By Byron Raal, CAS Founder-Editor · Last updated 12 August 2026 · About the author
Most free compressed air assessments are a sales call with a clipboard. That’s not an insult. The technician usually knows compressed air well, and the walk-through often surfaces real problems. Some vendors go further and offer free instrumented assessments, with data loggers on your system for a week or more, and those produce genuinely useful numbers. Either way, the visit is funded by an equipment vendor, so its conclusions naturally lean toward that vendor’s equipment. A paid independent audit changes the incentive, not just the method: the fee is the same whatever you buy, so “fix your leaks and drop the pressure” is an answer it’s free to give. In Australia, expect four figures to low five figures for a metered audit of a mid-sized site. Published pricing for structured energy audits runs from about $3,000 for a walk-through to $12,000 and beyond for data-logged work, scaling with site size and metering depth, and the fee can be recovered within the first year from the energy it finds, sometimes more than once over. Take the free assessment for what it is, then decide what you actually need with someone who has nothing to sell you.
What a free assessment actually is
Let’s be fair about this, because the free assessment gets a harder rap than it deserves. The person walking your plant with a clipboard is usually a genuine compressed air specialist. Vendors know their products, they see hundreds of compressor rooms a year, and a good rep will spot an undersized receiver or a dodgy drain trap in minutes. If your compressor is at end of life and you already know you’re buying, a vendor assessment is a sensible way to get sized correctly, and the walk-through version costs you nothing but an hour.
Free assessments come in more than one tier. The common one is the walk-through: a tour of the compressor room, a look at your nameplate data and duty cycle, perhaps a quick ultrasonic scan for the loudest leaks, a chat about your pressure settings, and a follow-up document. Some vendors offer a more serious free tier, an instrumented assessment where sales engineers attach data loggers to the incoming electrical supply for a week or more, then analyse utilisation and recommend fixes that can include pressure adjustments and leak repair. That tier produces real measurement and is worth taking seriously. In both tiers, though, the follow-up document is where the commercial context shows. It is, in the end, a proposal, and the recommendations inside it will naturally feature the equipment the assessor’s employer sells. Nobody is being dishonest. It’s simply how the economics of a free visit work: the assessment is paid for by the margin on whatever gets quoted at the end of it.
That has two practical consequences. First, the free assessment tends to look hardest at the supply side, the compressors themselves, because that’s where the products live. Second, the cheapest fixes on most sites, which are leak repair and pressure reduction, earn a vendor far less than a machine sale, even though many vendors do sell leak detection and repair as services, so the incentive still tilts toward equipment, and there’s less reason for those fixes to headline the report. In a walk-through they might get a mention without a metered dollar figure. The instrumented free tier does better and can genuinely flag both, but the visit is still funded by the eventual equipment sale, so watch which recommendations get the headline.
So the honest framing isn’t “free assessments are a trap”. It’s this: the three offers you’re most likely to field are a free walk-through, a free instrumented assessment and a paid independent audit. A free walk-through answers the question “what should I buy from this vendor”. A free instrumented assessment adds real logged data to that answer, and can be well worth accepting, but it’s still commissioned by someone with equipment to sell. They’re not the whole market: vendors also sell in-depth paid audits, distinct from their free assessments, and a capable maintenance team with its own metering can self-assess without buying anything at all. Among the services you can buy in, though, the fixed-fee independent audit carries the cleanest incentive, because the person doing the measuring has no stake in what you buy afterwards. Pick the arrangement that matches whose question you’re really asking.
What an independent audit does differently
An independent compressed air audit starts from measurement by someone with nothing to sell. The auditor logs your system in operation, commonly for a week or more, so the data covers a full production cycle, capturing shifts, weekends and peak demand rather than a snapshot. Power draw is metered at the compressors, pressure is logged at multiple points across the network, and flow is profiled so you can see exactly when air is being made and where it’s going. Our compressed air energy audit guide walks through the full methodology, which follows ISO 11011:2013, the international standard for compressed air system assessments.
The audit then covers the things a sales-oriented visit isn’t set up to prioritise:
A tagged leak survey. Every leak the instruments can find is located, tagged and costed individually, so your maintenance team gets a ranked repair list rather than a general observation that “some leaks were noted”. This matters because leaks alone can waste 20 to 30 per cent of a system’s compressed air output, per our 2026 leak cost report, and a handful of large leaks usually carry most of that loss.
A demand profile. Once flow is logged, you can see whether your compressors match your actual demand pattern, whether storage is adequate, and whether the system pressure is set higher than any machine on the floor actually needs. Dropping the setpoint is often the single cheapest saving on the list.
