Most Scope 2 carbon calculators I've reviewed do one of two things: hardcode a single global average factor and call it a day, or reach for a third-party API that charges per lookup and introduces a network dependency into a calculation that should be instant and deterministic. Neither is acceptable if you're building tools that practitioners will use to file regulatory disclosures. Here's how I structure the grid emission factor lookup at GreenCalculus.com , using a flat data object sourced from IEA 2026, DEFRA 2025, and EPA eGRID 2024 — with zero runtime dependencies.…