- The exam is 120 multiple-choice questions in 3 hours, closed book, with a 75% passing score.
- There are seven domains, including Respiratory Protection, which the handbook's six-heading list omits.
- First two-year term costs $500 in the US/Canada ($100 exam plus $400 certification); a retake is $100.
- Experience must span at least three of five areas, and certification requires unanimous board approval.
The One-Glance Exam Snapshot
This page condenses the facts that matter most for the Council-certified Indoor Environmental Consultant (CIEC) credential issued by the American Council for Accredited Certification (ACAC). Keep it beside your study materials, and verify anything date-sensitive against ACAC's live pages before you act on it.
| Item | Fact |
|---|---|
| Issuer | American Council for Accredited Certification (ACAC) |
| Format | 120 multiple-choice questions, at least four answer choices per item |
| Time | 3 hours, closed-book written examination |
| Passing score | 75%, set using the modified Angoff method |
| Delivery | Kryterion, at testing centers or by online video proctoring |
| Score reporting | Electronic scores available immediately |
| Credential validity | Two years |
Two format details are worth internalizing early. First, the exam is closed book, so reference-heavy recall (action thresholds, equipment names, regulatory titles) must live in your head, not in a binder. Second, the 75% cut score comes from the modified Angoff method, in which subject-matter experts judge how a minimally competent candidate would perform on each item. That means the standard reflects expected professional competence, not a curve against other test-takers. For more on how the cut score works, see our guide to the CIEC passing score.
Eligibility and Application Facts
CIEC is an experience-gated credential, so the application is as much a part of "passing" as the exam. Three eligibility pathways exist, each pairing education with documented IAQ investigation experience:
| Education | Documented IAQ investigation experience |
|---|---|
| Qualifying science-related four-year degree, or 30-credit equivalent | Four years |
| Qualifying two-year degree, or 15-credit equivalent | Six years |
| High-school diploma or GED | Eight years |
The five-area experience rule
Your experience must span at least three of these five areas: Lead/Asbestos, Microbial, IH/Chemicals/Toxicology, Building Sciences, and IAQ/HVAC. A consultant whose entire career is mold assessment, for example, would need documented work in at least two other areas before qualifying.
Application package
- Four project sheets documenting your investigations
- Applicable education transcripts
- Required email verifications
- Unanimous board approval before certification is conferred
One trap deserves emphasis: passing the examination for state licensing purposes alone does not confer the CIEC designation. If you sit the exam only to satisfy a state requirement, you do not hold the credential. No training course is mandatory, though structured prep is common. Our CIEC requirements guide walks through qualification scenarios in more detail.
Fees, Timing and Deadlines
| Cost item | Amount (USD) |
|---|---|
| Examination fee | $100 |
| Certification fee | $400 |
| First two-year term, US/Canada | $500 total |
| First two-year term, outside US/Canada | $525 |
| Retake | $100 |
The practical point is that the exam fee is small relative to the total, and a failed attempt costs $100 to retry. The larger investment is your preparation time and the documentation effort behind the application. For a full cost picture including renewal, see the CIEC certification cost breakdown.
The Seven Domains on One Page
The official scope is ACAC's CIEC and CIE Examinations domain chart, approved February 7, 2024. The chart lists seven domains. ACAC does not publish percentage weights in the complete chart, so any "Domain 3 is 25%" claim you encounter is not from the official source. Treat all seven as testable and allocate time by your own weak spots.
Domain 1: IAQ Contaminants and Potential Health Effects
Know the contaminant families an IAQ consultant investigates and how exposure connects to symptoms.
- Biological contaminants, especially mold and moisture-related growth
- Chemical contaminants and volatile sources in buildings
- Legacy hazards such as asbestos and lead, which also appear in the experience areas
- Linking occupant complaints to plausible sources without overstating causation
Domain 2: Principles of Building Science and the Built Environment
Understand how the building envelope, moisture, pressure and heat flow create or prevent problems.
- Moisture transport and condensation mechanisms
- Pressure relationships between spaces and the exterior
- How construction and materials influence contaminant pathways
Domain 3: HVAC
Be able to evaluate ventilation systems as both a cause and a control for IAQ problems.
- Ventilation, air distribution and filtration concepts
- Humidity control and its role in microbial growth
- Common system deficiencies that lead to complaints
Domain 4: Equipment Selection, Calibration and Operation
Expect questions about choosing the right instrument, keeping it accurate, and using it correctly.
- Matching instrument to the question being asked
- Why calibration matters for defensible data
- Proper operation and sampling technique
Domain 5: Guidelines, Regulations and Standards
Know which documents are mandatory, which are advisory, and what each actually covers.
- Distinguishing enforceable regulation from guidance
- Applying published guidelines to field scenarios
- Recognizing the limits of a standard's scope
Domain 6: Remediation
Understand containment, source removal and verification of completed work.
