If a company manufactures a car, a server, a refrigerator, or a gas boiler, the single biggest source of its carbon footprint is very often not its factory, its suppliers, or its offices. It's the years its customers will spend running the thing.
That's Category 11 — Use of Sold Products — and for entire sectors (automotive, consumer electronics, HVAC, industrial equipment, oil and gas), it can account for well over half of total emissions, