Title 24 · California Energy Code

What are the duct sealing and leakage testing requirements for residential, multifamily and nonresidential systems?

Homeowner summary: When HVAC ducts are installed or altered, California’s Energy Code requires they be sealed and tested. For multifamily units the code lets you meet either **12% total leakage** or **6% leakage‑to‑outside** of the air‑handler flow; residential altered systems often have stricter targets (for example, **5%** for completely new replacement ducts or **10% / 7%** for extensions); small or asbestos‑affected systems and tall multifamily buildings have specific exceptions. Tests must use the field procedures the code references (RA3 for residential/multifamily, NA7.5.3 for nonresidential), or else you must seal all accessible leaks and verify with a smoke/visual inspection.

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Last reviewed: July 6, 2026

What the code requires — 2–4 sentences

In plain English: when a forced‑air system is installed, altered, or extended, the ducts must be sealed and meet specific leakage targets based on the type of building and whether the leakage is measured as total leakage or leakage to outside. The applicable leakage limits and the required test procedures are specified in the Energy Code sections § 150.0(m) (residential, with Reference Appendix RA3 procedures), § 160.3(b)5K (multifamily), and § 120.4(g) / § 120.5 with Reference Nonresidential Appendix NA7.5.3 (nonresidential). See the cited code text for each rule and for which test procedure to use.

The single most important rule: seal ducts and verify with the test method referenced in the code (RA3 for residential/multifamily; NA7.5.3 for nonresidential) and meet the leakage percentage (or, if you cannot meet the percentage, seal all accessible leaks and verify by smoke/visual inspection).

Requirements in detail

Decision dimensions

  • Defined terms used below: air handler airflow (the airflow used to calculate percent leakage — determined per the referenced RA3 procedure), total leakage (all leakage measured with the duct pressurization procedure), leakage to outside (leakage that goes outside the conditioned envelope), and acceptance / diagnostic test (field verification and diagnostic testing performed per the referenced appendix procedures). These terms are used in the cited code language.

Quick reference table (decision‑relevant values)

Building type / condition When it applies (short) Leakage target(s) — percent of air‑handler airflow Test procedure / where to confirm Code reference
Multifamily — entirely new or complete replacement ducts (connected to air handler) New ducts for a dwelling unit Total leakage ≤ 12% OR Leakage to outside ≤ 6% Reference Residential Appendix RA3 procedures for measurement and airflow determination § 160.3(b)5K
Multifamily — extension of existing ducts (combined system) New ducts extend existing system Total leakage ≤ 15% OR Leakage to outside ≤ 10% RA3 field verification & diagnostic testing procedures § 160.3(b)5K
Residential (single‑family) — altered ducts or >25 ft new ducts (entirely new/complete replacement) Alteration where new ducts form a new/complete replacement Total leakage ≤ 5% (entirely new/complete replacement) RA3 procedures (duct sealing of altered/added ducts) § 150.0(m) (see related altered duct sections)
Residential — altered ducts, extension of existing system Alteration that extends existing ducts Total leakage ≤ 10% OR Leakage to outside ≤ 7% RA3 procedures § 150.0(m) / related altered duct rules
Residential — ducts or air handler located in a garage Altered ducts/air handler in garage space System leakage ≤ 6% (or seal all accessible leaks + smoke test) RA3 procedures / smoke/visual verification § 150.0(m) / altered duct garage clauses
Nonresidential — new duct systems (limited scope) New ducts that meet all criteria (single‑zone constant vol., <5,000 sf, >25% outdoor/unconditioned surface, not healthcare) Leakage ≤ 6% (nominal air handler airflow) as confirmed by acceptance testing Reference Nonresidential Appendix NA7.5.3 (acceptance testing) or CMC §603.9.2 where applicable § 120.4(g) & § 120.5

Notes about the table:

  • The code often provides two alternate compliance paths: a total leakage limit and a leakage‑to‑outside limit. Meeting either one (when allowed) satisfies the requirement.
  • When the required leakage target cannot be achieved, the code allows (in many cases) sealing of all accessible leaks plus verification using a visual inspection and smoke test performed by a qualified rater/technician — see the specific exception language.

Test procedures and who performs them

  • Residential and multifamily duct leakage measurement and airflow determination reference the procedures in Reference Residential Appendix RA3 (for example, RA3.1.4.3.1 for total leakage and RA3.1.4.3.4 for leakage‑to‑outside). The main code sections explicitly require using RA3 for the measurement and airflow methods. If you need step‑by‑step procedures (fan pressurization, connection, instrument requirements), consult RA3; RA3 text was referenced by the code sections.
  • Nonresidential acceptance testing required by § 120.4(g) and § 120.5 must follow Reference Nonresidential Appendix NA7.5.3; if NA7.5.3 does not apply, the code points to the California Mechanical Code duct test rules (CMC §603.9.2).

