
Data centers are often made up of hot and cold aisles, and the design of the hot / cold aisle data center is far from new. However, the traditional setup causes warm air exhaust from one aisle to flow into the air intake of the next, meaning that the overall efficiency of the data center is impacted. And really, that’s what hot and cool aisle containment is all about.
Key Takeaways
By the end of this article, you’ll know:
- The benefit of remote monitoring in temperature control.
- What Hot, Cold, and Partial Aisle Containment methods are.
- The importance of liquid cooling and airflow.

As rack density increases, especially in edge data centers and hyperscale data centers, the need for efficiency increases. This is also impacted by the fact that there are more green data centers, who may be generating their own energy using solar or other renewable resources.
How does containment work and how does it impact your data center?
Remote Monitoring and Temperature Control
Of course, before we get to containment itself, it’s a good reminder to revisit physical layer monitoring. To know how effective any containment effort is, it’s necessary to monitor temperatures. This is most often done with temperature indicating panels, three per rack at the top, middle, and bottom, so that intake temperatures can be monitored regularly.
Of course, someone entering the area to manually check temperatures is yet another disruption to airflow, so remote monitoring as a part of physical network security is essential. This allows managers not only to monitor these temperatures, but receive alerts and take action if something goes wrong.

But the most important fact for this discussion is to know what temperatures are so that efficiency and the effectiveness of containment can be monitored.
What is Aisle Containment?
Aisle containment is essentially isolating aisles by relative temperature. Essentially it means placing doors at the end of each aisle, and then adding panels, or barriers, from the top of the cabinet upwards.
The more airtight this containment is, the more efficient cooling can be, and the easier it is to manage airflow. It’s pretty simple, but there are a couple of different approaches, each with its own pros and cons.
Hot vs. Cold Aisle Containment
There are two ways to manage aisle containment: hot and cold aisle containment. And they work exactly the way they sound.
- Hot Aisle Containment: Hot aisles are contained, leaving the rest of the room at a more comfortable cool aisle temperature. It’s also easier to manage in many cases.
- Cold Aisle Containment: Cold aisles are isolated or contained, which means the rest of the room stays at the warmer hot aisle temperature. This can also make getting the right amount of airflow tricky due to pressure changes, but managed properly it can deliver the most uniform temperature air to servers..
Choosing the right type of aisle containment for your data center depends on your situation, but there are some differences between new data center construction and retrofitting an existing data center.
Retrofitting vs. New Data Center Construction
In the case of a new data center, most of the time hot aisle containment is the method of choice. This is easier to set up in a new data center, as that allows you to start with the type of containment you need, and to set up HVAC systems and sensors to accommodate that.
This creates an easier environment for technicians to work in when necessary, and is overall a more efficient choice. However, things are different when it comes to existing data centers
Existing data centers are easier to retrofit with cool aisle containment. While there is some additional monitoring, the way cooling systems work simply means this process is simpler in a currently operating system without creating expensive downtime for making moves and changes and installing containment.
That doesn’t mean that no new data center will be built with cool aisle containment. It simply means that hot aisle containment is a more frequent choice.
Partial Containment Solutions
When it comes to retrofitting, sometimes full aisle containment in either format is not possible. In those cases, partial containment is a solution. How is this achieved?
Often plastic strips can be used, similar to those you would go through walking into an industrial freezer or even certain restaurant kitchens. These can be hung at the end of aisles and from the tops of servers to the ceiling, just like other containment methods.
While not as effective, partial containment can be easy to retrofit and implement, and in some cases is about 75% as effective as full containment. For existing data centers looking for a quick and inexpensive efficiency solution, partial containment is a viable option.
But containment is just a part of rack cooling solutions, and there are some new and exciting ones.
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The Addition of Liquid Cooling
Data center cooling has evolved from older, inefficient systems to more contemporary ones in a relatively short period of time. However, one thing that has been around for a while but is experiencing a boom in denser, modern data centers is liquid cooling.
Why? Well, in most cases liquid cooling is more efficient than air cooling in data centers, and when the two are used in conjunction, generally the best results can be achieved. The larger data centers get, the more power they consume, the greater the push towards a blended approach to cooling that not only saves power and is better for the environment, but prolongs the life of equipment and saves space as well.
But even with the addition of liquid cooling, it’s all about efficient use of rack space and the airflow around them.
It’s All About Airflow
No matter what kind of aisle containment is used, and no matter how efficient the cooling system, saving space, improving efficiency, and keeping things organized, maximizing rack space efficiency and airflow is vital.
That’s why data centers choose ZeroU racks and cable management systems. They not only help avoid the spaghetti mess and all the cable issues that can arise from it, but also help maximize airflow and save significant rack space in any system.
Whether you are retrofitting a data center or engaged in new construction, we have the rack system that’s right for you.
Contact AnD Cable Products today for all of your cable, rack, and physical network security needs. We’d love to start a conversation about the right solution for you.
FAQs
What is hot and cold aisle containment in a data center?
Hot and cold aisle containment is a data center design strategy that separates the hot exhaust air from equipment from the cold supply air. This is done by physically enclosing either the hot aisles or the cold aisles to prevent the mixing of air, which improves cooling efficiency and reduces energy costs.
What are the two main types of aisle containment?
The two main types are hot aisle containment and cold aisle containment. Hot aisle containment encloses the hot aisles, directing hot exhaust air directly to the cooling units. Cold aisle containment, on the other hand, encloses the cold aisles, keeping the cool air localized for the equipment intakes.
Which type of containment is better for a new data center?
For new data center builds, hot aisle containment is often preferred. It is generally easier to integrate with new HVAC systems and provides a more comfortable working environment for technicians, as the majority of the room remains at a cooler temperature.
Which type of containment is better for retrofitting an existing data center?
For existing data centers, cold aisle containment is typically the easier and more cost-effective option for a retrofit. It is a simpler process that can be implemented without significant downtime.
Can partial containment be used, and how effective is it?
Yes, partial containment is a viable solution when full containment is not feasible. This can be achieved using plastic strips or similar materials and is noted to be about 75% as effective as a full containment system.
Why is monitoring important for aisle containment?
Regardless of the containment method, remote monitoring and temperature control are crucial. They allow data center managers to assess the effectiveness of the containment efforts, identify any thermal inefficiencies, and optimize the cooling system for peak performance.
About the Author

Louis established AnD Cable Products – Intelligently Designed Cable Management in 1989. Prior to this he enjoyed a 20+ year career with a leading global telecommunications company in a variety of senior data management positions. Louis is an enthusiastic inventor who designed, patented and brought to market his innovative Zero U cable management racks and Unitag cable labels, both of which have become industry-leading network cable management products. AnD Cable Products only offer products that are intelligently designed, increase efficiency, are durable and reliable, re-usable, easy to use or reduce equipment costs. He is the principal author of the Cable Management Blog, where you can find network cable management ideas, server rack cabling techniques and rack space saving tips, data center trends, latest innovations and more.
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