01 — Your Home & System
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. Count each indoor unit or zone separately.
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
$
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
Wasting Per Year
$0
in avoidable costs
Recommendation
—
based on your inputs
Est. Annual Savings
$0
with updated system(s)
Step 1 — Cost of a Non-Functioning System (Annual)
When a system is not conditioning air at all, homeowners incur ongoing out-of-pocket costs while waiting for repair or replacement. We apply a conservative floor estimate of $900/year — approximately $75/month — covering temporary cooling or heating solutions, portable unit rentals, service call fees, and daily comfort disruption. This figure is intentionally conservative. Actual costs are typically higher depending on the number of people in the home, local temperatures, and whether hotel stays or extended rentals are involved. If your situation involves more than basic inconvenience, your real cost-of-waiting is likely several times this estimate.
Operating Cost = $75/month × 12 = $900/year (applied only when system is not operating properly)
Step 2 — Age-Related Efficiency Loss
After year 8, systems lose approximately 3.5% efficiency per year up to a 40% cap. Applied to the HVAC portion of your bill (est. 45%) × home size × unit count × 12 months.
Efficiency Loss = (Age − 8) × 3.5% × sizeMultiplier — capped at 40%
Annual Waste = Monthly Bill × 45% × Efficiency Loss × unitCount × 12
Step 3 — Repair Costs
Each major repair averages $400, adjusted by maintenance history and number of units.
Repair Cost = Repairs × $400 × maintFactor × unitCount
Step 4 — Performance Signal Surcharge
Each warning signal you flagged adds a weighted annual cost — these behaviors indicate efficiency loss beyond what age alone explains.
Signal Cost = (sig1 ? $180 : 0) + (sig2 ? $240 : 0) + (sig3 ? $360 : 0) per year
Step 5 — Estimated Annual Savings
New high-efficiency systems typically reduce energy use by 25–35%. We use a conservative 30% savings rate × home size × unit count × 12 months.
Annual Savings = Monthly Bill × 30% × sizeMultiplier × unitCount × 12
Step 6 — The Rule of $5,000
Multiply your system age by any repair quote. Above $5,000, replacement is almost always the smarter financial decision.
Rule of $5,000 = System Age × Repair Quote
📌 Replacement cost data from Angi, HomeAdvisor, and Modernize 2026 reports. Efficiency loss rates from EPA and DOE HVAC data. All figures are estimates — actual costs vary by brand, region, and installation.
Your Full Cost Breakdown
Heads up: These are estimates based on industry averages and your inputs — not guaranteed outcomes or quotes. Real results depend on your equipment brand, local climate, utility rates, and usage. This tool is designed to help you understand the opportunity, not promise a specific dollar figure.
The Rule of $5,000
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