- Overview: Why the Seven Domains Matter
- Domain 1: Managing Commissioning Projects (18%)
- Domain 2: Preparing Commissioning Documentation (19%)
- Domain 3: Conducting Commissioning Activities (24%)
- Domain 4: Managing Training Activities (4%)
- Domain 5: Completing Warranty Phase Activities (5%)
- Domain 6: Conducting Existing Building Commissioning (23%)
- Domain 7: Conducting On-Going Commissioning (7%)
- How the Domains Map to Exam Mechanics
- Allocating Study Time by Domain Weight
- Frequently Asked Questions
- Domain 3 (Conducting Commissioning Activities, 24%) and Domain 6 (Existing Building Commissioning, 23%) together make up nearly half the exam.
- The exam has 125 multiple-choice questions in 4 hours 15 minutes, plus a separate 10-minute break.
- Domains 4 and 5 (Training and Warranty, 4% and 5%) are low-weight but still require mastery to avoid losing easy points.
- ACG's current study reference is Building Systems Commissioning Guideline Part 1, updated March 10, 2025.
Overview: Why the Seven Domains Matter
The Certified Commissioning Authority (CxA) credential, administered by the ACG Certification Council (AABC Commissioning Group), tests candidates across seven distinct content areas that mirror the actual lifecycle of a commissioning project. Unlike generic project-management exams, the CxA blueprint is weighted heavily toward field execution and existing-building work rather than theory, which tells you a lot about how to prioritize your preparation.
If you're still deciding whether this credential fits your career path, start with our overview of What Is CxA Certification? or the broader CxA Certification primer before diving into domain-level detail. This article assumes you already understand the basics and want a working map of exactly what's tested and how heavily.
Domain 1: Managing Commissioning Projects (18%)
This domain covers the administrative backbone of commissioning: developing the commissioning plan, defining roles and responsibilities, scheduling commissioning activities within the broader construction timeline, and coordinating among owners, design teams, and contractors. Expect scenario-based questions that test whether you know who is responsible for what at each project phase, not just textbook definitions.
Managing Commissioning Projects
Candidates must understand how a commissioning authority integrates into the project delivery process from pre-design through closeout.
- Developing and maintaining the Owner's Project Requirements (OPR) alignment
- Sequencing commissioning milestones against construction schedules
- Managing communication among stakeholders with competing priorities
Domain 2: Preparing Commissioning Documentation (19%)
Documentation is nearly a fifth of the exam, and it's one of the most fact-dense domains. This includes writing commissioning specifications, developing test procedures, and creating the documentation trail that proves systems were verified. Expect questions about what belongs in a commissioning plan versus a test script, and how documentation changes across design, construction, and acceptance phases.
- Commissioning specifications and their place in the contract documents
- Functional test procedure development and formatting
- Issue logs, tracking reports, and documentation required for closeout
Because this domain is heavy on specifics, it pairs well with focused review sessions using the CxA Cheat Sheet 2026: One-Page Review of Must-Know Facts as a quick-reference tool while you work through full-length review.
Domain 3: Conducting Commissioning Activities (24%)
This is the largest domain on the exam and deserves the largest share of your study time. It covers the hands-on execution of commissioning: pre-functional checklists, functional performance testing, verifying installation against design intent, and resolving deficiencies discovered during testing.
Conducting Commissioning Activities
This domain tests field judgment as much as procedural knowledge - expect questions that require you to interpret a testing scenario and choose the correct next step.
- Pre-functional checklist execution and sign-off criteria
- Functional performance testing of HVAC, controls, and related building systems
- Deficiency identification, documentation, and resolution workflows
- Coordinating retesting after corrective action
Key Takeaway
Because Domain 3 alone accounts for nearly a quarter of the exam, candidates who skip hands-on functional testing experience in favor of pure document review tend to struggle most here.
Domain 4: Managing Training Activities (4%)
A small but easy-to-master domain covering the coordination and verification of operator and occupant training as part of project closeout. Topics include confirming training requirements are met, reviewing training documentation, and verifying that facilities staff can operate the systems being handed over.
- Training plan review against OPR requirements
- Verifying training attendance and competency documentation
- Coordinating training schedules with substantial completion
Domain 5: Completing Warranty Phase Activities (5%)
Warranty-phase commissioning closes the loop after occupancy. This domain tests knowledge of seasonal testing, deferred testing items, warranty-period deficiency tracking, and the final commissioning report.
- Seasonal and deferred functional testing requirements
- Tracking and resolving warranty-period deficiencies
- Final commissioning report content and distribution
Domains 4 and 5 together only total 9% of the exam, but skipping them entirely is a common mistake candidates make when they assume low weight means low priority. A few missed questions in these areas can still matter given the criterion-referenced total-score passing standard discussed in our CxA Passing Score 2026: Exactly What You Need to Pass guide.
Domain 6: Conducting Existing Building Commissioning (23%)
At 23%, this is the second-largest domain and often the one candidates underestimate, especially if their field experience leans toward new construction. Existing building commissioning (sometimes called retro-commissioning) covers investigating current building performance, developing a master list of findings, and implementing low-cost and capital improvements.
Conducting Existing Building Commissioning
This domain assumes familiarity with buildings that are already occupied and operating, which requires a different investigative approach than new-construction commissioning.
