Paul,

Be aware that your request and my response (which ASHRAE's
Hammerling forwarded to you) was considered an "unofficial
interpretation".

Here is a note that I have included on unofficial
interpretations in the past:

"NOTE: An unofficial or personal interpretation is a written
explanation of the meaning of a specific provision of a
standard or guideline in response to a written request.
While every effort has been made to ensure its accuracy and
reliability, it is advisory and provided for informational
purposes only, and in many cases represents only one
person?s view. It is not intended and should not be relied
on as an official statement of ASHRAE."

A formal interpretation request to ASHRAE 90.1 takes much
longer and is voted on by the committee.

So please don't consider my quick note as "ASHRAE's Answer".

Jason