Exceptions & special cases

  • Buildings with four or more habitable stories: the field‑verification and ECC‑Provider registry requirements in RA2/RA3 are not required; the installer may instead certify that testing was performed in accordance with applicable procedures. (This is an explicit exception in the multifamily language.)
  • Asbestos: existing duct systems that are constructed, insulated, or sealed with asbestos are exempt from some duct sealing requirements for extensions/alterations.
  • Small runs: some residential altered‑duct provisions exclude systems with less than 40 linear feet of ducts from the full testing requirement; those cases may use the accessible leak sealing + smoke‑test option.
  • Garage location: ducts/air handlers in garage spaces have tighter limits or require smoke/visual verification when targets cannot be met (see the garage‑specific 6%/visual options).
  • When testing is not required: new systems that do not meet the specific criteria for the 6% nonresidential test path must comply with CMC §603.9.2 instead.

If you need the exact step‑by‑step measurement procedure, note that the Energy Code references RA3 and NA7.5.3 for the protocols; the test procedure text itself is in those appendices. The code sections we cited require use of those appendices. If the RA3 or NA7.5.3 procedure text is needed and was not included in the files you provided, say so and I will pull it (if available).

Common mistakes

  • Confusing total leakage vs leakage to outside targets; each limit is a different metric and the code often allows meeting either one. Always confirm which metric the specific subsection calls for.
  • Using the wrong airflow denominator — the code requires air handler airflow determined per RA3 procedures; using nominal equipment capacity or assumed cfm will produce incorrect percent leakage.
  • Failing to run the approved test procedure referenced by the code (RA3 for residential/multifamily, NA7.5.3 for nonresidential) and instead using an ad‑hoc “smoke test” unless the code explicitly allows smoke/visual as the alternate.
  • Not documenting or registering test data where the code requires ECC‑Provider registry or Certificates of Acceptance (multifamily exceptions exist for tall buildings; otherwise the registration/acceptance process must be followed).
  • Assuming the 6% nonresidential target applies to all nonresidential ducts — it applies only to systems that meet the specified criteria in § 120.4(g) (constant‑volume single zone, <5,000 sf served, >25% duct surface outdoors/unconditioned, and not healthcare). Otherwise, follow NA7.5.3 or CMC §603.9.2.

Worked example — concrete scenario

Scenario: a multifamily dwelling unit has a new duct system directly connected to the air handler. The measured air‑handler airflow (per RA3 airflow method) is 1,200 cfm.

Applicable code: § 160.3(b)5K (multifamily new/complete replacement ducts). The dwelling may comply by meeting either the total leakage limit or the leakage‑to‑outside limit.

Calculations:

  • Option A — total leakage limit: 12% of 1,200 cfm = 0.12 × 1,200 = 144 cfm. The measured total duct leakage (all leaks measured under RA3 test) must be ≤ 144 cfm to comply.
  • Option B — leakage‑to‑outside limit: 6% of 1,200 cfm = 72 cfm. If the measured leakage that delivers air to outside is ≤ 72 cfm, that also complies.

If neither target can be reached after sealing efforts, the code provides an alternate in many cases: seal all accessible leaks and verify via a certified ECC‑Rater using the RA3 smoke/visual method (the code allows this where meeting the numeric target is infeasible). Document the method and results per the field‑verification requirements.

Related provisions

  • § 150.0(m) — Residential duct sealing/insulation and references to RA3 for procedures (see related altered‑duct sections in Part 1).
  • § 160.3(b)5K — Multifamily duct sealing and the 12% / 6% leakage options and related exceptions.
  • § 120.4(g) — Nonresidential duct sealing criteria (6% target for qualifying new systems).
  • § 120.5 — Nonresidential acceptance tests and Certificate of Acceptance requirements — links to NA7.5.3.
  • Reference Residential Appendix RA3 — measurement procedures and airflow determination for residential and multifamily testing (RA3.1.4.3.* references in the code). The code requires using RA3 procedures for the cited leakage limits.
  • Reference Nonresidential Appendix NA7.5.3 — acceptance testing procedures for duct leakage in nonresidential systems (used by § 120.4(g) and § 120.5).

Code references

Grounded in the retrieved California Energy Code — click a citation to read the verbatim passage:

  • § 180.2 High relevance — show source text
    TABLE 180.2-C—DUCT INSULATION R-VALUE Col2 Col3
    Climate Zone 3, 5 through 7 1, 2, 4, 8 through 16
    Duct_R-_Value R-6 R-8

    I. Entirely new or complete replacement duct system. If the new ducts form an entirely new or complete replacement duct system directly connected to the air handler, the duct system shall meet one of the following requirements: A. The total leakage of the duct system shall not exceed 12 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1,

    or

    B. The duct system leakage to outside shall not exceed 6 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4. Entirely new or complete replacement duct systems installed as part of an alteration are constructed of at least 75 percent new duct material, and up to 25 percent may consist of reused parts from the dwelling unit's existing duct system, including but not limited to registers, grilles, boots, air handler, coil, plenums and duct material, if the reused parts are accessible and can be sealed to prevent leakage. Entirely new or complete replacement duct systems shall also conform to the requirements of Sections 160.2(a)1 and 160.3(b)5L. If the air handler and ducts are located within a vented attic, the requirements of Section 180.2(b)1Bi shall also be met. II. Extension of an existing duct system. If the new ducts are an extension of an existing duct system serving multifamily dwellings, the combined new and existing duct system shall meet one of the following requirements: A. The measured duct leakage shall be equal to or less than 15 percent of air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or B. The measured duct leakage to outside shall be equal to or less than 10 percent of air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or

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    C. If it is not possible to meet the duct sealing requirements of either Section 180.2(b)2AiicI or II then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5.

