What is the Purpose of a Hot Aisle & Cold Aisle Arrangement?

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The segmentation of data centers and server rooms into alternating cold and hot aisles has been embraced globally over recent years. 

The cold and hot aisle arrangements in data centers are part of an energy-conservative layout for server racks and other information technology equipment. 

Containment systems are used in ultra-modern data centers to isolate cool air from the hot air discharge. This separation of cold and cold air is achieved through either hot aisle containment or cold aisle containment.

Usually, cold aisles are composed of rack fronts and face the CRAC output ducts, while hot aisles face return ducts.

The primary reason for designing data centers with cold and hot aisle arrangements is to effectively control Heating, Ventilation, and Air Conditioning(HVAC) systems to conserve energy.

By containing the cold and hot aisles, the two air aisles have a low possibility of mixing, presenting data centers and server room operators with efficiency and reliability. 

This arrangement creates a partition to separate the exhaust air(hot aisle) and the server supply air(cold aisle).

In its simplest form, the goal of hot aisle and cold aisle arrangements is to manage airflow to lower cooling costs and conserve energy. 

Before we look at the purpose of the hot aisle and cold aisle arrangements, here is an outline of the two forms of the containment system.

Cold Aisle Containment

This arrangement is designed to improve the cooling of network cabinets and server racks. 

In this arrangement, the containment system limits and directs the flow of cold air, preventing it from combining with the hot air flow inside the data center or server room.

Consequently, the flow of cold air becomes predictable and uniform, eliminating hot spots while enhancing energy efficiency. 

The uncontained area has the same temperature as the hot aisle(hot air return plenum), and temperatures must be kept at reasonable ranges to avoid violating Occupational Safety and Health Administration(OSHA) regulations. 

Hot Aisle Containment

The hot aisle containment is designed to direct the flow of hot air exhaust from the data center or server room to the air conditioning return path. 

Basically, it works on the thermal properties of warm air to prevent the mixing of cold air flow and hot air flow.

This results in an overall lowering of room ambiance and a more comfortable working space.

Ideally, the cold aisle containment system encloses the cold aisle, and the rest of the data center becomes hot. 

In this arrangement, the uncontained area has the same temperature as the cold aisle, and this temperature should be kept at a reasonable range. 

So what is the purpose of the cold and hot aisle arrangements, and why should you adopt them?

Although it might seem like many server rooms and data centers line up racks because it’s the simplest way to arrange them, there is more science behind this configuration. Let’s dive in.

  • Energy saving. Considering how energy costs have escalated recently, data centers and server room professionals are considering cold and hot aisle containment strategies. It accommodates lower fan speeds and increases the use of weather-side and air-side economizers. 
  • Eliminates hot spots which may lead to server failure. Hot spots occur when heat is collected by cold air as it moves from the cooling unit to the front of the racks. Using cold aisle and hot aisle arrangements prevents cold and hot air from mixing. Therefore, the temperature of air that goes to IT inlets is uniform to the one leaving the conditioner. This effect holds true for all air conditioning equipment. 
  • It maximizes the cooling capacity of the existing HVAC equipment. This, therefore, eliminates the need for additional Computer Room Air Conditioning(CRAC) units. It also ensures a prolonged operational lifespan of the air conditioning system.  
  • It increases the data center and flow server cooling capacity by raising the return air temperature. Increased cooling system temperatures result in efficient and more effective heat exchange with the air conditioner cooling coils. 
  • It reduces humidification and dehumidification costs. Monitoring humidity levels in server rooms and data centers are pretty challenging but necessary. Without enough humidity, facilities face static shock and damage to sensitive equipment.

Besides, too much humidity can lead to condensation and subsequent electronic short-circuiting or corrosion. By eliminating the mixing of cold and hot air, the cooling systems operate above the dew point temperature, and no humidity will be removed from the air. 

Dehumidification is unnecessary if humidity is not removed from the air, thus saving water and energy. 

In Conclusion

Energy consumption has become a major concern in data centers. For this reason, cold and hot aisle arrangements are essential for any business or organization with solid servers. 

Despite keeping your equipment at optimal performance levels, they save your energy costs. 

Preventing hot and cold air from mixing is an excellent way to optimize cooling strategies in data centers.

To achieve high efficiency in your server room or data center, it’s essential to segregate hot air and cold air using cold and hot aisle arrangements. 

Both of these aisles offer efficiency when compared to traditional cooling systems.

If you have not planned the arrangement of corridors in your server room or data center, get in touch with us.

TRAX data center containment solutions are currently being used by some of the most recognized names in the high tech world.
Contact us to request a quote today.

Or call us at 1-800-248-8729 for more information