As the energy code requirements for California become more stringent, developers are finding a need for additional compliance credits to meet code. One in particular that can be misunderstood is the compliance credit for “Low Leakage Air Handlers”. This is a voluntary credit that can be chosen within a Title 24 low-rise residential energy model in order to increase the projected performance of your building. This credit implies that the air handler(s) for that building will have very low air leakage and will be rated as such by the California Energy Commission (CEC). Oftentimes a manufacturer will offer their own specifications that can be mistaken for a true certification. However, it should be noted that only a CEC approved “Low Leakage Air Handler” will meet the requirements for this compliance measure. The unit must be 3rd party tested and the manufacturer must submit the proper documentation to the CEC for approval and certification as a “Low Leakage Air Handler”. A manufacturer is not permitted to certify their own equipment (without CEC approval) to comply with this measure. Specifics on this certification and procedure can be found by referencing the sections outlined below. In addition, there is a list of approved “Low Leakage Air Handlers” on the CEC website that can be referenced. This list contains all the approved air handlers to comply with this measure:
From the California Energy Commission:
“To qualify as a low leakage air-handling unit for use for compliance with applicable performance compliance credits, the air-handling unit shall be certified to the Energy Commission according to the requirements contained in Joint Appendices 9.2.1, 9.2.2, 9.2.3, and 9.2.4”
- JA9.2.1: The air-handling unit shall be tested in accordance with the requirements given in ASHRAE Standard 193.
- JA9.2.2: The Air-Handling Unit shall be tested in a laboratory that has demonstrated compliance with ISO Standard 17025, General Criteria for the Competence of Testing and Calibration Laboratories, and is accredited for the ASHRAE Standard 193 test methods. The accreditation body shall be a signatory to the International Laboratory Accreditation Cooperation Mutual Recognition Arrangement (ILAC MRA)
- JA9.2.3: The nominal air-handling unit airflow used for determining the leakage criterion for qualification shall be as follows:
- (a) For heating-only systems the nominal air-handling unit airflow shall be 21.7 cfm per kBtu/hr of rated heating output capacity.
- (b) For systems that provide space cooling, the nominal air-handling unit airflow shall be 400 cfm per nominal ton of cooling capacity as specified by the manufacturer, or the heating-only value, whichever is greater.
- JA.2.4: Allowable leakage for qualification as a Low Leakage Air-Handling Unit shall be equal to or less than 1.4 percent of the nominal air-handling unit airflow determined by Section JA9.2.3.
All certifying manufacturers must submit a declaration statement for each air handler to be certified. Notes contained within this statement are as follows:
- For AHU Types, please use the following codes (F) Furnace, (FC) Fan-Coil Unit, (HP) Heat Pump, (AC) Air Conditioner.
- Nominal AHU Airflow Rate (cfm) for heating is based on 21.7 cfm per kBtu/hr of rated heating output capacity and for cooling is based on 400 cfm per nominal ton of cooling capacity.
- Certified AHU Leakage Rate (cfm) when pressurized to 125 Pa (0.5 inches of water).
- Certified Leakage Rate expressed as % of Nominal AHU Airflow Rate.
Much like other compliance credits in Title 24 energy models, the “Low Leakage Air Handler” credit is not one to be taken lightly. The air handler in question must meet the above criteria in order to be utilized for extra compliance credits. Otherwise, your project may have significant delays if the energy models need to be recalculated mid-construction (or worse: towards the end of construction). It is always important to ensure that the compliance credits selected in the energy model are appropriate for the project.
For more information on how to correctly identify required HERS measures and Title 24 energy compliance credits, contact VCA Green below.
Contributing Writer: Chris Halamandaris, HERS Energy Rater
Moe Fakih, Principal