    Exception to Section 180.2(b)2AiiaII: duct sealing. Existing duct systems that are extended, which are constructed, insulated or sealed with asbestos. Exception 1 to 180.2(b)2Aii: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. iii. **Altered space-conditioning system—duct sealing.

  • § 0.65 High relevance — show source text

    Duct leakage tests shall be performed by a technician certified by the Associated Air Balance Council (AABC), the National Environmental Balancing Bureau (NEBB), the Testing, Adjusting and Balancing Bureau (TABB), or other equivalent approved agencies. Representative sections totaling not less than 10 percent of the total installed duct area shall be tested. Where the tested 10 percent fail to comply with the requirements of this section, then 40 percent of the total installed duct area shall be tested. Where the tested 40 percent fail to comply with the requirements of this section, then 100 percent of the total installed duct area shall be tested. Sections shall be selected by the building owner or designated representative of the building owner. Positive pressure leakage testing shall be permitted for negative pressure ductwork. The permitted duct leakage shall be not more than the following:

    Lmax = CLP [0.65 ] (Equation 603.9.2)

    Where:

    Lmax = maximum permitted leakage, (ft [3] /min)/100 square feet [0.0001 (m [3] /s)/m [2] ] duct surface

    area.

    CL = six, duct leakage class, (ft [3] /min)/100 square feet [0.0001 (m [3] /s)/m [2] ] duct surface area at 1 inch water column (0.2 kPa).

    P = test pressure, which shall be equal to the design duct pressure class rating, inch water column (kPa).

    Exception: Transfer air duct operating at less than 1 inch of water column (0.25 kPa). 603.9.2.1 Duct Leakage Tests for Buildings that Meet Air Distribution System Duct Leak- age Sealing Criteria in Title 24, Part 6. For duct leakage testing, see California Energy Code Sec- tions 150.0(m)(11) for single family buildings, Sec- tion 160.3(b) for multifamily buildings, and Section 120.4(g) for nonresidential and Hotel Motel build- ings. 603.10 Cross Contamination. Exhaust ducts that convey Class 4 air shall be negatively pressurized relative to ducts, plenums, or occupiable spaces through which the ducts pass. Exhaust ducts under positive pressure that convey Class 2 or Class 3 air shall not extend into or pass through ducts, plenums, or occupiable spaces other than the space from which the exhaust air is drawn.

    603.11 Underground Installation. Ducts installed underground shall be approved for the installation and shall have a slope of not less than [1] ⁄ 8 inch per foot (10.4 mm/m) back to the main riser. Ducts, plenums, and fittings shall be permitted to be constructed of concrete, clay, or ceramics where installed in the ground or in a concrete slab, provided the joints are sealed and duct is secured in accordance with SMACNA

    HVAC Duct Construction Standards – Metal and Flexible.

    Metal ducts where installed in or under a concrete slab shall be encased in not less than 2 inches (51 mm) of concrete, secured in accordance with SMACNA HVAC Duct Con struction Standards – Metal and Flexible.

  • § 1.4.2. High relevance — show source text

    K. Duct system sealing and leakage testing. When space-conditioning systems utilize forced air duct systems to supply conditioned air to an individual dwelling unit, the ducts shall be sealed, as confirmed through field verification and diagnostic testing, in accordance with all applicable procedures specified in Reference Residential Appendix RA3.1. Air handler airflow for calculation of duct leakage rate compliance targets shall be determined according to methods specified in Reference Residential Appendix RA3.1.4.2. For multifamily dwellings with the air-handling unit installed and the ducts connected directly to the air handler, regardless of duct system location: i. The total leakage of the duct system shall not exceed 12 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or ii. The duct system leakage to outside shall not exceed 6 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4.

