4. Methodology Overview
How the methodology works at a high level.
Greenpixie's region scoring methodology produces four scores for each public cloud region of each supported provider, being a carbon grade, a water stress category, a pricing score, and an availability score.
The methodology operates through four parts, being carbon intensity calculation, water stress assignment, price scoring, and availability counting. Section 7 describes each in detail. Together they produce the scores published on the region scorecard.
Carbon intensity calculation averages the hourly grid carbon intensity factors for the grid serving each region into a single figure. Water stress assignment matches each region to the Aqueduct 4.0 area covering its location and carries the published category through unchanged.
Price scoring works around two obstacles. Prices arrive in units that cannot be added together, and regions sell different mixes of products, so a region selling only inexpensive products would appear inexpensive whatever its prices were. Price list entries are grouped into product categories, entries inconsistent with the same product category elsewhere are removed, and a comparison basket is fixed from the categories priced widely enough across a provider's regions. Each price then becomes a price ratio against the median price for its product category, and a region's relative cost percentage is the median of its ratios.
Availability counting compares the product categories a region prices against the count priced by the provider's most complete region.
Greenpixie assigns the relative cost percentage, the service availability percentage, and the average grid carbon intensity to bands using Jenks natural breaks, and publishes the resulting grades alongside them.