Home Energy Audit Calculator
Evaluate your home's energy efficiency and find potential savings from upgrades like better windows and insulation.
About this calculator
Annual Energy Cost is simply your Monthly Electric Bill plus Monthly Gas Bill, annualized -- it responds to your utility bills directly and is not adjusted by home age, size, windows, or insulation at all, since it's calculated straight from what you're actually paying today. Efficiency Rating and Potential Annual Savings work differently: they're built from a point-deduction model driven entirely by Home Age, Windows, and Insulation. Single-pane windows and poor insulation each carry the largest efficiency penalties in the model, and each also unlocks the largest potential savings estimate if upgraded -- roughly 15% of annual energy cost from replacing single-pane windows and up to 20% from fixing poor insulation. Home Square Feet and Home Age, on their own, do not move Annual Energy Cost at all -- that figure comes straight from your entered utility bills.
Home Square Feet does directly drive the separate Cost Per Sq Ft figure, since that output divides Annual Energy Cost by square footage; Home Age only affects the Efficiency Rating and, once past 20 years, adds a further savings estimate reflecting typical equipment and envelope wear. Upgrade Payback divides the estimated cost of the recommended upgrades by the estimated annual savings, giving a rough years-to-break-even figure. These are generic percentage-based estimates, not a substitute for a professional blower-door and infrared home energy audit, which measures your home's actual air leakage and thermal performance directly rather than inferring it from age and component category.
Inputs
Results
Annual Energy Cost
$2,760.00
How to Use This Calculator
- Enter your average monthly electric and gas bills, along with your home's square footage and age.
- Select your window type (single, double, or triple pane) and your insulation quality (poor, average, or good).
- Review your annual energy cost and cost per square foot.
- Check your efficiency rating, which reflects your home's age, windows, and insulation.
- Use the potential annual savings and payback years to decide whether upgrading windows or insulation is worth it.
How the result changes with Monthly Electric Bill
| Monthly Electric Bill | Annual Energy Cost |
|---|---|
| $75.00 | $1,860.00 |
| $113.00 | $2,316.00 |
| $225.00 | $3,660.00 |
| $375.00 | $5,460.00 |
What each input means
- Monthly Electric Bill
- Average monthly electricity cost from your utility bill
- Monthly Gas Bill
- Average monthly natural gas cost — enter 0 if all-electric home
- Home Size
- Total heated and cooled living area of your home in square feet
- Home Age
- How old your home is — older homes tend to be less energy efficient
- Windows
- Type of window glass installed — more panes means better insulation
- Insulation
- Overall quality of your home's wall and attic insulation
How this is calculated
Worked example, using the default values
- Identify Input Parameters6 parametersMonthly Electric Bill = 150, Monthly Gas Bill = 80, Home Size = 2000, Home Age = 25, Windows = 1, Insulation = 1 = 6 input(s) provided
- Calculate Annual Energy CostAnnual Energy Cost2760 = $2,760
- Calculate Cost Per Sq FtCost Per Sq Ft1.38 = $1.38
- Calculate Efficiency RatingEfficiency RatingGood = Good
Engine last updated . Checked against 1 independently-derived test — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What has the biggest effect on my Annual Energy Cost?
Monthly Electric Bill and Monthly Gas Bill together, and only those two -- Annual Energy Cost is just the two bills added together and multiplied by 12, with every dollar of either bill weighted identically. It responds directly and only to what you enter for your utility bills; home size, age, windows, and insulation don't factor into this particular output at all.
Why doesn't my home's square footage change the Annual Energy Cost?
Annual Energy Cost is calculated purely from your entered electric and gas bills, not derived from square footage. Home Square Feet is instead used to compute the separate Cost Per Sq Ft figure, which divides your annual cost by square footage to give a comparable efficiency benchmark against other homes.
Why doesn't my home's age affect the annual energy cost?
Home Age feeds into the Efficiency Rating and, past 20 years, adds a modest savings estimate reflecting general equipment and envelope wear -- but it does not change Annual Energy Cost itself, which is calculated straight from your entered utility bills regardless of how old the home is.
Which upgrade shows the biggest potential savings, windows or insulation?
In this model, poor insulation carries a larger potential savings estimate (about 20% of annual energy cost) than single-pane windows (about 15%), reflecting that whole-envelope insulation gaps typically waste more energy than window conduction losses alone. Average insulation still shows a smaller savings opportunity (about 10%) versus good insulation.
Should I rely on this instead of a professional energy audit?
No -- this calculator applies generic percentage estimates based on window type, insulation quality, and home age categories, not a direct measurement of your home's actual performance. A professional blower-door test and infrared scan measures real air leakage and thermal weak points, which can reveal issues (duct leakage, specific gaps) this category-based model cannot detect.
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