SMART TOOL
Furnace and AC Savings Calculator
Pick your system, answer up to three questions, and see the difference in percent and in dollars from your own bill.
The answer
A 96% AFUE furnace uses about 17% less gas than an 80% AFUE furnace for the same heat.
Based on the two ratings and your own number. Weather, the condition of the system and ductwork, and how you use it decide the real result. Equipment and installation prices are not included.
Market price in the Chicago area
- Furnace
- New furnace, installed — most local jobs: $5,500 – $9,400 (middle price about $7,200)
- Air conditioner
- New central AC with indoor coil, installed — most local jobs: $7,400 – $11,600 (middle price about $8,500)
- Both
- Furnace and AC together — most local jobs: $10,500 – $16,500 (middle price about $12,800)
Nicor Gas customers: a $150 rebate for a 95% AFUE furnace installed in 2026. Programs and eligibility can change. Confirm the current amount and requirements with Nicor Gas before purchase. Ask your contractor if it can be taken off the invoice. Nicor Gas rebates
The federal tax credit for efficient heating and cooling equipment does not apply to equipment installed after December 31, 2025. IRS
Market prices from about 570 heating and cooling installations completed in Chicago and the western suburbs between October 2025 and September 2026, as published by The Home Depot. The price for a specific home depends on its size, the equipment and the ductwork, and is set in a written quote.
Request a written quotePrices updated October 2026
Habits
Free saving: the thermostat
"You can save as much as 10% a year on heating and cooling by simply turning your thermostat back 7°-10°F for 8 hours a day from its normal setting."
The U.S. Department of Energy's own words. Read the Department of Energy guidance.
If you have a heat pump, use setbacks only with a thermostat designed for heat pumps; otherwise auxiliary heat can reduce the expected savings.
Next
Repair or replace?
Sources
- Department of Energy FEMP: the AFUE definition
- Department of Energy FEMP: SEER2 and the 2023 change (residential central air conditioners)
- Department of Energy: furnace types and AFUE ranges (PDF)
- Department of Energy: thermostat guidance
- The Home Depot, “Projects Completed” for heating and air conditioning installation
- Costadia: 2026 estimate for a furnace in Naperville (cross-check)
- Costadia: 2026 estimate for central AC in Naperville (cross-check)
- Nicor Gas 2026 rebates for your home
- IRS: energy efficient home improvement credit
Next step
Turn the numbers into a real decision
We assess the system, explain what we found and provide a written quote before any work begins. Utility history and current rates are needed before anyone can estimate dollar savings for a specific property.