How the WattGap Score works
Your WattGap Score (0-100) is a quick read on how much money you're already keeping versus how much your home is still leaving on the table. Higher is better. Here's exactly how we calculate it -- no black boxes.
What this score is not
- Not a credit score or financial rating -- no bearing on loan eligibility
- Not a certified energy audit result -- does not replace a professional inspection
- Not a guarantee of rebate eligibility or savings
- Not a certified home energy rating (HER) issued under any certification standard
How your score is calculated
For each part of your home's energy picture, WattGap works out two dollar figures: what is achievable for your home, and what you have already captured. Your score is the share you have captured, and the Gap is the rest. They are exact opposites of each other.
There are no category weights we set in advance. Each opportunity moves your score in proportion to the money in it for your home. The denominator is your own home's total, which is why a studio and a large house can both reach 100. If we cannot estimate a frontier for your home at all, we withhold the number rather than show you a zero or a guess.
What the dollar figures include
The achievable figure, and so the Gap beside your score, is your rebate and credit money: one-time incentives at full value. Recurring wins such as a better rate plan, bill assistance, or a demand-response program are not in those two numbers today. They do count toward your score, through the captured share below, but they will not show up in the Gap. So read the Gap as incentive money still on the table rather than as everything we found, and if your biggest opportunity is a rate switch you will see it move your score without moving your Gap. Bringing the displayed figures in line with everything the score weighs is a change to the engine, not to this page, and we have not made it yet.
Where the captured figure comes from
Before you tell us what you already have, the captured side is an estimate, not a measurement of your home. We start from how much of each opportunity US households typically capture, then weight those rates by the dollars in each part of your picture. Those are national rates drawn from EIA, FERC, and NREL data, the same figures for every home in the country: we do not yet vary them by your state, utility, or ZIP. So it is a national modeled starting point, and we would rather say so than let a nationwide average read as either local data or a fact about your house.
Three confirmations currently make it yours: a heat pump, rooftop solar, and attic or roof insulation. Telling us about any of those replaces the estimate for that part of your score with your actual situation. Everything else stays on the national estimate for now, including enrollments such as your rate plan, bill assistance, and demand-response programs. So a home that has done a lot can still read as more typical than it is, and we would rather you knew that than assume the number already accounts for everything you have done.
What does the WattGap Score look at?
These are the areas we examine in your home, written the way you would describe them. They are not the engine's internal buckets: behind the scenes it groups them differently, folding heating and water heating together under electrification, counting rebate dollars inside the area they belong to rather than as a category of their own, and adding bill assistance where a household qualifies for it.
Whatever the grouping, the arithmetic is the same: each area is weighted by the dollars actually in it for your home, not by a fixed percentage we assigned in advance. Those dollars are compared on an annual footing first, so a one-time rebate is spread over the life of what it buys rather than counted against a yearly saving at full size: an $8,000 heat-pump rebate on a system that lasts about 15 years is weighed at roughly $533 a year, next to a $400-a-year rate saving. That is why heating and cooling usually moves the score most, since it is typically 40-50% of what you pay every year. In a home where it is already efficient, it moves the score very little, and something else matters more.
Heating & cooling efficiency
How old and efficient is your heating and cooling system?
Rate plan optimization
Are you on the best electricity rate plan for your usage?
Insulation & weatherization
How well does your home hold in heated or cooled air?
Rebate capture
Have you claimed the rebates and credits available to you?
Water heating
What type of water heater do you have?
Solar readiness
Are you using solar energy (rooftop or community)?
Grid participation
Are you enrolled in programs that pay you to reduce peak energy use?
How the three-lane system works
The lanes organize what you can do by time horizon and action type. They are how your actions are grouped and sequenced, not how your score is computed: your score is the share of the money worth going after that you have already captured, and every opportunity moves it in proportion to the dollars in it for your home.
Claim Now
Rate plan savings, demand response enrollment, community solar -- money you can start capturing this week.
Fix Before Failure
Aging equipment rebates for systems likely to fail within 5 years. Replacing on your timeline beats replacing in a crisis.
Unlock Next
Solar installation, EV charging, major electrification upgrades. Often the largest single-action savings available, which is why they tend to move your score the most.
Within each lane, programs rank by dollar value, times how confident we are in the data, times how easy the program is to actually claim. Verified rebates always rank above estimated alternatives of the same value.
Uncertain numbers rank lower
Every program and estimate carries a confidence tier. Confidence describes how much we know about your home, not how well your home is doing, so it never moves your score up or down. What it does change is what we put in front of you: lower-confidence programs rank below better-evidenced ones of the same value. If our data on your home is thin, you get a clearly labelled lower-confidence reading, not a lower score.
Sourced from an official utility or state agency record. Ranking only, and not a freshness guarantee: see the verification date shown with each program.
Census or utility territory data; ZIP-level inference.
National averages applied locally; no direct source verification.
What does each score range mean?
