Minimum Indoor Air Quality Performance Calculation

My Project has one FAHU on roof which is supply treated Fresh air to all AHU"s, And each AHU further supplies the mixture of outdoor air and Recirculated air to various zone via VAV (no reheating, no recirculating fan) unit and this air (deducting Extract) is returning back to same AHU after serving to room load, so what would be my zone secondary recirculation fraction and what would be my zone primary air flow whether it would be same as zone discharge air flow or I need to consider the primary air flow value as (0.3*Vdz) as my minimum VAV flow setpoint is 30% in case of no load. In calculator, Vpz is mentioned as lowest primary airflow value expected at the designed condition, What is mean by these? If I am considering Vpz as a 0.3*Vdz my overall ventilation efficiency is coming around 17% which is very much lower.