- Principles of controlling the source before cleaning
- Containment and worker/occupant protection during work
- Post-remediation evaluation concepts
Domain 7: Respiratory Protection
This domain appears in the complete ACAC chart but not in the handbook's abbreviated six-heading list, so candidates who study only from the handbook list can miss it.
- Respirator selection logic and matching protection to hazard
- Program requirements under the OSHA respiratory protection framework
- Limitations of respirator types
Handbook Reading List
The handbook prescribes a set of preparation references. This is a verified reading list; contents of commercial reference books were not retrieved for this article, so I will not characterize chapter-level material beyond what the titles tell you.
- AIHA, Recognition, Evaluation & Control of Indoor Mold, second edition (2020)
- EPA, Building Air Quality: A Guide for Building Owners and Facility Managers (1991)
- Managing Indoor Air Quality, fourth or fifth edition (2008/2011)
- NIOSH, Respirator Selection Logic (2004)
- OSHA, Small Entity Compliance Guide for the Respiratory Protection Standard (2011)
Notice how the list maps onto the domains. The AIHA mold text supports contaminants and remediation. The EPA building guide and the Managing IAQ book support building science, HVAC and investigation practice. The NIOSH and OSHA documents are your anchors for Respiratory Protection. Several of these are older editions, so for Guidelines, Regulations and Standards, confirm that you understand the distinction between what a document says and whether a newer version supersedes it in practice.
Test-Day Logistics
Delivery options
Kryterion delivers the exam either at a testing center or through online video proctoring. Electronic scores are available immediately, so you leave knowing your result.
Identification
At a testing center, bring two government-issued IDs, including one photo ID. Check names against your registration so a mismatch does not cost you your appointment. The delivery policy is published on ACAC's exams page.
Pacing plan
- Pass one: answer everything you know immediately and flag the rest
- Pass two: return to flagged items and eliminate wrong choices, since each item has at least four options
- Reserve the final stretch for any question where you changed your mind, and only revise with a concrete reason
Renewal Math
The CIEC is valid for two years. Renewal requires $400 and 40 recertification credits, made up of:
- 10 credits for attesting to continued field activity
- 30 hours of professional development
Retain your documentation, because renewals can be audited. Recertification procedures are published on ACAC's procedures page. Because the field-activity attestation is built into renewal, the credential is designed to track practicing consultants rather than lapsed ones. If you are weighing long-term value, see whether the CIEC certification is worth it and the CIEC salary guide.
What the Pass Data Does and Does Not Say
ACAC's 2025 Exam Pass Ratio reports 61%, with 28 passing out of 46 examinations. Read that carefully: the report includes retakes and state-licensing-only examinations, so it is not a first-attempt pass rate and it is not a clean measure of how CIEC-track candidates perform. The sample is also small, which makes any single year noisy. Use it as a rough signal that the exam is passable but not trivial, not as a prediction of your own result. The CIEC pass rate analysis and the exam difficulty guide explore this in more depth.
Sequencing Your Review by Domain
Rather than a generic schedule, order your review by how the domains depend on each other. Building science and HVAC explain why contaminants appear; contaminants and standards explain what to measure and against what; equipment and remediation are the practical responses; respiratory protection protects the people doing the work. A sample progression:
Foundations: Domains 2 and 3
- Moisture, pressure and envelope concepts
- Ventilation, filtration and humidity control
Hazards and Rules: Domains 1 and 5
- Contaminant families and health-effect links
- Sorting regulation from guidance
Practice Side: Domains 4 and 6
- Instrument selection, calibration and sampling
- Containment, source control and verification
Respiratory Protection and Integration: Domain 7
- NIOSH selection logic and OSHA program basics
- Mixed-domain practice under timed conditions
Key Takeaway
Because no domain weights are published, do not skip the smallest-feeling domain. Respiratory Protection is the one most likely to be under-studied because it is missing from the handbook's short list. Pair it with timed mixed practice at our practice test site, and use the CIEC study guide for a fuller preparation plan.
FAQ
The exam has 120 multiple-choice questions with at least four answer choices each, taken in 3 hours with no reference materials. The passing score is 75%, which works out to 90 correct answers.
In the US and Canada, the first two-year term costs $500: a $100 examination fee plus a $400 certification fee. Outside the US and Canada it is $525. A retake costs $100. See the full cost breakdown for renewal expenses.
No training course is mandatory. Eligibility is based on a qualifying education level plus documented IAQ investigation experience across at least three of five areas. Many candidates still use structured prep; see CIEC training for options.
No. ACAC's 2025 figure of 61% (28 of 46 examinations) includes retakes and state-licensing-only examinations, so it is not a first-attempt pass rate. It is also a small sample.
Not necessarily. Passing the exam for state licensing alone does not confer the designation. The credential also requires an approved application with project sheets, transcripts and verifications, plus unanimous board approval. Learn more in what CIEC certification is.