SEER to EER Conversion Calculator — Efficiency Rating Comparison

ANA›Life Services Authority›National Calculator Authority›SEER to EER Conversion Calculator — Efficiency Rating Comparison

.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; } }

SEER to EER Conversion Calculator — Efficiency Rating Comparison

Convert between SEER and EER efficiency ratings for air conditioning systems. SEER measures seasonal performance while EER measures performance at a specific peak condition (95°F outdoor, 80°F indoor, 50% RH).

SEER Rating

SEER

EER Rating (optional — reverse convert)

EER

System Cooling Capacity

BTU/hr

Annual Cooling Hours

hrs/yr

Electricity Rate

$/kWh

Calculate

function seeCalc() { var seerVal = document.getElementById("see-seer").value.trim(); var eerVal = document.getElementById("see-eer").value.trim(); var capVal = document.getElementById("see-capacity").value.trim(); var hrsVal = document.getElementById("see-hours").value.trim(); var rateVal = document.getElementById("see-rate").value.trim();

var errors = [];

// At least one of SEER or EER must be provided if (seerVal === "" && eerVal === "") { errors.push("Please enter at least a SEER or EER value."); }

var seer = parseFloat(seerVal); var eer = parseFloat(eerVal);

if (seerVal !== "") { if (isNaN(seer) || seer 30) { errors.push("SEER must be between 8 and 30."); } } if (eerVal !== "") { if (isNaN(eer) || eer 25) { errors.push("EER must be between 6 and 25."); } }

var capacity = parseFloat(capVal); var hours = parseFloat(hrsVal); var rate = parseFloat(rateVal);

var hasCapacity = capVal !== "" && !isNaN(capacity) && capacity >= 5000 && capacity = 100 && hours = 0.01 && rate 0) { resultDiv.innerHTML = "Please fix the following:" + errors.map(function(e){ return ""; }).join("") + ""; return; }

// ── Core conversion formulas ────────────────────────────────────────────── // Industry-standard approximation (Carrier / AHRI method): // EER ≈ SEER × 0.875 (valid for single-stage systems) // More precise formula accounting for part-load factor: // EER = SEER / (1 + 0.02 × (SEER - 11.5)) [DOE/AHRI regression] // This calculator uses the DOE regression for SEER ≥ 11.5, linear for lower values.

var computed_eer_from_seer = null; var computed_seer_from_eer = null;

if (seerVal !== "" && !isNaN(seer)) { if (seer >= 11.5) { computed_eer_from_seer = seer / (1 + 0.02 * (seer - 11.5)); } else { computed_eer_from_seer = seer * 0.875; } }

if (eerVal !== "" && !isNaN(eer)) { // Reverse: SEER = EER × (1 + 0.02 × (SEER - 11.5)) // Solving: SEER = (EER + 0.02 × 11.5 × EER) / (1 - 0.02 × EER) [when denominator > 0] // Simplified: SEER = EER / (1 - 0.02 × (EER - 11.5)) [iterative or closed-form] // Closed-form rearrangement: // SEER × (1 + 0.02×SEER - 0.02×11.5) = EER // SEER + 0.02×SEER² - 0.23×SEER = EER // 0.02×SEER² + 0.77×SEER - EER = 0 // SEER = (-0.77 + sqrt(0.77² + 4×0.02×EER)) / (2×0.02) var a = 0.02, b = 0.77, c = -eer; var disc = bb - 4a*c; if (disc >= 0) { computed_seer_from_eer = (-b + Math.sqrt(disc)) / (2 * a); } else { computed_seer_from_eer = eer / 0.875; // fallback linear } }

// Use computed values if originals not provided var finalSEER = (!isNaN(seer)) ? seer : computed_seer_from_eer; var finalEER = (!isNaN(eer)) ? eer : computed_eer_from_seer; if (isNaN(finalEER) && computed_eer_from_seer !== null) finalEER = computed_eer_from_seer; if (isNaN(finalSEER) && computed_seer_from_eer !== null) finalSEER = computed_seer_from_eer;

