The following comments have been submitted:
Comment #1Page Number: 1-3Paragraph / Figure / Table / Note: Table 4.2.2(1) Specifications for the Energy Rating Reference and Rated HomesComment Intent: ObjectionComment Type: TechnicalComment: It is nonsensical, and a building science failure, to simulate the energy performance of an attached Dwelling-Unit using values obtained from the duct leakage to outside protocol, particularly since the protocol is almost always violated in attached housing (see section 5.2.3 of Std 380-2016, which requires “Any fans that could change the pressure in either the Conditioned Space Volume or any spaces containing ducts or air handlers shall be turned off.”). We know that ducts in apartments are frequently located in the space above the apartment ceiling, and all-too-frequently those spaces lack even visual barriers (let alone air barriers) from adjacent spaces in the building. The pressures in those spaces are routinely impacted by mechanical systems in adjacent units, corridors, and systems shared by multiple dwellings. Those systems can and do skew the results high, or low, rendering the measurement meaningless. In contrast, Total Duct Leakage measurements provide meaningful results, especially if conducted at rough, before the building has multiple mechanical systems running. Furthermore, this draft of Addendum L already contains a methodology (last paragraph of endnote m) for getting reasonably meaningful energy predictions from Total Duct Leakage measurements, by prorating the leakage based the locations of ductwork and air handling equipment. That methodology is the only one that is appropriate for ductwork in attached housing. Proposed Change: Table 4.2.2(1) Specifications for the Energy Rating Reference and Rated Homes Building Component Energy Rating Reference Home Rated Home Thermal distribution systems: Thermal distribution system efficiency (DSE) of 0.80 shall be applied to both the heating and cooling system efficiencies. Forced air distribution systems: appropriate duct leakage to outside tests (m) shall be conducted and documented by an Approved Tester in accordance with requirements of Standard ANSI/RESNET/ICC 380, with the air handler installed, and the energy impacts either calculated through hourly simulation or calculated in accordance with ASHRAE Standard 152 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 (m) When both of the following conditions are met and documented, duct leakage testing is not required. At a rough stage of construction, 100% of the ductwork and air handler shall be visible and visually verified to be contained inside the Conditioned Space Volume. At a final stage of construction, ductwork and the air handler shall be verified to still be contained in the Conditioned Space Volume. At a rough stage of construction, the ductwork shall be visually verified to be 100% fully ducted, with no building cavities used as supply or return ducts. To calculate the energy impacts on the Rated Home, a DSE of 0.88 shall be applied to both the heating and cooling system efficiencies. Alternatively, for Dwellings and Townhouses onlyWhere testing Detached Dwellings, when all of the following conditions are met and documented, total duct leakage testing is permitted to be conducted in lieu of duct leakage to outside testing and half of the measured total leakage shall be assigned duct leakage to outside: ? At a rough stage of construction, 100% of the ductwork and air handler shall be visible and visually verified to be contained inside the Infiltration Volume. At a final stage of construction, ductwork that is visible and the air handler shall be verified to still be contained in the Infiltration Volume. ? At a rough stage of construction, the ductwork shall be visually verified to be 100% fully ducted, with no building cavities used as supply or return ducts. ? At a final stage of construction, if visible ductwork or the air handler is observed outside the Infiltration Volume or ductwork is no longer 100% fully ducted, duct leakage to outside testing is required. ? At either a rough stage of construction or a final stage of construction, airtightness of the duct system shall be tested in accordance with requirements of Standard ANSI/RESNET/ICC 380 Total Duct Leakage Test (Section 4.4.1). The total leakage shall be less than or equal to the greater of: 4 cfm per 100 ft2 of Conditioned Floor Area served by the duct system being tested, or 40 cfm. For duct systems with 3 or more returns, the total leakage shall be less than or equal to the greater of: 6 cfm per 100 ft2 of Conditioned Floor Area served by the duct system being tested, or 60 cfm. ? Airtightness of the Rated Home shall be tested in accordance with requirements of Standard ANSI/RESNET/ICC 380 and shall be less than or equal to 3 ACH50. Alternatively, forWhere testing Attached Dwelling Units, excluding Dwellings and Townhouses, total duct leakage testing, at either rough or final stage of construction, is permitted toshall be conducted in lieu of duct leakage to outside testing and software shall calculate the energy impact of total duct leakage results by counting leakage only from duct surface area that is not in Rated Home Conditioned Space Volume, plus a contribution from the associated air handler if located outside the Rated Home Conditioned Space Volume. When located outside the Rated Home Conditioned Space Volume, the air handler contribution shall be a minimum of 2.5% of the supply airflow, where supply airflow is calculated as 400 cfm per 12,000 Btu/h of output capacity of the heating or cooling equipment; however, the sum shall not exceed the measured duct leakage from the entire duct system.
