The system
ventilation efficiency (Ev) shall be determined in accordance with Table 403.5.2 or Section 404.0. [ASHRAE 62.1:6.2.5.2]
Notes:
| MAX (Zpz) | Ev |
| ≤ 0.15 | 1.0 |
| ≤ 0.25 | 0.9 |
| ≤ 0.35 | 0.8 |
| ≤ 0.45 | 0.7 |
| ≤ 0.55 | 0.6 |
| > 0.55 | Use Section 404.0 |
1 "Max Zpz" refers to the largest value of Zpz, calculated in accordance with Equation 403.5.1, among the
ventilation zones served by the system.
2 For values of Max (Zpz) between 0.15 and 0.55, the corresponding value of Ev shall be permitted to be
determined by interpolating the values in the table.
3 The values of Ev in this table are based on a 0.15 average outdoor air fraction for the system (i.e., the ratio
of the uncorrected outdoor air intake (Vou) to the total zone primary airflow for the zones served by the air
handler). For systems with higher values of the average outdoor air fraction, this table is capable of resulting
in unrealistically low values of Ev and the use of Section 404.0 is capable of yielding more practical results.