Residential furnace savings calculator

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How much could you save?

Are you in the market for a new furnace?

High efficiency furnaces can help save energy, which can help you save money on your home utility bill.

To get started, collect the following:

  • Last 12 months of your Nicor Gas bills
  • Or, access your bills by clicking here

If you have already talked to a contractor or have a furnace you are evaluating, it will help to also have:

  • AFUE ratings from your existing and new furnaces
  • Cost of a new high-efficiency furnace
  • Cost of a new average efficiency furnace

Don't have this information? Don't worry! Just click on the "Use estimates" button on the next step.

Step 1: Where does my gas bill go?

Estimate your heating versus non-heating costs to understand your natural gas usage.

To help you estimate how much of your gas bill is spent on heating, compare your usage during cold months to your usage during warm months. In the summer, your gas usage is typically all from non-heating sources such as natural gas ranges, water heaters, and clothes dryers. Since gas usage from these non-heating sources is typically constant throughout the year, you may assume your additional usage during winter months is from space heating.

Enter your monthly gas usage for the last 12 months. Don't have your bills with you?

Monthly gas bill

Calculation explanation: Monthly non-heating costs are estimated by averaging your monthly bills for the typical non-heating months of June, July, August, and September, and treating that as a baseline for non-heating gas usage throughout the year. Additional gas costs are then attributed to heating costs.

Annual Non-Heating Cost = [(June + July + Aug + Sept) / 4] * 12

Annual Heating Cost = Total Annual Gas Bill - Annual Non-Heating Cost

Monthly therm usage in the estimates are based on the Illinois Commerce Commission household averages. Per therm monthly rates are from Nicor Gas gas prices for 2010-2011.

The information used and provided through use of this calculator are estimates only. Actual gas charges, including the heating and non-heating cost estimates may differ, and will likely change on an annual basis.

Step 2: What will my annual savings be?

Estimate your annual savings from upgrading to a high efficiency heating system.

Furnaces are rated with an Annual Fuel Utilization Efficiency (AFUE) value. Use the AFUE of your new furnace and the AFUE of your existing furnace, if available, to estimate your savings. If you do not know the AFUE of your existing furnace, please select an AFUE from the list below, based on when the furnace was installed.

When was your existing furnace installed?

  • Before 1970: Average AFUE is 60%
  • 1970 - 1974: Average AFUE is 65%
  • 1975 - 1987: Average AFUE is 68%
  • 1988 - 1991: Average AFUE is 76%
  • After 1992: Average AFUE is 78%
Why upgrade?

Natural gas savings are not the only benefits of upgrading to high efficiency. A new, high efficiency furnace can provide you with more efficient heating, keeping your family comfortable!

A high efficiency gas furnace has an AFUE of 90-95%. The Nicor Gas Energy Efficiency Program offers rebates for furnaces with an AFUE of 92% or greater.

Enter your furnace efficiency level (AFUE):

Existing furnace %
New furnace %

Calculation explanation: Estimated savings are calculated by taking the total annual heating cost and factoring in a more efficient furnace.

Estimated savings per year = Annual Heating Cost * [ 1 - (Current AFUE / New AFUE) ]

Average historical furnace ratings are from ENERGY STAR® Furnaces for Consumers - Savings Calculator.

The information used and provided through use of this calculator are estimates only. Actual efficiency ratings and savings will vary. Savings are in no way guaranteed by the Nicor Gas Energy Efficiency Program and depend on other factors not considered in these calculations.

Step 3: What will my lifetime savings be?

Estimate how long it will take for your savings to cover your initial investment.

Ask your contractor how much more a high efficiency furnace will cost over a standard efficiency furnace.

If you do not have this cost, please use these estimates:

  • A 92-94% AFUE furnace costs an additional $580 to $850 over a standard efficiency furnace
  • A 95%+ AFUE furnace costs an additional $850 or more over a standard efficiency furnace

Cash rebates for the following high efficiency furnaces are available to all residential Nicor Gas customers. Click here to learn more.

  • $200 for a 92-94.9% AFUE furnaces
  • $250 for a 95%+ AFUE furnaces
Additional cost for a high-efficiency furnace   $
Rebate - $

Calculation explanation:

Payback period = (Additional cost for a high efficiency furnace - Rebate) / (Annual savings estimate)

Lifetime savings estimate = Annual savings * Expected useful life of furnace ( years)

The information used and provided through use of this calculator are estimates only. Actual savings and payback will vary. Savings are in no way guaranteed by the Nicor Gas Energy Efficiency Program and depend on other factors not considered in these calculations.

What's next?

Upgrading to high efficiency equipment is a smart investment, and will provide you with savings over the life of your furnace.

The Home Energy Efficiency Rebate Program Can Help:

  1. Verify your eligibility. Review the Program requirements.
  2. Select a qualifying furnace. Visit the Rebate Information page for complete details, and select a furnace from a Qualified Products List.
  3. Have a professional contractor install your furnace.
  4. Apply for your rebate.

You will receive your rebate check within two weeks of submitting a complete and eligible rebate application!

Looking for more ways to save?

  • Work with your contractor to ensure your high efficiency upgrade provides you with maximum energy savings. Your furnace should be sized appropriately for your home. Installation of a programmable thermostat can offer you additional savings and improved comfort. You may have other opportunities to increase efficiency and improve the comfort of your home through insulation and sealing of cracks in the exterior of your home.
  • Explore natural gas efficiency opportunities throughout your home using the resources provided on the Program website.
  • Are you in the market for a new hot water heater? Find out more about the rebates available for qualifying natural gas storage water heaters.