Predominant spaces determined by square footage or hours of use?

Further expanding on my above post... The Common Space (8,200 sf) and the Office Space (4,300 sf) are the only areas open almost all week long. The remaining 35,500 sf is only occupied one or two days per week for up to 16 hours total for the week. I feel this 35,500 sf is the predominant case and should be modeled as a VAV system (one for the first floor and one for the second floor). However, I received a preliminary review comment saying the Classroom/Storage areas should be considered the non-predominant case which totals about 24,000 sf. The rest of the building totals about 24,000 sf also. Correct me if I'm wrong, but I believe it was recently decided the total building area shall not be used to decide the system type of the predominant case. That means neither case meets the 25,000 sf requirement for a VAV Baseline system which I was counting on. Thus now I have to compare our Single Zone design to a Single Zone baseline design. A quick analysis in HAP shows a 5-point decrease in LEED points.This is very discouraging at this point in the game. Any advice?

My proposed design is a combination of gas fired packaged rooftops and split system heat pumps with gas furnace backup. My baseline system was Type 5 with several Type 3 systems for the exceptions. The reviewer didn't directly mention any changing of system type; just that the areas with significantly more hours should be considered the predominant case and the areas with very few hours should be the exception. My argument is that the majority of the building is hardly occupied throughout the week so that should be the predominant case. The part of the building that is occupied frequently is a much smaller portion of the whole and therefore should be the exception. I had previously interpreted the Appendix G requirement to be based on predominant square footage, not predominant hours of occupancy. But another gray area under the exceptions is the minimum 20,000 sf requirement under exception a. Does Exception a trump all of the other exceptions or is it just one possible exception? In other words, even if a space varies by more than 40 hours of use from the majority of the building, can I only take exception for it if the space takes up at least 20,000 sf of the building? In regards to hours differing by more than 40 hours per week and lumping varying hours together to form a set of heavily occupied hours vs. lightly occupied hours would the following work: Lightly Occupied group: 14,700 sf 1st Floor Classroom/Storage Space used 0 to 4 hours per week 9,300 sf 2nd Floor Classroom/Storage Space used 0 to 4 hours per week 7,500 sf Worship Space used 12 hours per week 4,100 sf Multipurpose Space used 16 hours per week Weighted hours = 7 hours/week Heavily Occupied group: 4,300 sf Office Space used 50 hours per week 8,200 sf Common Space used 72 hours per week Weighted hours = 64 hours/week So 26% of the building area has 64 hours of occupancy per week while the remaining 74% of the building has 7 hours of occupancy per week. Again should the predominant case be based on the hours of use or the square footage? Thanks!

Ok so you're saying exception 'a' does not apply, but exception 'b' still does, correct?