# What is CUE and how is it different from reporting data centre Scope 2?

Canonical: https://senseible.earth/answers/data-centre-cue-carbon-usage-effectiveness

CUE, carbon usage effectiveness, is the CO2 from all energy a data centre uses divided by its IT equipment energy, in kg CO2 per IT kWh. Scope 2 is an absolute total of purchased electricity emissions only. CUE is a ratio, includes diesel generators, and is for tracking efficiency, not for your inventory.

## The formula

CUE = total CO2 from data centre energy / IT equipment energy in kWh. Total CO2 covers grid electricity and on-site generation such as diesel sets. For a site that runs only on grid power, CUE equals PUE x the grid factor, so with grid power alone it moves with both cooling efficiency and the grid's carbon intensity.

## Four ways it differs from Scope 2

- Units: CUE is kg CO2 per IT kWh; Scope 2 is tonnes CO2 for the year.
- Sources: CUE adds diesel generator fuel, which your inventory puts in Scope 1, not Scope 2.
- Boundary: CUE covers only the data centre space. Scope 2 covers every site in your organisational boundary.
- Purpose: CUE compares a site against itself over time. Scope 2 goes into a GHG inventory and BRSR or buyer reports.

## Location-based or market-based

CUE can be computed with either grid factor. State which. In India the location-based figure uses the CEA weighted average; a market-based figure needs certificates or a green tariff with matching units. Do not mix them across years or sites.

## For colocation customers

Your provider's CUE describes their whole site. Your own emissions come from your metered IT kWh x their PUE x the grid factor, and whether that sits in your Scope 2 or Scope 3 depends on who buys the electricity. Ask for the provider's CUE basis and period before quoting it.

## Illustrative example: one year with a diesel backup set

- Grid electricity: 510,000 kWh x 0.710 = 362,100 kg CO2 (Scope 2)
- DG diesel: 4,000 litres x 2.68 = 10,720 kg CO2 (Scope 1)
- IT energy at UPS output: 300,000 kWh
- CUE = (362,100 + 10,720) / 300,000 = 1.24 kg CO2 per IT kWh
- Grid only check: PUE 1.70 x 0.710 = 1.21, matching 362,100 / 300,000

Figures are illustrative. Factors: CEA CO2 Baseline Database version 21.0 and the IPCC 2006 diesel default.

## What Senseible does here

Senseible reads electricity bills (billing period, tariff category, sanctioned load, units) and applies the CEA grid factor of 0.710 kg CO2 per kWh, CO2 Baseline Database version 21.0, for location-based Scope 2, and reads diesel invoices at 2.68 kg CO2 per litre for Scope 1.

- [PUE formula and what a good PUE is](https://senseible.earth/answers/pue-formula-and-good-pue)
- [Colocation emissions with PUE](https://senseible.earth/answers/colocation-data-centre-emissions-with-pue)
- [Cloud and data centre emissions calculator](https://senseible.earth/calculators/cloud-data-centre-emissions)

Sources: [ISO/IEC 30134-8, Data centres key performance indicators, Part 8: Carbon usage effectiveness (iso.org)](https://www.iso.org), [GHG Protocol Scope 2 Guidance](https://ghgprotocol.org/scope-2-guidance), [CEA CO2 Baseline Database](https://cea.nic.in/cdm-co2-baseline-database/?lang=en)

Last reviewed 2026-10-18. Check the current edition of ISO/IEC 30134-8 before citing it in a report.