- What the Credential Actually Is
- Who Issues It and How the Process Works
- Eligibility: Education Plus Documented Field Experience
- The Examination: Format and Delivery
- The Seven Exam Domains
- The Handbook's Reading List
- Fees and the Two-Year Term
- What the Published Pass Data Does and Does Not Say
- Sequencing Your Preparation by Domain
- Who Uses the Credential
- Frequently Asked Questions
- CIEC stands for Council-certified Indoor Environmental Consultant, a credential issued by the American Council for Accredited Certification (ACAC).
- The exam has 120 multiple-choice questions, runs 3 hours, is closed-book, and requires a 75% score to pass.
- Eligibility combines education with four, six, or eight years of documented IAQ investigations, plus four project sheets.
- Seven domains are tested, including Respiratory Protection, which the handbook's abbreviated six-heading list omits.
What the Credential Actually Is
The Council-certified Indoor Environmental Consultant, abbreviated CIEC, is a professional certification for people who investigate and manage indoor air quality problems in buildings. It is not an entry-level course completion certificate. It is a peer-reviewed credential: you must demonstrate years of documented field work, submit project sheets describing real investigations, pass a written examination, and win unanimous approval from a certification board.
Because several unrelated credentials share the same four-letter acronym, it is worth being precise. This article covers only the Council-certified Indoor Environmental Consultant designation from ACAC. If you are searching for general definitions, our short explainers on what CIEC stands for and the meaning of CIEC cover the naming question. This guide goes deeper into how the certification works end to end.
Who Issues It and How the Process Works
The certifying body is the American Council for Accredited Certification (ACAC). ACAC publishes a CIEC Candidate Handbook, a chart of examination domains, a fee schedule, application instructions, and recertification procedures. The examination itself is delivered through the testing provider Kryterion, either at a computer-based testing center or by online video proctoring, and electronic scores are available immediately after you finish.
The process has two linked tracks that run in parallel:
- The application track: You submit the official CIEC application, four project sheets, applicable education transcripts, and required email verifications of your experience.
- The examination track: You sit the 120-question written exam through Kryterion.
Certification is conferred only when both tracks succeed. A passing exam score alone does not make you a CIEC, and the board must approve your application unanimously. One detail trips up candidates: passing the examination for state licensing alone does not confer the CIEC designation. If your state uses the same exam for licensure, you still need the full application approved to hold the credential.
Eligibility: Education Plus Documented Field Experience
CIEC eligibility is built on a sliding scale: the more formal education you have, the fewer years of experience ACAC requires. The experience must be documented IAQ investigations, not general industry employment.
| Education Level | Required 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 Experience Areas
Your experience must span at least three of these five areas:
- Lead/Asbestos
- Microbial
- IH/Chemicals/Toxicology
- Building Sciences
- IAQ/HVAC
This breadth requirement is deliberate. A consultant who has only ever done mold assessments, for example, would need documented work in at least two additional areas. Plan your project sheets with that spread in mind, and read our full walkthrough of CIEC requirements and how to qualify before you start compiling paperwork.
The Application Package
Beyond the education and experience thresholds, the application requires four project sheets, applicable transcripts, and email verifications from people who can confirm your work. No training course is mandatory, so there is no required classroom prerequisite. For deadline planning, note that ACAC's sources conflict: current application instructions allow six months, including the examination, while the handbook states 90 days. Treat the shorter window as a safe planning assumption and confirm the current rule with ACAC before you submit. Our guide to CIEC exam dates and scheduling covers timing in more detail.
The Examination: Format and Delivery
The CIEC exam is a closed-book written examination with these specifications:
- Questions: 120 multiple-choice items, each with at least four answer choices
- Time: 3 hours
- Passing score: 75%, set using the modified Angoff method
- Delivery: Kryterion, at a testing center or by online video proctoring
- Results: Electronic scores available immediately
The modified Angoff method is a standard-setting approach in which subject-matter experts judge how a minimally qualified candidate would perform on each item. The practical meaning for you: the 75% cut score reflects an expert judgment of competence, not a curve against other test-takers. You can read more about how the threshold works in our breakdown of the CIEC passing score.
At a testing center, you must present two government-issued IDs, including one photo ID. Because the exam is closed-book, you cannot bring reference materials, so the handbook's reading list is something to internalize rather than carry in with you. At three hours for 120 questions, you have roughly one and a half minutes per item, which is comfortable for candidates who know the material and tight for those who must reason from scratch on every question.
The Seven Exam Domains
The authoritative scope for the exam is ACAC's CIEC and CIE Examinations chart, approved February 7, 2024. It lists seven domains. ACAC does not publish percentage weights in the complete chart, so you should not assume any domain is worth a particular share of your score. The approval date is a document date, not an exam version number; no separate public exam code or release version is specified.
Domain 1: IAQ Contaminants and Potential Health Effects
Expect to connect contaminants to their sources and to the health outcomes they are associated with.
- Biological contaminants such as mold and bacteria
- Chemical contaminants including volatile organic compounds and combustion byproducts
- Particulates, fibers, and other airborne hazards
- How exposure and symptoms relate to building conditions
Domain 2: Principles of Building Science & the Built Environment
This domain treats the building as a system: moisture, pressure, heat, and air all move through the envelope.
- Moisture sources, migration, and condensation
- Pressure relationships between spaces and the outdoors
- Envelope behavior and how construction choices create IAQ problems
Domain 3: HVAC
Ventilation is often both the cause of and the cure for IAQ complaints.
