CxA from owner

Yes, as long as they are not a member of the design and construction team.

...and the project is not more than 50,000 square feet. Otherwise an independent CxA is required.

Yes. I didn't mean to exclude these additional requirements in my original response. I was simply trying to speak to the issue of whether the person can be on the owner's staff.

Regarding Steve Khouw's message:

p.221 Table 2 of the LEED Reference Guide clearly states that "Owner employee or staff" can be the CxA regardless of the square feet of the building.

Also in the text, both for the cases "larger than 50,000 sq.ft." and "smaller than 50,000 sq.ft." , the CxA can be "a qualified staff member of the owner".

Please correct me if I am wrong.

Yes, in any situation it  can be a qualified staff person for the owner.

The responsibility of the CxA is to verify the Owner's Project Requirements is being implemented throughout all the project phases. In another word, verifying owner's interest is being protected. So if the CxA is from the owner's side or an independent firm of the design or construction team (conflict of interest) would qualify.

As far as I know, if someone on the owners staff has the experiance and requisite projects, they can be the fundamental and enhanced commissioning agent. As long as they comply with all the requirements for the review and implementation.

I served that function for our office expansion which gained LEED Silver a couple of years ago, and we got both EAp1 and EAc3.