# Introduction | Compute methodology
Source: https://greenpixie.com/docs/methodology/cloud-compute/introduction

Purpose, audience, and context of the methodology.

This document describes Greenpixie's methodology for calculating the electricity consumed by the hardware of a public cloud compute instance, being its processor, its memory, its attached drives, and any accelerators. It is intended for customers, partners, procurement teams, auditors, regulators, and technically literate readers who require a clear understanding of how Greenpixie derives its cloud compute energy figures.

The parent cloud methodology states why organisations reporting under Scope 3 need cloud emissions data at the level of the individual unit of cloud usage. Where the unit is a compute instance, this document produces its Compute Electricity, traced back to the instance family, the processor, and the instance size it was calculated from. The parent methodology calculates the facility energy, usage emissions, and water consumption of that unit from it.

This document covers the computation, memory, and storage components of IT Electricity Usage for an instance, being everything physically part of the machine a customer is sold. It forms part of the [*Greenpixie Methodology for Cloud Emission Measurement*](/methodology/cloud), which defines the evaluation boundary, the facility overhead and grid carbon intensity treatment, the water calculation, and the embodied emissions calculation. Storage sold as its own service, and not with an instance, is outside the scope of this document. This methodology supports AWS, Azure, and Google Cloud.

The sections that follow describe the scope, inputs, calculation process, quality controls, governance, and outputs of this methodology.