Home Energy Efficiency Calculator
Score your home's energy efficiency based on its size, age, insulation, heating system, and climate zone. Use this audit tool to identify inefficiencies and estimate annual energy costs before calling a professional auditor.
Last updated: September 2026
Formula below · 2 sources (climate.gov, Wikipedia) · Updated Sep 2026
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About this calculator
This calculator estimates a home's annual energy cost from five factors. It starts from a typical US energy intensity of about 12 kWh-equivalent per square foot per year (EIA Residential Energy Consumption Survey 2020: about 77 million Btu of site energy for an average home), then multiplies by an age factor (1.4 before 1970, 1.2 for 1970–1990, 1.0 for 1990–2010, 0.8 after 2010), an insulation factor (1.3 poor to 0.5 excellent) and a climate factor (0.6 mild to 1.8 very cold). The heating option sets the average cost per kWh-equivalent of the energy used: about $0.095 for natural-gas-heated homes, $0.11 oil, $0.13 electric resistance and $0.085 heat pump. The formula is: Annual cost ($) = homeSize × 12 × ageFactor × insulationFactor × climateFactor × costPerKWh. A typical 2,000 sq ft gas-heated home built 1990–2010 in a moderate climate comes to about $2,280 a year, close to the US average residential energy bill. The factors are planning estimates; a professional audit with a blower-door test gives a home-specific answer.
How to use
Consider a 2,500 sq ft home built before 1970 (age factor 1.4) with poor insulation (1.3), electric resistance heating ($0.13), in a cold climate (1.4). Annual cost = 2,500 × 12 × 1.4 × 1.3 × 0.13 × 1.4 = $9,937. The same house with excellent insulation (0.5) and a heat pump ($0.085) would come to 2,500 × 12 × 1.4 × 0.5 × 0.085 × 1.4 ≈ $2,499 — showing why insulation and heat pumps are the biggest levers.
Frequently asked questions
What does the result mean and how should I interpret it?
The result is an estimated annual energy cost in dollars for a home with your characteristics, based on national-average energy intensity and typical prices. Compare it with your actual utility bills: if your real bills are much higher, the home is likely less efficient than the selections suggest (air leaks, old equipment); if lower, it is performing better than average. Use it as a starting point before commissioning a professional blower-door test or infrared audit.
How much can improving home insulation reduce energy bills?
According to the U.S. Department of Energy, properly insulating and air-sealing a home can reduce heating and cooling costs by 10–50%, depending on the existing insulation level and climate. In older homes with little or no attic insulation, adding R-38 to R-60 insulation can save hundreds of dollars per year. The payback period for insulation is typically 3–7 years, making it one of the highest-ROI home improvements available. Insulation improvements also improve comfort by eliminating cold drafts and reducing humidity infiltration.
Which climate zone has the biggest impact on home energy costs?
Homes in very cold climate zones (zones 6–8 under the IECC map, covering the northern U.S. and Alaska) typically pay 2–3 times more for heating than homes in mild zones like the Pacific Coast. In hot-humid zones such as the Southeast, cooling costs can be equally significant. Climate zone is one of the most powerful multipliers in any energy model because it determines both the heating degree days and cooling degree days a home must overcome. That is why the same house with identical insulation can have dramatically different energy bills depending on geography.