The following comments have been submitted:
Comment #1Page Number: 28Paragraph / Figure / Table / Note: 4.2.2(1)Comment Intent: ObjectionComment Type: GeneralComment: For untested systems that meet the requirements for the duct testing exemption DSE = 1.0. For systems that do not meet the requirements for the system then they should equal DSE= 0.70 Proposed Change: For untested forced air distribution systems: That meet the duct testing exemption DSE= 1.0. For duct systems that do not meet the exemption DSE=0.70 For tested f
For untested systems that meet the requirements for the duct testing exemption DSE = 1.0. For systems that do not meet the requirements for the system then they should equal DSE= 0.70
For untested forced air distribution systems: That meet the duct testing exemption DSE= 1.0. For duct systems that do not meet the exemption DSE=0.70
For tested f
Comment #2Page Number: 28Paragraph / Figure / Table / Note: 4.2.2(1)Comment Intent: ObjectionComment Type: GeneralComment: For untested systems that meet the requirements for the duct testing exemption DSE = 1.0. For systems that do not meet the requirements for the system then they should equal DSE= 0.70 Proposed Change: For untested forced air distribution systems: That meet the duct testing exemption DSE= 1.0. For duct systems that do not meet the exemption DSE=0.70 For tested f
Comment #3Page Number: 35Paragraph / Figure / Table / Note: x.2Comment Intent: ObjectionComment Type: TechnicalComment: For untested forced air distribution systems: That meet the duct testing exemption DSE= 1.0. For duct systems that do not meet the exemption DSE=0.70 to match the table above. Proposed Change: If at a pre-drywall stage of construction, the ductwork is visually verified to be 100 percent fully ducted with no building cavities used as supply or return ducts, a DSE of 0.88 1.0 shall be applied to both the heating and cooling system efficiencies.
For untested forced air distribution systems: That meet the duct testing exemption DSE= 1.0. For duct systems that do not meet the exemption DSE=0.70 to match the table above.
If at a pre-drywall stage of construction, the ductwork is visually verified to be 100 percent fully ducted with no building cavities used as supply or return ducts, a DSE of 0.88 1.0 shall be applied to both the heating and cooling system efficiencies.
Comment #4Page Number: 28Paragraph / Figure / Table / Note: x.2Comment Intent: ObjectionComment Type: GeneralComment: The concept of a duct leakage exception is acceptable based on the presuposition that the untested distrobution system would be as good, not applicable, or better than the proposed testing. 2021 IECC R403.3.6 allows duct leaking thresholds up to 8 cfm per 100 square feet so a DSE of .92 should be the applied DSE exemption rate applied to both the heating and cooling system efficiencies [OR] duct leakage exemptions for ducts within the thermal envelope should be disallowed. Proposed Change: If at a pre-drywall stage of construction, the ductwork is visually verified to be 100 percent fully ducted with no building cavities used as supply or return ducts, a DSE of 0.88 0.92 shall be applied to both the heating and cooling system efficiencies.
The concept of a duct leakage exception is acceptable based on the presuposition that the untested distrobution system would be as good, not applicable, or better than the proposed testing. 2021 IECC R403.3.6 allows duct leaking thresholds up to 8 cfm per 100 square feet so a DSE of .92 should be the applied DSE exemption rate applied to both the heating and cooling system efficiencies [OR] duct leakage exemptions for ducts within the thermal envelope should be disallowed.
If at a pre-drywall stage of construction, the ductwork is visually verified to be 100 percent fully ducted with no building cavities used as supply or return ducts, a DSE of 0.88 0.92 shall be applied to both the heating and cooling system efficiencies.
Comment #5Page Number: p28 & p35Paragraph / Figure / Table / Note: Table 4.2.2(1), row "Thermal Distribution Systems"Comment Intent: ObjectionComment Type: TechnicalComment: While I am fine with the intent, there is an internal conflict presented by the new Rated Home distinctions for Untested vs Tested forced air distribution. The imperative "For untested forced air distribution systems: DSE=0.70" contradicts the test-exempt simulation options specified in Note (x) to Table 4.2.2(1). Systems that are exempted from testing are inherently untested. The language conflict can be avoided and greater clarity achieved by tabulating all the options for untested forced-air thermal distribution systems, as follows: Distribution System DSE Untested forced air distribution 0.70 Test Exempt: 100% of Ductwork & AH contained with CSV 0.80 Test Exempt: 100% of Ductwork & AH contained with CSV And, fully ducted with no building cavities used as supply or return ducts 0.88
While I am fine with the intent, there is an internal conflict presented by the new Rated Home distinctions for Untested vs Tested forced air distribution.
The imperative "For untested forced air distribution systems: DSE=0.70" contradicts the test-exempt simulation options specified in Note (x) to Table 4.2.2(1). Systems that are exempted from testing are inherently untested.
The language conflict can be avoided and greater clarity achieved by tabulating all the options for untested forced-air thermal distribution systems, as follows:
Distribution System
DSE
Untested forced air distribution
0.70
Test Exempt:
0.80
0.88