    • Exception 1 to Section 160.3(b)5K: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four

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    habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. Exception 2 to Section 160.3(b)5K: Multifamily dwelling units in buildings four habitable stories and greater in Climate Zones 1, 3, 5 and 7. L. System airflow rate and fan efficacy. Space-conditioning systems that utilize forced air ducts to supply cooling to an individual dwelling unit shall: i. Static pressure probe. Have a hole for the placement of a static pressure probe (HSPP), or a permanently installed static pressure probe (PSPP) in the supply plenum downstream of the air conditioning evaporator coil. The size, location and labeling of the HSPP or PSPP shall conform to the requirements specified in Reference Residential Appendix RA3.3.1.1 as confirmed by field verification and diagnostic testing; and Exception to Section 160.3(b)5Li: Systems that cannot conform to the specifications for hole location in Reference Residential Appendix Figure RA3.3-1 shall not be required to provide holes as described in Figure RA3.3-1.

    ii. Single zone central forced air systems. Demonstrate, in every control mode, airflow greater than or equal to 350 cfm per ton of nominal cooling capacity through the return grilles, and an air-handling unit fan efficacy less than or equal to the maximum W/cfm specified in Subsection a or b below. The airflow rate and fan efficacy requirements in this section shall be confirmed by field verification and diagnostic testing in accordance with the procedures given in Reference Residential Appendix RA3.3. a. 0.45 W/cfm for gas furnace air-handling units. b. 0.58 W/cfm for air-handling units that are not gas furnaces. Exception 1 to Section 160.3(b)5Lii: Standard ducted systems without zoning dampers may comply by meeting the applicable requirements in Table 160.3-A or 160.3-B as confirmed by field verification and diagnostic testing in accordance with the procedures in Reference Residential Appendix Sections RA3.1.4.4 and RA3.1.4.5.

  • § 1.4.3.1 High relevance — show source text

    a. The measured duct leakage shall be equal to or less than 15 percent of air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or b. The measured duct leakage to outside shall be equal to or less than 10 percent of air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or c. If it is not possible to meet the duct sealing requirements of either Section 180.2(b)2Aiiia or b, then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5. Exception 1 to Section 180.2(b)2Aiii : duct sealing. Duct systems that are documented to have been previously sealed as confirmed through field verification and diagnostic testing in accordance with procedures in Reference Residential Appendix RA3.1. Exception 2 to Section 180.2(b)2Aiii: duct sealing. Duct systems with less than 40 linear feet as determined by visual inspection. Exception 3 to Section 180.2(b)2Aiii: duct sealing. Existing duct systems constructed, insulated or sealed with asbestos.

    Exception 4 to Section 180.2(b)2Aiii: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. iv. Altered space-conditioning system mechanical cooling. When a space-conditioning system is an air conditioner or heat pump that is altered by the installation or replacement of refrigerant-containing system components such as the compressor, condensing coil, evaporator coil, refrigerant metering device or refrigerant piping, the altered system shall comply with the following requirements: a. All thermostats associated with the system shall be replaced with setback thermostats meeting the requirements of Section 110.2(c). b. In Climate Zones 2 and 8 through 15, air-cooled air conditioners and air-source heat pumps, including but not limited to ducted split systems, ducted package systems, small duct high velocity air systems, and minisplit systems, shall comply with Subsections I and II, unless the system is of a type that cannot be verified using the specified procedures. Systems that cannot comply with the requirements of Section 180.2(b)2Aivb shall comply with Section 180.2(b)2Aivc. Exception to Section 180.2(b)2Aivb: Entirely new or complete replacement packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify that the packaged system was pre-charged at the factory and has not been altered in a way that would affect the charge. Ducted systems shall comply with the minimum system airflow rate requirement in Section 180.2(b)2AivbI, provided that the system is of a type that can be verified using the procedure specified in RA3.3 or an approved alternative in RA1. I. The minimum system airflow rate shall comply with the applicable Subsection A or B below as confirmed through field verification and diagnostic testing in accordance with the procedures specified in Reference Residential Appendix Section RA3.3 or an approved alternative procedure as specified in Section RA1.

  • § 180.2 High relevance — show source text

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    C. If it is not possible to meet the duct sealing requirements of either Section 180.2(b)2AiicI or II then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5.

    Exception to Section 180.2(b)2AiiaII: duct sealing. Existing duct systems that are extended, which are constructed, insulated or sealed with asbestos. Exception 1 to 180.2(b)2Aii: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. iii. Altered space-conditioning system—duct sealing. In all climate zones, when a space-conditioning system serving a multifamily dwelling is altered by the installation or replacement of space-conditioning system equipment, including replacement of the air handler, outdoor condensing unit of a split system air conditioner or heat pump, or cooling or heating coil, the duct system that is connected to the altered space-conditioning system equipment shall be sealed, as confirmed through field verification and diagnostic testing in accordance with the applicable procedures for duct sealing of altered existing duct systems as specified in Reference Residential Appendix RA3.1 and the leakage compliance criteria specified in Subsection a, b or c below. a. The measured duct leakage shall be equal to or less than 15 percent of air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or b. The measured duct leakage to outside shall be equal to or less than 10 percent of air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or c. If it is not possible to meet the duct sealing requirements of either Section 180.2(b)2Aiiia or b, then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5. Exception 1 to Section 180.2(b)2Aiii : duct sealing. Duct systems that are documented to have been previously sealed as confirmed through field verification and diagnostic testing in accordance with procedures in Reference Residential Appendix RA3.1. Exception 2 to Section 180.2(b)2Aiii: duct sealing. Duct systems with less than 40 linear feet as determined by visual inspection. Exception 3 to Section 180.2(b)2Aiii: duct sealing. Existing duct systems constructed, insulated or sealed with asbestos.

