jen@environmentalleader.com
My organization has long recognized the astounding energy use of data centers – everything from server closets to massive Costco-sized server farms – that currently use two percent of the electricity in United States. For the past five years, we have embarked on an effort to certify energy efficient data centers through the Energy Star Buildings program.
Kaiser Permanente was the first health care provider to earn Energy Star data center certification. Their data centers house applications for over 200,000 employees and provide real time, technology-enabled healthcare for over 9,000,000 members. By ranking in the top 25% most efficient data centers in the United States, Kaiser Permanente’s Napa data center was certified in 2010. To gain certification, Kaiser Permanente submitted twelve months of energy use data into an online tool, Portfolio Manager, whose algorithm compares a data center’s efficiency to hundreds of other data centers across the country.
Below, we highlight the efficiency measures implemented by Kaiser Permanente’s data center facilities team.
Raised floor optimization
As early as 2008, Kaiser Permanente’s data center facilities team realized there was always excessive air circulation with minimal heat rejection in the organization’s data centers. The Raised Floor Optimization (RFO) program addressed these issues by:
- Installing variable speed fans to allow the cooling system to match the load and minimize excess air circulation. 31 existing computer room air handler (CRAH) units were switched from constant speed fans to electronically commutated (EC) variable speed fans. 57 new CRAH units, with EC variable speed fans, were purchased and installed.
- Deploying wireless sensors to afford careful monitoring of data center conditions. 489 temperature and humidity wireless sensors were installed at the server inlet, 96 pressure sensors above and below the raised floor, and 90 additional temperature sensors at the return air to the CRAH units.
- Isolating and sealing leaks and bypass air to improve cooling system efficiency. This effort included cold aisle containment, 40 custom-made CRAH covers to prevent bypass air, and underfloor baffles to partition off unoccupied raised floor space. The cold aisle containment included flexible curtains that would automatically shrink and fallout during high temperature – avoiding the costs on an in-aisle fire prevention system. The CRAH covers were made working with a boat cover company and could be quickly removed through a system of bungee cords and hooks.
According to a study conducted by Pacific Gas & Electric (PG&E), this project saved enough energy annually to cover the cost of the improvements in 4.5 years – too long a time period for the data center facilities team.
Computer room functional efficiency
The data center facilities team looked to better quantify and improve the energy savings gained from implementing energy-efficient projects. The team identified the different stages of the air circulation/heat rejection cycle and used the data center’s Automatic Logic Controls (ALC) energy management system (EMS) to evaluate temperature quality degradation throughout the cycle. This data was collected into a unique computer room functional efficiency (CRFE) metric -- allowing operators to optimize the heat removal cycle efficiency, identify problem spots precisely, and validate the benefits of efficiency measures. Using CRFE, Kaiser Permanente optimized the measures to the point where the efficiency projects paid for itself in less than two years.
Data center expansion
Most recently, during a 40,000 square foot data center expansion and cooling system replacement, the team improved efficiency in the following manner:
- Chilled water plant design: The new chiller plant included all new variable speed drive chillers, chilled water pumps, condenser water pumps and cooling tower fans.
- Air-side and water-side economizers: The new addition uses 100 percent outside air during the majority of the year. Two new waterside economizers can now be run in parallel with chillers or in stand-alone mode.
- Water conservation: Water discharged from the cooling towers is now routed to collection tanks, where it is used to meet irrigation needs across the site.
- Multi-mode uninterruptible power source (UPS) systems: New UPS systems have the ability to run in a highly efficient “line interactive” mode or the traditional (and safer) “double conversion” mode (since August 2012, EPA listed Energy Star certified UPSs, including multi-mode UPSs -- see www.energystar.gov/products)
- Waste heat recovery: Warm or hot exhaust air from the UPS rooms is now routed to the generator room next door to eliminate the need to operate a boiler/heater to temper the generator rooms, and to decrease the power draw for the diesel engine block heaters.
- Hot aisle containment: The team deployed fully-enclosed return air chimneys tied to a drop ceiling return plenum back to the Air Handling Units and eliminating air recirculation through the compute space.
Project lessons
Kaiser Permanente’s efforts demonstrate three essential components of a successful data center energy efficiency retrofit:
- Leadership commitment: Kaiser Permanente demonstrated its leadership and commitment to sustainability by supporting the efforts at the data center at the highest levels of management. The retrofit at the data center complemented the company’s ongoing sustainability efforts.
- Life cycle cost analysis: During the bidding process for the chiller plant, life cycle cost analysis led to winning bids being 40% to 50% more affordable than the most expensive bids. Incorporating the value of annual energy savings led Kaiser Permanente to make the correct long-term decisions.
- Monitoring network: The wireless temperature/humidity/pressure sensor network, integrated with their energy management system, allowed facilities staff to directly monitor the cooling system and make adjustments to optimize efficiency while assuring IT staff that cooling levels are appropriate.
Steve Ryan is a project manager with the EPA. EPA Energy Star can help organizations save money and energy in the data center space. See our Top 12 list of energy efficiency measures and the benefits of benchmarking through the Energy Star data center certification program at www.energystar.gov/lowcarbonit.
This article was co-authored by Robert Huang, Cadmus (technical contractor to EPA).
