- What This Cheat Sheet Covers (and What It Doesn't)
- The Exam at a Glance
- The Five Published Coverage Areas
- Core Concepts to Know Cold
- The Hands-On Component
- Expressing Results: Units and Reporting Logic
- Terminology Quick-Reference
- What Is Not Publicly Verified
- Sequencing Your Review by Coverage Area
- Where This Credential Gets Used
- FAQ
- CDET here means Certified Duct and Envelope Testing, offered by ESCO Group under HVAC Excellence Specialty Certifications.
- The exam has a written part and a mandatory hands-on part, and you must pass both.
- ESCO publishes five coverage areas, but no weights, so study all five rather than betting on one.
- ESCO lists no prerequisites; the suggested 4-6 hours is course delivery time, not exam length.
What This Cheat Sheet Covers (and What It Doesn't)
This one-page-style review is about Certified Duct and Envelope Testing, the specialty certification published by ESCO Group under its HVAC Excellence Specialty Certifications program. It concerns the field skills of measuring how leaky a building's air distribution system and enclosure are. If you arrived looking for a different credential that happens to share the same letters, this is not that material, and none of the facts below should be carried across.
One honest caveat up front: "CDET" is the identifier used on this site, and the ESCO pages reviewed do not establish it as an official abbreviation. If you need a primer on naming, see What Does CDET Stand For? and What Is CDET Certification?. For the broader picture of the credential, start with CDET Certification.
The Exam at a Glance
The table below separates what is publicly documented from what is not. Treat anything marked "not publicly disclosed" as unknown until ESCO or your proctor confirms it directly.
| Item | What is known |
|---|---|
| Certifying body | ESCO Group, under HVAC Excellence Specialty Certifications |
| Components | Written examination plus a mandatory hands-on examination |
| Passing rule | Both components must be passed |
| Prerequisites | None listed by ESCO |
| Suggested course time | 4-6 hours of course delivery (not exam duration, not required training) |
| Manual | Separately listed at $47.95; this is not an exam fee |
| Exam fee, member/nonmember pricing | Not publicly verified |
| Question format and item counts | Not publicly disclosed |
| Timers (written and hands-on) | Not publicly disclosed |
| Cut score and pass rate | Not publicly disclosed |
| Exam-version identifier / weighted blueprint | Not located |
| Open book, calculator rules, remote delivery | Not publicly verified |
| Validity period, renewal, CEUs | Not publicly verified |
The Five Published Coverage Areas
ESCO publishes five coverage-area names. These are not a verified weighted blueprint, so no domain can be called "the biggest" on the evidence available. The practical consequence is simple: do not skip a domain on the theory that it is lightly tested.
Domain 1: Understanding of the envelope
The building enclosure as a system: what separates conditioned space from outside and from unconditioned space, and why leakage through it matters.
- Where air moves through an enclosure and what drives that movement
- How envelope leakage interacts with the duct system
- Why the location of the pressure boundary matters before any test begins
Domain 2: Duct leakage testing procedures
The step-by-step field method for quantifying leakage in a duct distribution system.
- Equipment setup and sealing of registers and grilles
- Pressurizing the system and reading flow against a reference pressure
- Recognizing when a setup error is corrupting your reading
Domain 3: Envelope (structure) testing procedures
The field method for testing the building shell itself, typically by depressurizing or pressurizing the structure.
- Preparing the building: closing or sealing openings, setting up the test fixture
- Establishing and holding a target pressure difference
- Documenting conditions that affect the result
Domain 4: Methods expressing results
Turning a raw measurement into a number someone else can compare against a requirement.
- Which units and normalizations are used for duct results versus envelope results
- How results are reported so they can be checked
Domain 5: Terminology
The vocabulary that appears in both the written exam and the work itself.
- Pressure terms, flow terms, and leakage terms used precisely
- Telling similar-sounding terms apart
For a deeper walkthrough of each area, see CDET Exam Domains 2026: Complete Guide to All 5 Content Areas.
Core Concepts to Know Cold
Because the five coverage areas lean on the same underlying physics, a few ideas show up everywhere. If you can explain each of these in plain language, you have the foundation for both the written and hands-on parts.
Pressure and flow are linked, not interchangeable
Leakage testing works by creating a known pressure difference and measuring how much air flow it takes to hold it. A leakier assembly needs more flow to maintain the same pressure. Keep the two quantities straight: pressure is the condition you set, flow is the thing you measure.
The pressure reference point matters
A duct pressure reading is meaningful only relative to a defined reference. Mixing up which side you are referencing against is a classic way to get a number that looks reasonable and is wrong.
Total leakage versus leakage to a specific place
An enclosure or duct system can leak into conditioned space or to the outside, and those are not the same finding. Be able to explain why a test that captures one does not automatically describe the other, and why the test configuration defines what you are actually measuring.
Key Takeaway
When a written question describes a test setup, work out what the pressure boundary is and what is being pressurized before you touch the numbers. Most wrong answers come from misreading the setup, not from arithmetic.
The Hands-On Component
The mandatory hands-on examination is the part candidates tend to underestimate. A written pass does not substitute for it, and a hands-on pass does not substitute for the written. Both must be passed. How the hands-on portion is timed and scored is not publicly disclosed, so prepare by building real procedural fluency rather than memorizing a script.
- Setup discipline: sealing, connecting hoses, and positioning equipment correctly are where field errors begin.