    Exception 4 to Section 180.2(b)2Aiii: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. iv. **Altered space-conditioning system mechanical cooling.

  • § 150.2 High relevance — show source text

    Additionally, when altered ducts, air-handling units, cooling or heating coils, or plenums are located in garage spaces, the system shall comply with Section 150.2(b)1Diic regardless of the length of any new or replacement space-conditioning ducts installed in the garage space. i. The measured duct leakage shall be equal to or less than 10 percent of system air handler airflow as determined utilizing the procedures in Reference Residential Appendix RA3.1.4.3.1; or ii. The measured duct leakage to outside shall be equal to or less than 7 percent of system air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or iii. If it is not possible to meet the duct sealing requirements of either Section 150.2(b)1Ei or 150.2(b)1Eii, then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECCRater utilizing the methods specified in Reference Residential Appendix Section RA3.1.4.3.5. Exception 1 to Section 150.2(b)1E: Duct sealing. Duct systems that are documented to have been previously sealed as confirmed through field verification and diagnostic testing in accordance with procedures in the Reference Residential Appendix RA3.1. Exception 2 to Section 150.2(b)1E: Duct sealing. Duct systems with less than 40 linear feet as determined by visual inspection. Exception 3 to Section 150.2(b)1E: Duct sealing. Existing duct systems constructed, insulated or sealed with asbestos.

    F. Altered space-conditioning system—mechanical cooling. When a space-conditioning system is an air conditioner or heat pump that is altered by the installation or replacement of refrigerant-containing system components such as the compressor, condensing coil, evaporator coil, refrigerant metering device or refrigerant piping, the altered system shall comply with the following requirements: i. All thermostats associated with the system shall be replaced with setback thermostats meeting the requirements of Section 110.2(c).

    ii. Air-cooled air conditioners in Climate Zones 2 and 8 through 15 and air-source heat pumps in all climate zones, including but not limited to ducted split systems, ducted package systems, small duct high-velocity air systems, and minisplit systems shall comply with Subsections a and b, unless the system is of a type that cannot be verified using the specified procedures. Systems that cannot comply with the requirements of Section 150.2(b)1Fii shall comply with Section 150.2(b)1Fiii. Exception to Section 150.2(b)1Fii: Entirely new or complete replacement packaged systems for which the manufacturer has verified correct system refrigerant charge prior to shipment from the factory are not required to have refrigerant charge confirmed through field verification and diagnostic testing. The installer of these packaged systems shall certify on the Certificate of Installation that the packaged

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    system was pre-charged at the factory and has not been altered in a way that would affect the charge.

  • § 180.2 High relevance — show source text

    See FAN SYSTEM, MULTI-ZONE VARIABLE AIR VOLUME (VAV) for the definition of a multi-zone VAV system.|1. See FAN SYSTEM, MULTI-ZONE VARIABLE AIR VOLUME (VAV) for the definition of a multi-zone VAV system.|

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    Exception 1 to Section 180.2(b)2Bi: Section 180.2(b)2Av does not apply to replacement of electric reheat of equivalent or lower capacity electric resistance space heaters, when natural gas is not available. Exception 2 to Section 180.2(b)2Bi: Operable wall or roof openings that have been previously installed without interlock controls are exempt from complying with Section 170.2(c)4L. Exception 3 to Section 180.2(b)2Bi: Section 170.2(c)4Ci is not applicable to systems that meet both of the following:

    1. The system is not a single package air-cooled commercial unitary air conditioner or heat pump; and
    2. The cooling capacity of the system is less than 54,000 Btu/h. ii. Altered duct systems. When new or replacement space-conditioning system ducts are installed to serve an existing building, the new ducts shall meet the requirements of Section 160.3(c)2 and meet a or b below:

    a. Reserved.

    b. Entirely new or replacement duct systems installed as part of an alteration shall be leakage-tested in accordance with Section 160.2(c)2H. Entirely new or replacement duct systems installed as part of an alteration shall be constructed of at least 75 percent new duct material, and up to 25 percent may consist of reused parts from the building's existing duct system, including registers, grilles, boots, air handlers, coils, plenums and ducts, if the reused parts are accessible and can be sealed to prevent leakage. Exception 1 to Section 180.2(b)2Biib: When it is not possible to achieve the duct leakage criteria in Section 180.2(b)2Biib, all accessible leaks shall be sealed and verified through a visual inspection and a smoke test performed by a certified mechanical acceptance test technician utilizing the methods specified in Reference Nonresidential Appendix NA7.5.3 Exception 2 to Section 180.2(b)2Biib: Duct sealing. Existing duct systems that are extended, which are constructed, insulated or sealed with asbestos, are not required to comply with Subsection 180.2(b)2Biib. c. If the new ducts are an extension of an existing duct system, the combined new and existing duct system meets the criteria in Subsections I, II and III below. The duct system shall be sealed to a leakage rate not to exceed 15 percent of the nominal air handler airflow rate as confirmed through acceptance testing, in accordance with Reference Nonresidential Appendix NA7.5.3: I. The duct system provides conditioned air to an occupiable space for a constant volume, single zone, space-conditioning system; and II. The space-conditioning system serves less than 5,000 square feet of conditioned floor area; and III. The combined surface area of the ducts located in the following spaces is more than 25 percent of the total surface area of the entire duct system:

