Service-Level GHG Accounting for Suppliers

Short answer: service-level GHG accounting is the process of estimating the emissions connected to a specific service, contract, product line, customer account, or delivery path. A normal company footprint tells the customer what your whole company emitted. Service-level accounting tries to answer a narrower question: what share of those emissions is connected to the service we provide to this customer? It usually requires a clear service boundary, activity data, allocation method, emission factors, assumptions, and a short methodology note.

Many suppliers first learn about service-level accounting when a large customer says that a company-wide emissions number is not enough. The customer may be trying to improve its own Scope 3 data, understand emissions from a specific outsourced service, compare supplier responses, support a procurement decision, or meet an internal reporting requirement.

That request can feel strange. Your company may already have a Scope 1 and Scope 2 footprint. You may even have relevant Scope 3 categories. But the customer is asking a more pointed question: how much of that footprint should be associated with the work you do for us?

Company-level, product-level, and service-level are not the same

A company-level GHG inventory covers the emissions of an organization. The GHG Protocol Corporate Standard is the usual starting point for that kind of inventory. It asks: what did this company emit during the reporting period, within a defined organizational and operational boundary?

A product carbon footprint looks at the life cycle emissions of a product. The GHG Protocol Product Standard is designed for product life cycle accounting and can cover raw materials, production, transport, use, and disposal. Product-level approaches are especially relevant when the buyer is purchasing a physical product or product family.

Service-level GHG accounting sits between those ideas. It is often needed when a supplier provides a service, outsourced function, platform, contract, facility activity, logistics route, or customer-specific workstream. The output may not be a full product carbon footprint. It may be an allocated emissions number linked to a defined service unit, customer account, contract year, or reference unit.

When a customer may ask for service-level accounting

Service-level accounting is most likely when the buyer cannot use your company-wide footprint directly. Examples include:

• an outsourced service provider asked to report emissions connected to one client account;
• a logistics provider asked for emissions from a lane, shipment type, or contract;
• a software or cloud-enabled service provider asked to allocate office, cloud, travel, or subcontractor emissions to a customer service;
• a manufacturer asked for an emissions intensity for a specific product, product family, or production run;
• a professional services firm asked for emissions from travel, staff time, offices, and subcontractors supporting one customer; or
• a supplier responding to a customer-specific GHG request that names service-level accounting or a similar allocation requirement.

The request wording matters. "Provide your company's Scope 1 and 2 emissions" is different from "provide emissions associated with the services you deliver to us." The first is a company footprint. The second may require an allocation model.

What data is usually needed

A service-level calculation usually starts with company-level data, then narrows it. The working file should define the service boundary, reporting period, customer, legal entity, sites, activities, and emissions categories included.

Depending on the service, the data may include electricity use, fuel use, office floor area, employee headcount or time allocation, travel records, freight activity, cloud usage, subcontractor spend, purchased materials, waste, leased assets, and other relevant Scope 3 activity. The data does not have to be perfect in the first year, but the assumptions must be explicit.

The most important decision is the allocation driver. You may allocate emissions by revenue, staff hours, transactions, units delivered, floor area, server usage, shipment volume, contract-specific activity, or another driver that better reflects the service. The right driver depends on the nature of the service and the data available.

A practical service-level accounting workflow

A clean workflow usually looks like this:

1. Read the customer request and preserve the exact wording.
2. Confirm whether the customer wants a company footprint, product footprint, service-level allocation, or all three.
3. Define the service boundary and reporting period.
4. Identify the emissions categories relevant to that service.
5. Collect activity data and supporting evidence.
6. Select allocation drivers and explain why they are reasonable.
7. Calculate emissions and convert them to a service-level result.
8. Document assumptions, limitations, exclusions, and source data.
9. Prepare a customer-ready response and retain a file for annual refreshes.

The output should be understandable by someone outside your company. If the buyer asks how the number was produced, the method should be traceable from the final figure back to data sources and assumptions.

What makes service-level accounting difficult

The difficulty is rarely the final spreadsheet formula. It is boundary judgment. Does the service include only direct delivery activity, or also support teams? Should office emissions be allocated by headcount, time, floor area, or revenue? Should cloud usage be included? Should supplier spend be allocated by project code, customer revenue, or a more specific activity driver?

There may not be a single perfect answer. The practical standard is to choose a method that is relevant, transparent, and consistently applied. If better data becomes available next year, document the change rather than quietly changing the method.

Service-level accounting is not independent assurance

A service-level accounting project can produce a methodology note, calculation file, evidence pack, and, where appropriate, a consultant letter describing the support provided. That is still different from independent assurance. If the customer explicitly asks for assurance, verification, or an assurance opinion, read that requirement carefully and consider whether a separate assurance provider is needed. Keslio explains this distinction in Consultant Letter vs Independent Assurance.

Where to start

If the request names a customer, service, contract, or account, do not assume a standard company footprint will be enough. Start with the request wording and compare it against your available data. Keslio's supplier request support can help identify whether service-level accounting is required. If the calculation path is clear, Keslio's GHG emissions calculations work can help build the company-level and service-level calculation files. The Supplier GHG Reporting Checklist is a useful first data-collection companion.

Source notes

This article draws on the GHG Protocol Corporate Standard, the Scope 3 Standard, the Product Standard, and product-level data exchange work from PACT.