Per ID#ad-100000891 and the Credit Language, the "contiguous floor area" requirement was removed.

Can we now fully ignore how many floors an air handling unit (AHU) serves when determining how many air quality testing samples are required?

For instance, I have an AHU that serves approximately 40,000 square feet which is split evenly between four floors (i.e., 10,000 square feet per floor). Would I need only 2 tests since my total floor area is less than 50,000 square feet?  

Here is the old language for quick reference (emphasis is my own): "For each portion of the building served by a separate ventilation system, the number of sampling points must not be less than 1 per 25,000 square feet or for each contiguous floor area, whichever is larger. Include areas with the least ventilation and greatest presumed source strength."

Her is the new language: "The number of sampling locations must include the entire building and all representative situations."

By the way, the "25,000 square feet" language was also removed but I assume that still applies because I see it in the Implementation section of my Reference Guide hard copy. I'm also aware that the v4 Step-by-Step Guidance seems to explain the phase "include the entire building and all representative situations". However, my project is under v2009 so I'm assuming that v4 information doesn't strictly apply.