Energy Savings Calculator (Old vs New HVAC System)

ANA›Life Services Authority›National Calculator Authority›Energy Savings Calculator (Old vs New HVAC System)

.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; } }

Energy Savings Calculator (Old vs New HVAC System)

Compare the energy costs of your old HVAC system versus a new high-efficiency unit to estimate your annual and lifetime savings.

Old System SEER Rating

Seasonal Energy Efficiency Ratio of existing unit (typically 6–14 for older systems)

New System SEER2 Rating

SEER2 rating of new unit (modern systems: 14–26+)

System Size (Tons)

Cooling capacity of the HVAC system (1 ton = 12,000 BTU/hr)

Annual Cooling Hours

Estimated hours the AC runs per year (varies by climate; 800–2000 typical)

Electricity Rate ($/kWh)

Your local utility rate per kilowatt-hour (U.S. average ~$0.13/kWh)

System Lifetime (Years)

Expected lifespan of the new HVAC system (typically 15–20 years)

New System Installation Cost ($)

Total installed cost of the new HVAC system (optional, for payback calculation)

Calculate Savings

function eneCalc() { var oldSeer = parseFloat(document.getElementById('ene-old-seer').value); var newSeer = parseFloat(document.getElementById('ene-new-seer').value); var tonnage = parseFloat(document.getElementById('ene-tonnage').value); var hours = parseFloat(document.getElementById('ene-hours').value); var rate = parseFloat(document.getElementById('ene-rate').value); var lifetime = parseFloat(document.getElementById('ene-lifetime').value); var installCost = parseFloat(document.getElementById('ene-install-cost').value) || 0;

var errors = []; if (isNaN(oldSeer) || oldSeer 30) errors.push("Old SEER must be between 6 and 30."); if (isNaN(newSeer) || newSeer 30) errors.push("New SEER2 must be between 13 and 30."); if (isNaN(tonnage) || tonnage 20) errors.push("System size must be between 0.5 and 20 tons."); if (isNaN(hours) || hours 8760) errors.push("Annual cooling hours must be between 100 and 8,760."); if (isNaN(rate) || rate 1.00) errors.push("Electricity rate must be between $0.01 and $1.00/kWh."); if (isNaN(lifetime) || lifetime 30) errors.push("System lifetime must be between 1 and 30 years."); if (newSeer 0) { document.getElementById('ene-result').innerHTML = 'Please fix the following:' + errors.map(function(e){ return ''; }).join('') + ''; return; }

// --- Core Formulas --- // BTU/hr capacity = tonnage * 12,000 var btuPerHour = tonnage * 12000;

// kW draw = BTU/hr / (SEER * 1000) [SEER is in BTU/Wh, so divide by 1000 for kW] // Annual kWh = kW_draw * annual_hours var oldKw = btuPerHour / (oldSeer * 1000); var newKw = btuPerHour / (newSeer * 1000);

var oldAnnualKwh = oldKw * hours; var newAnnualKwh = newKw * hours;

var annualKwhSaved = oldAnnualKwh - newAnnualKwh;

// Annual cost savings var oldAnnualCost = oldAnnualKwh * rate; var newAnnualCost = newAnnualKwh * rate; var annualCostSaving = oldAnnualCost - newAnnualCost;

// Lifetime savings var lifetimeSaving = annualCostSaving * lifetime;

// Payback period (years) = install cost / annual savings
var payback = (annualCostSaving > 0 && installCost > 0)
? (installCost / annualCostSaving)
null;

// Net lifetime savings after install cost var netLifetimeSaving = lifetimeSaving - installCost;

// Efficiency improvement % var effImprovement = ((newSeer - oldSeer) / oldSeer) * 100;

// CO2 reduction (EPA avg: 0.386 kg CO2 per kWh in the U.S.) var co2PerKwh = 0.386; var annualCo2Saved = annualKwhSaved * co2PerKwh; var lifetimeCo2Saved = annualCo2Saved * lifetime;

function fmt(n, dec) { dec = dec === undefined ? 2 : dec; return n.toLocaleString('en-US', {minimumFractionDigits: dec, maximumFractionDigits: dec}); } function fmtUSD(n) { return '$' + fmt(Math.abs(n), 2); }

var paybackHtml = ''; if (payback !== null) { paybackHtml = 'Simple Payback Period' + fmt(payback, 1) + ' years'; } var netHtml = ''; if (installCost > 0) { var netClass = netLifetimeSaving >= 0 ? 'calc-highlight-green' : 'calc-highlight-red'; netHtml = 'Net Lifetime Savings (after install cost)' + (netLifetimeSaving >= 0 ? '' : '-') + fmtUSD(netLifetimeSaving) + ''; }

document.getElementById('ene-result').innerHTML = '### Results ' + '' + 'MetricOld SystemNew System' + '' + 'SEER Rating' + fmt(oldSeer,1) + '' + fmt(newSeer,1) + '' + 'Power Draw (kW)' + fmt(oldKw,3) + ' kW' + fmt(newKw,3) + ' kW' + 'Annual Energy Use (kWh)' + fmt(oldAnnualKwh,0) + ' kWh' + fmt(newAnnualKwh,0) + ' kWh' + 'Annual Energy Cost' + fmtUSD(oldAnnualCost) + '' + fmtUSD(newAnnualCost) + '' + '' + '' + '' + 'Savings Summary' + '' + 'Efficiency Improvement' + fmt(effImprovement,1) + '%' + 'Annual kWh Saved' + fmt(annualKwhSaved,0) + ' kWh' + 'Annual Cost Savings' + fmtUSD(annualCostSaving) + '/yr' + 'Lifetime Cost Savings (' + fmt(lifetime,0) + ' yrs)' + fmtUSD(lifetimeSaving) + '' + paybackHtml + netHtml + 'Annual CO₂ Reduction' + fmt(annualCo2Saved,0) + ' kg CO₂' + 'Lifetime CO₂ Reduction' + fmt(lifetimeCo2Saved,0) + ' kg CO₂' + '' + ''; }

#### Formulas Used

Power Draw (kW): kW = (Tons × 12,000 BTU/hr) ÷ (SEER × 1,000)

Annual Energy Consumption (kWh): Annual kWh = kW × Annual Cooling Hours

Annual Energy Cost ($): Annual Cost = Annual kWh × Electricity Rate ($/kWh)

Annual Savings: Annual Savings = Old Annual Cost − New Annual Cost

Lifetime Savings: Lifetime Savings = Annual Savings × System Lifetime (years)

Simple Payback Period: Payback (years) = Installation Cost ÷ Annual Savings

CO₂ Reduction: CO₂ Saved (kg) = kWh Saved × 0.386 kg CO₂/kWh (EPA eGRID national average emission factor)

#### Assumptions & References

More Calculators

Read Next

Study Time Planner Authority Network America › Life Services Authority › National Calculator Authority .calc-container { max-width: 640px;...

References

Related Authorities

Life Services Authority › Professional Services Authority › Trade Services Authority › United States Authority ›