Tempered vs Laminated Glass U-Value Calculator
ANA›Life Services Authority›National Calculator Authority›Tempered vs Laminated Glass U-Value 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; } }
Tempered vs Laminated Glass U-Value Calculator
Calculate and compare the thermal transmittance (U-value) for tempered and laminated glass configurations, including single, double, and triple glazing options.
### Glass Configuration
Glass Type
Tempered Glass Laminated Glass
Glazing Type
Single Glazing Double Glazing (IGU) Triple Glazing
Glass Pane Thickness (mm)
Interlayer Type
PVB (Polyvinyl Butyral) — 0.38 mm PVB Thick — 0.76 mm SGP (SentryGlas) — 0.89 mm EVA (Ethylene Vinyl Acetate) — 0.38 mm
Gap 1 Width (mm)
Gap 1 Fill Gas
Air Argon Krypton
Gap 2 Width (mm)
Gap 2 Fill Gas
Air Argon Krypton
Low-E Coating
None (ε = 0.89) Soft Coat Low-E (ε = 0.04) Hard Coat Low-E (ε = 0.15) Double Low-E (ε = 0.02)
Frame Correction Factor
No frame correction Aluminum frame (+0.1 W/m²K) Thermally broken frame (+0.05 W/m²K) PVC/Wood frame (+0.02 W/m²K)
### Environmental Conditions
Interior Surface Resistance Rsi (m²K/W)
Exterior Surface Resistance Rso (m²K/W)
Interior Temperature (°C)
Exterior Temperature (°C)
Quick Reference U-Values (W/m²K)
Calculate U-Value
function temUpdateFields() { var glazing = document.getElementById('tem-glazing').value; var glassType = document.getElementById('tem-glass-type').value;
document.getElementById('tem-gap-fields').style.display = (glazing === 'double' || glazing === 'triple') ? 'block' : 'none'; document.getElementById('tem-gap2-fields').style.display = (glazing === 'triple') ? 'block' : 'none'; document.getElementById('tem-laminated-fields').style.display = (glassType === 'laminated') ? 'block' : 'none'; }
function temGetGasConductivity(gas, gapMm) { // Returns effective thermal conductance of gas gap (W/m²K) // Based on ISO 10292 simplified method var gap = gapMm / 1000; // convert to meters
// Thermal conductivity (W/mK) at mean temp ~10°C var lambda = { air: 0.0241, argon: 0.0163, krypton: 0.00926 }; var lam = lambda[gas] || 0.0241;
// Nusselt number for vertical glazing (simplified) // Nu = 0.035 * Ra^0.38 for 5 25) errors.push("Glass thickness must be between 3 and 25 mm."); if (isNaN(Rsi) || Rsi 0.30) errors.push("Interior surface resistance must be between 0.05 and 0.30 m²K/W."); if (isNaN(Rso) || Rso 0.15) errors.push("Exterior surface resistance must be between 0.02 and 0.15 m²K/W."); if (isNaN(Tin) || isNaN(Tout)) errors.push("Temperatures must be valid numbers."); if (Tin 20) errors.push("Gap 1 width must be between 6 and 20 mm."); } if (glazing === 'triple') { var gap2 = parseFloat(document.getElementById('tem-gap2').value); if (isNaN(gap2) || gap2 20) errors.push("Gap 2 width must be between 6 and 20 mm."); }
if (errors.length > 0) { document.getElementById('tem-result').style.display = 'block'; document.getElementById('tem-result-content').innerHTML = '' + 'Input Errors:' + errors.map(function(e){ return ''; }).join('') + ''; return; }
// --- Emissivity from coating --- var emissivity = { none: 0.89, soft: 0.04, hard: 0.15, double: 0.02 }[coating];
// --- Build R-value stack --- // R_total = Rsi + R_glass_layers + R_gaps + Rso // U = 1 / R_total
var R_glass = temGetGlassConductance(thickness, glassType, interlayer);
var R_total = Rsi + R_glass + Rso; var gapDetails = [];
if (glazing === 'double' || glazing === 'triple') { var gap1Val = parseFloat(document.getElementById('tem-gap1').value); var gas1 = document.getElementById('tem-gas1').value;
