New Limits under Consideration in ENERGY STAR Computers Version 8.0

Tue, 05/08/2018 - 12:29 -- MrGreen

On March 12, the ENERGY STAR Computers team met with stakeholders to discuss desktop computer categorization for total energy consumption (TEC) limits as groundwork for ENERGY STAR Computers Version 8.0.

Studies measuring the TEC for desktop and all-in-one computers have shown the importance of categorization in implementing appropriate energy consumption limits.  Washington D.C.-based Information Technology Industry Council (ITI) compared 214 computers in its database and found large variation in TEC. Effectiveness of ENERGY STAR Computers’ current method for categorization, along with two possible alternatives, was discussed at the meeting:


ENERGY STAR Computer Versions 6.1 and 7.0 adopt the P-Score categorization, which are often criticized for their weak correlation with the TEC. According to Colorado-based Xergy Consulting, the P-Score ignores growth in high-bandwidth interfaces and does not capture differences in amenity between large and small form factors and power supply upsizing.

Expandability Score

California Energy Commission’s (CEC) computer regulations currently use the Expandability Score system for categorization, which starts with a base score of 100 points, accounting for basic components found in most desktops, and then adds an interfaces expandability score (for USB, Thunderbolt, PCI, IDE, SATA, etc.) as well as energy adders for system memory, external hard drives, etc.  Strong correlation between the base TEC and Expandability Score supports the use of the latter to set limits.  The CEC believes that such a scoring system reduces the number of different domestic standards for computer energy efficiency, and harmonization with the Expandability Score framework increases California Title 20 compliance rate.

Simplified Expandability Score

As an alternative solution, a Simplified Expandability Score (SES) was proposed by California’s Investor-Owned Utilities (IOUs). The system uses a combination of power supply sizing and expandability attributes to differentiate amenity and performance among categories for high-expandability gaming computers, mainstream business PCs, and low-expandability mini-desktops.  The SES concept would track the TEC well, achieving similar segmentation as the CEC Expandability Score but with fewer attributes and less complexity.

Finally, the Canadian Standards Association (CSA) Group led a discussion on how to evolve test and measurement procedures for computers to reflect more accurately actual, real-world energy use.  Suggested use cases included web browsing, video and audio streaming, and real-world idle, which have the largest share of the typical computer duty cycle.

The U.S. Environmental Protection Agency (EPA) has taken a two-pronged approach to revision of the ENERGY STAR computer specification, with Version 7.0 focusing on notebook computers and Version 8.0 on desktop computers. A copy of the current Version 7.0 program specification can be found here. Copies of the Version 8 announcement and recent stakeholder webinar presentation are available for download on the ENERGY STAR computer specification development webpage.