Keep It Cool: Can A Data Center Ceiling Contribute To Energy Savings?

One of the key challenges in data center management is capacity planning and the resulting energy requirements needed to support the equipment that keeps critical systems operating. As capacity increases by adding more server racks and containment aisles, finding more efficient power consumption becomes increasingly important and challenging.

When designing a data center, factoring in cooling critical hardware and containing air temperature is key. Containment walls are a common strategy, but a facility’s ceiling can negatively impact air containment management and efficiency. Without a proper horizontal barrier above the hot and cool containment aisles, there is risk of unnecessary bypass leakages resulting in decreased efficiency of cooling systems.

Ultimately, this leads to hot spots where cool air gets pushed past the building structure’s plenum — an area in the ceiling where the air circulates. This draws in more heat while wasting energy.

Armstrong World Industries, a Pennsylvania-based ceiling solutions company, recognizes the long-term problem of bypass leaks and provides functional structural ceilings that also contribute to a better air containment strategy for data centers.

“By ignoring the airflow problem, bypass leakages can reduce the amount of air passed through the server cabinet, causing the hardware to run too hot,” Armstrong Senior Principal Scientist Bill Frantz said. “This leak path greatly impacts the racks, aisles and ceilings, all of which are pivotal to running data centers optimally.”

Frantz said the American Society of Heating, Refrigerating and Air-Conditioning Engineers established guidelines for the maximum allowable temperatures in a data center. Data center designers should heed these guidelines and pay attention to sources of bypass leaks at the beginning of the design process because they are a constant energy drain in the life cycle of the facility. Even if the leakage is small, it is “an ongoing energy penalty” that the facility suffers every day, he said.

Frantz compared this leakage effect to what happens when a car uses air conditioning while a back window is open: The rear passenger is likely not getting the benefit of the cool air.

“Even if most of the data hall is cool, small temperature increases throughout the hall can starve the equipment from the cooling it needs,” he said.

Armstrong has designed two complementary solutions to battle the containment problem and maintain optimal airflow and temperature management. The DynaMax structural grid system can support heavy loads, which helps avoid penetrations through standard suspension systems, while AirAssure factory-gasketed tile reduces bypass leakage attributed to the ceiling plane, he said.

“When both systems are used together, it's a better air containment strategy that improves cooling efficiency and saves fan energy,” he said. “The ceiling plane is just one source of leakage because leaks also happen in the server racks and hot aisle containment systems, which is why these should be all designed together in the beginning.”

The company ran experiments to test systems to control airflow to ceilings as far back as 2001. However, it wasn't until nearly two decades later that Armstrong began to see serious demand for these solutions.

“We restarted our experiments once the coronavirus pandemic hit because of the high demand to create expedient pressure-controlled spaces in hospitals and senior living centers,” Frantz said. 

As for data centers, Armstrong found that the average ceiling leakage rate was between 0.6% and 2%. By combining its AirAssure tiles with the DynaMax grid system, the company reduced leakage to less than 0.6%, significantly eliminating local hot spots, Frantz said.

The leakage rate in a nongasketed ceiling tile is 1.4 cubic feet per minute per square foot. DynaMax and AirAssure can reduce this sevenfold at a rate of 0.2 cubic feet per minute per square foot, requiring much less energy output, Frantz said. 

This was just the start of Armstrong’s mission to find a solution to air containment issues in data centers. The company began collaborating in 2023 with Applied Math Modeling Inc., a software and consulting service company in New Hampshire. 

Applied Math created a system called CoolSim, which is a computational fluid dynamics modeling and design software for data center airflow management. While Armstrong just scratched the surface with its heat and airflow calculations, Applied Math took it further by providing the company with a more three-dimensional approach.

“Applied Math Modeling’s CoolSim software made it easy to define specific leakage rates for the ceiling systems with its user-defined functions,” Frantz said. “We ran a number of scenarios involving ceiling systems with varying leakage rates to draw conclusions about the value of our new system.”

Frantz said the new insights allowed Armstrong to map how complex the airflow patterns can be as they travel through the server room, its racks, aisles and above to the ceiling plenum. Subtle changes in leakage paths can dramatically affect overall cooling performance in a data hall, he said. 

Through these findings, the company was able to better prove the contribution these ceilings have on increased energy efficiency, Frantz said. Armstrong also saw that it could run cool air more consistently throughout data halls and maintain more uniform plenum pressures, reducing instances of hot spots.

Armstrong Sales Manager of Data Centers and Structural Ceilings Mark Dunn said he is excited about what the future holds and how Armstrong continues to search for ways to optimize data center operations.

“Armstrong is exploring a broader solution to maximize air control in data centers by seamlessly integrating the ceiling plane and containment systems to allow for simpler installation and to help data centers to run more efficiently,” Dunn said. 

This article was produced in collaboration between Studio B and Armstrong World Industries. Bisnow news staff was not involved in the production of this content.

Studio B is Bisnow’s in-house content and design studio. To learn more about how Studio B can help your team, reach out to studio@bisnow.com.