# Inputs and Evidence Sources | Embodied Emissions methodology
Source: https://greenpixie.com/docs/methodology/cloud-embodied-emissions/inputs-and-evidence-sources

The data categories and evidence sources the methodology draws on.

The methodology draws on the following categories of inputs.

## 5.1 Cloud Usage Data [#51-cloud-usage-data]

To produce a figure for a unit of cloud usage, the methodology requires the usage attributes that identify it, being the cloud provider, the service or SKU, the usage period, and the quantity or duration of use. These attributes are read from the customer's cloud usage data, most commonly a cloud usage report. No cost or spend information is required.

## 5.2 Instance Specification Data [#52-instance-specification-data]

Per-instance vCPU counts, memory allocations, processor models, attached drive counts and capacities, and accelerator attachments come from each cloud provider's own published specifications. Those are the AWS instance type documentation, the Azure virtual machine sizes documentation, and the Google Cloud machine family documentation.

## 5.3 Hardware Specification Data [#53-hardware-specification-data]

Die areas, process nodes, high bandwidth and graphics double data rate memory capacities, and thermal design power figures come from the chip vendor's own documentation where the chip vendor publishes them. Where it does not, those quantities come from third-party hardware specification databases. Where a cloud provider designs its own processor and publishes neither a die area nor a process node, Greenpixie estimates those quantities and records each as an estimate.

## 5.4 Semiconductor Manufacturing Data [#54-semiconductor-manufacturing-data]

Greenpixie derives the emissions of fabricating a unit area of silicon at a given process node from the architectural carbon modelling work of Gupta, U. et al., which publishes fabrication energy per unit of wafer area, process gas emissions, and a materials footprint for each process node, together with the model that combines them. Greenpixie takes the carbon intensity of the electricity supplying a fabrication plant, and the yield assumption that goes with it, from the same work.

## 5.5 Memory and Storage Die Density Data [#55-memory-and-storage-die-density-data]

Storage capacity is converted into die area using the die density held for each memory and NAND flash generation. Those densities are adapted from third-party semiconductor die analyses of production parts and from open life cycle inventory datasets. The coefficients applied to the resulting area, and the fixed values added for the module and drive assemblies around it, are adapted from the life cycle inventory published by Gröger, J. et al. at the German Federal Environment Agency.

## 5.6 Published Hardware Life Cycle Assessments [#56-published-hardware-life-cycle-assessments]

Values for the fixed server components are adapted from the cradle-to-grave LCAs Dell publishes for its PowerEdge rack servers. Dell states that each was prepared by an external consultancy to ISO 14040 and ISO 14044. Greenpixie derives the accelerator memory, board, and cooling solution terms from the product carbon footprint summaries NVIDIA publishes for its HGX baseboards, each critically reviewed for conformance to ISO 14067 on primary supplier data. Transport and end-of-life rates are adapted from those Dell assessments, from the UL-verified sustainability reports Seagate publishes for its enterprise drives, from the ADEME-funded cradle-to-grave assessment of a data centre accelerator by Falk, S. et al., and from the ISO-aligned assessment Cisco publishes for a data centre switch.

## 5.7 Hardware Lifetime Data [#57-hardware-lifetime-data]

The operating life a server is assumed to have follows the useful life the three supported cloud providers state for their own server and networking equipment in their published financial reporting. Greenpixie amortises the embodied emissions of the server, of the drives inside it, and of the drives behind storage a cloud provider sells as a separate service over that lifetime.

## 5.8 Regulatory and Standards Sources [#58-regulatory-and-standards-sources]

The methodology references the GHG Protocol Corporate Standard, the GHG Protocol Scope 3 Standard, the GHG Protocol Product Life Cycle Accounting and Reporting Standard, and ISO 14064-1. Regulatory context is drawn from the EU Corporate Sustainability Reporting Directive, the UK Streamlined Energy and Carbon Reporting framework, and the US Securities and Exchange Commission climate disclosure guidance.