It is nonsensical, and a building science failure, to simulate the energy performance of an attached Dwelling-Unit using values obtained from the duct leakage to outside protocol, particularly since the protocol is almost always violated in attached housing (see section 5.2.3 of Std 380-2016, which requires “Any fans that could change the pressure in either the Conditioned Space Volume or any spaces containing ducts or air handlers shall be turned off.”).
We know that ducts in apartments are frequently located in the space above the apartment ceiling, and all-too-frequently those spaces lack even visual barriers (let alone air barriers) from adjacent spaces in the building. The pressures in those spaces are routinely impacted by mechanical systems in adjacent units, corridors, and systems shared by multiple dwellings. Those systems can and do skew the results high, or low, rendering the measurement meaningless.
In contrast, Total Duct Leakage measurements provide meaningful results, especially if conducted at rough, before the building has multiple mechanical systems running. Furthermore, this draft of Addendum L already contains a methodology (last paragraph of endnote m) for getting reasonably meaningful energy predictions from Total Duct Leakage measurements, by prorating the leakage based the locations of ductwork and air handling equipment. That methodology is the only one that is appropriate for ductwork in attached housing.
Table 4.2.2(1) Specifications for the Energy Rating Reference and Rated Homes
Building Component
Energy Rating Reference Home
Rated Home
Thermal distribution systems:
Thermal distribution system efficiency (DSE) of 0.80 shall be applied to both the heating and cooling system efficiencies.
Forced air distribution systems: appropriate duct leakage to outside tests (m) shall be conducted and documented by an Approved Tester in accordance with requirements of Standard ANSI/RESNET/ICC 380, with the air handler installed, and the energy impacts either calculated through hourly simulation or calculated in accordance with ASHRAE Standard 152 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
(m) When both of the following conditions are met and documented, duct leakage testing is not required.
To calculate the energy impacts on the Rated Home, a DSE of 0.88 shall be applied to both the heating and cooling system efficiencies.
Alternatively, for Dwellings and Townhouses onlyWhere testing Detached Dwellings, when all of the following conditions are met and documented, total duct leakage testing is permitted to be conducted in lieu of duct leakage to outside testing and half of the measured total leakage shall be assigned duct leakage to outside:
? At a rough stage of construction, 100% of the ductwork and air handler shall be visible and visually verified to be contained inside the Infiltration Volume. At a final stage of construction, ductwork that is visible and the air handler shall be verified to still be contained in the Infiltration Volume.
? At a rough stage of construction, the ductwork shall be visually verified to be 100% fully ducted, with no building cavities used as supply or return ducts.
? At a final stage of construction, if visible ductwork or the air handler is observed outside the Infiltration Volume or ductwork is no longer 100% fully ducted, duct leakage to outside testing is required.
? At either a rough stage of construction or a final stage of construction, airtightness of the duct system shall be tested in accordance with requirements of Standard ANSI/RESNET/ICC 380 Total Duct Leakage Test (Section 4.4.1). The total leakage shall be less than or equal to the greater of: 4 cfm per 100 ft2 of Conditioned Floor Area served by the duct system being tested, or 40 cfm. For duct systems with 3 or more returns, the total leakage shall be less than or equal to the greater of: 6 cfm per 100 ft2 of Conditioned Floor Area served by the duct system being tested, or 60 cfm.
? Airtightness of the Rated Home shall be tested in accordance with requirements of Standard ANSI/RESNET/ICC 380 and shall be less than or equal to 3 ACH50.
