The following comments have been submitted:
Comment #1Page Number: 1Comment Intent: ObjectionComment Type: GeneralComment: The RESNET Board of Directors has repeatedly affirmed a desire for software consistency, to the point of establishing a Software Consistency Task Force that reports to the Board of Directors (apparently). This proposed amendment does exactly the opposite of improving consistency by allowing software developers to use non-standard equations to calculate duct efficiencies. Since the Board adopted a policy that NO standards would be developed contrary to the Board's clearly stated position, this proposed draft standard should never have seen the light of day as it clearly has the effect of decreasing consistency between software tools. I urge the Committee to reject this proposed draft standard in its entirety and re-affirm the Board's position on software consistency. Proposed Change: Thermal distribution systems: Thermal distribution system efficiency (DSE) of 0.80 shall be applied to both the heating and cooling system efficiencies. For forced air distribution systems: Tested in accordance with requirements of Standard ANSI/RESNET/ICC 380-2016 or equivalent (m) and then either calculated through hourly simulation or calculated in accordance with ASHRAE Standard 152-2004 and calculated with the ducts located and insulated as in the Rated Home. For ductless distribution systems: DSE=1.00 For hydronic distribution systems: DSE=1.00
I urge the Committee to reject this proposed draft standard in its entirety and re-affirm the Board's position on software consistency.
Thermal distribution systems:
Thermal distribution system efficiency (DSE) of 0.80 shall be applied to both the heating and cooling system efficiencies.
For forced air distribution systems: Tested in accordance with requirements of Standard ANSI/RESNET/ICC 380-2016 or equivalent (m) and then either calculated through hourly simulation or calculated in accordance with ASHRAE Standard 152-2004 and calculated with the ducts located and insulated as in the Rated Home.
For ductless distribution systems: DSE=1.00
For hydronic distribution systems: DSE=1.00
Comment #2Page Number: 1Comment Intent: ObjectionComment Type: TechnicalComment: This proposal is 100% in contradiction to the RESNET Board of Directors efforts to make HERS ratings more consistent. For nearly 5 years now, the RESNET BOD has created policies and established working groups and task forces to ensure that policies are making the delta of difference in a HERS rating from software to software, and rater to rater more consistent. Yet this proposed amendement seeks to do the exact opposite ... by no longer requiring a specific calculation methodology that all rating software must follow, it undermines consistency by creating absolutley no rules or accountability for how software shall produce DSE. Either this amendment should be struck down, or the SDC 300 should be required to present an alternative consistent protocol. I think it would be unwise for RESNET to try to recreate the wheel, and as such recommend you simply leave it as is. Proposed Change: Thermal distribution systems: Thermal distribution system efficiency (DSE) of 0.80 shall be applied to both the heating and cooling system efficiencies. For forced air distribution systems: Tested in accordance with requirements of Standard ANSI/RESNET/ICC 380-2016 or equivalent (m) and then either calculated through hourly simulation or calculated in accordance with ASHRAE Standard 152-2004 and calculated with the ducts located and insulated as in the Rated Home. For ductless distribution systems: DSE=1.00 For hydronic distribution systems: DSE=1.00
This proposal is 100% in contradiction to the RESNET Board of Directors efforts to make HERS ratings more consistent. For nearly 5 years now, the RESNET BOD has created policies and established working groups and task forces to ensure that policies are making the delta of difference in a HERS rating from software to software, and rater to rater more consistent. Yet this proposed amendement seeks to do the exact opposite ... by no longer requiring a specific calculation methodology that all rating software must follow, it undermines consistency by creating absolutley no rules or accountability for how software shall produce DSE.
Either this amendment should be struck down, or the SDC 300 should be required to present an alternative consistent protocol. I think it would be unwise for RESNET to try to recreate the wheel, and as such recommend you simply leave it as is.
For forced air distribution systems: Tested in accordance with requirements of Standard ANSI/RESNET/ICC 380-2016 or equivalent (m)
and then either calculated through hourly simulation or calculated in accordance with ASHRAE Standard 152-2004 and calculated with the ducts located and insulated as in the Rated Home.
