Chapter 09 · Sustainability & AISustainability & AI
Carbon usage effectiveness (CUE)
Definition
A data-centre metric relating total greenhouse-gas emissions associated with a facility's energy use to the energy delivered to IT equipment.
References
This source provides part of the technical or institutional basis for the definition.
This source supports the explanation of how the term is applied, measured or governed in practice.
Overview
What it means
Developed by The Green Grid as a companion to PUE and standardised in the ISO/IEC 30134 series, CUE adds a carbon dimension to facility energy use. It remains an operational facility metric: it does not by itself capture embodied emissions from servers, chips, construction or the wider AI supply chain.
How it is used
CUE is used in data-centre sustainability reporting and procurement comparisons, complementing energy-efficiency KPIs with an emissions view. In practice many operators now report carbon via corporate GHG accounting instead, with CUE as a facility-level diagnostic.
Why it matters
CUE helps distinguish energy efficiency from low-carbon operation, but it is not a complete life-cycle carbon footprint or an overall sustainability score. It should be read alongside hardware, supply-chain and full greenhouse-gas accounting.