Alternatively, forWhere testing Attached Dwelling Units, excluding Dwellings and Townhouses, total duct leakage testing, at either rough or final stage of construction, is permitted toshall be conducted in lieu of duct leakage to outside testing and software shall calculate the energy impact of total duct leakage results by counting leakage only from duct surface area that is not in Rated Home Conditioned Space Volume, plus a contribution from the associated air handler if located outside the Rated Home Conditioned Space Volume. When located outside the Rated Home Conditioned Space Volume, the air handler contribution shall be a minimum of 2.5% of the supply airflow, where supply airflow is calculated as 400 cfm per 12,000 Btu/h of output capacity of the heating or cooling equipment; however, the sum shall not exceed the measured duct leakage from the entire duct system.
Comment #2Page Number: 1Comment Intent: Not an ObjectionComment Type: TechnicalComment: Please pass this exception/ammentment. When all ducts and equipment are inside conditioned space, this test gives useless results. The leakier the duct system is to inside space the better the results seem to be for the leakage to outside test. Do the experiment yourself. Test a system, then un-tape a couple of your supply vents and run the leakage to outside test again. You will get a better result. (that is false.) A leakage to outside test when all ducts are inside conditioned space does not give valid, helpful or reliable information.
Please pass this exception/ammentment.
When all ducts and equipment are inside conditioned space, this test gives useless results. The leakier the duct system is to inside space the better the results seem to be for the leakage to outside test. Do the experiment yourself. Test a system, then un-tape a couple of your supply vents and run the leakage to outside test again. You will get a better result. (that is false.)
A leakage to outside test when all ducts are inside conditioned space does not give valid, helpful or reliable information.
Comment #3Page Number: 3Comment Intent: ObjectionComment Type: TechnicalComment: I don’t understand why ACH50 thresholds are getting outlined within ANSI 301 when they are already clearly defined within IECC R402.4.1.2. I was under the impression that HERS ratings were supposed to be a measure of efficacy and performance not a minimum threshold for performance. The implication here is that all HERS ratings conducted on preexisting homes would require extensive retrofits (many of which might have a poor ROI) in order for the homes to even receive a rating. The imposed ACH50 threshold would be more stringent than 2015 IECC and 2018 IECC in climate zones 1 and 2. Proposed Change: Airtightness of the Rated Home shall be tested in accordance with requirements of Standard ANSI/RESNET/ICC 380 and shall be less than or equal to 3 ACH50.
I don’t understand why ACH50 thresholds are getting outlined within ANSI 301 when they are already clearly defined within IECC R402.4.1.2. I was under the impression that HERS ratings were supposed to be a measure of efficacy and performance not a minimum threshold for performance.
The implication here is that all HERS ratings conducted on preexisting homes would require extensive retrofits (many of which might have a poor ROI) in order for the homes to even receive a rating. The imposed ACH50 threshold would be more stringent than 2015 IECC and 2018 IECC in climate zones 1 and 2.
Airtightness of the Rated Home shall be tested in accordance with requirements of Standard ANSI/RESNET/ICC 380 and shall be less than or equal to 3 ACH50.
Comment #4Page Number: 3Paragraph / Figure / Table / Note: Attached Dwelling UnitsComment Intent: Not an ObjectionComment Type: TechnicalComment: I support this amendment, especially the section that applies to attached dwellings. However, the description for attached dwellings needs to explain how to handle situations where 100% of the ductwork is inside the building envelope for attached dwellings. The amendment says to run a total leakage test and then to only apply the percentage of the leakage equal to the percentage of the duct system outside the envelope to the rating. But if 0% of the ductwork is outside the envelope, you would be multiplying your total duct leakage results by 0. Obviously, there is no reason to run the duct leakage test at all in this circumstance. The standard should come out and say that clearly. Proposed Change: Alternatively, for Attached Dwelling Units, excluding Dwellings and Townhouses, total duct leakage testing, at either rough or final stage of construction, is permitted to be conducted in lieu of duct leakage to outside testing and software shall calculate the energy impact of total duct leakage results by counting leakage only from duct surface area that is not in Rated Home Conditioned Space Volume, plus a contribution from the associated air handler if located outside the Rated Home Conditioned Space Volume. When located outside the Rated Home Conditioned Space Volume, the air handler contribution shall be a minimum of 2.5% of the supply airflow, where supply airflow is calculated as 400 cfm per 12,000 Btu/h of output capacity of the heating or cooling equipment; however, the sum shall not exceed the measured duct leakage from the entire duct system. If 100% of the ductwork and air handler are located inside Rated Home Conditioned Space Volume, duct leakage testing is not required.
