01 — Your Home & System
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Enter your city — we'll apply the correct IECC climate zone to your results automatically.
Larger homes put more demand on your system and have higher exposure to efficiency loss.
Most common whole-home system. Avg. replacement cost: $5,000–$12,000 per unit.
A standard home has 1. Mini-splits or multi-zone systems may have 2–5 or more.
years
Most HVAC systems last 15–20 years. Efficiency drops significantly after year 10.
No repairs — that's a good sign.
Systems that are never serviced lose efficiency faster and fail sooner.
02 — Performance & Costs
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Think about your highest summer or winter month. Check your last utility bill for accuracy.
$
If a technician has quoted you a repair, enter it here. Otherwise leave as 0.
Energy bill noticeably higher than it used to be?Unexplained bill spikes are a leading efficiency indicator
Some rooms harder to heat or cool than others?Uneven temps point to a system struggling to keep up
System running constantly or making unusual noises?Short-cycling or strange sounds often signal imminent failure
Two things to keep an eye on
Wasting Per Year
$0
in avoidable costs
Recommendation
—
based on your inputs
Est. Annual Savings
$0
with updated system(s)
Cited Fact
Step 1 — IECC Climate Zone Detection
Your city is mapped to an IECC (International Energy Conservation Code) climate zone — the same framework used by HVAC manufacturers, energy codes, and utility companies nationally. Eight zones based on heating and cooling degree-days. Zone 1 is South Florida (maximum cooling intensity). Zone 8 is Alaska. Your zone directly adjusts age thresholds, efficiency loss rates, repair cost multipliers, signal weights, and savings potential — because the same system in Phoenix and Minneapolis faces fundamentally different wear conditions.
Zone 4 (Mixed/Humid) — National average baseline
Conservative Estimate
Step 2 — Cost of a Non-Functioning System
When a system isn't conditioning air, we apply a conservative floor of $900/year (~$75/month) covering temporary solutions and daily disruption costs. Actual costs are typically significantly higher.
Operating Cost = $75/month × 12 = $900/year (applied when system is not operating properly)
Cited Fact
Regional Note
Step 3 — Zone-Adjusted Efficiency Loss & Age Thresholds
Based on EPA and DOE HVAC performance data, systems lose approximately 3–5% efficiency per year after year 8. The exact rate and age thresholds vary by IECC zone. Hot/humid zones (1–2) see higher rates and flag systems earlier. Cold zones (6–7) have lower rates and longer useful lives. The age threshold triggering replacement urgency shifts from 12 years (Zone 1) to 20 years (Zone 8).
Zone 4: 3.5% efficiency loss/year after year 8. Replace threshold: age 15.
Conservative Estimate
Regional Note
Step 4 — Zone-Adjusted Repair Costs & Signal Weights
Base repair cost per event: $400 (HomeAdvisor/Angi average), adjusted by a zone repair multiplier. Hot/humid zones carry higher multipliers due to increased wear frequency. Performance signals are also zone-weighted — "system running constantly" is more urgent in hot zones (cooling failure in extreme heat); "uneven temperatures" is more urgent in cold zones (heating distribution failure in winter).
Zone 4 repair multiplier: 1.00×. Signal multiplier: 1.00×.
Cited Fact
Regional Note
Step 5 — Zone-Adjusted Savings Estimate
Based on ENERGY STAR replacement data, a new high-efficiency system reduces energy use by 25–35%. We use a conservative 30% baseline adjusted by a zone savings multiplier from EIA residential energy consumption survey data. Zone 1–2 homeowners see the highest returns (systems run the most hours). Zone 7–8 see lower overall savings multipliers but higher heating efficiency gains.
Savings = Bill × 30% × sizeMult × unitCount × 12 × zoneSavingsMult
Industry Standard
Step 6 — The Rule of $5,000
A real heuristic used by HVAC professionals: multiply your system's age by any repair quote. If the result exceeds $5,000, replacement is generally the more financially sound choice. Widely used in the industry — not a guarantee, but a reliable decision framework.
Rule of $5,000 = System Age (years) × Repair Quote → exceeds $5,000 → replacement favored
📌 IECC climate zone boundaries per International Energy Conservation Code (IECC 2021). Efficiency loss rates from EPA and DOE HVAC performance data. Repair averages from HomeAdvisor and Angi (2024–2025). Savings from ENERGY STAR replacement data. Zone multipliers from EIA residential energy consumption survey by climate zone. All figures are estimates — actual results vary by system, market, and circumstances. Designed to help you ask better questions, not replace a professional assessment.
Your Full Cost Breakdown
Heads up: These are estimates based on industry averages, your inputs, and your IECC climate zone — not guaranteed outcomes or quotes. Real results depend on your equipment brand, local utility rates, and usage. Designed to help you understand the opportunity and ask better questions, not promise a specific dollar figure.
The Rule of $5,000
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