// Gap conductance = conductive + radiative var hc1 = temGetGasConductivity(gas1, gap1Val); var hr1 = temGetRadiativeHTC(emissivity); var hg1 = hc1 + hr1; var Rg1 = 1 / hg1; R_total += R_glass + Rg1; // second pane + gap
gapDetails.push({ gap: gap1Val, gas: gas1, hc: hc1, hr: hr1, hg: hg1, Rg: Rg1 }); }
if (glazing === 'triple') { var gap2Val = parseFloat(document.getElementById('tem-gap2').value); var gas2 = document.getElementById('tem-gas2').value;
var hc2 = temGetGasConductivity(gas2, gap2Val); // For triple, inner gap typically uncoated on both sides unless double Low-E var hr2 = temGetRadiativeHTC(coating === 'double' ? emissivity : 0.89); var hg2 = hc2 + hr2; var Rg2 = 1 / hg2; R_total += R_glass + Rg2; // third pane + second gap
gapDetails.push({ gap: gap2Val, gas: gas2, hc: hc2, hr: hr2, hg: hg2, Rg: Rg2 }); }
var U_center = 1 / R_total; var U_total = U_center + frameCor;
// --- Heat flux --- var deltaT = Tin - Tout; var heatFlux = U_total * deltaT; // W/m²
// --- Performance rating --- var rating, ratingColor; if (U_total Gap ' + (i+1) + ' (' + g.gap + ' mm ' + g.gas + ')' + '' + g.hc.toFixed(3) + ' W/m²K (conv) + ' + g.hr.toFixed(3) + ' W/m²K (rad)' + '' + g.Rg.toFixed(4) + ' m²K/W'; });
var numPanes = glazing === 'single' ? 1 : glazing === 'double' ? 2 : 3; var paneLabel = glassType === 'laminated' ? 'Laminated pane (2× ' + thickness + ' mm glass + interlayer)' : 'Tempered pane (' + thickness + ' mm)';
var html = '### Results ' +
'' +
'' + '' + glassLabel + ' Glass U-Value' + '' + U_center.toFixed(3) + '' + 'W/m²K (center of glass)' + '' + U_total.toFixed(3) + ' W/m²K' + '(with frame correction)' + '' +
'' + '' + altLabel + ' Glass U-Value' + '' + (1/(R_total_alt - frameCor)).toFixed(3) + '' + 'W/m²K (center of glass)' + '' + U_alt.toFixed(3) + ' W/m²K' + '(with frame correction)' + '' +
'' +
'' + 'Performance: ' + rating + '' + '' +
'' + '' + 'Component' + 'Detail' + 'R-Value (m²K/W)' + '' + 'Interior surface (Rsi)Still air film' + Rsi.toFixed(3) + '' + '' + paneLabel + 'k = 1.0 W/mK' + (glassType==='laminated'?' + interlayer':'') + '' + R_glass.toFixed(4) + '' + gapHTML + (glazing !== 'single' ? 'Additional pane(s)' + (numPanes-1) + '× ' + paneLabel + '' + ((numPanes-1)*R_glass).toFixed(4) + '' : '') + 'Exterior surface (Rso)Wind-exposed film' + Rso.toFixed(3) + '' + 'Total R-Value' + R_total.toFixed(4) + '' + '' +
'' + '' + 'Heat Flux' + '' + heatFlux.toFixed(1) + '' + 'W/m² (ΔT = ' + deltaT + '°C)' + '' + '' + 'R-Value (imperial)' + '' + (R_total * 5.678).toFixed(3) + '' + 'ft²·°F·h/BTU' + '' + '' + 'Difference vs ' + altLabel + '' + '' + (U_total ' + 'W/m²K (' + (U_total ' + '' + '' +
'Configuration: ' + glazingLabel + ' | ' + glassLabel + ' | Thickness: ' + thickness + ' mm | Coating: ' + coatingLabel + '
';
document.getElementById('tem-result').style.display = 'block'; document.getElementById('tem-result-content').innerHTML = html; }
// Initialize field visibility temUpdateFields();
#### Formulas Used
Overall U-Value (ISO 10292 / EN 673):
U = 1 / Rtotal + ΔUframe
Rtotal = Rsi + Σ Rglass + Σ Rgap + Rso
Glass pane resistance: Rglass = d / k where d = thickness (m), k = 1.0 W/mK
Laminated interlayer resistance: Ril = dil / kil (PVB: k = 0.23 W/mK; SGP: k = 0.35 W/mK)
Gas gap total conductance: hgap = hc + hr
Convective component: hc = Nu · λgas / dgap (Nu ≈ 1.0–1.15 for vertical glazing)
Radiative component: hr = 4σTm³ / (1/ε₁ + 1/ε₂ − 1) where σ = 5.67×10⁻⁸ W/m²K⁴, Tm = 283 K
Heat flux: q = U · ΔT (W/m²)
#### Assumptions & References
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