I support this amendment, especially the section that applies to attached dwellings. However, the description for attached dwellings needs to explain how to handle situations where 100% of the ductwork is inside the building envelope for attached dwellings. The amendment says to run a total leakage test and then to only apply the percentage of the leakage equal to the percentage of the duct system outside the envelope to the rating. But if 0% of the ductwork is outside the envelope, you would be multiplying your total duct leakage results by 0. Obviously, there is no reason to run the duct leakage test at all in this circumstance. The standard should come out and say that clearly.
Alternatively, for Attached Dwelling Units, excluding Dwellings and Townhouses, total duct leakage testing, at either rough or final stage of construction, is permitted to be conducted in lieu of duct leakage to outside testing and software shall calculate the energy impact of total duct leakage results by counting leakage only from duct surface area that is not in Rated Home Conditioned Space Volume, plus a contribution from the associated air handler if located outside the Rated Home Conditioned Space Volume. When located outside the Rated Home Conditioned Space Volume, the air handler contribution shall be a minimum of 2.5% of the supply airflow, where supply airflow is calculated as 400 cfm per 12,000 Btu/h of output capacity of the heating or cooling equipment; however, the sum shall not exceed the measured duct leakage from the entire duct system.
If 100% of the ductwork and air handler are located inside Rated Home Conditioned Space Volume, duct leakage testing is not required.
Comment #5Page Number: 3Comment Intent: ObjectionComment Type: TechnicalComment: The proposed amendment does not take into effect different ventilation systems that are installed in dwellings. In markets that use HRV’s or ERV’s that are connected to the duct work this proposed amendment does not reflect the energy use of the homes being rated. There are situations where 100% of the ductwork is installed inside the infiltration volume of the home and this can be verified at rough in. Once an HRV or ERV is installed that does not run continuously and does not have mechanical dampers the system now has a direct connection to the outside with two 6-inch openings. Since HRV’s and ERV’s are often connected directly to the ductwork there is now a direct connection to the outside of the home. Here is an example with real test results. The following house was verified at rough in to have all ductwork inside the infiltration volume and was not using stud cavities as ductwork. HRV/ERV Leakage to Outside Results HERS Index Dampers Open 52 51 Dampers Closed “Lo” 50 LTO Exemption 0 50 This above example shows that this proposed amendment will have a minimum of a 1-point swing on the HERS Index and it will not capture the energy penalty for using a ventilation system that does not have dampers. The alternative method proposed is equally problematic. This amendment states that you can use a Total Leakage Test at rough in stage or final stage of the home as an alternative to performing a Leakage to Outside Test. The proposal gives a threshold of 40 cfm or 4 cfm per 100 square feet (whichever is greater). This proposed amendment does not clarify if the air handling and ventilation equipment must be installed at rough in for this test to be completed. Furthermore, if this test is completed at rough in and then an HRV or ERV is installed that does not run continuously or have dampers the rating will be giving false information because the home was not properly tested to capture the true duct leakage. A similar home to the one listed above was tested and the following results were gathered. At the final the Duct Leakage to Outside was tested at 39 cfm. The HRB/ERV did not have dampers and did not run continuously therefore the unit was not sealed. A Total Duct Leakage test was completed on this home and because the ventilation system did not run continuously it was not sealed. The results were 575 cfm of Total Leakage because there were two holes directly connected to the outside. This proposal should not be accepted until the authors show their data and provide vetted testing results showing how this proposal affects all types of mechanical equipment. In addition, RESNET needs to clarify how to address HRV’s and ERV’s that are connected to the distribution system that run intermittently, and do not have dampers if we as an industry are going to accurately perform HERS Ratings. Is an ERV/HRV considered a “continuously” operating ventilation system? I believe this is a point of confusion in the industry.
The proposed amendment does not take into effect different ventilation systems that are installed in dwellings.