    A. Outdoors;

  • § 150.2 High relevance — show source text

    Exception to Section 150.2(b)1Diib: Duct sealing. Existing duct systems that are extended, which are constructed, insulated or sealed with asbestos.

    c. Altered ducts and duct system components in garage spaces. When new or replacement space-conditioning ducts, air-handling units, cooling or heating coils, or plenums are located in a garage space, compliance with either I or II below is required. I. The measured system duct leakage shall be less than or equal to 6 percent of system air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or II. All accessible leaks located in the garage space shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5. E. Altered space-conditioning system—duct sealing. In all climate zones, when a space-conditioning system serving a single-family dwelling is altered by the installation or replacement of space-conditioning system equipment, including replacement of the air handler, outdoor condensing unit of a split system air conditioner or heat pump, or cooling or heating coil, the duct system that is connected to the altered space-conditioning system equipment shall be sealed, as confirmed through field verification and diagnostic testing in accordance with the applicable procedures for duct sealing of altered existing duct systems as specified in Reference Residential Appendix RA3.1, and the leakage compliance criteria specified in Subsection i, ii, or iii below. Additionally, when altered ducts, air-handling units, cooling or heating coils, or plenums are located in garage spaces, the system shall comply with Section 150.2(b)1Diic regardless of the length of any new or replacement space-conditioning ducts installed in the garage space. i. The measured duct leakage shall be equal to or less than 10 percent of system air handler airflow as determined utilizing the procedures in Reference Residential Appendix RA3.1.4.3.1; or ii. The measured duct leakage to outside shall be equal to or less than 7 percent of system air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or iii. If it is not possible to meet the duct sealing requirements of either Section 150.2(b)1Ei or 150.2(b)1Eii, then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECCRater utilizing the methods specified in Reference Residential Appendix Section RA3.1.4.3.5. Exception 1 to Section 150.2(b)1E: Duct sealing. Duct systems that are documented to have been previously sealed as confirmed through field verification and diagnostic testing in accordance with procedures in the Reference Residential Appendix RA3.1. Exception 2 to Section 150.2(b)1E: Duct sealing. Duct systems with less than 40 linear feet as determined by visual inspection. Exception 3 to Section 150.2(b)1E: Duct sealing. Existing duct systems constructed, insulated or sealed with asbestos.

  • § 150.2 High relevance — show source text

    D. Altered duct systems—duct sealing. In all climate zones, when more than 25 feet of new or replacement spaceconditioning system ducts are installed, the ducts shall comply with the applicable requirements of Subsections i and ii below. Additionally, when altered ducts, air-handling units, cooling or heating coils, or plenums are located in garage spaces, the system shall comply with Subsection 150.2(b)1Diic regardless of the length of any new or replacement space-conditioning ducts installed in the garage space. i. New ducts located in unconditioned space shall meet the applicable requirements of Sections 150.0(m)1 through 150.0(m)10, and the duct insulation requirements of Table 150.2-D; and

    TABLE 150.2-D—DUCT INSULATION R-VALUE Col2 Col3
    Climate Zone 3, 5 through 7 1, 2, 4, 8 through 16
    DuctR-Value R-6 R-8

    ii. The altered duct system, regardless of location, shall be sealed as confirmed through field verification and diagnostic testing in accordance with all applicable procedures for duct sealing of altered existing duct systems as specified in Reference Residential Appendix Section RA3.1, utilizing the leakage compliance criteria specified in Subsection a or b below.

    a. Entirely new or complete replacement duct system. If the new ducts form an entirely new or complete replacement duct system directly connected to the air handler, the duct system measured leakage shall be equal to or less than 5 percent of the system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1. Entirely new or complete replacement duct systems installed as part of an alteration is constructed of at least 75 percent new duct material, and up to 25 percent may consist of reused parts from the dwelling unit’s existing duct system, including but not limited to registers, grilles, boots, air handler, coil, plenums, duct material; if the reused parts are accessible and can be sealed to prevent leakage. Entirely new or complete replacement duct systems shall also conform to the requirements of Sections 150.0(m)12 and 150.0(m)13. If the air handler and ducts are located within a vented attic, the requirements of Section 150.2(b)1J shall also be met.

