Data centers continue to evolve and become more efficient. With this in mind, the need for efficient HVAC is becoming essential to ensure cost-effective, reliable operation given servers generate significant amounts of heat.
As part of a facility upgrade, Waste Management, headquartered in Houston, replaced its chiller plants to serve its production data center facility in Austin, one of two data centers the Fortune 250 Company operates.
Over time, it became clear that the two original air-cooled chiller plants in the 2002-built facility needed replacement.
“The main thing we noticed is deterioration in the cooling coils of the chillers. Overall, we required more efficiency from the chillers and the pumps,” says Brian Kirkpatrick, director of infrastructure operations at Waste Management.
Waste Management performed due diligence to examine HVAC solutions. To do this, they brought in a data center design build specialist. The requirement called for a chiller replacement at N+N, also known as 2N redundancy, suitable to cover 10,250 sq ft of raised-floor data center operations, plus office space and a mechanical, electrical, and plumbing (MEP) service room. Ultimately, Waste Management required a cost-effective solution that delivered both a high level of energy efficiency and mission-critical reliability.
The company’s need was filled by installing two Daikin 400-ton Pathfinder air-cooled chillers. In addition, the chiller plant includes VFDs that add a high power-factor rating without the use of capacitors.
“This solution met our specification for a redundant solution at the 2N level. Additionally, we have four pumps with VFDs to bring 2N+1 redundancy,” says Vernon Williams, data center manager at Waste Management.
Replacement of such large chiller units requires heavy lifting — each Pathfinder weighs approximately 12 tons — and significant planning to keep the data center fully operational.
“The level of risk to keep our production data center operational during the chiller plant replacement process meant contingency planning,” Kirkpatrick says.
During the heat of the Texas summer, a phased installation of the chillers took place over several weekends. Pre-connections were made in advance to mitigate risk to the data center.
The chiller plants were lifted in and out by crane from the walled service yard, which is dedicated to Waste Management’s operations at the building. Overhead piping and other space constraints meant the first replacement to remove the old chiller and install the new units required that a segment of the concrete wall be cut out temporarily.
“One of the existing chillers was kept running while we made the first replacement in addition to the installation of a temporary rental chiller,” Williams explains.
A temporary Daikin rental 300-ton chiller was used as a reserve chiller during the decommissioning of the first existing chiller.
“Should something have happened during the replacement, we had the temporary trailer-mounted chiller with dual pumps available on site as a redundant system to bring back operations as quickly as possible,” Williams says.
Each chiller replacement was a success. “The level of redundancy we had available during the change-out and the level of collaboration among all parties was remarkable. We didn’t encounter a single minute of downtime,” Kirkpatrick says.
In addition, throughout the life of the chillers, Rapid Restore technology and a fast-loading option ensures uptime.
“In the remote chance there is a power outage that’s not handled by the back-up power supply, RapidRestore brings back the chiller to full performance within three to five minutes,” Kirkpatrick says.
The tech refresh at the Austin data center also encompassed a major upgrade to the BAS.
“A number of control systems by different manufacturers were integrated into the existing infrastructure. We replaced the former chiller controls to the BACnet® controllers on the Daikin Applied chillers,” says Kirkpatrick.
Since the chiller replacement, the energy savings have been dramatic.
“We’re seeing about a 100 kWh drop in monthly power utilization, which is about a 10% reduction in our usage overall at the facility, attributable to the new chillers, pumps, and CRAH units, when compared to the former chillers,” Williams says.
Waste Management predicts its annual savings on straight energy usage translates to approximately 11.3% or greater, along with a power factor correction savings, resulting in combined savings of more than 13.2% annually.
“Our power factor was low at 0.75 and it has improved considerably to 0.88,” Williams says.
He also says the chiller plants at the Austin data center have also contributed to the facility’s improvement of its Power Utilization Effectiveness (PUE) rate, which is currently 1.54.
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