- Air distribution, outdoor air supply, and filtration
- How system design, operation, and maintenance affect indoor conditions
- Diagnosing ventilation-related complaints
Domain 4: Equipment Selection, Calibration and Operation
Measurement quality determines whether your findings hold up.
- Choosing instruments appropriate to a given investigation
- Calibration practices and their effect on data reliability
- Correct operation and the limits of field instruments
Domain 5: Guidelines, Regulations and Standards
Consultants must know which documents carry authority and which are advisory.
- Distinguishing enforceable regulations from voluntary guidelines
- Applying published standards and guidance to investigation findings
Domain 6: Remediation
Finding a problem is only half the job; this domain covers correcting it.
- Containment, cleaning, and removal approaches
- Source control versus symptom management
- Verifying that remediation worked
Domain 7: Respiratory Protection
Worker and occupant protection during investigation and remediation.
- Respirator selection logic and limitations
- The compliance framework around respirator programs
Key Takeaway
Do not rely on the handbook's six-heading summary alone. It omits Respiratory Protection, but the complete domain chart includes it. Study all seven domains, and use the complete guide to all seven CIEC content areas to map your knowledge gaps.
The Handbook's Reading List
The CIEC Candidate Handbook prescribes preparation references. These are worth treating as the backbone of your study plan, since they come directly from the certifying body:
- 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 these map onto the domains. The mold text supports contaminants, building science, and remediation; the EPA guide supports building science and HVAC; the NIOSH and OSHA documents anchor respiratory protection. Instrument calibration and standards knowledge will lean more on your field experience and on the regulations and guidance you work with daily. Our CIEC study guide shows how to work through this material systematically, and the one-page CIEC cheat sheet is useful for last-minute consolidation.
Fees and the Two-Year Term
Costs are published on ACAC's fee schedule. For the first two-year certification term:
| Item | Amount (USD) |
|---|---|
| Examination fee | $100 |
| Certification fee | $400 |
| Total, US/Canada | $500 |
| Total, outside US/Canada | $525 |
| Exam retake | $100 |
The certification is valid for two years. To renew, you pay $400 and earn 40 recertification credits: 10 credits for attesting to continued field activity plus 30 hours of professional development. Keep documentation of all of it, because ACAC can audit your submission. For a fuller budget picture, see the CIEC certification cost breakdown.
What the Published Pass Data Does and Does Not Say
ACAC's 2025 Exam Pass Ratio reports 61%, with 28 candidates passing out of 46 examinations. Read that figure carefully. The report includes retakes and state-licensing-only examinations, so it is not a first-attempt pass rate for CIEC candidates. The sample is also small, which means year-to-year swings are expected. Anyone quoting a first-attempt CIEC pass rate from this report is misreading it. We discuss the nuance in our CIEC pass rate analysis and in the guide to how hard the exam is.
Sequencing Your Preparation by Domain
Because the exam is closed-book and spans seven domains, the most useful planning question is which domains to tackle first. Experienced consultants often have lopsided knowledge: strong in the area they practice, thin elsewhere. A domain-ordered plan makes that visible early.
Foundations: Domains 2 and 3
- Building science and HVAC underpin almost every other topic
- Work through the EPA building air quality guide and Managing Indoor Air Quality
Contaminants and Remediation: Domains 1 and 6
- Use the AIHA mold text for sources, health effects, and control
- Tie each contaminant to a remediation approach
Measurement and Rules: Domains 4 and 5
- Review instrument selection, calibration, and the authority behind each standard or guideline
Respiratory Protection and Review: Domain 7
- Work the NIOSH selection logic and the OSHA compliance guide
- Finish with timed practice on our CIEC practice tests
The logic is that building science and HVAC give you the vocabulary to understand contaminant behavior and remediation, so they come first. Respiratory protection goes last in the content sequence only because it is the domain most easily skipped, since it is missing from the handbook's short list, so give it a dedicated block rather than leaving it to chance. Adjust the timeline to your own gaps; someone with a long remediation background might compress Weeks 3 and 4 and expand Week 5.
Who Uses the Credential
The CIEC is relevant to professionals who evaluate indoor environments and advise on corrective action. The five experience areas hint at the typical employers and roles: environmental consulting firms, industrial hygiene practices, building and facilities operations, and organizations that assess or remediate lead, asbestos, and microbial problems. Some candidates pursue it because their state licensing process involves the same examination, though, as noted, a state-licensing pass does not by itself confer the designation.
For the earnings and career side, see our CIEC salary guide, the overview of CIEC jobs, and the ROI analysis of whether CIEC is worth it. We avoid quoting salary figures here because ACAC does not publish them, and numbers from other sources may describe different credentials. If you want to test your readiness before committing to the application, start with a free CIEC practice test.
Frequently Asked Questions
In this context, CIEC stands for Council-certified Indoor Environmental Consultant, a credential issued by the American Council for Accredited Certification (ACAC). Other credentials use the same acronym, so always confirm the issuer.
No. No training course is mandatory. Eligibility is based on a qualifying education level plus four, six, or eight years of documented IAQ investigation experience, spanning at least three of five experience areas.
The exam has 120 multiple-choice questions, each with at least four answer choices, and lasts 3 hours. It is closed-book, and the passing score is 75%, set using the modified Angoff method.
Certification is valid for two years. Renewal costs $400 and requires 40 recertification credits: 10 for attesting to continued field activity plus 30 hours of professional development. Keep documentation in case of audit.
No. Passing the examination for state licensing alone does not confer the CIEC designation. You must also complete the application, including four project sheets, and receive unanimous board approval.