Recommendations ranked by payback. A proper audit report ranks every measure by capital cost, annual saving and payback period. And here’s the structural difference: the auditor’s fee is the same whether you buy equipment or not. When the honest answer is “repair these forty leaks, drop the pressure 50 kPa and buy nothing”, an independent auditor can write that down. On a lot of Australian sites, that’s exactly what the data says.
None of this makes the independent audit a magic wand. It costs real money, it takes longer, and it borrows time from your maintenance crew during the site visit. What you’re paying for is a conclusion that was reached after the measurement, not before it.
What audits cost in Australia and what the payback looks like
Here’s the part most pages on this topic dodge: actual numbers. Compressed air auditors in Australia generally quote per site rather than publishing rate cards, so the cleanest published benchmark is pricing for structured energy audits, the same discipline the compressed air audit sits inside. One Australian energy-audit referral service, ESD Consultants, publishes the following price guide for audits aligned to the AS/NZS 3598 levels (what ESD calls levels, the standard itself calls Type 1, Type 2 and Type 3 audits):
| Audit level | What it involves | Published price range (AUD) |
|---|---|---|
| Level 1, walk-through | Broad overview, quick-win identification | $3,000 to $5,000 |
| Level 2, detailed | Site-wide analysis with financial ranking of measures | $5,000 to $12,000 |
| Level 3, investment grade | Data logging, sub-metering, engineering-level analysis | $12,000 to $25,000 plus |
Government records back the same territory. Sustainability Victoria’s Energy Assessment Grants program part-funded energy assessments across 231 recipients, with individual grants recorded from $2,000 for small hospitality venues up to $20,000 for manufacturers, large farms and alpine resorts. Those are funding amounts, not audit invoices, so read them as the scale of per-site assessment spend a government considered worth subsidising rather than a market rate card. The spread still tells you something useful, which is that assessment scope grows with site size and complexity, but for actual pricing the published ESD bands above are the better anchor, and they put mid-sized industrial sites in the four-figure to low-five-figure band. The program has since closed, so it’s historical context, not available funding.
A compressed-air-specific audit is a subsystem audit rather than a whole-of-site one, so for a single compressor room with data logging, expect four figures to low five figures, with the exact number driven by how many compressors you run, how many metering points the auditor installs, and how long the logging period runs. A multi-compressor site with branch flow metering will sit toward the top of the range. We haven’t found a published AUD rate card for compressed-air-only audits, which is itself worth knowing: anyone quoting you should be able to explain exactly what measurement scope their number buys.
Now the other side of the ledger. Per our guide to what audits cost and return across Australian states, a first audit of a poorly maintained system can recover 20 to 35 per cent of compressed-air energy spend, with the full package of measures paying back within 12 to 24 months in some cases, and the recovered electricity can repay the audit fee within the first year, sometimes more than once over. The arithmetic is simple enough to sanity-check yourself. Electricity is commonly estimated at 70 to 80 per cent of a compressor’s lifetime cost at Australian industrial tariffs. Take the illustrative mid-sized site from our leak cost report, spending $48,000 a year on compressed-air power; that’s the report’s worked archetype, not survey data. If leaks are wasting 20 to 30 per cent of its compressed air output, that’s roughly $9,600 to $14,400 a year of that spend on a straight-line conversion. Treat that conversion as an illustration rather than an invoice, because output share doesn’t map one for one onto dollars without assumptions about compressor controls and how load responds. Even so, a $6,000 audit doesn’t need many tagged leaks fixed before it looks cheap. You can put a number on your own leaks in about two minutes with our leak cost calculator.
One caveat on all of the above: these are indicative published figures, not quotes. Site size, metering depth and travel all move the number. The point isn’t the exact dollar figure, it’s the shape of the deal: a known fee in the four-figure to low-five-figure range against a measured annual saving that often runs into five figures.
Questions to ask anyone assessing your system
Whether the person in your compressor room is free or paid, the same short list of questions tells you what kind of advice you’re about to receive. None of them are hostile. A good assessor of either kind will answer all six without flinching.
“Who pays you if I follow this advice?” This is the question that matters most, so ask it first. If the answer involves equipment margin, the advice isn’t invalid, but you now know which way it leans. If the answer is “you’ve already paid me, my fee is the same either way”, the recommendations and the assessor’s income are pointing in the same direction: yours.
