3. Definitions
Key terms used throughout the methodology.
Chiplet. One of several small dies that together make up a processor package. Modern server CPUs pair compute chiplets, which hold the cores, with an IO die that holds the memory and PCIe controllers.
Cloud Provider. A company that offers cloud computing services and solutions to businesses and individuals. In this methodology, the term refers to AWS, Azure, and GCP.
CO₂e. Carbon dioxide equivalent. A metric that expresses the global warming potential of various greenhouse gases as the equivalent amount of carbon dioxide.
Data Centre. A facility composed of networked computers and storage used to process, store, and distribute data.
Die. In semiconductor manufacturing, a small block of semiconducting material on which a functional circuit is fabricated.
Electricity Generation Water Consumption. The water consumed during the generation of the electricity that a data centre draws, reflecting the regional generation mix. Classified as Scope 2.
Electricity Grid. The interconnected network for delivering electricity from producers to consumers, consisting of generating stations, transmission lines, and distribution lines.
Embodied Emissions. The greenhouse gas emissions associated with the manufacturing and transport of physical server components, together with estimated allowances for end-of-life processing and for data centre shell construction.
Emissions. The discharge of greenhouse gases into the atmosphere, expressed in CO₂e.
Expansion Card. A small printed circuit board plugged into a server's motherboard rather than built onto it. The network interface card, the PCIe riser cards and the RAID controller card are counted as a fixed value per server.
GHG. Greenhouse gases. Gases that trap heat in the atmosphere and contribute to the greenhouse effect and global warming.
GPU. Graphics processing unit. In this methodology, any accelerator card counted separately from the CPU, including NVIDIA and AMD data centre GPUs, FPGAs and cloud providers' own inference and training chips.
Grid Carbon Intensity. The average emissions produced per unit of electricity consumed from a given electricity grid, varying by region and time. Abbreviated as GCI.
HBM. High bandwidth memory. Stacked memory placed beside a GPU die on the same package. Its capacity is the main driver of a GPU's manufacturing footprint after the die itself.
Instance. In cloud computing, a virtual server used for running applications on the cloud.
IO Die. The die in a chiplet processor that carries the memory controllers, PCIe lanes and other input and output logic. Counted in the CPU die area alongside the compute chiplets.
IT Cooling Water Consumption. The water consumed on site in cooling the IT equipment of a data centre, for example through cooling loops, evaporative cooling, and humidification. Classified as Scope 1.
IT Electricity Usage. The sum of electricity consumed by the four component categories within the IT equipment of a data centre, being computation, memory, storage, and networking. Abbreviated as ITEU.
kWh. Kilowatt-hour. The unit of energy consumption used to calculate associated GHG emissions based on the carbon intensity of the energy source.
LCA. Life Cycle Assessment. A method for assessing the environmental impacts associated with all stages of a product's life, from raw material extraction through manufacturing, use, and end of life.
Location-Based Method. A method for calculating carbon emissions based on the average emissions intensity of the electricity grid on which energy consumption occurs.
NAND Generation. The layer count of the 3D NAND flash in an SSD, such as 64, 128, 176 or 232 layers. A taller stack holds more data per cm² of die and costs more to make per cm², so both the die density and the die coefficient used for SSDs depend on it.
Power Usage Effectiveness. A ratio expressing the energy efficiency of a data centre, defined as Total Facility Energy divided by IT Electricity Usage. A PUE of 1.0 would indicate no energy overhead beyond the IT equipment itself. Abbreviated as PUE.
Process Node. The feature size of a chip's manufacturing process in nanometres, such as 5 nm or 14 nm. A newer node takes more lithography energy and more process gas per cm² of wafer, so the die coefficient used for CPUs and GPUs depends on it.
Public Cloud. A model of delivering computing services over the internet through third-party providers, typically on a pay-as-you-go basis, without the user owning or maintaining the underlying physical infrastructure.
Recycled Content Method. The GHG Protocol Product Standard's method for end-of-life accounting in which no credit is taken for material recycled at end of life. Used here where cloud hardware recycling is neither under Greenpixie's control nor visible to it.
Semiconductor. A material with controllable electrical conductivity used in creating electronic components such as transistors and integrated circuits in computer hardware.
Server. A computer or system that provides resources, data, services, or programs to other computers over a network.
SKU. Stock Keeping Unit. In cloud billing, a distinct combination of service, resource type, region, and pricing tier that appears as a line item on a cloud usage report.
Thermal Design Power. The maximum heat a chip is designed to produce under sustained load, in watts. Abbreviated as TDP. The thermal solution term of the GPU formula scales with it.
Total Facility Energy. The total energy consumed by a data centre, comprising both IT Electricity Usage and facility overhead such as cooling, lighting, and power distribution. Abbreviated as TFE.
Usage Emissions. The greenhouse gas emissions arising from the electricity consumed during cloud operations, calculated by multiplying Total Facility Energy by Grid Carbon Intensity. Abbreviated as UE.
vCPU. Virtual central processing unit. The standard unit of compute capacity allocated to a cloud instance, representing a share of a physical processor core.
Water Usage Effectiveness. The ratio between the water consumed by data centre systems and the energy consumed by the IT equipment, expressed in litres per kilowatt-hour. Abbreviated as WUE.