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    SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

    b. Extension of an existing duct system. If the new ducts are an extension of an existing duct system serving single-family dwellings, the combined new and existing duct system shall meet one of the following requirements: I. The measured duct leakage shall be equal to or less than 10 percent of system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or II. The measured duct leakage to outside shall be equal to or less than 7 percent of system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or III.

  • § 150.0 High relevance — show source text

    Entirely new or complete replacement duct systems installed as part of an alteration is constructed of at least 75 percent new duct material, and up to 25 percent may consist of reused parts from the dwelling unit’s existing duct system, including but not limited to registers, grilles, boots, air handler, coil, plenums, duct material; if the reused parts are accessible and can be sealed to prevent leakage. Entirely new or complete replacement duct systems shall also conform to the requirements of Sections 150.0(m)12 and 150.0(m)13. If the air handler and ducts are located within a vented attic, the requirements of Section 150.2(b)1J shall also be met.

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    b. Extension of an existing duct system. If the new ducts are an extension of an existing duct system serving single-family dwellings, the combined new and existing duct system shall meet one of the following requirements: I. The measured duct leakage shall be equal to or less than 10 percent of system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or II. The measured duct leakage to outside shall be equal to or less than 7 percent of system air handler airflow as confirmed by field verification and diagnostic testing utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4; or III. If it is not possible to meet the duct sealing requirements of either Section 150.2(b)1DiibI or 150.2(b)1DiibII, then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5. Exception to Section 150.2(b)1Diib: Duct sealing. Existing duct systems that are extended, which are constructed, insulated or sealed with asbestos.

    c. Altered ducts and duct system components in garage spaces. When new or replacement space-conditioning ducts, air-handling units, cooling or heating coils, or plenums are located in a garage space, compliance with either I or II below is required. I. The measured system duct leakage shall be less than or equal to 6 percent of system air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or II. All accessible leaks located in the garage space shall be sealed and verified through a visual inspection and a smoke test by a certified ECC-Rater utilizing the methods specified in Reference Residential Appendix RA3.1.4.3.5. E. Altered space-conditioning system—duct sealing. In all climate zones, when a space-conditioning system serving a single-family dwelling is altered by the installation or replacement of space-conditioning system equipment, including replacement of the air handler, outdoor condensing unit of a split system air conditioner or heat pump, or cooling or heating coil, the duct system that is connected to the altered space-conditioning system equipment shall be sealed, as confirmed through field verification and diagnostic testing in accordance with the applicable procedures for duct sealing of altered existing duct systems as specified in Reference Residential Appendix RA3.1, and the leakage compliance criteria specified in Subsection i, ii, or iii below.

  • § 160.3 High relevance — show source text

    ii. For duct wrap, installed thickness shall be assumed to be 75 percent (25 percent compression) of nominal thickness.

    iii. For factory-made flexible air ducts, the installed thickness shall be determined by dividing the difference between the actual outside diameter and nominal inside diameter by two. F. Duct labeling. Insulated flexible duct products installed to meet this requirement shall include labels, in maximum intervals of 3 feet, showing the thermal performance R- value for the duct insulation itself (excluding air films, vapor retarder or other duct components), based on the tests in Section 160.3(b)5D and the installed thickness determined by Section 160.3(b)5Eiii. G. Backdraft dampers. All fan systems, regardless of volumetric capacity, that exchange air between the building conditioned space and the outside of the building shall be provided with backdraft or automatic dampers to prevent unintended air leakage through the fan system when the fan system is not operating. H. Gravity ventilation dampers. All gravity ventilating systems that serve conditioned space shall be provided with either automatic or readily accessible, manually operated dampers in all openings to the outside except combustion inlet and outlet air openings and elevator shaft vents. I. Protection of insulation. Insulation shall be protected from damage, including that due to sunlight, moisture, equipment maintenance and wind but not limited to the following: Insulation exposed to weather shall be suitable for outdoor service (e.g., protected by aluminum, sheet metal, painted canvas or plastic cover). Cellular foam insulation shall be protected as above or painted with a coating that is water retardant and provides shielding from solar radiation that can cause degradation of the material. J. Porous inner core flex duct. Flexible ducts having porous inner cores shall have a nonporous layer or air barrier between the inner core and the outer vapor barrier. K. Duct system sealing and leakage testing. When space-conditioning systems utilize forced air duct systems to supply conditioned air to an individual dwelling unit, the ducts shall be sealed, as confirmed through field verification and diagnostic testing, in accordance with all applicable procedures specified in Reference Residential Appendix RA3.1. Air handler airflow for calculation of duct leakage rate compliance targets shall be determined according to methods specified in Reference Residential Appendix RA3.1.4.2. For multifamily dwellings with the air-handling unit installed and the ducts connected directly to the air handler, regardless of duct system location: i. The total leakage of the duct system shall not exceed 12 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.1; or ii. The duct system leakage to outside shall not exceed 6 percent of the air handler airflow as determined utilizing the procedures in Reference Residential Appendix Section RA3.1.4.3.4.

