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100+ Free CIEC Practice Questions

Pass your ACAC Council-certified Indoor Environmental Consultant (CIEC) exam on the first try — instant access, no signup required.

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Which is the BEST description of 'CIEC peer-review' of an engagement before report finalization?

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2026 Statistics

Key Facts: CIEC Exam

120

Exam Questions

ACAC Candidate Handbook

75%

Passing Score

ACAC Candidate Handbook

3 hours

Exam Duration (closed-book)

ACAC Candidate Handbook

$500

Total Fee ($400 cert + $100 exam)

ACAC fees page

8 years

Field Experience (4 yrs with 4-yr degree)

ACAC

62.1

Primary Ventilation Standard (ASHRAE)

ASHRAE

40 RCs

Recertification Credits per 2-year Cycle

ACAC

The ACAC CIEC (Council-certified Indoor Environmental Consultant) is the senior consulting credential for indoor air quality (IAQ) practitioners issued by the American Council for Accredited Certification (ACAC). It is the most rigorous certification in the ACAC IAQ track, intended for experienced consultants who design sampling strategies, lead complex investigations, interpret advanced HVAC data, and provide expert testimony. The 120-question, 3-hour, closed-book exam (75% passing score) covers indoor air pollutants and risk analysis, advanced HVAC and building science, ASHRAE 62.1/55, sampling strategy and lab QA/QC, regulatory frameworks (AHERA, RRP, NESHAP), LEED v4 IEQ, WELL Building Standard, and the ACAC Code of Ethics. Prerequisites: 8 years field experience in IAQ (4 years with a 4-year science/engineering degree; 6 years with a 2-year degree). Certification is valid for 2 years and requires 40 Recertification Credits plus unanimous approval of the CIEC certification board.

Sample CIEC Practice Questions

Try these sample questions to test your CIEC exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1The ACAC CIEC examination contains how many multiple-choice questions per the official Candidate Handbook?
A.75
B.100
C.120
D.150
Explanation: ACAC's CIEC examination is a 120-question, 3-hour, closed-book exam. A score of 75% is required to pass. This 120-question length distinguishes the senior CIEC from the CIE (100 questions).
2ACAC requires CIEC candidates WITHOUT a qualifying degree to have how many years of documented field experience in indoor air quality investigation?
A.2 years
B.4 years
C.6 years
D.8 years
Explanation: ACAC requires 8 years of field experience for the CIEC. The requirement is reduced to 4 years with a 4-year college degree in science/engineering, or 6 years with a 2-year degree.
3ASHRAE 62.1's Ventilation Rate Procedure breathing-zone outdoor airflow (Vbz) equation is:
A.Vbz = Rp × Pz + Ra × Az
B.Vbz = Rp × Az + Ra × Pz
C.Vbz = Rp / Pz × Ra × Az
D.Vbz = (Rp + Ra) × (Pz + Az)
Explanation: Vbz = Rp × Pz + Ra × Az, where Rp is cfm/person, Pz is zone population, Ra is cfm/sq ft, and Az is zone area. The two components address occupant- and building-related sources of indoor pollution.
4In ASHRAE 62.1, Vou (uncorrected outdoor air intake) relates to Vbz how?
A.Vou is the sum of all zone Vbz values divided by zone air distribution effectiveness (Ez)
B.Vou equals total floor area
C.Vou equals total occupant count
D.Vou is unrelated to Vbz
Explanation: ASHRAE 62.1 calculates Vou by summing zone-level Vbz/Ez (where Ez is zone air distribution effectiveness, often 1.0 for ceiling supply / ceiling return). System-level Vot then accounts for system efficiency (Ev).
5Which BEST describes the role of Ev (system ventilation efficiency) in ASHRAE 62.1?
A.A factor that increases outdoor air intake when multi-zone systems share air streams; Vot = Vou / Ev
B.Energy use of fans
C.Filter efficiency
D.Outdoor air dewpoint
Explanation: Ev accounts for system-level inefficiency in multi-zone systems where outdoor air may not reach the critical zone equally. Vot = Vou / Ev. Multi-zone systems generally require higher outdoor air at the air handler than single-zone systems for the same per-zone delivery.
6Which CIEC investigation step typically COMES BEFORE designing the sampling plan?
A.Lab selection
B.Walk-through assessment, occupant interview, moisture mapping, HVAC inspection, and hypothesis formation
C.Final report writing
D.Invoicing
Explanation: Defensible CIEC practice is hypothesis-driven. The sampling plan flows from a structured walk-through, occupant interview, moisture mapping, HVAC inspection, and explicit hypothesis. Sampling without context is inefficient and may be uninterpretable.
7Which method is BEST suited for speciated VOC analysis in indoor air?
A.EPA TO-15 (summa canister) with GC/MS
B.Air-O-Cell with direct microscopy
C.NIOSH 7400 with PCM
D.Pin moisture meter
Explanation: EPA Method TO-15 uses evacuated, passivated (Summa) canisters to collect whole-air samples for GC/MS analysis of speciated VOCs. Sorbent tubes (TO-17) are an alternative for selected VOCs.
8OSHA's formaldehyde Permissible Exposure Limit (8-hour TWA) is:
A.0.1 ppm
B.0.5 ppm
C.0.75 ppm
D.2 ppm
Explanation: 29 CFR 1910.1048 sets OSHA's formaldehyde PEL at 0.75 ppm 8-hour TWA, with an action level of 0.5 ppm and a 2 ppm STEL (15 minutes). ATSDR chronic MRL is much lower (~8 ppb).
9EPA's residential radon action level is:
A.0.4 pCi/L
B.2 pCi/L
C.4 pCi/L
D.10 pCi/L
Explanation: EPA recommends action at 4 pCi/L, with mitigation encouraged in the 2-4 pCi/L range. WHO's recommended level is lower (~2.7 pCi/L), but in U.S. CIEC practice 4 pCi/L is the operative number.
10OSHA's general industry CO PEL is:
A.5 ppm
B.50 ppm 8-hr TWA
C.200 ppm
D.1,000 ppm
Explanation: OSHA's CO PEL is 50 ppm 8-hour TWA. NIOSH REL is 35 ppm. ACGIH TLV is 25 ppm. Indoor IAQ targets are typically much lower than these occupational PELs.

