G3.1.1 exception d exhaust hood airflow baseline

G3.1.1d does not state that you should be using a secondary system. These are exceptions to the primary system and therefore replace it. It states that you should use a system 5/7 for the kitchen instead of the primary baseline system from Table G3.1.1A if the hood airfloww is greater than the value you cite. If it is less then you would model the primary baseline system. Kitchen echaust is a process load so it should be modeled identically with the same exhaust rate and schedule.

Dear Marcus,

Our project includes a kitchen with a total exhaust airflow rate exceeding the 2400 L/s threshold specified in G3.1.1 Exception (d). However, because the proposed kitchen area lacks a mechanical heating or cooling system, we are seeking clarification on whether to apply Exception (d) or treat the kitchen hood and makeup air systems strictly as process loads.Please note that per G3.1.1 Exception (d), a baseline System Type 5 or 7 (with electric resistance for an all-electric building) would normally be required. If we apply this baseline system to a space that is unconditioned in the proposed model, it will result in a discrepancy in conditioned floor area between the Proposed and Baseline designs. This appears to conflict with Section 1 (Design Model) of Table G3.1, which mandates that the baseline building be modeled with an identical conditioned floor area to the proposed design.Given these conflicting requirements, is it acceptable to classify the kitchen hood and makeup air fans as process loads under Section 12 of Table G3.1 to ensure floor area consistency between the two models?
 

If the kitchen is unconditioned space then the hood is a process load and the area of the kitchen should not be included in the determination of the baseline HVAC system. So yes model the kitchen hood as process and keep the floor area the same.