comcheck - PEMB

[Hyrax4978]

looking at some PEMB insulation options and running them through comcheck to find our most economical option.

I see in ashrae 90.1 that there are limits to what you are allowed to claim for insulation when it comes to metal buildings. ahshrae seems to limit you to a more realistic U value rather than what the metal building suppliers "claim" the insulated walls can produce. I also see that fenestration looks like it needs to meet NFRC 100.

IECC doesn't seem to have the same restrictions on the metal buildings in the terms of advertised versus real U values as well as fenestration tests meeting NFRC 100.

Any insight would be appreciated.

 

[steveray]

Usually the Comchecks I see have a footnote requiring more verification of the claimed U factor...Manufacturers installation instructions? Testing paperwork?

 

[Hyrax4978]

I do have product data, but its the sales data which usually offers R or U values of items such as center of glass, or door panel, which is completely different than the tested NFRC data. Ashrae seems to require NFRC compliant data, where IECC doesn't seem to have the same requirement. Unless i am missing something.
Here is an example, i have a flyer from a PEMB door assembly that shows the calculated U factor as 0.14 meeting certain ASTM methods. But the NFRC compliant method resulted in only a 0.43 U factor. thats a big difference. Ashrae seems to require the NFRC, but i don't see where IECC requires the NFRC. obviously if i just plug in the better of the two U factors it helps me, but i was hoping to better understand this so i can do it correctly.

Thanks.

 

[RLGA]

See IECC C303.1.3.

 

[Hyrax4978]

And there it is!!! thanks so much!

 

[RLGA]

A bit of advice on standards referenced in the I-Codes: Check the "Reference Standards" chapter (the last chapter in each code) for the standard that you're looking for. If it's not listed, then it is not referenced by that particular I-Code. If it is listed, then just below it are all of the locations where that standard is referenced within the code. Please note that the standards are listed in alphabetical order according to the name of organization that publishes the standard, then numerically for each standard; so, you'll need to know the name of the organization that publishes the standard you're seeking.

In Chapter 1 of each code there is a section called "Referenced codes and standards," which states in part, "The codes and standards referenced in this code shall be considered to be a part of the requirements of this code to the prescribed extent of each such reference..." This means that just by listing the standard in the Reference Standards Chapter does not mean that the entire content of the standard is part of the code. For example, if the reference is to "Table 10 of XYZ Standard," then only Table 10 is made part of the code. If there is no such specific reference or limitation, then the entirety of the standard is made part of the code.