What an Energy Audit Should Actually Find

An energy audit exists to answer a question homeowners otherwise guess at: where is this specific house losing energy, and which fix returns the most per pound spent?

Guessing is expensive here, because intuition is consistently wrong. People replace windows, which are usually a poor return, while the attic and the ductwork — the two items that typically dominate — go untouched because they are not visible.

What a real energy audit includes

There is a large difference between a walkthrough and a diagnostic audit. The distinguishing feature is measurement.

A blower door test is the core of it. A fan mounted in a doorway depressurises the house, and the airflow required to hold that pressure quantifies total leakage. It converts "the house feels draughty" into a number, and it lets the auditor find leaks by feeling where air rushes in while the fan runs.

Thermal imaging shows temperature differences across surfaces, revealing missing insulation, thermal bridges and air paths inside walls that are invisible otherwise.

Duct leakage testing, where there is forced air. Ducts running through an unconditioned attic or crawl space can lose a substantial share of what they carry, and this is frequently the largest single finding in a house that has one.

Combustion safety testing on any fuel-burning appliance — checking for backdrafting and carbon monoxide. This is a safety item rather than an energy one and is a good reason not to skip the professional version.

Insulation inspection in accessible areas, with actual depths recorded.

A written report listing findings with estimated costs and savings, ranked.

A walkthrough without a blower door is worth something but is essentially an informed opinion. The test is what makes the report specific to your house.

Why the ranking matters more than the list

The value of the report is the ordering, and a good auditor is explicit about it.

The pattern that holds across most housing stock, roughly in order of return:

Air sealing, particularly at the top of the house. Cheap, high impact, and the prerequisite for insulation performing as rated — the insulation guide covers why sequence matters here.

Attic insulation to recommended depth for the climate. The attic insulation guide covers depth, and the insulation payback calculator covers the return.

Duct sealing where ducts pass through unconditioned space.

Water heating, the second-largest load in many homes — the water heater operating cost calculator covers the running cost and the first hour rating guide covers sizing a replacement.

Heating and cooling equipment, once the load has been reduced, so a smaller system can be specified — the heat pump comparison covers that decision.

LED lighting and phantom loads, cheap and quick, worth doing regardless of where they rank.

Windows, almost always last on a return basis, despite being the item most households consider first — the window upgrade guide covers why.

The energy audit priority calculator ranks measures by payback so the report's recommendations can be compared on a common basis rather than in the order the auditor happened to write them.

Reading the report critically

Check whether the auditor sells the work. An audit from a company that also installs is not automatically compromised, but the incentive is obvious. A fee-only auditor with no installation business gives a cleaner recommendation, and where the auditor does both, get the work quoted independently.

Check the assumed energy prices. Savings estimates are only as good as the rate used. If the report assumes a national average and you pay considerably more or less, every payback figure shifts — the energy cost calculator is how you check.

Check whether savings are additive. They frequently are not. Sealing air leaks reduces the savings available from insulation, and vice versa, because both address overlapping losses. A report totalling every measure's individual saving overstates the combined result.

Look for the ventilation note. A house sealed substantially needs controlled ventilation. An audit recommending aggressive air sealing without addressing it is incomplete, and indoor air quality is not a marginal concern.

What it costs and how to get one cheaply

Professional audits are priced in the low hundreds, and there are several routes to paying less or nothing.

Utility programmes. Many utilities offer subsidised or free audits, sometimes bundled with direct installation of cheap measures — LEDs, aerators, pipe insulation — on the day. This is the first place to check.

State and municipal programmes, particularly income-qualified ones, which sometimes include the remedial work as well as the audit.

Tax credits, which have covered a share of audit costs and change frequently. Verify current availability with the Department of Energy rather than relying on remembered figures.

A do-it-yourself version is worth doing if a professional audit is not available. You can inspect attic insulation depth, look for gaps around penetrations and the attic hatch, check the rim joist, feel for draughts on a windy day, examine visible ductwork for disconnected joints, and read your own meter to establish a baseline. What you cannot do is quantify total leakage or test combustion safety, which is where the professional version earns its fee.

Use it as a baseline, not just a list

The most underused part of an audit is the measurement itself.

A blower door number before and after work quantifies what the work achieved, which turns a vague improvement into a verified one. If you are spending meaningfully on air sealing, a follow-up test is worth its cost — it is the only way to know whether the contractor delivered what was specified, and it catches the case where the work was done poorly and the house is no tighter than before.