›National Calculator Authority›Home Insulation R-Value Savings Calculator
.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }
Home Insulation R-Value Savings Calculator
Estimate your annual heating and cooling cost savings when upgrading your home's insulation from a current R-value to a higher R-value.
Insulated Area (sq ft)
Current R-Value
Upgraded R-Value
Heating Degree Days (HDD)
Cooling Degree Days (CDD)
Heating System Efficiency (AFUE or COP, e.g. 0.80 for gas, 3.0 for heat pump)
Cooling System SEER (e.g. 14)
Heating Energy Cost ($/MMBtu for gas; $/kWh for electric)
Heating Fuel Type
Natural Gas ($/MMBtu) Electric ($/kWh)
Electricity Cost for Cooling ($/kWh)
Calculate Savings
function homCalc() { var resultDiv = document.getElementById('hom-result'); resultDiv.innerHTML = '';
var area = parseFloat(document.getElementById('hom-area').value); var rCurrent = parseFloat(document.getElementById('hom-r-current').value); var rNew = parseFloat(document.getElementById('hom-r-new').value); var hdd = parseFloat(document.getElementById('hom-hdd').value); var cdd = parseFloat(document.getElementById('hom-cdd').value); var heatEff = parseFloat(document.getElementById('hom-heat-eff').value); var coolSEER = parseFloat(document.getElementById('hom-cool-eff').value); var heatCost = parseFloat(document.getElementById('hom-heat-cost').value); var heatType = document.getElementById('hom-heat-type').value; var coolCost = parseFloat(document.getElementById('hom-cool-cost').value);
// --- Validation --- var errors = []; if (isNaN(area) || area 0) { resultDiv.innerHTML = ''; return; }
/ * HEAT LOSS / GAIN FORMULA * Q (BTU/hr) = Area (ft²) × ΔT (°F) / R-value (ft²·°F·hr/BTU) * * Annual heat loss reduction (BTU): * ΔQ_heat = Area × HDD × 24 × (1/R_current − 1/R_new) * * Annual heat gain reduction (BTU): * ΔQ_cool = Area × CDD × 24 × (1/R_current − 1/R_new) * * Heating savings: * If gas: savings_heat ($) = ΔQ_heat / (heatEff × 1,000,000) × heatCost [MMBtu] * If electric:savings_heat ($) = ΔQ_heat / (heatEff × 3412.14) × heatCost [kWh] * * Cooling savings: * COP_cool = SEER / 3.412 (converts SEER BTU/Wh → dimensionless COP) * savings_cool ($) = ΔQ_cool / (COP_cool × 3412.14) × coolCost [kWh] /
var uDiff = (1.0 / rCurrent) - (1.0 / rNew); // ft²·°F·hr/BTU difference in U-value
// Annual BTU reduction var deltaHeat = area * hdd * 24.0 * uDiff; // BTU/year saved on heating var deltaCool = area * cdd * 24.0 * uDiff; // BTU/year saved on cooling
// Heating cost savings var heatSavings = 0; if (heatType === 'gas') { // Convert BTU → MMBtu, divide by efficiency heatSavings = (deltaHeat / (heatEff * 1e6)) * heatCost; } else { // Electric: BTU → kWh (1 kWh = 3412.14 BTU), divide by COP (heatEff) heatSavings = (deltaHeat / (heatEff * 3412.14)) * heatCost; }
// Cooling cost savings // SEER (BTU/Wh) → COP: divide by 3.412 (Wh per BTU × 1000 / 1000 cancels) var copCool = coolSEER / 3.412; // BTU → kWh: divide by 3412.14, then divide by COP var coolSavings = (deltaCool / (copCool * 3412.14)) * coolCost;
var totalSavings = heatSavings + coolSavings;
// Payback helper (rough installed cost estimate: ~$1.50/sq ft per R-10 added) var rAdded = rNew - rCurrent; var estInstallCost = area * 1.50 * (rAdded / 10.0); var payback = (totalSavings > 0) ? (estInstallCost / totalSavings) : Infinity;
resultDiv.innerHTML = '### Results ' + '' + 'Annual Heat Loss Reduction' + (deltaHeat / 1e6).toFixed(2) + ' MMBtu/yr' + 'Annual Heat Gain Reduction' + (deltaCool / 1e6).toFixed(2) + ' MMBtu/yr' + 'Annual Heating Cost Savings$' + heatSavings.toFixed(2) + '' + 'Annual Cooling Cost Savings$' + coolSavings.toFixed(2) + '' + 'Total Annual Savings$' + totalSavings.toFixed(2) + '' + 'Estimated Install Cost (rough)$' + estInstallCost.toFixed(0) + '' + 'Simple Payback Period' + (isFinite(payback) ? payback.toFixed(1) + ' years' : 'N/A') + '' + ''; }
#### Formulas Used
Annual BTU Reduction (heating or cooling):
ΔQ = Area (ft²) × Degree Days × 24 hr/day × (1/Rcurrent − 1/Rnew)
Heating Savings (gas): Savings = ΔQheat ÷ (η × 1,000,000) × Costgas
Heating Savings (electric): Savings = ΔQheat ÷ (COPheat × 3,412.14) × Costelec
Cooling COP: COPcool = SEER ÷ 3.412
Cooling Savings: Savings = ΔQcool ÷ (COPcool × 3,412.14) × Costelec
Simple Payback: Payback = Estimated Install Cost ÷ Total Annual Savings
#### Assumptions & References
- Reference: DOE Energy Saver – Insulation; ASHRAE 90.1 Standard; Oak Ridge National Laboratory Building Envelope Research.
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