Quantifying Data Center Scope 3 GHG Emissions to Prioritize Reduction Efforts

Overview

The starting point is that as operators switch to renewable electricity, Scope 2 shrinks and Scope 3 becomes the largest share. Scope 3 is dominated by the embodied carbon of IT and facility equipment plus upstream purchased energy. A carbon report that looks only at operating energy can therefore point a decision maker at the wrong target. The authors quantify this with a hypothetical but detailed example.

The reference model is a 1 MW, Tier 3 facility, 50% loaded, with an annual PUE of 1.34. It assumes N+1 power redundancy and chilled-water cooling, so it represents a mid-sized, redundant enterprise hall using half of its capacity. The IT mix is 94% servers with storage and 6% networking, and racks are 50% populated. Because these assumptions are explicit, a reader can adapt the model to their own site; rack fill and the IT load ratio matter most, since they set the basis on which embodied carbon is allocated.

The method is stepwise: embodied carbon is first separated into IT, facility infrastructure and subsystems. Embodied carbon is then allocated on the assumption that the installed IT fraction equals the IT load ratio. The paper also introduces a companion lifecycle CO2e calculator. This breakdown exists to rank which item deserves reduction effort first. IT equipment, facility infrastructure and subsystems each appear as a separate carbon line, so the discussion can focus on which line would give the largest drop rather than on the total alone.

The conclusion fits in two statements: once Scope 2 is decarbonised, Scope 3 is the largest emission source, and within it the embodied carbon of IT equipment dominates. The limit is that results rest on one hypothetical 1 MW model. A site with a different load ratio, cooling architecture or refresh cycle may see a different split, so the paper teaches the ranking logic rather than universal percentages.

Key points

1. Reference model: 1 MW, Tier 3, 50% loaded, annual PUE 1.34.
2. N+1 power redundancy and chilled-water cooling are assumed.
3. IT mix: servers with storage 94%, networking 6%; racks 50% populated.
4. Scope 3 becomes the largest source once Scope 2 is decarbonised.
5. IT equipment embodied carbon dominates within Scope 3.
6. Embodied carbon allocation assumes installed IT fraction equals IT load ratio.
7. Embodied carbon is separated into IT, facility infrastructure and subsystems.
8. A companion lifecycle CO2e calculator is introduced.

Using it in design

• Add embodied-carbon parameters to the catalog: kgCO2e per server, per kW of UPS or cooling, and per m2 of building.
• Produce the lifecycle carbon report split by Scope 1/2/3 and by IT versus facility.
• Default the IT refresh cycle to 4-5 years and let users change it.
• In renewable-supply scenarios, show the Scope 3 share separately so the reduction priority is visible.

Who should read it

Sustainability specialists doing carbon reporting and designers building catalog and lifecycle models.

Related standards

• GHG Protocol Scope 3 Standard
• ISO 14064
• EN 50600-4-8

Publication details

Authors

Paul Lin; Robert Bunger; Victor Avelar

Publisher

Schneider Electric

Year

2023

Document number

WP 99

Document language

English

Source type

Manufacturer

Access

Free to read

Licence

Copyright retained; citation only — the publisher’s terms apply to the original document

Citation