GHG Inventory Scope 1-2-3 for SMEs: A 2026 Practical Guide

What a GHG inventory is, and why SMEs should act now

A greenhouse-gas (GHG) inventory is the first, non-negotiable step of any ESG or Net Zero journey: what you don't measure, you can't manage, reduce, or prove to customers. The most widely used international framework is the GHG Protocol Corporate Standard, which splits emissions into three scopes to avoid double-counting when many companies report along one value chain.

Three pressures are converging on Vietnamese SMEs at once:

1. Domestic law: Decree 06/2022/ND-CP sets the basis for mandatory inventories and for allocating emission quotas over 2026–2030.
2. Carbon market: Vietnam has launched a pilot Emissions Trading Scheme (ETS) for three high-emitting sectors (coal thermal power, steel, cement), piloting 2025–2028 and going fully operational from 2029.
3. Supply chain: selling to EU customers or large corporates means being asked for product-level emissions — which is the customer's Scope 3 and the SME's own Scope 1+2.

SMEs should not wait until they land on the mandatory list. Measuring early means having the numbers ready when partners ask — and avoiding legal exposure from unsubstantiated "green" claims.

The three scopes, defined

The difference between the scopes is about who controls the emitting source and where in the value chain the emission occurs (per the GHG Protocol):

Table 1 — Scope 1, 2, 3 under the GHG Protocol Corporate Standard

Scope	Nature	Typical example at a manufacturing SME	Who controls it
Scope 1 — direct	Emissions from sources the company owns or controls	Boilers, furnaces; company vehicles; refrigerant leaks	The company
Scope 2 — indirect energy	Emissions from purchased electricity, steam, heat, cooling	Grid electricity used for production lines, lighting, compressors	Energy seller (but consumed by the company)
Scope 3 — value chain	All other indirect emissions, upstream & downstream (15 categories)	Purchased materials, outsourced transport, business travel, use of sold products, end-of-life	Suppliers / customers

An important technical note: Scope 2 has two methods — location-based (national grid-average factor) and market-based (contractual factor, e.g. renewable certificates). SMEs should start with location-based because the data is easier to obtain.

The 15 Scope 3 categories

Scope 3 is usually the largest part of a company's total emissions, yet the hardest to measure because it sits outside the control boundary. The GHG Protocol splits Scope 3 into 15 categories — 8 upstream and 7 downstream. SMEs do not need to measure all 15 at once. Best practice is a screening assessment to find the 2–3 material categories (usually category 1 — purchased goods, and 4/9 — transport), then measure those in depth first.

Table 2 — The 15 Scope 3 categories per the GHG Protocol Corporate Value Chain Standard

#	Category	Chain position
1	Purchased goods and services	Upstream
2	Capital goods	Upstream
3	Fuel- and energy-related activities (not already in Scope 1 & 2)	Upstream
4	Upstream transportation and distribution	Upstream
5	Waste generated in operations	Upstream
6	Business travel	Upstream
7	Employee commuting	Upstream
8	Upstream leased assets	Upstream
9	Downstream transportation and distribution	Downstream
10	Processing of sold products	Downstream
11	Use of sold products	Downstream
12	End-of-life treatment of sold products	Downstream
13	Downstream leased assets	Downstream
14	Franchises	Downstream
15	Investments	Downstream

Which standards and rules apply?

Vietnamese rules define who must report and to whom; international standards define how to measure and disclose. Key thresholds under Vietnamese guidance: facilities emitting ≥3,000 tonnes CO₂e per year (or large energy users ≥1,000 TOE/year) on the Decision 13/2024 list are mandatory reporters. Decision 13/2024/QD-TTg took effect on 1 October 2024, replacing Decision 01/2022, and covers 2,166 facilities across 6 sectors (Energy; Transport; Construction; Industrial processes; Agriculture, forestry & land use; Waste). Internationally, IFRS S1 & S2 (ISSB) were issued June 2023, for annual reporting periods from FY2024, subject to each jurisdiction's adoption; S2 requires disclosing Scope 1, 2 and 3, with a first-year transition relief for Scope 3.

Table 3 — Frameworks & rules relevant to a GHG inventory for SMEs

Framework / instrument	Role	Key point
GHG Protocol Corporate Standard	Standard for measuring & calculating emissions (Scope 1-2-3)	The common foundation that almost every other standard references
ISSB — IFRS S1 & S2	Standard for disclosing sustainability & climate information to capital markets	Issued June 2023, for reporting periods from FY2024 (subject to each jurisdiction's adoption); S2 requires Scope 1, 2, 3 disclosure, with a first-year relief for Scope 3
Decree 06/2022/ND-CP	Vietnam's rule mandating inventories & emissions mitigation	Basis for allocating emission quotas over 2026–2030
Decision 13/2024/QD-TTg	The list of facilities required to inventory GHGs	In force 1 Oct 2024, replacing Decision 01/2022; 2,166 facilities, 6 sectors
CBAM (EU)	The EU's carbon border adjustment mechanism	Requires EU importers to declare the embedded emissions of imports — creating Scope 3 pressure on Vietnamese suppliers

A 5-step GHG inventory roadmap for SMEs

Table 4 — A practical 5-step roadmap (framework only, no sample emission figures)

Step	What to do	Output
1. Define boundaries	Choose the consolidation approach (financial/operational); list facilities and equipment	Organizational & operational boundary map
2. Collect activity data	Electricity and fuel invoices, refrigerants, transport distances…	Monthly/annual activity-data table
3. Select emission factors	Use official factors (national/IPCC); state the source	Factor & source list
4. Calculate & allocate by scope	Multiply data × factor; assign to Scope 1/2/3	Emissions-by-scope table
5. Report & verify	Prepare the report; file under Vietnamese rules if in scope; consider independent verification	GHG inventory report

Anti-greenwashing

Every published emission figure or "green" claim must be measurable, sourced, and scope-transparent. Under Vietnamese law (Advertising Law, Consumer Rights Protection Law 2023, Environmental Protection Law 2020), misleading environmental claims are prohibited. This article therefore gives no specific carbon figures for any sample company — those depend on real activity data and must be computed by each business using official emission factors.

Under Vietnam's Advertising Law, Consumer Rights Protection Law 2023 and Environmental Protection Law 2020, environmental advertising and disclosures must be substantiated and must not be misleading.