90-100: Excellent
You've already captured most of the savings available to your home. Equipment is efficient and you're enrolled in the programs that pay you back.
70-89: Good
Solid shape. A handful of upgrades or program enrollments could push you into the top tier.
50-69: Average
Meaningful money is still sitting in your bills. This is where most homes start -- and the easiest wins are usually right here.
30-49: Below average
Quick wins everywhere. Rate plan switches and rebates alone could save you hundreds a year.
0-29: Needs attention
A lot of money is going unclaimed -- which is actually good news, because the biggest improvements are still ahead of you.
Where does the data come from?
8 public and partner sources -- most of them the same ones the government and utilities use. No black boxes, no guesswork. Every number has a name on it.
Home age, heating fuel type, median income, and home value by ZIP code
Rebate eligibility, program details, and machine-learning savings predictions
3,700+ utility rate structures for rate plan optimization
Heating and cooling degree days, solar irradiance, and climate zones (MERRA-2 reanalysis)
Electricity rates, utility service territories, and bill averages by state
Solar production estimates by location
Rooftop solar potential for 320+ million US buildings
State and local incentive program database (CC BY-SA 4.0, NC Clean Energy Technology Center)
Why should you trust this number?
Transparency first. Every data point shows a confidence indicator: green (verified from an official source), amber (estimated from area data), or gray (unverified). You always know what's solid and what's a ballpark.
No hidden agenda. WattGap is not currently charging households for the diagnostic or core guidance. Any future optional service would be clearly priced. No one can pay to change your score, your rankings, or your recommendations. The diagnostic is never for sale. WattGap never sells your personal information.
Real numbers, not vibes. Every rebate amount, rate plan saving, and financing option comes from actual program data. We cite sources. If a number is uncertain, we say so out loud.
Open methodology. You're reading it right now. The dimensions, the formula, and the data sources are all documented on this page. No proprietary algorithm hiding in the basement.
Data limitations
The score is built on the best public data available, but data has limits. Know these before acting on any estimate.
- !Programs change frequently. Always verify details with the administering agency before making a purchase.
- !ZIP-level inputs. Home age, heating fuel, and income use Census ZIP averages -- your address may differ.
- !The federal 25C efficiency and 25D solar credits expired December 31, 2025 and are excluded from every estimate; solar incentives are now state and utility programs only. Federal programs that remain depend on continued appropriations.
- !Income-based eligibility requires self-attestation through the program administrator, not just a score.
- !Equipment condition is inferred from Census home age data -- not an inspection. A qualified auditor may find different conditions.
Why existing home energy scores fall short
Most home energy scores were designed before real-time rebate data was available at scale. Three structural gaps:
1. Static scores don't track real-time programs
A score from January may not reflect a new rebate that launched in March or a credit that expired in December. WattGap checks program sources on a rolling schedule.
2. They don't rank by financial value + friction
Generic scores tell you to upgrade insulation without telling you a specific rebate covers 60% of the cost and a qualified contractor is available in your ZIP in two weeks.
3. They don't filter by your eligibility
A renter can't claim a solar installation rebate. A homeowner outside a utility's territory can't access that utility's program. WattGap filters by eligibility from the first question.
Full methodology reference: docs/methodology/wattgap-score-methodology.md
Frequently asked questions
How accurate is the WattGap Score?
Pretty accurate. The score runs on real data from government and utility sources. When we have address-level data, accuracy is high. When we have to fall back on ZIP-level averages, we mark that point "estimated" so you can see the difference. Every data point carries a confidence indicator (verified, estimated, or unverified) so you always know what's solid and what's a ballpark.
Do you sell my data?
No. WattGap does not sell your personal information to anyone. We never share your exact income, and we only collect what we need to show you an accurate result. See our privacy policy for the full details.
How often is the data updated?
Rebate programs get checked weekly. Utility rate data updates whenever OpenEI publishes changes. Census data refreshes annually. Climate data updates daily. If a source is temporarily down, we show cached data with a note so you know what you're looking at.
Why is my score low even though I have a new house?
A brand-new home can still score low if you haven't enrolled in the programs that pay you back (community solar, demand response), aren't on the best rate plan for your usage, or haven't claimed the rebates available for equipment upgrades. The score measures total optimization, not just how new your equipment is.
Can I improve my score?
Yes -- and usually faster than you'd expect. Every dimension has specific actions. The easiest wins are usually switching to a better rate plan (saves $100-$400 a year with one phone call) and enrolling in community solar (saves 5-10% on your electric bill with no installation). Your results page shows every step with estimated savings.
How is this different from an energy audit?
A professional energy audit sends a person to your home and costs $200-$500. WattGap gives you a free instant analysis from public data and covers rebates, rate plans, and financing -- things auditors typically don't touch. For deep equipment analysis, we recommend an audit as a complement to WattGap, not a replacement.
$500-$1,100 a year. That's what most homes leave unclaimed. What's yours?
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