In markets that use HRV’s or ERV’s that are connected to the duct work this proposed amendment does not reflect the energy use of the homes being rated. There are situations where 100% of the ductwork is installed inside the infiltration volume of the home and this can be verified at rough in. Once an HRV or ERV is installed that does not run continuously and does not have mechanical dampers the system now has a direct connection to the outside with two 6-inch openings. Since HRV’s and ERV’s are often connected directly to the ductwork there is now a direct connection to the outside of the home.
Here is an example with real test results. The following house was verified at rough in to have all ductwork inside the infiltration volume and was not using stud cavities as ductwork.
HRV/ERV
Leakage to Outside Results
HERS Index
Dampers Open
52
51
Dampers Closed
“Lo”
50
LTO Exemption
0
This above example shows that this proposed amendment will have a minimum of a 1-point swing on the HERS Index and it will not capture the energy penalty for using a ventilation system that does not have dampers.
The alternative method proposed is equally problematic.
This amendment states that you can use a Total Leakage Test at rough in stage or final stage of the home as an alternative to performing a Leakage to Outside Test. The proposal gives a threshold of 40 cfm or 4 cfm per 100 square feet (whichever is greater). This proposed amendment does not clarify if the air handling and ventilation equipment must be installed at rough in for this test to be completed. Furthermore, if this test is completed at rough in and then an HRV or ERV is installed that does not run continuously or have dampers the rating will be giving false information because the home was not properly tested to capture the true duct leakage.
A similar home to the one listed above was tested and the following results were gathered. At the final the Duct Leakage to Outside was tested at 39 cfm. The HRB/ERV did not have dampers and did not run continuously therefore the unit was not sealed. A Total Duct Leakage test was completed on this home and because the ventilation system did not run continuously it was not sealed. The results were 575 cfm of Total Leakage because there were two holes directly connected to the outside.
This proposal should not be accepted until the authors show their data and provide vetted testing results showing how this proposal affects all types of mechanical equipment. In addition, RESNET needs to clarify how to address HRV’s and ERV’s that are connected to the distribution system that run intermittently, and do not have dampers if we as an industry are going to accurately perform HERS Ratings.
Is an ERV/HRV considered a “continuously” operating ventilation system? I believe this is a point of confusion in the industry.
Comment #6Page Number: 3Comment Intent: Not an ObjectionComment Type: TechnicalComment: This comment is being issued on behalf of the Standards Committee of the North East Home Energy Rating Alliance, which represents more than 350 Raters and 11 Providers from New Jersey to Maine. For Attached Dwelling Units, we enthusiastically support the retention of the use of duct leakage to outside (DLTO) testing as an approved testing method, as found in the final paragraph of the proposed Addendum L. While the exception being offered for use of a total duct leakage test in lieu of the DLTO test makes sense in many situations, it is our experience that the DLTO often provides more accurate, if not always more advantageous, information than the calculated alternative. In the case of a duct system with the air handler within the conditioned space volume and duct system primarily located in attic space, the result of a DLTO test may be less than the calculated alternative and, therefore, advantageous. In any case, it is our position that a more accurate method of testing should always be an acceptable alternative to a more expedient option. We respectfully disagree with the author of Comment #1 to this proposed addendum, who has recommended that the language allowing the use of a DLTO test be removed from Addendum L. Proposed Change: None
This comment is being issued on behalf of the Standards Committee of the North East Home Energy Rating Alliance, which represents more than 350 Raters and 11 Providers from New Jersey to Maine.
For Attached Dwelling Units, we enthusiastically support the retention of the use of duct leakage to outside (DLTO) testing as an approved testing method, as found in the final paragraph of the proposed Addendum L. While the exception being offered for use of a total duct leakage test in lieu of the DLTO test makes sense in many situations, it is our experience that the DLTO often provides more accurate, if not always more advantageous, information than the calculated alternative.
In the case of a duct system with the air handler within the conditioned space volume and duct system primarily located in attic space, the result of a DLTO test may be less than the calculated alternative and, therefore, advantageous.
In any case, it is our position that a more accurate method of testing should always be an acceptable alternative to a more expedient option.
We respectfully disagree with the author of Comment #1 to this proposed addendum, who has recommended that the language allowing the use of a DLTO test be removed from Addendum L.
None