Table 1.
Zone air distribution effectiveness(ASHRAE, 2019).
| Air Distribution Configuration | Ez |
|---|---|
| Well-Mixed Air Distribution Systems | |
| Ceiling supply of cool air | 1.0 |
| Ceiling supply of warm air and floor return | 1.0 |
| Ceiling supply of warm air 15 F (8℃) or more above space temperature and ceiling return | 0.8 |
| Ceiling supply of warm air less than 15 F (8℃) above average space temperature where the supply air-jet velocity is less than 150 fpm(0.8 m/s) within 4.5 ft (1.4 m) of the floor and ceiling return | 0.8 |
| Ceiling supply of warm air less than 15 F(8℃) above average space temperature where the supply air-jet velocity is equal to or greater than 150 fpm(0.8 m/s) within 4.5 ft (1.4 m) of the floor and ceiling return | 1.0 |
| Floor supply of warm air and floor return | 1.0 |
| Floor supply of warm air and ceiling return | 0.7 |
| Makeup supply outlet located more than half the length of the space from the exhaust, return, or both | 0.8 |
| Makeup supply outlet located less than half the length of the space from the exhaust, return, or both | 0.5 |
| Stratified Air Distribution Systems (Section 6.2.1.2.1) | |
| Floor supply of cool air where the vertical throw is greater than or equal to 60 fpm (0.25 m/s) at a height of 4.5 ft (1.4 m) above the floor and ceiling return at a height less than or equal to 18 ft (5.5 m) above the floor | 1.05 |
| Floor supply of cool air where the vertical throw is less than or equal to 60 fpm (0.25 m/s) at a height of 4.5 ft (1.4 m) above the floor and ceiling return at a height less than or equal to 18 ft (5.5 m) above the floor | 1.2 |
| Floor supply of cool air where the vertical throw is less than or equal to 60 fpm (0.25 m/s) at a height of 4.5 ft (1.4 m) above the floor and ceiling return at a height greater than 18 ft (5.5 m) above the floor | 1.5 |
| Personalized Ventilation Systems(Section 6.2.1.2.2) | |
| Personalized air at a height of 4.5 ft (1.4 m) above the floor combined with ceiling supply of cool air and ceiling return | 1.40 |
| Personalized air at a height of 4.5 ft (1.4 m) above the floor combined with ceiling supply of warm air and ceiling return | 1.40 |
| Personalized air at a height of 4.5 ft (1.4 m) above the floor combined with a stratified air distribution system with nonaspirating floor supply devices and ceiling return | 1.20 |
| Personalized air at a height of 4.5 ft (1.4 m) above the floor combined with a stratified air distribution system with aspirating floor supply devices and ceiling return | 1.50 |