Air Emissions (Stack) Testing Company Valuation: EV/EBITDA & EV/Revenue

Stack testing firms are built on years of accredited method work, trained crews and the trust of plant operators facing a permit deadline. Since 2021, more of their owners have heard from buyers, many of them roll-ups such as Alliance Technical Group. What the firm fetches depends on how many credible buyers compete for it, and 68 different buyers have bought stack testing and field environmental monitoring firms since 2015. Here we look at the stack testing deal record, what moves value and who is buying.

We count 138 acquisitions of stack testing and field environmental monitoring firms since 2015, 89 of them since 2021, made by 68 different buyers, and private equity-backed buyers made 61% of them, so a well-run firm can draw several buyers into a process. About half of these deals, 67, were stack or source testing firms, including continuous emissions monitoring (CEMS) service and audit work. Another 18 were leak detection and repair (LDAR) firms that survey oil, gas and chemical sites for fugitive emissions. The other 53 were field monitoring and sampling businesses that measure ambient air, noise and vibration, water, marine and soil conditions at the customer’s site.

This article sets that record against inspection company valuations as a whole and the wider TIC sector, and covers what drives the value of a stack testing business and who is buying.

In short, the segment has one deal with a revenue multiple and zero with an EBITDA multiple, so both segment medians are shown as n/a. The better reference is inspection as a whole: a median of 9.5x EBITDA across 25 deals and 1.6x revenue across 63, set against 9.9x and 1.8x for all TIC deals. The 25 inspection deals with an EBITDA multiple have a median deal size of about $120M, while the median stack testing deal with a disclosed value is about $7.6M.

Stack Testing Deal Multiples Compared With the Wider TIC Market

Of the 138 stack testing and field environmental monitoring deals in our database since 2015, 13 disclose a deal value. Adding company filings and announcements, we could calculate an EV/Revenue multiple for one transaction and an EV/EBITDA multiple for zero, so the segment column shows n/a for both multiples and a median for deal size only.

Where your own firm lands against the inspection medians depends on the accreditations it holds, how much of its revenue is recurring compliance testing and how many certified testers it keeps. Most firms should expect a multiple below those medians unless several buyers compete for the firm and it can show wide accreditation scope and mostly recurring compliance work.

We track every stack testing and field environmental monitoring acquisition since 2015, 138 deals by 68 different buyers, so we know which buyers fit a firm like yours and what they have paid.

What Drives a Stack Testing Company Valuation

A buyer tests each point below in due diligence, and each one moves a stack testing business up or down the range. Accreditation scope and certified staff take a year or two to build.

Accreditation and method scope. In the UK, the Environment Agency’s MCERTS scheme has two parts: organizations that monitor stack emissions are accredited by UKAS to ISO/IEC 17025 against the MCERTS performance standard, and the people doing the work are certified individually under a personnel competency standard. In the US, relative accuracy test audits and certain other tests under 40 CFR Part 75 must be carried out by an Air Emission Testing Body conforming to ASTM D7036. Under EN 14181, the laboratory doing QAL2 calibration and the annual surveillance test needs ISO/IEC 17025 accreditation for that standard. Buyers check which methods and pollutants each accreditation covers and whether it sits with the company or with named individuals. A schedule listing each accreditation, its scope by method and pollutant, and its renewal date answers the first round of questions.

Recurring compliance work. Much of a stack testing firm’s revenue comes back on a schedule set by regulation. Under Part 75, continuous emissions monitors are audited against a reference method every two operating quarters, or every four when the monitor tests within 7.5% relative accuracy, and EN 14181 adds an annual surveillance test in Europe and the UK. New plants add one-off initial performance tests. Buyers look at how much revenue repeats each year and how long customers have stayed. A customer list showing each recurring test, its regulatory basis and its next due date shows this in one document.

Certified people and field crews. A stack test needs a crew on site with sampling trains, analyzers and often a mobile laboratory, led by people whose certification the regulator and the customer accept. Buyers count crews and certified staff, look at turnover and at how many tests the owner still leads, and ask which senior testers will stay after a sale. Prepare a staff list with each person’s certifications, the methods they can lead and their length of service.

Service mix. A buyer values stack testing, LDAR and ambient monitoring each on its own drivers. LDAR revenue at oil and gas sites depends on methane rules, and in July 2025 the US EPA extended by 18 months several compliance deadlines in its 2024 oil and gas standards (NSPS OOOOb and OOOOc), including those for equipment leaks. Show revenue and gross margin by service line so the buyer can value each part.

Customer and industry spread. Demand for emission testing follows the industries that hold air permits: power generation, oil and gas, refining, chemicals, cement, metals and waste incineration. Buyers check how much revenue the largest customers and the largest industry supply, and what a plant closure or a change of fuel at one customer would do to the plan. A spread across industries and permit types supports the value.

Laboratory and equipment. Some stack testing firms analyze their own samples and others send them to outside laboratories. An in-house laboratory adds margin and control over turnaround, and it also adds accreditation scope and equipment to keep current. Buyers look at the age of analyzers, sampling trains and mobile laboratories and at the capital spending needed to keep them in service. An equipment register with purchase dates and calibration records saves time in due diligence.

Size and regional density. Field testing is priced around crew days and travel. A firm with dense coverage of one industrial region, or approvals to test in several states or countries, fits a platform’s map better than one spread thinly. Smaller firms are mostly bought as add-ons by the platforms in the buyer table below, which take on the integration work.

How we present these to buyers. A buyer pays for what it can see and check. Part of our work in a sale is to present the business as strongly as the facts allow: we set out the accreditation and method scope, the recurring compliance work and the certified field crews, and we deal with weak points before a buyer finds them and uses them to lower the offer, and the valuation assessment above is the place to start, a year or two before a sale.

