Air-side economization
Air-side economization uses a system of supply and return fans, filters, and dampers that maintain positive air pressure with respect to the IT equipment exhaust, and positive data center air pressure with respect to the outside. Air-side economization may also include supplemental cooling coils that you can switch in and out of circuit as needed for changes in climate. You can implement air-side economization as either a direct or indirect system. In direct air-side economization, outside air is filtered, stabilized for relative humidity, and then delivered to the ITE racks (Figure 4). The ITE rack layout and exhaust venting is similar to a hot-aisle containment strategy.
Figure 4: Air-side economization (direct method)
| Exhaust |
Input | Filter/fan |
|
Filters/fans | |
| Exhaust |
| air to |
| outside |
Air from outside
ITE racks
Room requirements:
Air circulation system built into facility
Air-side economization using the direct method is more applicable in cool regions where outside air requires little or no refrigeration.
With indirect air-side economization, outside air cools data center air through an air-to-air heat exchanger. This method uses two air circulation circuits: one for outside air and one for inside air. Outside air is collected, cooled, and then used to cool re-circulated indoor air in a heat exchanger that is common to both air circulation circuits. The two air circuits share the heat exchanger, but indoor and outside air flows are segregated. Even though it requires two fan systems, indirect air-side economization can be more energy efficient and may be the preferred method for warmer climates.
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