- What the Credential Is
- Who Issues It and How It Is Accredited
- The Four Competency Areas
- The Science Underneath the Inspections
- Eligibility and the Application Package
- Exam Format and Delivery
- Fees at a Glance
- Application Timeline and Board Approval
- Validity and Renewal
- Where the Credential Fits in the Job Market
- Sequencing Your Preparation
- Frequently Asked Questions
- CETI stands for Council-certified Environmental Thermography Investigator, issued by the American Council for Accredited Certification (ACAC).
- The initial cost is $500 for US/Canada applicants: a $100 examination fee plus a $400 certification fee.
- You need at least 75% on a closed-book, computer-delivered multiple-choice exam.
- Eligibility requires two combined years of science-related education and field experience, with at least one actual year in the field.
What the Credential Is
The Council-certified Environmental Thermography Investigator credential, abbreviated CETI, recognizes professionals who use infrared thermography to investigate building conditions. It is not a general thermal-imaging badge. The credential is organized around four practical investigation settings: roofs, building exteriors, building interiors, and plumbing systems. If your daily work involves pointing an infrared camera at a building and explaining what the thermal patterns mean, this is the credential designed around that work.
The acronym is shared by several unrelated credentials in other industries, so be careful when researching. Everything on this page refers specifically to the environmental thermography certification administered by ACAC. If you want a shorter orientation to the terminology, see our explainers on what CETI stands for and what a CETI is.
Who Issues It and How It Is Accredited
The credential is issued by the American Council for Accredited Certification (ACAC). ACAC's CETI program is CESB-accredited, which means the certification program itself has been reviewed against an external standard for certification bodies rather than being a simple vendor certificate. For candidates, accreditation is a credibility signal when presenting the credential to employers, clients, insurers, or courts that may scrutinize an investigator's qualifications.
Examinations are delivered through the testing provider Kryterion. ACAC's reporting is also worth knowing about: its December 31, 2025 activity report lists 3 current CETI certifications. That figure counts certificate holders, not exam takers, and it tells you the credential is a small, specialized one rather than a mass-market certification. It also means you should not expect a large community of study groups and third-party prep products the way you would for a popular IT credential.
The Four Competency Areas
ACAC's application lists four competency headings. These are the issuer's listed application competencies, not an exhaustive exam blueprint, and ACAC does not publish weights for them. Treat them as the core scope and expect the exam to draw on the related thermographic science as well. For a deeper breakdown, read our complete guide to all four CETI content areas.
Domain 1: Roof inspections
Roofs are a classic infrared application because moisture trapped in roofing assemblies holds and releases heat differently than dry material.
- How solar loading and nighttime cooling reveal subsurface moisture patterns
- Distinguishing true moisture from surface artifacts, reflectivity, and construction details
- Documenting findings so a reader can locate the anomaly on the roof
Domain 2: Building exterior investigations
Exterior scans look at the envelope from outside, where weather, sun angle, and wind all influence what the camera sees.
- Recognizing thermal patterns associated with envelope defects versus normal construction features
- Accounting for environmental conditions that can mask or mimic anomalies
- Choosing viewing angles and timing that make findings defensible
Domain 3: Building interior investigations
Interior work targets conditions behind finished surfaces, where the camera is often the only non-destructive way to see them.
- Interpreting temperature differences on walls, ceilings, and floors
- Separating moisture indications from air movement, insulation gaps, and heat sources
- Knowing when a thermal image needs confirmation by another method
Domain 4: Plumbing investigations
Thermography can help trace piping and identify suspected leaks without opening walls.
- Reading thermal signatures associated with supply lines and leak conditions
- Understanding how fluid temperature and surrounding materials affect contrast
- Reporting limitations honestly when thermal evidence is inconclusive
Because the four domains are unweighted in the published materials, avoid the temptation to over-invest in the one you already know. A roofing specialist who skips plumbing is taking an unnecessary risk.
The Science Underneath the Inspections
ACAC's materials also describe thermal and infrared physics along with infrared-camera selection, calibration, and operation. In practice, that means the exam is not only about recognizing patterns in images. Candidates should be ready to explain why a camera shows what it shows and what can go wrong with the measurement.
Topics worth mastering
- Infrared physics fundamentals: how thermal energy is emitted, reflected, and transmitted by building surfaces, and why the camera cannot simply "see through" materials.
- Camera selection: matching equipment capability to the inspection task rather than assuming any thermal camera suits any job.
- Calibration and operation: setting up the camera properly, understanding what affects measurement accuracy, and recognizing when readings should not be trusted.
- Interpretation discipline: separating apparent temperature differences from real building-condition problems.
Key Takeaway
Study the physics and the camera operation alongside the four inspection domains. A candidate who can describe a roof moisture pattern but cannot explain why reflective surfaces distort readings has only half the picture.
Eligibility and the Application Package
Eligibility is built on a combination of education and field experience. Applicants need two combined years of relevant science-related postsecondary education and field experience, and ACAC's eligibility FAQ requires at least one actual year of field experience. In other words, education can contribute toward the two-year total, but it cannot replace hands-on work entirely. There is no mandatory training course. Our CETI requirements guide goes deeper on qualifying.
