If carbon accounting still feels like a once-a-year spreadsheet chore, this guide is for you. We’ll show you how to build a clean, auditable baseline in Excel, then level it up into Microsoft Sustainability Manager so it actually drives decisions—not just disclosure.
We’ll keep it practical: what data to collect, how to organise your tabs, where NGER methods apply for Scope 1 and 2, and how to tackle Scope 3 with NGA or GHG Protocol guidance without getting lost in the weeds.
By the end, you’ll have a simple operating model you can run month to month, with clear factors, controls, and a path to automation. Less fiddling, more progress.
TL;DR
- In Australia, estimate Scope 1 and Scope 2 using the NGER Measurement Determination methods and factors (latest in-force version). Federal Register of Legislation
- For Scope 3, use NGA Factors and the GHG Protocol Scope 3 Calculation Guidance, supplemented with credible industry factor sets where needed; document method, source, vintage and GWP set. DCCEEW+1
- Start in a structured spreadsheet to get ownership and controls right, then move to Microsoft Sustainability Manager for governed factor libraries, mappings, workflows and audit trails. Microsoft Learn
Scope 1 & 2 → NGER Measurement Determination: use the prescribed methods and factors for fuels, stationary energy and electricity. Ensure you’re on the current in-force Determination for the reporting period. Federal Register of Legislation
Scope 3 → NGA / GHG Protocol: start with National Greenhouse Accounts (NGA) Factors and apply the GHG Protocol Scope 3 Calculation Guidance to choose spend, activity or supplier-specific methods.
Where NGA does not cover a need, use credible sector sources (for example IEA electricity for international operations, DEFRA waste/water) and record them in a factor register. DCCEEW+1
If you don’t have a carbon accounting tool, start in a structured spreadsheet to get ownership and controls right, then move to a tool such as Microsoft Sustainability Manager for governed factor libraries, mappings, workflows and audit trails.
Spreadsheet build: the practical, auditable way to start
Create these tabs (copy this structure exactly – it scales and auditors like it):
- Parameters
Period, entities, boundary method (equity share / control), GWP set, rounding rules. - Factor Register(single source of truth)
Columns: Factor Name | Scope | Category | Source (NGER/NGA/other) | Jurisdiction | Vintage (year) | Unit | GWP version | URL to source | Notes (assumptions/limits).- Populate NGER factors/methods for Scopes 1-2. Federal Register of Legislation
- Populate NGA / GHG-aligned factors for Scope 3. DCCEEW+1
- Reference Data
Sites, NMIs/meters, cost centres, vehicles, fuel types/units, suppliers, GL spend categories, travel modes & cabin classes, waste streams/treatments. - Raw Activity – Energy
- Electricity: site, NMI, month, kWh, invoice #, period start/end.
- Gas: site, GJ or m³, invoice #.
- Fuels: site/vehicle, litres, card batch, dates.
- Raw Activity – Refrigerants
Gas type, kg added/leaked, asset ID, service date. - Raw Activity – Scope 3 Priority
- Travel: trip legs, cabin class, km.
- Freight: tonne-km, mode, lane.
- Waste: tonnes by stream and treatment.
- Purchased Goods & Services: supplier, category, spend (start with spend-based; plan to upgrade to activity/supplier data guided by GHG Protocol). GHG Protocol
- Calc – Scope 1 (NGER)
Formula pattern:tCO₂-e = Activity × NGER factor × (unit conversion)(CH₄/N₂O included per NGER method). Keep method references in a side column (e.g., “NGER s.2.4.1 Method 1”). Federal Register of Legislation - Calc – Scope 2 (NGER)
- Location-based: kWh × NGER jurisdictional factor.
- If you disclose any additional view (e.g., supplier statements), keep it clearly separate; your NGER calculation remains authoritative. Federal Register of Legislation
- Calc – Scope 3 (NGA / GHG)
Examples:- Travel: passenger-km × NGA/airline factor.
- Freight: tonne-km × mode factor.
- Waste: tonnes × treatment factor.
- Purchased goods/services: spend × intensity; mark categories targeted for activity/supplier data upgrades. DCCEEW+1
- Controls & QA
Completeness (expected vs received invoices), duplicates, unit checks, outlier flags, period gaps; Change Log noting any restatements when factors or methods change. - Inventory – Roll-Up
Pivot by Scope / Category / Site / Month; link to charts, variance analysis, and finance reconciliation. - Disclosure Pack
Boundary memo, methodology note (by category), factor list with links, assumptions, exclusions and uncertainties — ready for assurance.
Moving from spreadsheet to Microsoft Sustainability Manager (MSM)
Why move: once the processes are proven in Excel, MSM gives you governed factor libraries, reference data mappings, workflow, evidence attachments and audit trails. Microsoft Learn
Mapping guide:
- Factor Register → Factor libraries: import NGER (Scopes 1–2) and NGA/sector libraries (Scope 3) as separate libraries with vintages, then map to reference data so the right factor is auto-applied. Microsoft Learn
- Reference Data: create tables for sites, meters, vehicles, suppliers.
- Raw Activity tabs → Ingestion: upload CSV/Excel or automate via Power Platform / Azure Data Factory pipelines.
- Calc sheets → Calculation profiles: MSM applies mapped factors to each activity record; re-run calculations when factor libraries update. Microsoft Learn
- Controls & QA: use review/approval workflows and attach invoices/meter files; MSM maintains change history for assurance.
- Reporting: Power BI dashboards for trends, intensity metrics and disclosures (ASRS-aligned pack if you need it later alongside assurance phasing). auasb.gov.au
90-day accelerator (kept, aligned to NGER/NGA/GHG)
- Weeks 1–2: Boundary definition; NGER (S1–S2) and NGA/GHG (S3) factor libraries set; spreadsheet prototype with QA controls. Federal Register of Legislation+2DCCEEW+2
- Weeks 3–6: Automate electricity/fuel data loads; MSM factor mappings; first MSM runs; baseline Power BI. Microsoft Learn
- Weeks 7–10: Extend Scope 3 categories; supplier engagement to replace spend-based with activity data; assurance readiness check (evidence pack complete). GHG Protocol+1
Pitfalls to avoid
- Mixing factor vintages mid-period or using NGA where NGER is required for Scopes 1–2; always cite the Determination and period. Federal Register of Legislation
- Using ad-hoc web factors for Scope 3 without NGA/GHG method rationale, source links and GWP version. DCCEEW+1
- No audit trail for spreadsheet changes; unprotected factor cells; undocumented restatements.
Next Steps
Book a 90-minute workshop: “Sustainability Accelerated” – we map your current workbook, configure factor libraries, and stand up your first automated calculation.
