The data center industry spoke, and ASHRAE listened. The
society is no longer proposing the use of PUE to set data center efficiency
standards in a new standard document that’s currently in the works.
ASHRAE drew criticism from some prominent industry voices last year after it released the first draft of standard 90.4, whose goal is to set energy efficiency standards specifically for data centers, recognizing that large stand-alone data centers need a special approach and cannot be lumped in with other building types as they currently are in standard 90.1.
Standard 90.4 is being created to work together with 90.1 and references a lot of definitions in the older standard, meant for all building types, except low-rise residential buildings.
ASHRAE doesn’t enforce compliance with its building standards, but they are a big deal because local building officials in the US use them extensively in building inspection and permitting.
PUE Gone from the Standard
The most controversial part of the first draft of 90.4, released for review and comment in February 2015, was its reliance on PUE, or Power Usage Effectiveness, as the data center energy efficiency metric.
Developed and promoted by The Green Grid, it is the industry’s most widely used (and most widely misused) metric, but the draft’s critics argued that using PUE in the ASHRAE standard would disadvantage colocation providers, whose facilities often run at partial load for the majority of their lifespan.
Put simply, the metric compares power consumed by IT to total power supplied to the facility. The bigger the portion of total power that doesn’t make it to IT equipment on the data center floor, the more inefficient the facility’s infrastructure is. Therefore, the more power IT equipment consumes, the better the overall PUE. If the success of your business relies to a great extent on having available capacity for more servers, that unused capacity will theoretically have negative impact on your PUE.
Second draft of 90.4, got rid of PUE, introducing instead two new efficiency metrics – Mechanical Load Component and Electrical Loss Component – but made PUE one of the alternative options for compliance.
The latest draft, released for review, gets rid of PUE altogether, replacing it in the alternative compliance section with a metric that combines MLC and PLC.
The point of the alternative compliance method is to give data center operators more flexibility. If the mechanical system doesn’t meet the required MLC level, but the electrical system is so efficient that it compensates for inefficiency of the mechanical system, they can use the combined metric to comply with the standard.
ASHRAE drew criticism from some prominent industry voices last year after it released the first draft of standard 90.4, whose goal is to set energy efficiency standards specifically for data centers, recognizing that large stand-alone data centers need a special approach and cannot be lumped in with other building types as they currently are in standard 90.1.
Standard 90.4 is being created to work together with 90.1 and references a lot of definitions in the older standard, meant for all building types, except low-rise residential buildings.
ASHRAE doesn’t enforce compliance with its building standards, but they are a big deal because local building officials in the US use them extensively in building inspection and permitting.
PUE Gone from the Standard
The most controversial part of the first draft of 90.4, released for review and comment in February 2015, was its reliance on PUE, or Power Usage Effectiveness, as the data center energy efficiency metric.
Developed and promoted by The Green Grid, it is the industry’s most widely used (and most widely misused) metric, but the draft’s critics argued that using PUE in the ASHRAE standard would disadvantage colocation providers, whose facilities often run at partial load for the majority of their lifespan.
Put simply, the metric compares power consumed by IT to total power supplied to the facility. The bigger the portion of total power that doesn’t make it to IT equipment on the data center floor, the more inefficient the facility’s infrastructure is. Therefore, the more power IT equipment consumes, the better the overall PUE. If the success of your business relies to a great extent on having available capacity for more servers, that unused capacity will theoretically have negative impact on your PUE.
Second draft of 90.4, got rid of PUE, introducing instead two new efficiency metrics – Mechanical Load Component and Electrical Loss Component – but made PUE one of the alternative options for compliance.
The latest draft, released for review, gets rid of PUE altogether, replacing it in the alternative compliance section with a metric that combines MLC and PLC.
The point of the alternative compliance method is to give data center operators more flexibility. If the mechanical system doesn’t meet the required MLC level, but the electrical system is so efficient that it compensates for inefficiency of the mechanical system, they can use the combined metric to comply with the standard.
