Inputs
Example data table
| Scenario | Current SEER | New SEER | Tons | Hours | Rate | Year‑1 Savings | Payback |
|---|---|---|---|---|---|---|---|
| Typical upgrade | 13 | 16 | 3.0 | 1200 | $0.18 | $155 | ~39 yrs |
| High usage home | 12 | 18 | 4.0 | 1800 | $0.22 | $616 | ~10 yrs |
| Lower rate area | 14 | 16 | 2.5 | 900 | $0.12 | $58 | Long |
Formula used
- SEER definition: SEER = seasonal cooling output (BTU) ÷ electric energy input (Wh).
- Estimate annual cooling output: Annual BTU = (Tons × 12,000) × Full‑load hours.
- Annual electricity: kWh = (Annual BTU ÷ SEER) ÷ 1,000.
- Annual bill: Cost = kWh × Rate.
- Year‑1 savings: Savings = (Costcurrent − Costnew) + Maintenance savings.
- NPV: NPV = −Net cost + Σ [Savingsy ÷ (1 + Discount)y].
How to use this calculator
- Enter your current and target SEER values from equipment specs.
- Pick Estimate if you know system tons and annual cooling hours.
- Pick Known kWh if you have annual cooling electricity use.
- Add your electric rate, upgrade cost, and any rebates.
- Optional: adjust escalation, discount rate, and analysis years.
- Click Calculate Savings to see payback, ROI, and NPV above.
How SEER translates into energy spending
SEER measures seasonal cooling output divided by electrical input. For the same cooling load, expected kWh scales with the ratio Current SEER ÷ New SEER. A move from 13 to 16 implies about 18.75% lower electricity use, before installation and duct factors. This calculator converts that efficiency change into annual dollars using your local rate and chosen usage method. In warm climates, the baseline hours often dominate savings more than SEER.
Building a realistic usage baseline
If you cannot isolate cooling kWh, estimate annual output from capacity and equivalent full‑load hours. Capacity equals Tons × 12,000 BTU per hour. Seasonal output equals Capacity × Hours. Annual kWh equals (Seasonal BTU ÷ SEER) ÷ 1,000. Using known annual cooling kWh can be even better, because it anchors results to your past bills. Try ranges for hours to reflect seasons.
From annual savings to payback
Year‑one energy savings equals the difference between current and new annual bills. You can add maintenance savings if you expect fewer repairs or lower service costs. Net upfront cost equals installed upgrade cost minus rebates or incentives. Simple payback equals Net cost ÷ Year‑one total savings. A long payback often signals low cooling hours, low rates, or a small SEER gap. If rebates are large, payback can drop fast.
NPV and IRR for a finance view
Because energy prices can rise, the tool escalates savings by your selected annual percentage. It then discounts each future year back to today using your discount rate to compute net present value. A positive NPV means the upgrade beats your required return under those assumptions. The IRR estimate summarizes the annualized return of the cash flows for easy comparison. Stress-test discount rates for confidence.
Using the results to choose an option
Review annual kWh, bill comparison, and the cumulative savings curve. If cumulative savings does not cross zero within the analysis years, the upgrade may still be justified by comfort, noise, humidity control, or reliability. Run scenarios for different SEER targets, rebate levels, and cooling hours to see sensitivity. Download the CSV to document your assumptions and share decisions. Compare bids and warranty terms.
FAQs
1) What SEER values are common today?
Many entry systems start around SEER 14–15, with higher‑efficiency options in the high teens or above. Availability and requirements vary by region and equipment type.
2) Is savings always proportional to current SEER divided by new SEER?
As a first‑order estimate, yes: electricity use scales roughly with SEER ratio for the same cooling load. Real savings can differ due to installation quality, duct losses, and part‑load performance.
3) What are equivalent full‑load hours?
They approximate how many hours the system would run at full capacity to deliver the season’s total cooling. It compresses varying daily loads into one annual number for planning.
4) Should I include maintenance savings?
Only if you have a solid basis, such as reduced repair risk under warranty or known service cost differences. Otherwise set it to zero to keep the estimate conservative.
5) What discount rate should I use?
Use a rate that reflects your opportunity cost or required return. Some homeowners choose 5–10%. Higher discount rates reduce the present value of future energy savings.
6) Can this compare multiple upgrade options?
Yes. Run the calculator once for each target SEER and cost scenario. Download each CSV and compare NPV, payback, and IRR side by side.