How to Choose Between Hot-Aisle & Cold-Aisle Containment in a Data Center

Historically data center racks and cabinets are arranged in hot-aisle / cold-aisle configurations to improve cooling efficiency by reducing the mixing of hot exhaust air with chilled air from cooling units. However, air mixing still occurs when using this method, resulting in hotspots and higher energy costs. Aisle containment systems address this problem by fully isolating either the hot or cold aisles for greater efficiency and reduced operating costs.

With hot-aisle containment, a physical barrier is constructed to direct exhaust airflow into the air conditioning return. With cold-aisle containment, the cold aisle is capped and doors are installed at either end to contain the cold air. Choosing the right approach depends upon several factors.

When to Choose Hot-Aisle Containment

Existing Cooling Units Have Inadequate Capacity

Hot-aisle containment traps exhaust air at its hottest point and provides it with a direct path into the AC return. This increases cooling capacity, which is the ratio of the difference between supply and return air temperatures.

The Data Center Has a Hot-Air Plenum

Adding hot-aisle containment is fairly straightforward if a hot-air plenum is available. However, the system should be designed to avoid obstructing fire-suppression systems.

Racks and Cabinets Aren’t in Uniform Rows

With hot-aisle containment, the open areas of the data center are flooded with chilled air from the cooling units. Racks and cabinets that sit outside of the cold-aisle area benefit from the lower overall temperature of the data center. 

When to Choose Cold-Aisle Containment

Data Center Densities and Heat Loads Are High

A cold-aisle system is typically used in high-density data centers because it is more efficient to direct cold air onto densely populated racks than to cool the entire room. The goal is to create a smaller area to cool and focus the cooling on the fronts of the systems.

Raised-Floor Cooling Is Used

Cold-aisle containment is often used in environments in which cold air is generated outside the containment area and brought in through a raised floor. Most existing data centers employ this type of cooling system, which can be retrofitted for cold-aisle containment with minimal impact on operations.

In-Row Cooling Is Desired

Cold-aisle containment facilitates the use of an in-row cooling system. The cooling units are positioned within the containment area, enabling even more focused airflow and thus greater capacity and efficiency. Less energy is required for air movement, and air temperatures can be set higher. 

Conclusion

An aisle containment solution can minimize hot and cold air mixing by effectively capturing the air within a given aisle. Chilled air within the cold aisle is recirculated while exhaust air in the hot aisle is vented out of the data center environment.

As data center densities and heat loads continue to increase, organizations can see significant energy savings by adding aisle containment. Enconnex can help you select the right containment strategy and design a solution that will improve cooling efficiency.