403.2 Zone Calculations
|Az||=||zone floor area: the net occupiable floor area of the ventilation zone, square feet (m2).|
|Pz||=||zone population: The number of people in the ventilation zone during typical usage.|
|Rp||=||outdoor airflow rate required per person as determined from Table 402.1.|
|Ra||=||outdoor airflow rate required per unit area as determined from Table 402.1. [ASHRAE 62.1:18.104.22.168]|
TABLE 403.2.2 ZONE AIR DISTRIBUTION EFFECTIVENESS1, 2, 3, 4, 5
[ASHRAE 62.1:TABLE 22.214.171.124]
|AIR DISTRIBUTION CONFIGURATION||Ez|
|Ceiling supply of cool air.||1.0|
|Ceiling supply of warm air and floor return.||1.0|
|Ceiling supply of warm air 15°F or more above space temperature and ceiling return.||0.8|
|Ceiling supply of warm air less than 15°F above space temperature and ceiling return provided that the 150 feet per minute (fpm) supply air jet reaches to within 4.5 feet of floor level.||1.06|
|Floor supply of cool air and ceiling return provided that the vertical throw is more than 50 fpm at a height of 4.5 feet or more above the floor.||1.0|
|Floor supply of cool air and ceiling return, provided low-velocity displacement ventilation achieves unidirectional flow and thermal stratification, or underfloor air distribution systems where the vertical throw is 50 fpm or less at a height of 4.5 feet above the floor.||1.2|
|Floor supply of warm air and floor return.||1.0|
|Floor supply of warm air and ceiling return.||0.7|
|Makeup supply drawn in on the opposite side of the room from the exhaust, return, or both.||0.8|
|Makeup supply drawn in near to the exhaust, return, or both locations.||0.5|
For SI units: °C = (°F—32)/1.8, 1 foot per minute = 0.005 m/s, 1 foot = 304.8 mm
1 "Cool air" is air cooler than space temperature.
2 "Warm air" is air warmer than space temperature.
3 "Ceiling supply" includes any point above the breathing zone.
4 "Floor supply" includes any point below the breathing zone.
5 As an alternative to using the above values, Ez shall be permitted to be regarded as equal to air change effectiveness determined in accordance with ASHRAE 129 for air distribution configurations except unidirectional flow.
6 For lower velocity supply air, Ez = 0.8