About the CIEC Exam

The CIEC is the senior indoor environmental consulting credential from ACAC, certifying advanced competence in IAQ investigation, sampling strategy, HVAC analysis, regulatory interpretation, and consulting practice. The 120-question exam is the most rigorous in the ACAC IAQ track.

Questions

120 scored questions

Time Limit

3 hours

Passing Score

75%

Exam Fee

$500 (certification + exam) (ACAC (American Council for Accredited Certification))

CIEC Exam Content Outline

~20%

Indoor Air Pollutants & Health Risk

VOCs, formaldehyde, radon, PM, CO/CO2, ozone, NO2, asbestos, lead, dose-response, sensitive populations

~20%

Advanced HVAC & Building Science

ASHRAE 62.1 (Vbz, Vou, Vot), ASHRAE 55, MERV/HEPA, BAS, pressurization, dehumidification, dew point

~20%

Sampling Strategy & Lab Interpretation

Direct-reading instruments, NIOSH/OSHA methods, calibration, AIHA-LAP accreditation, lab report interpretation

~20%

Standards, Codes & Regulations

ASHRAE, EPA IAQ, OSHA, AHERA, NESHAP, RRP, LEED v4 IEQ, WELL

~20%

Consulting Practice, Reporting & Ethics

Scope of work, hypothesis-driven sampling, expert testimony, conflict of interest, ACAC Code of Ethics

How to Pass the CIEC Exam

What You Need to Know

  • Passing score: 75%
  • Exam length: 120 questions
  • Time limit: 3 hours
  • Exam fee: $500 (certification + exam)

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

CIEC Study Tips from Top Performers

1Master the ASHRAE 62.1 Ventilation Rate Procedure — calculate breathing zone outdoor airflow (Vbz), uncorrected outdoor air intake (Vou), and outdoor air intake (Vot) for multi-zone systems
2Know key exposure limits cold: OSHA formaldehyde PEL 0.75 ppm (action 0.5 ppm), CO PEL 50 ppm, EPA radon action 4 pCi/L, ATSDR formaldehyde MRL 8 ppb chronic, ASHRAE 1,000 ppm CO2 rule of thumb
3Study sampling strategy — hypothesis-driven design, NIOSH method selection (e.g., NIOSH 2016 for formaldehyde, NIOSH 7400 for fibers), and how analytical limits of detection affect interpretation
4Understand the recommendation hierarchy: source control > ventilation > filtration > administrative controls > PPE
5Know the regulatory landscape: AHERA (40 CFR Part 763) for asbestos in schools, NESHAP for renovation/demolition, RRP (40 CFR Part 745) for lead in pre-1978 housing, OSHA general duty for IAQ
6Review the ACAC Code of Ethics — separation of assessment from remediation, conflict of interest, and limits of scientific certainty in expert testimony

Frequently Asked Questions

What is the CIEC exam?

The CIEC (Council-certified Indoor Environmental Consultant) exam is the senior IAQ consulting credential from ACAC (American Council for Accredited Certification). It tests advanced competency in indoor air quality investigation, sampling strategy design, HVAC analysis, regulatory interpretation, and consulting practice including expert testimony.

How many questions are on the CIEC exam?

The ACAC CIEC exam contains 120 multiple-choice questions delivered as a 3-hour, closed-book examination through Kryterion testing centers, with a remote-proctored webcam option also available. A score of 75% is required to pass.

How is the CIEC different from the CIE?

The CIE (Council-certified Indoor Environmentalist) is the standard IAQ practitioner credential requiring 2 years of field experience and a 100-question exam. The CIEC (Council-certified Indoor Environmental Consultant) is the senior consulting tier requiring 8 years of experience (or 4 years with a 4-year degree), a 120-question exam, and unanimous board approval. CIEC holders typically lead complex investigations and provide expert testimony.

What are the prerequisites for the CIEC credential?

ACAC requires 8 years of documented field experience in indoor air quality investigation. This is reduced to 4 years with a 4-year college degree in science, engineering, or a related field, or 6 years with a 2-year degree. Candidates must demonstrate familiarity with industry reference materials, receive unanimous board approval, and agree to the ACAC Code of Ethics.

How long is the CIEC certification valid?

The CIEC certification is valid for 2 years from the date of issue. Holders must accumulate 40 Recertification Credits (RCs) — each representing 1 hour of continuing education or professional development — prior to expiration to maintain the credential.

What is the passing score for the CIEC exam?

ACAC requires a score of 75% to pass the CIEC exam. Scores are graded electronically at the testing facility and are available to candidates immediately upon completion.

How long should I study for the CIEC exam?

Most candidates prepare for 100-150 hours over 8-12 weeks. Prioritize ASHRAE 62.1 ventilation rate procedure (Vbz, Vou, Vot), advanced sampling strategy, building science (vapor drive, dew point), pollutant exposure limits, and the regulatory landscape (AHERA, NESHAP, RRP, OSHA general duty).