- Investigation phase: trend data analysis, interviews, and system surveys
- Developing a master list of deficiencies and improvement opportunities
- Prioritizing findings by cost, energy impact, and occupant comfort
- Implementation and verification of corrective measures
If your professional background is heavily weighted toward new construction, dedicate extra review time here. Combined with Domain 3, these two domains make up 47% of the exam - nearly half your score rides on these two content areas alone.
Domain 7: Conducting On-Going Commissioning (7%)
On-going commissioning (sometimes called continuous or monitoring-based commissioning) addresses the long-term persistence of performance after initial commissioning or retro-commissioning is complete. This domain covers establishing ongoing commissioning plans, trend monitoring, and periodic re-verification of system performance over time.
- Establishing persistence tracking and monitoring plans
- Using trend data to detect performance drift
- Scheduling periodic re-commissioning activities
How the Domains Map to Exam Mechanics
The CxA exam consists of 125 multiple-choice questions administered over 4 hours and 15 minutes, with a separate 10-minute break built into the appointment. Most candidates test at a Kryterion/Webassessor test center, though select ACG event exams are administered paper-and-pencil at conferences; at-home proctoring is not a confirmed option, so plan your logistics accordingly. The exam is closed book, though a scientific non-programmable calculator is permitted - useful for any load or energy-related calculations that may appear within the testing and existing-building domains.
Scoring uses a criterion-referenced total-score passing standard rather than a domain-by-domain cutoff, meaning strong performance in your best domains (likely Domain 3 or Domain 6, depending on your background) can help offset weaker areas elsewhere - but you still need broad competency since no single domain can be skipped entirely. For a deeper breakdown of how scoring works, see CxA Passing Score 2026: Exactly What You Need to Pass.
| Domain | Weight | Primary Focus |
|---|---|---|
| 1. Managing Commissioning Projects | 18% | Planning, scheduling, stakeholder coordination |
| 2. Preparing Commissioning Documentation | 19% | Specs, test procedures, documentation trail |
| 3. Conducting Commissioning Activities | 24% | Checklists, functional testing, deficiency resolution |
| 4. Managing Training Activities | 4% | Operator/occupant training verification |
| 5. Completing Warranty Phase Activities | 5% | Seasonal testing, warranty deficiency tracking |
| 6. Conducting Existing Building Commissioning | 23% | Investigation, master list, implementation |
| 7. Conducting On-Going Commissioning | 7% | Persistence monitoring, periodic re-verification |
Allocating Study Time by Domain Weight
Given the weighting above, the most efficient approach is to allocate study hours roughly proportional to exam weight, with extra attention to whichever of Domain 3 or Domain 6 is less familiar from your day-to-day work. A candidate coming from a new-construction commissioning background should over-invest in Domain 6, while a retro-commissioning specialist should do the reverse for Domain 3.
Documentation & Project Management (Domains 1-2, 37% combined)
- Review commissioning plan structure and OPR alignment
- Practice writing and interpreting functional test procedures
Field Activities (Domain 3, 24%)
- Work through functional performance testing scenarios
- Drill deficiency identification and retest workflows
Existing Buildings (Domain 6, 23%)
- Study investigation methods and master-list prioritization
- Review trend-data interpretation for retro-commissioning
Training, Warranty & On-Going (Domains 4, 5, 7 - 16% combined)
- Review training verification and warranty-phase closeout steps
- Study persistence tracking for on-going commissioning
- Take full-length timed practice exams
For a more detailed week-by-week study plan with scheduling logistics, registration deadlines, and resource recommendations, see our full CxA Study Guide 2026: How to Pass on Your First Attempt. If you're still confirming testing windows against the July 8, 2026 application cycle, check CxA Exam Dates 2026: Testing Windows, Deadlines & Scheduling before locking in your study schedule.
Before registering, confirm you meet one of the four eligibility tracks - these range from a PE or architect license plus three years of commissioning experience, up to a high school diploma or GED plus ten years of building-industry experience including five in commissioning. Full details, including the three qualifying projects and six of eight specified activities requirement, are covered in CxA Requirements 2026: Eligibility, Prerequisites & How to Qualify.
Once you understand the domain weighting, it's worth asking how difficult the exam actually is in practice and what the data shows about outcomes. Our companion articles on How Hard Is the CxA Exam? Complete Difficulty Guide 2026 and CxA Pass Rate 2026: What the Data Shows walk through what reported outcomes mean for your preparation strategy. You can also run through realistic domain-weighted questions using the practice exams at CxA Exam Prep to see how your knowledge of each domain actually holds up under timed conditions.
Frequently Asked Questions
Start wherever your practical experience is weakest, but prioritize Domain 3 (Conducting Commissioning Activities, 24%) and Domain 6 (Existing Building Commissioning, 23%) early since they carry the most weight and typically require the most review time to master.
Yes. Domains 4, 5, and 7 combined still total 16% of the exam, and because scoring uses a criterion-referenced total-score standard, points lost in these smaller domains still count against your overall result.
No. New-construction-oriented activities are spread across Domains 1, 2, 3, 4, and 5, while Domain 6 alone covers existing building commissioning at 23% - a substantial, standalone content area that requires dedicated review.
The exam consists of 125 multiple-choice questions delivered over 4 hours 15 minutes, with a separate 10-minute break. It is closed book, though a scientific non-programmable calculator is permitted.
ACG's current study reference is the Building Systems Commissioning Guideline Part 1, which was updated as the designated reference material effective March 10, 2025.