“What will you measure, and for how long?” A visual walk-through, spot readings from existing gauges and handheld instruments, and a week of logged kW, pressure and flow data are all different products. Spot measurements are still measurements, and ultrasonic testing or your own site meters can carry real weight. The line worth probing is between readings taken on the day and continuous logged trend data that shows how the system behaves across a full cycle. Know which one you’re being quoted, and price it accordingly.
“Will I get the raw data?” Logged data belongs in your hands, not just the conclusions drawn from it. It’s also what lets a second opinion check the first one.
“Will every recommendation carry a cost, a saving and a payback period?” “Consider upgrading” is not a recommendation. “$4,200 to repair tagged leaks, saving $13,000 a year” is.
“What happens if the answer is that I shouldn’t buy anything?” Watch how this one lands. An independent auditor hears it as a normal outcome. For a free assessment, it’s a commercially awkward one, and the reaction tells you plenty.
“What methodology do you follow?” For compressed air work, ISO 11011:2013 is the recognised assessment methodology, and the AS/NZS 3598 series of 2014 is the voluntary Australian standard for energy audits, describing audit types and rigour levels, with Part 2 (AS/NZS 3598.2:2014) covering industrial sites. An assessor doesn’t have to recite clause numbers, but “we follow ISO 11011” is a better answer than a blank look.
Frequently Asked Questions
Are free compressed air assessments worth doing?
Often, yes. The assessor usually knows compressed air well, the visit costs you nothing but time, and it can surface genuine problems. Just read the result as what it is: a proposal from an equipment vendor, strongest on the supply side and naturally aligned with that vendor’s product range. If you’re already committed to buying a compressor, it’s a sensible sizing exercise, and some vendors offer free instrumented assessments with a week or more of data logging behind them, which are more useful again. If you want outside advice from someone with no stake in what you buy next, an independent audit is the cleanest way to get it.
How much does a compressed air audit cost in Australia?
Expect four figures to low five figures for a metered audit of a mid-sized site. Published Australian pricing for structured energy audits runs from about $3,000 to $5,000 for a walk-through level audit, $5,000 to $12,000 for a detailed site audit, and $12,000 to $25,000 or more for investment-grade work with data logging. A compressed-air-specific audit is a subsystem study, and its price scales with the number of compressors, metering points and the length of the logging period. Get the measurement scope in writing with any quote.
How long does a compressed air audit take?
Auditors commonly log the system for a week or more, so the data covers a full production cycle, with its shifts, weekends and peaks, rather than a single afternoon. Allow a few hours of site access for instrument installation and the leak survey, then one to two weeks for logging and reporting. A free walk-through assessment, by contrast, is usually done in a single visit of an hour or two, though some vendors’ free instrumented assessments also log for a week or more.
What savings does an audit typically find?
A first audit of a poorly maintained system can recover 20 to 35 per cent of compressed-air energy spend, mostly through leak repair, pressure setpoint reduction and better compressor control, with the full package paying back within 12 to 24 months in some cases. The audit fee itself can be recovered from savings inside the first year, sometimes more than once over. Poorly maintained systems can lose 20 to 30 per cent of compressor output to leaks alone, which is why leak repair headlines most audit reports.
Will an independent audit just tell me to buy a new compressor anyway?
Sometimes the data genuinely supports replacement, for example where an oversized fixed-speed machine is running long hours at part load and a variable speed unit would pay for itself. The difference is sequencing: an independent audit reaches that conclusion from metered data, after the cheaper fixes have been costed, and the auditor earns nothing extra if you buy. When replacement shows up in an independent report, it tends to be the last item on the list, not the first.
Is a compressed air audit required by law in Australia?
The audit itself is a commercial decision, and this page isn’t legal advice. The standards involved are voluntary ones: the AS/NZS 3598 series of 2014 describes energy audit types and rigour levels, and ISO 11011:2013 describes compressed air assessment methodology. Whether any audit obligation applies to your site depends on your state, your industry and any scheme you’re participating in, so check the rules that actually cover you. Some government efficiency programs have used audits as an entry requirement for funding, so if you’re chasing a grant, read that program’s conditions specifically.
Get matched with an independent assessor
This whole page boils down to one question: who benefits from the advice you’re about to get? We built our supplier match service to make the independent answer easy to reach. Tell us your state, your compressor setup and what you’re trying to find out, and we’ll match you with an independent specialist who follows the ISO 11011 methodology and doesn’t sell compressors. To be straight about our own economics, since we’ve just spent a page asking assessors to be straight about theirs: we don’t sell equipment and we don’t run the audits ourselves; supplier partners pay CAS a commission when a match goes ahead, and the match costs you nothing, with no obligation.
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