• which simulation engine?
• new vs existing building? existing HVAC?
• similar retail units, e.g. similar occupancy + setpoints + lighting? vs food court?
• central vs individual RTUs? local WC exhaust?

... so it depends. Yet in general, it's usually fine to merge typical sales and backroom areas as a single thermal zone per retail unit. How return vs WC exhaust air is taken into account depends on available simulation engine options. And based on the simulation engine, one can also look into deleting interzone surfaces between units and/or relying on unit multipliers (fewer (less surfaces == faster runs).

• simulation engine?
engine?
• new vs existing building? existing HVAC?
• similar retail units, e.g. similar occupancy + setpoints + lighting? vs food court?
• central vs individual RTUs? local WC exhaust?

... so it depends. Yet in general, it's usually fine to merge typical sales and backroom areas as a single thermal zone per retail unit. How return vs WC exhaust air is taken into account depends on available simulation engine options. And based on the simulation engine, one can also look into deleting interzone surfaces between units and/or unit multipliers (less surfaces == faster runs).