Cold Aisle Containment Conundrum: Common Issues and Solutions
Welcome to Keep Your Cool - our blog dedicated to simplifying cooling optimization for busy data center operators.
Over the past couple of weeks, we’ve explored about the potential problems that can occur after containment is installed, and how to use our Uniformity Metric to evaluate your efficiency.
This week we’re going to do a deep dive into cold aisle containment - what it is, how to manage it post-installation and what to look out for.
What is Cold Aisle Containment?
Cold aisle containment is one solution to prevent the cold supply air and hot return air from mixing and increasing airflow issues in your aisles. The prevalent design involves directing cold supply air into the contained aisle, either from underneath a raised floor or from the top in constructions with a slab floor, with the aim of efficiently filling the enclosed space with cold air. However, the reality within contained cold aisles often reveals challenges that go beyond the surface.
Figure 1: Cold Aisle Containment in a Raised Floor Setting
Figure 2: Cold Aisle Containment
What Happens After You Install Your Cold Aisle Containment
Unfortunately, installing cold aisle containment isn’t the end to your cooling problems. You need to regularly check your aisle environments to make sure there are no leaks, gaps or other issues. We’ve conducted thermal surveys of hundreds of contained aisles, and we’ve found that you can still have thermal issues even with containment. We’ve created two tools - Static Temperature Map and the Uniformity Metric to quickly evaluate your cold aisle containment automatically with our AUDIT-MATE 2.0 software.
After using the AUDIT-BUDDY system to measure every cabinet at three different heights across an aisle (or an entire room) and then generate a Static Temperature Map of the environment. The Uniformity Metric is calculated. You can use the table below to gauge the uniformity.
| Uniformity Rating | Range | Description |
|---|---|---|
| VERY GOOD | 0 to 0.49 | Excellent temperature uniformity |
| GOOD | 0.5 to 0.99 | Commendable uniformity with minor variations |
| FAIR | 1.0 to 1.49 | Acceptable uniformity with noticeable variations |
| NEEDS IMPROVEMENT | ⥸1.5 | Significant temperature variations, improvement needed |
With the uniformity metric, you don’t have to rely on just looking at a map, you now have a numerical basis to judge the variance.
However, achieving low variance in a cold aisle is not the sole goal. Even if an aisle appears uniform, meeting desired temperature values is crucial. An example underscores this point: despite a seemingly uniform aisle with a measured average temperature of 79°F, exceeding the desired 74°F, adjustments to airflow become imperative.
Real Life Application:
Take the following examples for two different customer sites. Both spaces are contained cold aisles, however there is a significant temperature variation between the two. In Figure 3, the temperature color is very consistent — only two shades of blue. The uniformity metric for this aisle is .39, which shows that this aisle is VERY GOOD. In contrast, Figure 4 has a lot of variation — four different shades, and a uniformity metric of 1.94 which NEEDs improvement. Utilizing both the visual aid of the Static Heat Map and the numerical assessment are easy ways to determine your cooling effectiveness.
Figure 3: Contained Aisle with Uniformity Metric: 0.39
Figure 4: Contained Aisle with Uniformity Metric: 1.94
What are some common issues to look for?
Missing or Improperly Installed Blanking Plates: Blanking plates are used to seal empty spaces in server racks, preventing hot air from recirculating to the cold aisle. If these plates are missing or installed incorrectly, it can lead to inefficiencies in the containment system.
Gaps at the Bottom of Cabinets: Any openings or gaps at the bottom of server cabinets can allow hot air to escape into the cold aisle, reducing the overall efficiency of the containment strategy.
Mismatched Cabinet Heights: Inconsistent heights of server cabinets can create uneven airflow patterns, disrupting the intended containment. It's essential to ensure uniformity in cabinet heights to maintain efficient cooling.
Inadequate Sealing of Containment Structure: The physical barriers used for containment, such as plastic or glass panels, need to be properly sealed. If there are gaps or leaks in the containment structure, it can compromise the separation of hot and cold air.
Incorrect Temperature Settings: Setting the wrong temperature parameters for the cold aisle can result in inadequate cooling or, conversely, excessive cooling. It's crucial to align the temperature settings with the specific requirements of the data center.
Lack of Regular Maintenance: Cold aisle containment systems require regular inspections and maintenance to identify and address issues promptly. Without consistent upkeep, problems may go unnoticed and lead to decreased efficiency over time.
Airflow Imbalances: Uneven airflow within the cold aisle, caused by factors like misplaced perforated floor tiles or obstructed airflow paths, can undermine the effectiveness of the containment system.
Server Configuration Changes: As data centers evolve and server configurations are adjusted, the original design of the containment system may no longer align with the new layout. This can result in mismatched airflow patterns and reduced efficiency.