What you submit
- The online application (the Official CETI Application)
- Transcripts, if you are claiming education toward the combined two years
- Verifiable investigation reports or contracts showing relevant investigations, consulting, or report writing
- Four separate project sheets
- Email verifications
The documentation emphasis is what separates this credential from a simple knowledge test. ACAC wants evidence that you have actually performed thermographic investigations, and that others can verify it. Start collecting reports and contact details for verifiers before you begin the formal application.
Exam Format and Delivery
ACAC's general examination policy specifies closed-book, computer-delivered multiple-choice testing with at least four answer choices per question. Delivery is available through test centers or through secure online video proctoring, so you can generally choose between a testing location and a remote session. The passing threshold is at least 75%, verified against the current Official CETI Application. See our passing score breakdown for more on what that means for your preparation.
Closed-book multiple choice has real implications for a field-based credential. You cannot lean on your camera's manual or your own reference notes during the exam, so concepts like emissivity, reflected apparent temperature, and the conditions that favor good moisture contrast need to be recalled from memory. Questions with four or more plausible choices tend to reward careful reading, particularly where one option is technically true but not the best answer for the scenario described.
If you want to gauge how challenging the exam feels, our CETI difficulty guide discusses it, and you can try scenario-style questions on the CETI practice test site. For a look at what published data exists, see what the pass-rate data shows.
Fees at a Glance
| Item | Amount (USD) |
|---|---|
| Examination fee | $100 |
| Certification fee | $400 |
| Initial total, US/Canada applicants | $500 |
| Initial total, applicants outside US/Canada (per the official application) | $525 |
| Exam retake | $100 |
| Renewal | $400 |
The fee structure separates the examination from the certification itself, which is helpful to know if you fail and need a retake: the retake fee is $100 rather than a repeat of the full cost. For a fuller treatment, including budgeting for renewal, see our CETI certification cost breakdown.
Application Timeline and Board Approval
The entire application process, including the examination, must be completed within six months. That window is an important planning constraint: submitting your application before you are ready to sit the exam can eat into the time you have. Review our notes on scheduling and timing before you commit.
Passing the exam is also not the final step. Certification requires unanimous board approval, which means the board reviews your overall file. This is another reason to take the documentation seriously. A strong exam score will not compensate for weak or unverifiable project sheets and reports.
Validity and Renewal
The credential is valid for two years. ACAC's central renewal procedure requires 40 recertification credits (RCs), comprising 10 for continued field activity and 30 hours of professional development. The renewal fee is $400.
Whichever number applies, the practical lesson is the same: renewal rewards people who stay active in the field and keep learning. Log your inspections and training as you go rather than reconstructing them at the end of the two-year cycle.
Where the Credential Fits in the Job Market
Environmental thermography is used wherever someone needs non-destructive insight into building conditions. The four domains point to the likely settings: roofing consultants and inspectors, building envelope and exterior evaluators, interior condition and moisture investigators, and plumbing-focused leak detection work. Consultants and report writers are explicitly part of the eligibility language, which tells you the credential is aimed at people who produce documented findings, not just operate equipment.
Be realistic about the market. With only a handful of current certification holders reported by ACAC, the credential is a differentiator rather than a baseline requirement most employers screen for. We do not publish invented earnings figures here; our salary analysis, jobs overview, and ROI discussion cover how to weigh the investment qualitatively.
Sequencing Your Preparation
Preparation for this credential has two tracks: assembling the application evidence and studying for the exam. Run them in parallel, with the documentation work starting first because verifiers and old reports take time to chase down. The sequence below ties the study order to the CETI domains. For a fuller plan, see the CETI study guide, and keep the cheat sheet handy for last-week review.
Evidence and physics foundation
- Gather reports, contracts, transcripts, and verifier contacts; draft the four project sheets
- Review infrared physics and camera calibration and operation, since every domain depends on them
Roofs and exteriors
- Study Domains 1 and 2 together, since both depend on solar loading and weather conditions
- Practice explaining what masks or mimics an anomaly outdoors
Interiors and plumbing
- Cover Domains 3 and 4, where limitations and confirmation methods matter most
- Finish with mixed practice questions across all four domains
Keep your total timeline inside the six-month application window, and leave buffer in case a retake is needed.
Frequently Asked Questions
It stands for Council-certified Environmental Thermography Investigator, a credential issued by the American Council for Accredited Certification (ACAC). It is unrelated to other credentials that share the same acronym.
For US and Canada applicants, the initial total is $500: $100 for the examination and $400 for certification. The official application lists $525 for applicants outside the US and Canada. A retake costs $100 and renewal costs $400.
The passing threshold is at least 75%, as verified in the current Official CETI Application. The exam is closed-book, computer-delivered multiple choice with at least four answer choices per question.
No. There is no mandatory training course. Instead, you must show two combined years of relevant science-related education and field experience, including at least one actual year of field experience, backed by transcripts, reports or contracts, four project sheets, and email verifications.
Certification is valid for two years. The central renewal procedure requires 40 recertification credits, including 10 for continued field activity and 30 hours of professional development, though the credential page describes 20 hours annually, so confirm the current requirement with ACAC.