    • Exception 1 to Section 160.3(b)5K: The field verification and ECC-Provider data registry requirements of Reference Residential Appendix RA2 and RA3 are not required for multifamily dwelling units in buildings four

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    habitable stories and greater. The installer shall certify that diagnostic testing was performed in accordance with the applicable procedures. Exception 2 to Section 160.3(b)5K: Multifamily dwelling units in buildings four habitable stories and greater in Climate Zones 1, 3, 5 and 7. L.

  • § 120.4 High relevance — show source text

    The system is not a single package air-cooled commercial unitary air conditioner or heat pump; and 2. The cooling capacity of the system is less than 54,000 Btu/h. D. Altered duct systems. New or replacement space-conditioning system ducts installed to serve an existing building shall meet the requirements of Section 120.4 (a) through (f) and meet i, ii or iii below: i. Entirely new or complete replacement duct systems installed as part of an alteration shall be leakage tested in accordance with Section 120.4(g). This applies to replacement duct systems installed as part of an alteration that are constructed of at least 75 percent new duct material. Up to 25 percent of that alteration may consist of reused parts from the building’s existing duct system (including registers, grilles, boots, air handlers, coils, plenums and ducts) if the reused parts are accessible and can be sealed to prevent leakage. ii. If the new ducts are an extension of an existing duct system and the combined new and existing duct system meets the criteria in Subsections 1, 2, 3 and 4 below, the duct system shall be sealed to a leakage rate not to exceed 15 percent of the nominal air handler airflow rate as confirmed through acceptance testing, in accordance with the applicable procedures in Reference Nonresidential Appendix NA7.5.3:

    1. The duct system does not serve a healthcare facility;
    2. The duct system provides conditioned air to an occupiable space for a constant volume, single zone, space-conditioning system;
    3. The space-conditioning system serves less than 5,000 square feet of conditioned floor area; and
    4. The combined surface area of the ducts located outdoors or in unconditioned space is more than 25 percent of the total surface area of the entire duct system. Exception 1 to Section 141.0(b)2Dii: When it is not possible to achieve the duct leakage criteria in Section 141.0(b)2Dii, then all accessible leaks shall be sealed and verified through a visual inspection and a smoke test performed by a certified mechanical acceptance test technician utilizing the methods specified in Reference Nonresidential Appendix NA7.5.3. Exception 2 to Section 141.0(b)2Dii: Duct sealing. Existing duct systems that are extended, which are constructed insulated or sealed with asbestos are not required to comply with Subsection 141.0(b)2Dii. iii. If new ducts installed as part of an alteration are not required to comply with leakage testing specified by Section 141.0(b)2Di or 141.0(b)2Dii, then the new ducts shall meet the duct leakage testing requirements of CMC Section 603.9.2.

    E. Altered space-conditioning systems. When a space-conditioning system is altered by the installation or replacement of space-conditioning system equipment (including replacement of the air handler, outdoor condensing unit of a split system air conditioner or heat pump, or cooling or heating coil: i. For all altered units where the existing thermostat does not comply with the requirements for demand responsive controls specified in Section 110.12, the existing thermostat shall be replaced with a demand responsive thermostat that complies with Section 110.12. All newly installed space-conditioning systems requiring a thermostat shall be equipped with a demand responsive thermostat that complies with Section 110.12; and ii. The duct system that is connected to the new or replaced space-conditioning system equipment shall be sealed in accordance with Section 141.0(b)2Dii.

Frequently asked questions

Who must perform the duct leakage test?

The code requires field verification and diagnostic testing per RA3 (residential/multifamily) or NA7.5.3 (nonresidential). Tests must be performed by qualified/certified raters or acceptance test technicians as required by the referenced appendices and by the enforcement agency.

Which is stricter: total leakage or leakage‑to‑outside?

Leakage‑to‑outside limits are usually numerically smaller (for many provisions 6% or 7%) and therefore stricter on what may escape outdoors; meeting either the total‑leakage or leakage‑to‑outside option (where both are offered) satisfies the code. Confirm which metric the specific subsection requires.

If we can’t meet the percent target, what then?

When numeric targets are infeasible, many Energy Code subsections permit sealing all accessible leaks and verification via visual inspection and smoke test by a certified rater/technician. This alternate path is explicitly allowed in the cited sections.

Do all nonresidential ducts have to meet 6%?

No. § 120.4(g)'s 6% target applies only to new duct systems that meet all listed criteria (constant‑volume single‑zone, <5,000 ft² served, >25% of duct surface outdoors/unconditioned, not healthcare). Other nonresidential systems follow NA7.5.3 or CMC §603.9.2.

Is duct insulation covered here or only leakage?

Duct insulation requirements are covered elsewhere in the code (e.g., tables such as Table 150.2‑D / 180.2‑C), and the duct‑sealing requirements are separate but often referenced together in altered/new duct rules. See the related insulation tables and sections.

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