Zone Calculation Ds% for VAV System

I received this question in IEQp1: "The ventilation calculations indicate that the value of the flow rate of air projected under the condition tested (DS) was modeled as 100% level for each of the areas system; however the DS system is typically much lower for systems including VAV terminal units in the worst possible case. For the worst case, the DS can be determined for each area by dividing the minimum volume of the primary air VAV terminal during the worst possible case the peak volume of the VAV air terminal during the maximum cooling." I'm working on a project, which has raised floor and fan coil air blowing underfloor. I've maded all analysis based on LEED Tool for multizones and considered the 100% Ds% in each zone. How calculate this value "Ds%" for each zone? Thanks everyone!