Overview

In March 2022, CEG completed implementation of a highly innovative Energy Savings Performance Contract (ESPC) project at the 951k SF CalEPA Headquarters complex in Sacramento, CA. The high-rise office building was already LEED Platinum certified and had an Energy Star energy performance rating of 100 (top percentile of all buildings) prior to our project. Because the building was already exceptionally efficient, the project required an innovative approach that re-architected the building’s data center. This achieved a 34% reduction in total building energy consumption while significantly improving the resiliency of this mission-critical facility. 

The Primary Challenge: Achieving Significant Energy Savings in Already-Efficient Facilities.

Before the project began, the CalEPA Headquarters was already a LEED Platinum facility with an EnergyStar energy performance rating of 100 (on a scale of 1 to 100). CalEPA had previously implemented many traditional energy-saving opportunities: LED lighting, delamping, high-efficiency chillers, variable speed pumps and fans, economization, a wide deadband between cooling and heating (68F-76F), after-hours setbacks, etc. As such, there were limited obvious opportunities for further savings, but CalEPA and CEG were committed to finding creative solutions that would make the building even more efficient.

The Secondary Challenge: Increasing Resilience of Mission-Critical Systems.

CalEPA operated a mission-critical data center that lacked backup power or redundancy and depended upon near-end-of-life infrastructure. To pay for the needed resiliency and infrastructure upgrades, CalEPA sought to identify sufficient operational savings to use ESPC financing. 

An Innovative Three-Prong Approach: CEG applied an innovative three-prong approach to address these challenges.

• Step 1: Reduce Load by Upgrading, Virtualizing, and Consolidating IT Equipment. Because much of the data center’s IT inventory was inefficient and operating at a low utilization, CalEPA and CEG made a focused effort to upgrade the IT inventory. By upgrading, virtualizing, and consolidating the existing IT inventory into a high-density computing environment, the team reduced the IT loads by about 42%. These changes reduced the required electrical and cooling capacities.

• Step 2: Updated IT Equipment, Increased Economization, and Decoupled Data Center from the Central Plant. Next, CEG coupled the IT upgrades with a series of HVAC improvements that leveraged modern data center cooling strategies like expanded operating temperatures and containment strategies. Critically, these compounding upgrades also allowed for a complete decoupling of the data center from the central cooling plant so that the building’s chillers, cooling towers, and pumps could be setback. This was a major operational improvement, as prior to the ESPC, the data center’s cooling design required the central chiller plant to run 24/7, including during nighttime and weekend unoccupied periods. To achieve this, CEG:

  • Installed new IT equipment that was rated for higher operating temperatures, and implemented hot aisle/cold aisle containment for server racks with physical barriers between the aisles to reduce mixing of cold supply air and hot return air. 

  • Adjusted temperature and humidity setpoints based on revised ASHRAE guidance for data centers, to allow for a wider range of space conditions and for more air-side economization.

  • Installed louvers to allow air-side economization whenever outside enthalpy was lower than the return air enthalpy, resulting in over 7,000 hours/year of full economization.

  • Replaced existing water-cooled CRAH units with two air-cooled CRACs, sized to meet the data center cooling load and facilitate the air-side economization detailed above. This measure eliminated the need for the building’s main chilled water plant to run continuously during nights and weekends and improved cooling resiliency.

• Step 3: Redesign Infrastructure to Improve Resilience. The ESPC upgraded the building’s electrical systems by adding energy storage (with 2N redundancy), installing back-up natural gas generation, and increasing redundancy of critical components (i.e., 2N redundant PDUs and power distribution, 2N redundant cooling). The redundant power system included installation of dual lithium-ion battery energy storage systems with a natural gas-powered standby generator that can provide sufficient backup power to critical infrastructure through an extended electrical grid outage. Redundancy was introduced across the critical electrical systems from the generation sources (grid or genset) to the parallel UPS and redundant PDUs. These power infrastructure measures reduced energy waste and vulnerability to system failure.

Other Results

CEG coordinated extensively with CalEPA to ensure that the data center remained operational during implementation. CEG also worked closely with the client so that IT consolidation occurred in parallel with the infrastructure upgrades. As a result of these efforts, the data center footprint was reduced by 40%, freeing up ~4,700 SF of valuable real estate.