- Sequence: know the order of operations for a duct test and for an envelope test, and why the order exists.
- Sanity checks: be able to notice a reading that does not make physical sense and trace it to a likely cause.
- Recording: capture the conditions and readings the way a reviewer would expect to see them.
Because the format specifics are undisclosed, confirm logistics with your registered proctor in advance. ESCO's registered-proctor network is documented, though a separate testing vendor is unverified. Details on timing and scheduling are covered in CDET Exam Dates 2026: Testing Windows, Deadlines & Scheduling.
Expressing Results: Units and Reporting Logic
Domain 4 is about methods of expressing results, and it rewards candidates who understand why a raw flow number is not enough. A leakage figure only becomes useful when it is normalized in a way that lets you compare it to a requirement or to another building.
- Know the measured quantity. Identify exactly what flow was recorded and at what reference pressure.
- Know the normalizer. Results are commonly scaled against something about the building or system, so that size does not hide the comparison.
- Match the metric to the test. Duct results and envelope results are not expressed identically; do not carry one convention into the other.
- State the conditions. A result without its test conditions cannot be verified.
Terminology Quick-Reference
Domain 5 is vocabulary, but it is also the connective tissue of the other four areas. The terms below are the kinds of pairs that get confused. Define each in your own words before test day.
| Concept pair | The distinction to be able to state |
|---|---|
| Pressure vs. flow | One is the condition you establish, the other is what you measure to maintain it |
| Supply vs. return leakage | Different sides of the duct system, with different effects on the building |
| Conditioned vs. unconditioned space | Defines where the thermal and pressure boundaries sit |
| Pressurization vs. depressurization | Two ways to create the test pressure difference |
| Leakage to outside vs. total leakage | Test configuration determines which one you captured |
| Measured value vs. normalized result | The raw reading and the reportable figure are different things |
What Is Not Publicly Verified
A good cheat sheet is honest about its gaps. The following were not located in publicly available information, so do not plan around any figure you may see quoted elsewhere without confirming it with ESCO or your proctor:
- The current examination fee and any member/nonmember price difference
- The written question format and the number of total, scored, and unscored items
- Both test timers
- The numerical cut score and the pass rate
- A current exam-version identifier or a weighted content blueprint (the manual's 2015 copyright is not an exam-version declaration)
- Whether books or calculators are permitted, and whether remote or adaptive delivery is available
- Certification validity and any renewal or continuing-education requirements
Because of this, articles claiming a precise pass rate or passing score deserve skepticism. Our own tracking is in CDET Pass Rate 2026: What the Data Shows and CDET Passing Score 2026: Exactly What You Need to Pass, which explain what can and cannot be stated. For a candid look at difficulty without invented numbers, see How Hard Is the CDET Exam? Complete Difficulty Guide 2026.
Sequencing Your Review by Coverage Area
With no published weights, the sensible plan is balanced coverage, ordered by dependency. Terminology and envelope fundamentals come first because the procedures in Domains 2 and 3 assume them. Results reporting comes after you have performed or walked through the procedures. This is a suggested sequence, not an ESCO requirement.
Foundations: Domains 1 and 5
- Read the envelope material in the manual and list every term you cannot define
- Build the concept-pair table above in your own words
Procedures: Domains 2 and 3
- Walk through the duct test and the envelope test step by step, including the reason for each step
- If you can, practice the physical setup and connections
Results and integration: Domain 4
- Work example readings through to a reportable result
- Take practice questions mixing all five areas and review every miss
For a fuller plan, see the CDET Study Guide 2026: How to Pass on Your First Attempt and the options described under CDET Training. When you are ready to test yourself, the CDET practice test lets you drill all five areas.
Where This Credential Gets Used
Duct and envelope testing sits where HVAC service, weatherization, and energy-efficiency work meet. The people who put the skill to use include HVAC technicians who commission or diagnose systems, energy auditors and home performance contractors, weatherization crews, and inspectors or raters who verify that a building meets a leakage requirement. The credential demonstrates that you understand the method and can carry it out in the field, which is the practical value to an employer.
We deliberately do not attach pay figures to this credential, because no verified earnings data tied specifically to it was located. For how to think about the value question honestly, read Is the CDET Certification Worth It? Complete ROI Analysis 2026 and CDET Salary Guide 2026: Complete Earnings Analysis, and browse CDET Jobs for the roles where this skill appears.
Key Takeaway
Think of the credential as proof of a field method, not a generic study subject. The strongest preparation mirrors the work: understand the building, run the test correctly, and report the result so someone else can trust it.
If you want to pressure-test your recall across the five areas, try the practice questions on the main site before you book.
FAQ
ESCO Group offers it under HVAC Excellence Specialty Certifications. The "CDET" label is the identifier used on this site, and the ESCO pages reviewed do not establish it as an official abbreviation.
There are two components: a written examination and a mandatory hands-on examination. Both must be passed. Timers, question counts, and scoring details for each are not publicly disclosed.
No. The suggested 4-6 hours refers to course delivery time. It is not a required training amount and it is not the exam duration. Confirm actual exam length with ESCO or your registered proctor.
ESCO lists no prerequisites. That said, hands-on familiarity with HVAC or building-performance work will make the practical component easier. See the requirements article for the full picture.
That is unknown. ESCO publishes five coverage-area names, but no verified weighting, so no domain can be identified as largest. Study all five rather than concentrating on one.