In the Voz formula, what does Ez represent?

• A. Zone outdoor air factor
• B. Exhaust zero return
• C. Air distribution effectiveness
• D. Environmental zero-point

Answer: (C)

The main idea is how the outdoor air you provide actually gets to the occupants. Ez in the Voz formula is the zone air distribution effectiveness, a factor that describes how efficiently outdoor supply air is delivered and mixed into the breathing zone. It captures the impact of the air distribution pattern (diffuser type, placement, mixing vs displacement, and potential short-circuiting or stratification). If the distribution is ideal, Ez is near 1.0; if the air doesn’t reach the occupants well, Ez is less than 1, meaning only a portion of the supplied outdoor air contributes to the zone’s ventilation. For example, with Ez = 0.7, 100 cfm of outdoor air effectively provides about 70 cfm of ventilation in the occupied space.