🌿CUE
When considering environmental sustainability and climate change, greenhouse gas contribution is a major area of focus. In assessing the sustainability of a data center, we must examine how carbon effective its operations are. Carbon Usage Effectiveness (CUE), another metric by the Green Grid aims to do exactly that.
Formula
Defined in above, CUE has a unit of carbon dioxide per energy use, with unit prefixes to be determined and properly communicated when reporting. Note that the numerator should included equivalent CO2 emissions from other greenhouse gases. The metric has a target minimum value of 0.0 indicating no carbon emissions associated with DC operations and features no upper bound. CUE alone does not encompass the life cycle assessment of a data center, simply the sustainability of the energy used.
Evaluation
The calculation of Total CO2 Emissions Caused by Data Center Energy is not clearly standardized and can be difficult to do. Each power generation source will incur different carbon emissions and access to this data is often rare or lacking. As such best guest efforts must be made. Calculations should also take into account any emissions from onsite electricity generation.
CUE allows data center operators and relevant stakeholders to see opportunity for work- load scheduling based on emissions and procurement of more sustainable energy. Additionally, unlike many metrics mentioned thus far, CUE can be used as a comparison metric between data centers as it is clear that regional differences will affect the value. This can even be useful in determining the construction site of a new data center.
Improvement Strategies
Sourcing greener energy
Load shifting
Onsite green energy production
Wait for improvements in CO2 electricity emissions at a national level
Sources
[1] WP#32 - CARBON USAGE EFFECTIVENESS (CUE): A GREEN GRID DATA CENTER SUSTAINABILITY METRIC [pdf]
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