Comment #1Amendment: Proposed MINHERS Addendum 47f, Test Exception for Ducts in Conditioned Space, Draft PDS-01Page Number: 2Paragraph / Figure / Table / Note: Exception 5Comment Intent: ObjectionComment Type: TechnicalComment: This topic has been an ongoing frustration for raters in my area. It has been unclear when duct testing has been required so I appreciate this effort to straghten this out but.... I test many single story ranch homes with basements, 100% of the ducts are inside. Supply ducts come up under the floor from the basement (100% visible) and return ducts using interior wall cavities (nothing inside the exterior walls, be they hard-ducted or not). In these homes, EVERY TIME, the LTO test reads at or near zero duct leakage. When we do this test it takes time and materials and we have to charge the buidler to do this. Not only that, we have to explain to the builder why we are doing this test that provides NO BENEFIT to them - they understand that ducts completely inside a tight envelope can't leak to the outside. I appreciate that we can use an exemption, however I question the ".88 duct efficiency" penalty. How was this number arrived at? I have asked people for years in the "business" where this number comes from and what research was used to come up with it, but I have not heard anything. How can this one number be justifiyably applied to the many diverse types of houses that are out there? Is it possible to come up with an appropriate duct efficiency penalty for the various types of houses based on it's construction type and included features? Also, I was wondering about the language that was dropped which required hard-panning ducts throughout the house. Where is the data that shows how much more efficient a duct system done this way performs? Does the house perform measurably worse if it is done with panning but completely inside the conditioned space? In our Wisconsin New Homes program, we are required to do an LTO test if there is any ductwork "outside of conditioned space", which makes total sense and is good for us to do. Infact, I advise builders to "design out" any exterior ducts and bring them inside if possible so as to avoid performance issues as well as to keep their costs down. This is an easier sell when my bill to them will also be lower as I'm not charging them for the LTO test. Builders are smart and they like what we do but once they start to think we are pushing unnecesary and expensive "pumpkin-head" requirements, we stand a good chance of loosing them (our program is volunatry and a rating is not required in our state for code compliance) Proposed Change: I don't really know how I'd change the language based on what I wrote above.
I don't really know how I'd change the language based on what I wrote above.
Comment #2Amendment: Proposed MINHERS Addendum 47f, Test Exception for Ducts in Conditioned Space, Draft PDS-01Page Number: 2Paragraph / Figure / Table / Note: Exception 5Comment Intent: ObjectionComment Type: TechnicalComment: It is not clear why a penalty would need to be applied to heating and cooling getting delivered to conditioned space. To take this a step further, there are several published articles that suggest having cooling, either directly or through distribution losses, or some means of dehumidification in the encapsulated conditioned attic space is actually beneficial to decrease humidity and prevent moisture issues (microbial or otherwise). Its difficult to understand the line of thinking to penalize leakage within a conditioned space, especially if the science points to benefits in directly cooling the space altogether. Separately, please provide the studies and support for the DSE of .88 to validate the penalty. https://www.buildingscience.com/documents/reports/rr-9801-vented-and-sealed-attics-in-hot-climates/view https://www.buildingscience.com/documents/reports/rr-9701-measurement-of-attic-temperatures-and-cooling-energy-use-in-vented-and-sealed-attics-in-las-vegas-nevada/view Proposed Change: To calculate the energy impacts on the Rated Home, a DSE of 0.88 shall not be applied to both either the heating and or cooling system efficiencies.
It is not clear why a penalty would need to be applied to heating and cooling getting delivered to conditioned space. To take this a step further, there are several published articles that suggest having cooling, either directly or through distribution losses, or some means of dehumidification in the encapsulated conditioned attic space is actually beneficial to decrease humidity and prevent moisture issues (microbial or otherwise). Its difficult to understand the line of thinking to penalize leakage within a conditioned space, especially if the science points to benefits in directly cooling the space altogether. Separately, please provide the studies and support for the DSE of .88 to validate the penalty.
https://www.buildingscience.com/documents/reports/rr-9801-vented-and-sealed-attics-in-hot-climates/view
https://www.buildingscience.com/documents/reports/rr-9701-measurement-of-attic-temperatures-and-cooling-energy-use-in-vented-and-sealed-attics-in-las-vegas-nevada/view
To calculate the energy impacts on the Rated Home, a DSE of 0.88 shall not be applied to both either the heating and or cooling system efficiencies.
Comment #3Amendment: Proposed MINHERS Addendum 47f, Test Exception for Ducts in Conditioned Space, Draft PDS-01Page Number: 2Paragraph / Figure / Table / Note: Section 5Comment Intent: ObjectionComment Type: TechnicalComment: If all the ductwork is inside condition space where do you come up with a .88 efficiency to the heating and cooling distribution and equipment. Was there any studies done to come up with this number. After doing hundreds of duct blaster tests I can’t believe there’s that much leakage when all the ductwork is inside condition space. Imposing the .88 efficiency to the equipment seems very high. How do I explained to the builder I need to test the ductwork for leakage to outside when they’re all inside a condition basement and if I don’t the house will be imposed a .88 efficiency to the equipment. Proposed Change: Exception 5: RESNET Home Energy Ratings shall comply with the requirements of ANSI/RESNET/ICC 301and its Addenda except that Ratings on homes with a building permit date, or alternate pursuant to Addendum 43, prior to January 1, 2021 are permitted to use the following exception: When the following condition is met and documented, duct leakage testing is not required. At a pre-drywall stage of construction, 100% of the distribution system and air handler shall be visible and visually verified to be contained inside the Conditioned Space Volume. At a final stage of construction, ductwork that is visible and the air handler shall again be verified to be contained in the Conditioned Space Volume. 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.
