Scope 3 Category 1 Emissions

Q: How do you calculate Scope 3 category 1 emissions?

The GHG Protocol defines three methods: supplier-specific (the supplier provides actual product or service emissions — most accurate), hybrid (supplier-specific data for key suppliers, average data for the rest), and spend-based (spend multiplied by an emissions intensity factor such as DEFRA supply chain emission factors). Spend-based is the starting point for a baseline; supplier-specific or hybrid methods are required for CSRD supply chain responses and third-party verification.

Q: Does Scope 3 category 1 include professional services?

Yes. The GHG Protocol definition of purchased goods and services explicitly includes professional and business services such as legal, accounting, consulting, and IT software subscriptions, alongside physical goods.

Q: What is the difference between Scope 3 category 1 and category 2?

Category 1 covers purchased goods and services in general. Category 2 covers capital goods specifically — assets such as equipment, machinery, buildings and vehicles that the company uses for more than one year. Capital goods are separated because their emissions are amortised across the asset's useful life.

Scope 3 category 1 — purchased goods and services — is typically the largest single category in a company's GHG inventory. For most manufacturing businesses it represents between 70 and 90 per cent of total Scope 3 emissions; for services businesses the share is often lower, but still commonly 40 to 60 per cent of the total.

Despite its prominence, category 1 is also one of the harder categories to quantify reliably. Understanding the three calculation methods the GHG Protocol defines, and knowing which is appropriate at each stage of maturity, is the practical starting point for any category 1 programme.

What does Scope 3 category 1 cover?

Per the GHG Protocol Scope 3 Standard, category 1 covers cradle-to-gate emissions from all goods and services a company purchases or acquires that are not produced by the company itself.

Included

Raw materials and commodities
Manufactured components
Professional services (legal, consulting)
IT hardware and software
Office consumables and stationery
Packaging materials

Excluded

Capital goods (category 2)
Purchased fuel (category 3)
Purchased electricity (category 4)
Other defined categories

The most common classification error is confusing category 1 and category 2. Capital goods — machinery, vehicles, buildings — belong in category 2, where emissions are amortised across the asset's useful life. Everything a company buys to consume or incorporate into its products typically falls under category 1.

The three calculation methods

The GHG Protocol defines three approaches for category 1, in descending order of accuracy and ascending order of practicality. Most organisations use a combination of all three.

1
Supplier-specific method. The supplier provides ISO 14067 product carbon footprint data. Most accurate — but requires suppliers to have done their own carbon accounting.
2
Hybrid method. Supplier-specific data where available; EEIO factors for the remainder. Most practical for large, diverse supply bases.
3
Spend-based method. Spend × EEIO emission intensity factor (e.g. DEFRA supply chain factors). Practical baseline — not an end state for CSRD or ISO 14064-3 assurance.

For CSRD supply chain data requests and ISO 14064-3 verification, supplier-specific or hybrid methods are strongly preferred. A spend-based baseline is a useful starting point, but not an end state for companies with significant reporting obligations.

Why category 1 is harder than it looks

The spend-based method sounds simple — take the purchase ledger, apply an emission factor, sum the result. In practice it carries significant uncertainty: EEIO factors carry uncertainty ranges of 30 per cent or more, a single spend category may map to several codes with different intensities, and foreign-currency purchases introduce exchange-rate effects.

The supplier-specific method avoids averaging errors but requires suppliers to have their own carbon accounting in order. Most SMEs do not yet. The CSRD reporting wave is accelerating supplier data availability — but coverage remains uneven.

The practical answer is a hybrid approach: spend-based for the long tail, supplier-specific data for the top 20 per cent of suppliers by estimated emissions intensity — typically steel, concrete, chemicals, protein commodities, and air freight. Concentrating effort there captures roughly 80 per cent of total category 1 emissions.

CarbonPlus Platform

Scope 3 category 1 tracking, built in

Spend-based baselines, primary supplier data collection, and the evidence record for third-party verification — in one platform.

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What category 1 looks like: services vs manufacturer

Dimension	Services business	Manufacturer
Dominant spend	IT, professional services, facilities	Raw materials, components, chemicals
Share of Scope 3	40–60%	70–90%
Key challenge	Breadth: many low-value EEIO mappings	Depth: high-intensity categories need supplier data
Where to start	IT hardware refresh; data centres	Top 5 materials by spend; ISO 14067 footprints

For a services business the challenge is breadth — many low-value line items mapped to EEIO codes. For a manufacturer it is depth — fewer categories dominate, but they carry high emission intensities and require supplier-specific data to quantify accurately.

How category 1 connects to CSRD and CBAM

For UK companies supplying EU customers who are themselves CSRD reporters, your category 1 embedded emissions data is precisely what your customer needs to populate their own Scope 3. A UK exporter with a well-evidenced product footprint can answer both a CSRD supply chain data request and a CBAM embedded-emissions enquiry from the same underlying evidence base. Category 1 measurement is an operational data asset, not just a reporting exercise.

How CarbonPlus handles Scope 3 category 1

CarbonPlus is carbon accounting software that tracks category 1 alongside all 14 other Scope 3 categories, combining spend-based baselines with primary supplier data in a single evidence record. The platform supports automated EEIO mapping from purchase ledger categories using the DEFRA supply chain emission factors dataset, and facilitates structured ISO 14067-aligned supplier data collection. Every figure is connected to its source, ready for CSRD supply chain responses, third-party verification under ISO 14064-3, and CBAM declarations.

If you are starting a Scope 3 measurement programme or improving an existing category 1 baseline, we are happy to discuss your specific supplier base and reporting obligations.

Frequently asked questions

What is Scope 3 category 1?

Scope 3 category 1 covers cradle-to-gate emissions from all goods and services a company purchases or acquires that are not produced by the company itself. This includes raw materials, components, professional services, IT hardware, and office consumables. It is typically the largest single Scope 3 category for both manufacturing and services businesses.

How do you calculate Scope 3 category 1 emissions?

The GHG Protocol defines three methods: supplier-specific (most accurate — the supplier provides ISO 14067 product footprint data), hybrid (supplier data for key suppliers, EEIO averages for the rest), and spend-based (spend multiplied by a DEFRA EEIO factor). Spend-based is the starting point; hybrid or supplier-specific methods are required for CSRD and ISO 14064-3 assurance.

Does Scope 3 category 1 include professional services?

Yes. The GHG Protocol definition explicitly includes professional and business services such as legal, accounting, consulting, and IT software subscriptions, alongside physical goods.

What is the difference between Scope 3 category 1 and category 2?

Category 1 covers purchased goods and services for consumption or incorporation into products. Category 2 covers capital goods — assets such as equipment, machinery, and buildings used for more than one year — where emissions are amortised across the asset's useful life.

Sources and further reading

GHG Protocol — Corporate Value Chain (Scope 3) Accounting and Reporting Standard
UK DESNZ / DEFRA — Greenhouse gas reporting: conversion factors 2024