Add GHG Protocol v3 Tools documentation

Add a new Tools.md documenting the GHGP Framework tools for the GHG Protocol Corporate Standard v3. The file describes the layered architecture, four tool categories (source calculation, activity data, secondary data, supplemental reporting), and includes a published tools table with examples (Scope 1/2/3 tools, activity and secondary data tools) and IPFS timestamps for each tool. This provides a centralized reference for how activity data and emission factors feed into source calculations and supplemental reporting integrations.

Author: danielnorkin

Methodology Library/Greenhouse Gas (GHG)/GHG Protocol Corporate Standard v3/Tools/Tools.md

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+# GHG Protocol Corporate Standard v3 – Tools
+
+## Architecture
+
+The GHGP Framework is a layered architecture where tools and modules feed into the main policy framework:
+
+```
+  ┌─────────────────────────────────┐
+  │     Organizational Profile      │
+  ├─────────────────────────────────┤
+  │           Entities              │      ┌──────────────────────┐
+  ├─────────────────────────────────┤      │  Universal GHGP      │
+  │       Facilities/Assets         │  ──► │  Reporting Metrics   │
+  ├─────────────────────────────────┤      ├──────────────────────┤
+  │            Source               │◄──┐  │  Supplemental        │
+  ├─────────────────────────────────┤   │  │  Reporting           │
+  │         Activity Data           │   │  │  (CDP, SBTi, PACT,  │
+  └─────────────────────────────────┘   │  │   ESRS, SEC, etc.)   │
+                                        │  └──────────────────────┘
+                              ┌─────────┴─────────┐
+                              │  Emission Factors  │
+                              │ & Secondary Data   │
+                              └────────────────────┘
+```
+
+**Activity Data** tools and **Emission Factors / Secondary Data** tools sit at the bottom two tiers of the framework, feeding into the **Source** calculation layer in the main policy. Source calculation tools orchestrate the activity data and secondary data sub-tools to produce scope-level emission outputs.
+
+The tools fall into four categories:
+
+- **Source calculation tools** – Main orchestrators that chain sub-tools to calculate emissions (Scope 1: Stationary Combustion, Scope 2: Purchased Electricity, Scope 3 Category 1: Purchased Goods and Services)
+- **Activity data collection tools** – Capture and normalize primary activity data from meters, invoices, spend records, and ERP systems
+- **Secondary data tools** – Provide emission factors, global warming potentials, and other reference data from authoritative sources (EPA, Defra, IPCC, Green-e, PACT)
+- **Supplemental reporting tools** – Support additional reporting frameworks beyond core GHGP requirements (e.g., PACT v3 PCF)
+
+## Published Tools
+
+| Tool Name | Description | IPFS Timestamp |
+|-----------|-------------|----------------|
+| Scope 1: Stationary Combustion (Basic) | This tool calculates scope 1 emissions from stationary combustion based on quantities of fuel consumed or fuel spend. | 1772210533.900636000 |
+| Activity data tool (meter data) | Captures fuel consumption from meter readings, calculating usage as the difference between start and end readings. | 1772209946.573268000 |
+| Activity data tool (fuel invoice data) | Captures fuel consumption data from utility invoices, including relevant account, billing, and activity information. | 1772209962.643965000 |
+| Activity data tool (fuel spend data) | Captures fuel spend data and calculates fuel quantity from total spend and unit price. | 1772210035.254120311 |
+| Secondary data tool (emission factors) | Provides EPA emission factors (CO2, CH4, N2O) for 63 fuel types used in stationary combustion calculations. | 1772206222.392600000 |
+| Secondary data tool (global warming potentials) | Applies IPCC AR5 100-year Global Warming Potentials (CH4 = 28, N2O = 265) to convert greenhouse gas emissions into CO2e. | 1772206268.684341314 |
+| Scope 2 - Electricity (Basic) | This tool calculates scope 2 emissions from electricity based on electricity consumption. | 1773068363.452347908 |
+| Activity data tool (electricity meter data) | Enables detailed, interval-level recording and calculation of electricity consumption by capturing meter readings, associated metadata, and relevant activity and source information. | 1772640466.195961484 |
+| Activity data tool (electricity invoice data) | Captures electricity consumption from utility invoices, including relevant account, meter, billing, and activity information. | 1772640546.753614000 |
+| Secondary Data – tool – EPA GHG Emission Factors Hub (Electricity) | Standardizes the application of EPA electricity emission factors for calculating location-based Scope 2 emissions from electricity consumption. | 1772207115.765736339 |
+| Secondary Data – tool – Defra annual grid average emission factor (UK) | Standardizes the application of UK government annual grid average electricity emission factors for location-based Scope 2 reporting. | 1772207182.278682892 |
+| Secondary Data – tool – Green-e® Residual Mix Emission Rates | Applies Green-e residual mix emission factors to calculate market-based Scope 2 emissions for electricity consumption not covered by contractual instruments. | 1773067768.184586954 |
+| Secondary Data – tool – IPCC Fifth Assessment Report (AR5) | Applies IPCC AR5 Global Warming Potentials (GWPs) to convert greenhouse gas emissions into CO2e in accordance with internationally recognized climate science. | 1772207303.117956000 |
+| Scope 3 category 1: Purchased goods and services | Calculates scope 3 category 1 emissions from purchased goods and services. | 1772210426.122313000 |
+| Activity data tool (ERP product purchase) | Captures product purchase data from ERP systems, calculating unit quantities from total spend and unit price. | 1772213527.878249000 |
+| Secondary Data PACT v3 PCF | Applies supplier-specific Product Carbon Footprints (PCFs) per the PACT v3 standard. | 1772060075.935144000 |