If all the ductwork is inside condition space where do you come up with a .88 efficiency to the heating and cooling distribution and equipment. Was there any studies done to come up with this number. After doing hundreds of duct blaster tests I can’t believe there’s that much leakage when all the ductwork is inside condition space. Imposing the .88 efficiency to the equipment seems very high. How do I explained to the builder I need to test the ductwork for leakage to outside when they’re all inside a condition basement and if I don’t the house will be imposed a .88 efficiency to the equipment.
Exception 5: RESNET Home Energy Ratings shall comply with the requirements of ANSI/RESNET/ICC 301and its Addenda except that Ratings on homes with a building permit date, or alternate pursuant to Addendum 43, prior to January 1, 2021 are permitted to use the following exception:
When the following condition is met and documented, duct leakage testing is not required. At a pre-drywall stage of construction, 100% of the distribution system and air handler shall be visible and visually verified to be contained inside the Conditioned Space Volume. At a final stage of construction, ductwork that is visible and the air handler shall again be verified to be contained in the Conditioned Space Volume.
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.
Comment #4Amendment: Proposed MINHERS Addendum 47f, Test Exception for Ducts in Conditioned Space, Draft PDS-01Page Number: 2Comment Intent: Not an ObjectionComment Type: TechnicalComment: In Draft PDS-01 MINHERS ADDENDUM 47f. Test Exception for Ducts in Conditioned Space The definition of Conditioned Space should be clarified so as to include ducts in indirectly conditioned unvented attics and conditioned crawlspaces (i.e. crawlspaces insulated at the perimeter walls.) In many cases, these spaces are not occupied and indirectly conditioned so there might be confusion, but duct leakage is not escaping to the exterior since the thermal boundary is on the exterior of these spaces and ducts are effectively contained within conditioned space. Proposed Change: Reword Exception 5 as follows: Exception 5: RESNET Home Energy Ratings shall comply with the requirements of ANSI/RESNET/ICC 301and its Addenda except that Ratings on homes with a building permit date, or alternate pursuant to Addendum 43, prior to January 1, 2021 are permitted to use the following exception: When the following condition is met and documented, duct leakage testing is not required. At a pre-drywall stage of construction, 100% of the distribution system and air handler shall be visible and visually verified to be contained inside the Conditioned Space Volume*. At a final stage of construction, ductwork that is visible and the air handler shall again be verified to be contained in the Conditioned Space Volume. 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. * Note: Conditioned Space Volume includes indirectly conditioned, unvented attics and crawlspaces.
In Draft PDS-01 MINHERS ADDENDUM 47f. Test Exception for Ducts in Conditioned Space
The definition of Conditioned Space should be clarified so as to include ducts in indirectly conditioned unvented attics and conditioned crawlspaces (i.e. crawlspaces insulated at the perimeter walls.) In many cases, these spaces are not occupied and indirectly conditioned so there might be confusion, but duct leakage is not escaping to the exterior since the thermal boundary is on the exterior of these spaces and ducts are effectively contained within conditioned space.
Reword Exception 5 as follows:
When the following condition is met and documented, duct leakage testing is not required. At a pre-drywall stage of construction, 100% of the distribution system and air handler shall be visible and visually verified to be contained inside the Conditioned Space Volume*. At a final stage of construction, ductwork that is visible and the air handler shall again be verified to be contained in the Conditioned Space Volume.
* Note: Conditioned Space Volume includes indirectly conditioned, unvented attics and crawlspaces.
Comment #5Amendment: Proposed MINHERS Addendum 47f, Test Exception for Ducts in Conditioned Space, Draft PDS-01Page Number: 2Paragraph / Figure / Table / Note: Exception 5Comment Intent: ObjectionComment Type: EditorialComment: "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." There is so much more to DSE than just an air flow number but if I (and many others it seems) am reading this right you are assuming 12% leakage with all of it also going outside... You know we have this interesting thing called a registry so that we could actually run a querry and say that if all ducts are inside the conditioned space it stands to reason that there is actually at max 2 or 3% LTO while most of us who have tested 100's if not more units find less than 1% LTO with units running anywhere 2 to 10% total leakage. If the DSE is calculating other things than you might wish to clarify this - i.e. one of the examples above (say one that hits the code minimum 4% tested with less than 1% LTO = a .9 DSE or whatever number that is) I know this might be problematic as we have sealed crawls, hot roof systems, all inside a single floor (slab on grade via soffits), basment, etc... but you can still find legitimate ranges for most of these if not all where all of these which can be deemed inside "conditioned" space Proposed Change: "To calculate the energy impacts on the Rated Home, a DSE of 0.88 (a legitimate not arbitrary) number shall be applied to both the heating and cooling system efficiencies."
"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."
There is so much more to DSE than just an air flow number but if I (and many others it seems) am reading this right you are assuming 12% leakage with all of it also going outside... You know we have this interesting thing called a registry so that we could actually run a querry and say that if all ducts are inside the conditioned space it stands to reason that there is actually at max 2 or 3% LTO while most of us who have tested 100's if not more units find less than 1% LTO with units running anywhere 2 to 10% total leakage.
If the DSE is calculating other things than you might wish to clarify this - i.e. one of the examples above (say one that hits the code minimum 4% tested with less than 1% LTO = a .9 DSE or whatever number that is)
I know this might be problematic as we have sealed crawls, hot roof systems, all inside a single floor (slab on grade via soffits), basment, etc... but you can still find legitimate ranges for most of these if not all where all of these which can be deemed inside "conditioned" space
"To calculate the energy impacts on the Rated Home, a DSE of 0.88 (a legitimate not arbitrary) number shall be applied to both the heating and cooling system efficiencies."
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