Before LEEDuser set up these credit-specific Healthcare forums, there was a general Healthcare forum on which this MRc4.2 question was posted. I am reposting the Q&A here for convenience:
Question:       Per the LEED reference guide and LEEDonline signatory, copper piping joints can only be one of the following:
    - mechanically crimped
    - soldered in compliance to ASTM B828 with flux in compliance to ASTM B813
    According to the above, is brazing allowed (brazing is none of the above)?
Answer:    I believe that brazing is the process and solder is the material in the process. Does anyone know more about mechanical crimping? My questions to the plumbing engineers usually are answered with a 'we don't do that'. Is it a regional thing?

Reply:    Soldering happens at 450 degrees C or below while brazing happens above 450 degrees C. Both ASTM B828 and ASTM B813 are only applicable to soldering.
    We received similar answers on mechanical crimping as well. The concern seems to be on joint strength.
Reply:    Have you submitted this yet or called? I'm wondering if we aren't splitting hairs on the solder versus brazing. I've been rumbling this through my head and can't figure out a reason brazing isn't mentioned (and not allowed?) and it is in the MR section.

    We received the following email from USGBC LEED HC Committee upon contact:
    "Brazing is not addressed explicitly one way or the other by the Rating System Requirements. You could take this lack of instruction either way: 1- brazing is allowed b/c it is not explicitly disallowed, or 2- brazing is not specifically allowed, thus it is not allowed to be used in any copper joint applications when pursuing this credit.
    However, if you look on page 191 of the LEED for Healthcare supplement it states: “Consider silver and other lead-free solder …”…so it is implied that the approach proposed in your inquiry (brazing w/silver) would be acceptable."
    It is still not very clear how this complies with one of the two criteria, but brazing is allowed.