Who Is Buying Stack Testing Companies

We count 138 acquisitions of stack testing and field environmental monitoring companies since January 2015, by 68 different buyers. Private equity firms and their platforms made 61% of them: 65% of the 49 deals in 2015 to 2020 and 58% of the 89 deals since 2021. Across inspection as a whole the private equity share moved the other way, from 47% to 66%. The targets were in 23 countries: 74 in North America, 42 in continental Europe (13 countries), 6 in the UK, 8 in Asia-Pacific, 7 in Latin America and 1 in Africa.

Two North American environmental testing groups made 52 of the 138 deals, all for targets in the US and Canada. Most of Onterris‘s deals here came before its 2020 listing, while Oaktree owned it, which lifts the private equity share for 2015 to 2020. The table shows each buyer’s deals in this segment and its other TIC acquisitions since 2015, which add up to its total.

A North American firm doing mainly stack testing, CEMS work or LDAR is most likely to hear from the two environmental testing groups. A firm that adds water, noise or ambient air monitoring, or works outside North America, also fits the listed TIC groups. Ownership is a second split: a private equity-backed buyer and a strategic buyer value the same firm differently and expect a different role from the owner after completion; see strategic vs financial buyers.

One buyer’s offer tells you what that buyer would like to pay. Offers from several buyers, made at the same time on the same information, tell you what the business is worth. That is what a sale process does, and it is the work we do for owners: talk to us before you reply to an approach.

Selling a Stack Testing Company: What a Run Process Changes

An approach usually comes on the buyer’s timetable, on the buyer’s terms and with no rival offer to compare it against, so an owner who answers it alone is negotiating with one party. A competitive sale process changes that in four ways, and running it is what we do for owners.

Several buyers bid at the same time. Private equity-backed buyers made 58% of the 89 deals since 2021, and 68 different buyers have acquired firms in this segment since 2015. An environmental testing platform adding crews and accreditations in a new region and a listed TIC group adding field services to its laboratories value the same business differently, and offers that arrive in the same week, on the same information, show what the market will pay.

The process sets the terms of engagement. The timetable, the information each buyer sees and the date offers are due are set for the seller, so competition decides the value instead of the first buyer’s opening figure.

Every term is negotiated while alternatives exist. Cash at completion, any earn-out and the revenue or test volumes it is measured on, and the time the buyer wants you to stay all change what you take home. Where accreditations or customer relationships depend on you or on a small group of senior testers, the buyer will want those people to stay, and their terms move most while a second buyer is still in the process.

The business is ready before the first call. Your MCERTS, ISO/IEC 17025 or ASTM D7036 accreditations with their scopes, the schedule of recurring compliance tests by customer with due dates, revenue and margin split between stack testing, CEMS work, LDAR and other monitoring, certified staff by method, and an equipment register for analyzers and mobile laboratories. Buyers discount what they cannot check, so we prepare this with you before any buyer is contacted.

Why Stack Testing Owners Work With Us

We advise owners on sales with typical enterprise values between $5M and $100M, as partners of the Globalscope network. We also advise serial acquirers, which is how we know the way their offers are built and where they leave room.

Recent transactions

• Advice to Apave on its acquisitions of ISOCERT and De Duurzame Adviseurs.
• Sale of CKSource, the rich-text editor developer, to PSG via Tiugo Technologies, after a global process that drew several letters of intent.
• Advice to Visma on its acquisition of SaldeoSMART.

“We were impressed with Marcin’s negotiating skills and Aventis’ ability to make things happen.”

Sindre Talleraas Holen, M&A Director, Visma

“Aventis Advisors did the heavy lifting so that our management team could stay focused on our business.”

Wiktor Walc, President, CKSource

Talk to Us

If you own a stack testing or field monitoring business, talk to us before you reply to an approach, agree a price or sign a letter of intent. We run competitive sale processes for owners: we prepare the business for buyers, approach the TIC groups and private equity platforms most likely to pay for your accreditations, test crews and recurring compliance work, bring their offers to a single deadline and negotiate the terms through to closing. Write to us at marcin.majewski@aventis-advisors.com. The first conversation is confidential. For more on how we work, see our M&A advisory for TIC companies.

Methodology

The figures cover majority acquisitions of companies whose main business is stack and source emissions testing, CEMS service and audits, leak detection and repair, or field monitoring and sampling of air, noise, water and soil at the customer’s site, worldwide, since January 2015. Laboratories whose main work is sample analysis are covered on our environmental testing laboratory page, and vehicle emissions testing sits in vehicle inspection. Equipment makers, environmental consultancies, remediation contractors and training providers are excluded.

The deals come from the Aventis Advisors TIC deal database, which combines Mergermarket with acquirer announcements and our own research. EV/EBITDA and EV/Revenue use enterprise value (EV), which is equity value plus net debt; EBITDA is earnings before interest, tax, depreciation and amortization. Median deal size uses EV where disclosed, otherwise the disclosed deal value, which is the consideration for the stake acquired; stakes of 51% to 99% count only where an EV is stated. Distressed sales, and multiples outside 1x to 60x EBITDA or 0.05x to 20x revenue, are excluded from the multiples. Most private deals close at undisclosed values, so the deals with a published figure are a small sample. Medians are shown where at least five deals disclose the figure, and ranges where at least ten do. EV/EBITDA is shown where the multiple or the EBITDA was published by the buyer, the seller, filings or a reputable data source; EBITDA derived from a stated margin is excluded. Each deal is counted under the buyer’s group at the time of the deal, and private equity buyers are private equity firms and the companies they owned then. All TIC combines the inspection, testing laboratory and certification deals on our pages, 2,841 since 2015.