// Efficiency tier classification (AHRI / DOE standards) function seerTier(s) { if (s >= 21) return "Ultra-High Efficiency"; if (s >= 18) return "Very High Efficiency"; if (s >= 16) return "High Efficiency"; if (s >= 14) return "Standard Efficiency"; if (s >= 13) return "Minimum Federal Standard (South)"; return "Below Current Federal Minimum"; } function eerTier(e) { if (e >= 14) return "Excellent"; if (e >= 12) return "Very Good"; if (e >= 10) return "Good"; if (e >= 8.5) return "Average"; return "Below Average"; }

// Power draw at rated capacity var powerKW_seer = null, powerKW_eer = null; var annualCost_seer = null, annualCost_eer = null; var annualKWh_seer = null, annualKWh_eer = null;

if (hasCapacity) { // Power (kW) = Capacity (BTU/hr) / (EER × 1000) [since EER = BTU/hr per Watt] powerKW_eer = capacity / (finalEER * 1000); powerKW_seer = capacity / (finalSEER * 1000); // approximate seasonal avg power

if (hasHours) { annualKWh_eer = powerKW_eer * hours; annualKWh_seer = powerKW_seer * hours;

if (hasRate) { annualCost_eer = annualKWh_eer * rate; annualCost_seer = annualKWh_seer * rate; } } }

// ── Build output ────────────────────────────────────────────────────────── var html = "### Conversion Results "; html += "MetricValue";

if (computed_eer_from_seer !== null) { html += "SEER → EER (converted)" + computed_eer_from_seer.toFixed(2) + " EER"; } if (computed_seer_from_eer !== null) { html += "EER → SEER (converted)" + computed_seer_from_eer.toFixed(2) + " SEER"; }

html += "SEER Efficiency Tier" + seerTier(finalSEER) + ""; html += "EER Efficiency Tier" + eerTier(finalEER) + "";

if (powerKW_eer !== null) { html += "Power Draw at Peak (EER basis)" + (powerKW_eer * 1000).toFixed(0) + " W (" + powerKW_eer.toFixed(3) + " kW)"; } if (annualKWh_eer !== null) { html += "Est. Annual Energy Use (EER basis)" + annualKWh_eer.toFixed(0) + " kWh/yr"; } if (annualCost_eer !== null) { html += "Est. Annual Operating Cost (EER basis)$" + annualCost_eer.toFixed(2) + "/yr"; } if (annualKWh_seer !== null) { html += "Est. Annual Energy Use (SEER basis)" + annualKWh_seer.toFixed(0) + " kWh/yr"; } if (annualCost_seer !== null) { html += "Est. Annual Operating Cost (SEER basis)$" + annualCost_seer.toFixed(2) + "/yr"; }

// Savings vs minimum standard (SEER 14) if (hasCapacity && hasHours && hasRate) { var minSEER = 14; var minEER = minSEER / (1 + 0.02 * (minSEER - 11.5)); var minPower = capacity / (minEER * 1000); var minCost = minPower * hours * rate; var savings = minCost - annualCost_eer; if (savings > 0) { html += "Annual Savings vs SEER 14 Baseline$" + savings.toFixed(2) + "/yr"; } }

html += "";

// Comparison bar var seerPct = Math.min(100, ((finalSEER - 8) / (30 - 8)) * 100); var eerPct = Math.min(100, ((finalEER - 6) / (25 - 6)) * 100); html += ""; html += "SEER Scale (8–30):

"; html += ""; html += ""; html += "EER Scale (6–25):

"; html += ""; html += ""; html += "";

resultDiv.innerHTML = html; }

#### Formulas Used

SEER → EER (DOE/AHRI regression, SEER ≥ 11.5):

EER = SEER / (1 + 0.02 × (SEER − 11.5)) SEER → EER (linear approximation, SEER < 11.5):

EER = SEER × 0.875 EER → SEER (quadratic inverse):

0.02 × SEER² + 0.77 × SEER − EER = 0 SEER = (−0.77 + √(0.77² + 4 × 0.02 × EER)) / (2 × 0.02) Power Draw:

Power (kW) = Capacity (BTU/hr) / (EER × 1,000) Annual Energy & Cost:

Annual kWh = Power (kW) × Annual Hours Annual Cost ($) = Annual kWh × Rate ($/kWh)

#### Assumptions & References

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References

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