The outdoor airflow required (Vbz) is based on people-related sources and area-related sources. The equation for the calculation of Vbz is as follows:

Vbz = Rp * Pz + Ra * Az

Where:

Rp (Unit: CFM/person or L/s/person) = Outdoor airflow rate required per person as determined from Table 6.2.2.1

Pz = Number of people in the ventilation zone during use. cove.tool calculates this number based on the occupant density and the floor area of the project.

Ra (Unit: CFM/ft2 or L/s/m2) = Outdoor airflow rate required per unit area as determined from Table 6.2.2.1

Az (Unit: ft2 or m2) = Net occupiable floor area of the ventilation zone.

The outdoor airflow rate Vbz has the unit of CFM when IP system is selected and L/s when the SI system is selected.

The outdoor airflow rate to the zone (Vz) is determined according to the following equations:

Vz = Ra * Az (Equation 120.1-F)

Where:

Ra (Unit: CFM/ft2 or L/s/m2) = Outdoor airflow rate required per unit area as determined from Table 120.1-A.

Az (Unit: ft2 or m2) = Net occupiable floor area of the ventilation zone.

Vz = Rp * Pz (Equation 120.1-G)

Where:

Rp = 15 CFM of outdoor airflow per person

Pz = Expected number of occupants.

The maximum value from equations 120.1-F and 120.1-G is considered for outdoor airflow rate (Vz). Typically, the equation 120.1-F yields highest value so cove.tool refer that equation for the calculation of outdoor airflow rates.

It can be easily edited according to the project from 'Building System' tab.

The NCM Activity Database contains the l/s/p value for different building types. Cove.tool refers those values along with occupant density and the total floor area to calculate total L/s value for the project.

The minimum amount of introduced outdoor air for the system (Qf) shall be calculated as the greater of the area-based minimum and the occupancy-based minimum as follows:

(a) Area-based minimum:

Qf = (A * 0.35) L/s.m2

Where:

A (Unit: ft2 or m2) = Net occupiable floor area of the ventilation zone.

(b) Occupancy-based minimum:

Qf = (n * qf)

Where:

qf (Unit: CFM/person or L/s/person) = Outdoor airflow rate required per person as determined from AS 1668.2 standard.

n = Expected number of occupants.