Hot Aisle Containment Systems (HAC)

The Cool Shield hot aisle containment systems (HAC) channel the heat from the server exhaust directly back to the returns on the cooling units.

First and foremost, hot aisle containment contains the hot exhaust air. This prevents warm air from re-circulating over the top of server cabinets and mixing with the supply air.

HAC Systems: How They Work

Typically, the perimeter of the hot aisle is enclosed with a vertical partition from the top of the server cabinets to the drop ceiling return. An aisle containment door is installed at both ends to facilitate access into the aisle. If there is no ceiling return, a duct system can be used to channel the exhaust air to one or more CRAC units directly. Since the hot exhaust air is removed from the room, the cooling units can be set to deliver supply air at a comfortable temperature for servers without the need to over-cool.

Returning warmer air to the CRAC/CRAH units actually increases their capacity. A 20-ton cooling unit may be able to deliver 25 or even 30-tons if the return air temperature is high enough. Besides increasing capacity, this will also improve efficiency, especially if the cooling units have variable speed fans. The increased capacity reduces wear on compressor and allows fans to operate on a more efficient spot on the energy curve.

Hot Aisle Containment (HAC) Systems:

Conditions Needed For Implementation

Hot Aisle Containment Data Center Servers

As effective as hot aisle containment is, it can be difficult to implement unless the site conditions are well-suited. The following conditions are ideal for this system:

  1. Unobstructed drop ceiling return plenum at least 24″ high.
  2. Top return CRAC/CRAH units with vertical extensions to drop ceiling.
  3. Variable speed fans on cooling units.
  4. Fully sealed cabinets with blanking panels, floor covers and no gaps between cabinets.

These conditions can allow for huge efficiency gains and energy savings. It is not unrealistic to reduce cooling costs by as much as 40%. If your site does not have these ideal conditions, it will not prevent you from implementing an effective containment solution. Contact one of our experienced Project Managers for a free site assessment, and to discuss our installation process.

Hot Aisle Containment (HAC) Systems:

Benefits Of Using A HAC System:

top view of airflow in aisle containment system

A hot aisle containment system in data centers optimizes cooling efficiency by isolating and channeling hot exhaust air from servers and equipment, preventing its mixing with cooler intake air. This targeted airflow containment minimizes energy consumption and enhances equipment performance, leading to improved overall operational cost savings and reduced environmental impact.

  • A single, redundant cooling unit can be applied to multiple aisle containments.
  • HAC with in-row cooling can improve overall efficiency versus traditional, raised-floor cooling with HAC.
  • Minimizes cold air from mixing with the hot, expelled air, returning warmer air to the CRAC, making the system more efficient.
  • HAC systems with in-row cooling are able to cool more than 30kW heat load per rack.

Containment Products & Accessories


Sliding and Hinged Doors


Sliding, Solid and Thermal Panels


Containment Accessories

Data Center Environment Specialists

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