Comment #3Page Number: 1Comment Intent: ObjectionComment Type: GeneralComment: Industry stakeholders have repeatedly identified major inconsistencies between HERS Rating software that through rigorous investigation can be directly attributed to Thermal Distribution System efficiency calculation differences between software tools. These cases can result in 5-10 HERS Index pt differences for typical new production homes, or up to 30 pts for low efficiency retrofit projects. In these identified cases, one software tool was not following ANSI 301 by not using ASHRAE Standard 152 or an hourly simulation. If this amendment passes, the inconsistency will remain. If the amendment does not pass, consistency will be greatly increased. The RESNET Board and RESNET Staff have consistently and unequivocally stressed the importance of increasing consistency of calculations of HERS Rating software. A recent BOD Policy installed a Software Consistency Committee as a permanent committee of the Board with a primary goal of improving software consistency. Allowing this amendment to pass and thereby allowing this inconsistency to remain is clearly incongruous with the stated BOD position, and it is against RESNET policy to pass an amendment opposing the BOD’s position. ASHRAE 152 is not necessarily the "truth", and in fact there is no definitive truth in energy modeling. It is conceivable that software tools might be able to develop a more accurate duct efficiency algorithm without using ASHRAE 152 (I can't say whether it is the case today, but it is conceivable). However, ASHRAE 152 is a well-vetted industry standard developed by experts, approved by ASHRAE, and it is consistently reproduce-able. RESNET's duct efficiency test boundaries are based around ASHRAE 152, but they are sufficiently wide that many algorithms could pass, and they are sufficiently limited in scope that many bad algorithms could pass. There are no tests for edge cases, various locations, radiant barriers, very high leakage, etc. As a result, we see the inconsistencies identified in point # 1. Proposed Change: Thermal distribution systems: Thermal distribution system efficiency (DSE) of 0.80 shall be applied to both the heating and cooling system efficiencies. For forced air distribution systems: Tested in accordance with requirements of Standard ANSI/RESNET/ICC 380-2016 or equivalent (m) and then either calculated through hourly simulation or calculated in accordance with ASHRAE Standard 152-2004 and calculated with the ducts located and insulated as in the Rated Home. For ductless distribution systems: DSE=1.00 For hydronic distribution systems: DSE=1.00
Industry stakeholders have repeatedly identified major inconsistencies between HERS Rating software that through rigorous investigation can be directly attributed to Thermal Distribution System efficiency calculation differences between software tools. These cases can result in 5-10 HERS Index pt differences for typical new production homes, or up to 30 pts for low efficiency retrofit projects. In these identified cases, one software tool was not following ANSI 301 by not using ASHRAE Standard 152 or an hourly simulation.
If this amendment passes, the inconsistency will remain. If the amendment does not pass, consistency will be greatly increased.
The RESNET Board and RESNET Staff have consistently and unequivocally stressed the importance of increasing consistency of calculations of HERS Rating software. A recent BOD Policy installed a Software Consistency Committee as a permanent committee of the Board with a primary goal of improving software consistency. Allowing this amendment to pass and thereby allowing this inconsistency to remain is clearly incongruous with the stated BOD position, and it is against RESNET policy to pass an amendment opposing the BOD’s position.
ASHRAE 152 is not necessarily the "truth", and in fact there is no definitive truth in energy modeling. It is conceivable that software tools might be able to develop a more accurate duct efficiency algorithm without using ASHRAE 152 (I can't say whether it is the case today, but it is conceivable). However, ASHRAE 152 is a well-vetted industry standard developed by experts, approved by ASHRAE, and it is consistently reproduce-able. RESNET's duct efficiency test boundaries are based around ASHRAE 152, but they are sufficiently wide that many algorithms could pass, and they are sufficiently limited in scope that many bad algorithms could pass. There are no tests for edge cases, various locations, radiant barriers, very high leakage, etc. As a result, we see the inconsistencies identified in point # 1.