In the quest for greener, more efficient data centers, we often find ourselves enamored with high-tech, expensive solutions. However, there is a fundamental aspect that is frequently underestimated: airflow management.
Many data center operators may not fully realize the power of effective airflow management. While containment strategies might be attempted, they are sometimes not implemented optimally, leading to missed opportunities for significant cost savings and efficiency improvements.
The key to unlocking cost savings lies in understanding that proper airflow management is foundational to all other cooling strategies. Effective airflow management ensures that cool air reaches the right places and hot air is efficiently expelled, maintaining optimal operating conditions for equipment without unnecessary energy expenditure.
At CPI, we take an approach we call Passive Cooling®—an innovative method that incorporates advanced airflow management techniques to bring down cooling costs without relying on active components. By leveraging what you already have—air—our techniques can reduce energy consumption and maximize the efficiency of any advanced system, such as liquid cooling.
In this blog post, we’ll unpack the principles of passive cooling, explore its benefits, and examine how it can be integrated into older and newer data center designs.
What is Passive Cooling?
Chatsworth Product’s Passive Cooling® Solutions are innovative airflow management techniques that allow you to achieve 30+ kW of cooling without the use of mechanical cooling systems like fans, in-row air conditioners or other close-coupled cooling techniques.
Passive Cooling is a tested and proven concept that leverages natural airflow, is eco-friendly and can be used in any Tier facility.
Here are just a few benefits of Passive Cooling:
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Uses Existing Standard Cooling Equipment: Guides hot air out of the cabinet without fans, additional power or maintenance requirements. If the cooling capacity of your existing air handlers (CRAHs) exceeds your heat load, there is no need to add expensive supplemental in-row cooling.
For older, legacy data centers, this approach means you don't have to rip everything out and start over.
And for new data centers, Passive Cooling techniques can help maximize cooling efficiency from the start to properly support advanced cooling technologies such as liquid cooling and AI-driven systems and provide long-term operational stability.
How CPI Passive Cooling Works:
Passive Cooling is built on the principle that isolating hot air from cool air is the most crucial step to maximizing cooling capacity.
By removing all the hot air from the data center and completely separating it from the supply airstream, it becomes impossible to create a hot spot for any server in the data center.
Secondly, you can support much higher densities in the data center because you remove that hot air.
Step 1: Cabinet-Level Airflow Control
We start with controlling airflow through the equipment cabinet using a specific combination of thermal management accessories to prevent air from mixing and guide hot air out of the cabinet without fans, additional power or maintenance requirements.
- Snap-In Filler Panels block airflow through open rack-mount spaces and keep the hot air at the back of the cabinet.
- Air Dam Kit blocks airflow around the sides and top of the equipment mounting space so cold air passes through equipment and hot air does not recirculate around equipment.
- Side Panels with Grommet or Brush Seal Cable Openings allow cables to enter the side of the cabinet while containing exhaust air within each cabinet.
- Equipment Mounting Rail Brush Kit conceals openings in the equipment mounting rails to block airflow around the equipment.
- A Floor Seal Kit seals the space between the bottom of the cabinet and the floor when leveling feet or casters are in use and are ideal for aisle containment applications.
In the image below, a sectional view of the cabinets below shows bypass airflow around equipment (left) and good airflow management guiding air through equipment and blocking recirculation (right).
Step 2: Isolation at the Room Level
Traditionally, without containment, when heat loads reach 6-7 kW per cabinet, the volume of cold air required to remove heat from the cabinet typically exceeds the amount of cold air that can be practically delivered to the cabinet. As a result, air is borrowed from the room, and the air near the top of the cabinet is much higher in temperature because it mixes with hot air that re-circulates over and around the cabinet from the hot aisle.
The solution for this is to isolate and remove the heat (the hot exhaust air) from the room with the Vertical Exhaust Duct.
CPI pioneered the “chimney” cabinet which uses a VED (Vertical Exhaust Duct) to funnel hot air into the drop ceiling, guaranteeing heat transfer directly from equipment to the cooling unit.
The cabinet is fitted with a solid rear door to guide hot exhaust air to the Vertical Exhaust Duct. The duct is attached to a drop ceiling or is extended to a point high above the cabinet. It creates a one-way airflow pathway through the cabinet that eliminates the mixing of hot and cold air.
Since hot air is directed up, there is no hot aisle. The air that re-circulates over and around cabinets is lower in temperature and can be used to cool equipment because it has not been mixed with hot exhaust air. This means cabinet heat loads are not limited by the amount of air that can be delivered through the access floor tiles positioned directly in front of the cabinet, allowing you to increase your cabinet density.
As an alternative, we also offer the Build to Spec Kit, which is a field-fabricated containment system that is used over a hot aisle as part of a closed hot air return. This solution integrates with perimeter cooling, provides immediate improved cooling efficiency and is compatible with economization methods. It is ideal for retrofit applications over a mix of different types of cabinets, including cabinets of varying heights, widths and depths.
Watch the video below to learn more about how Passive Cooling helps you take care of this low hanging fruit before moving on to more advanced techniques:
Get Free Computational Fluid Dynamics Analysis from CPI
To help you understand the before and after conditions of airflow through your data center cabinet, CPI offers free Computational Fluid Dynamics (CFD) analysis to its customers. CFD uses numerical analysis and data structures to provide visual guidance on the best containment solution and the extent needed for each application and can help justify design changes to your planned or legacy data center.
As part of this service, you'll have access to a panel of onsite consultants, field application engineers and technical experts who provide a rigorous checklist of your installation's existing and planned airflow, equipment placement, and take into account the following factors:
- Shape and size of your data center
- Raised floor and ceiling heights
- Location and type of CRAC units
- Location and open area perforated tiles, cut-outs and under-floor obstructions
Schedule a free consultation today.