© Copyright CalCERTS, Inc. 2019
Code Cycle: 2016 & 2019 Standards
Reference: RCM 184.108.40.206
Reference: 2019 CalCERTS New Construction Training Manual Chapter 6, Section 3
Using the performance compliance approach, the approved software allows three levels of compliance credit for duct systems installed in conditioned spaces including both directly conditioned and indirectly conditioned spaces.
- Verification of 12 Linear Feet or Less of Duct Located Outside Of Conditioned Space
- Visual Verification of Ducts Located Entirely In Conditioned Space
- Verification of Low Leakage Ducts Located Entirely In Conditioned Space
All three levels of credit require a visual verification by the HERS Rater to confirm that the installed duct system meets compliance criteria detailed in the Reference Appendices. The third credit adds an additional constraint that affects the mandatory duct leakage test criteria. When VLLDCS is triggered, instead of meeting a total duct leakage =5%, the system must pass a duct leakage to outside test =25 CFM.
In the compliance software, if duct location is specified as in conditioned space then the second level of compliance credit, DLCS, will be automatically triggered. In conjunction with duct location specified as in conditioned space, the Energy Consultant may explicitly choose to reduce the level of compliance credit by selection <12 of ducts outside conditioned space or increase the level of credit by selecting verified low leakage ducts in conditioned space.
Reference: RCM 220.127.116.11
- Credit is available if no more than 12 linear feet of supply ducts are outside of conditioned space and the user chooses the high-performance attic (HPA) as explained in Section 18.104.22.168 of the Residential Compliance Manual. The total length includes the air handler and supply plenum which can easily consume more than half of the allowed length. This credit results in a reduction of duct surface area used in the compliance software calculations. This option requires certification by the installer and field verification by a HERS Rater.
- The second alternative applies when 100 percent of the ducts are located in conditioned space and the user chooses high-performance attic (HPA) as explained in Section 22.214.171.124. This credit results in eliminating the conduction losses associated with both the return and supply ducts; however, leakage rates still apply. This option requires field verification of the duct system by means of a visual inspection by a HERS Rater.
- Credit for a high-efficiency duct design is available and requires field verification of duct location, surface area, and R-value compliance option, which are described below. This option requires field verification of the duct design layout drawing(s) by a HERS Rater. Verified duct design, when required, will be included in the HERS Required Verification list on the certificate of compliance (CF-1R). This approach provides energy savings credits for having shorter duct runs, fewer ducts, ducts in beneficial locations of ductwork, and other benefits of a well-designed duct system. This credit is available regardless of whether a high-performance attic (HPA) or ducts in conditioned space (DCS) option is chosen, as explained in Section 126.96.36.199 of the Residential Compliance manual.
The following are applicable excerpts from the Reference Appendices for each credit:
RA188.8.131.52.2 Verification of 12 Linear Feet or Less of Duct Located Outside Of Conditioned Space
A visual inspection shall confirm space conditioning systems with air handlers located outside the conditioned space have 12 linear feet or less of duct located outside the conditioned space including air handler and plenum. If the space conditioning system has more than 12 feet of duct outside of conditioned space, the system does not pass.
RA184.108.40.206.3 Visual Verification of Ducts Located Entirely In Conditioned Space (DLCS)
A visual inspection shall confirm space conditioning duct systems are located entirely in conditioned space. If any part of the space conditioning duct system is outside of conditioned space, the system does not pass.
RA220.127.116.11.8 Verification of Low Leakage Ducts Located Entirely In Conditioned Space (VLLDCS)
A visual inspection shall confirm the duct system location as specified by Section RA18.104.22.168.3. Additionally, d to have less than or equal to 25 cfm leakage to outside when measured as specified by Section RA22.214.171.124.4.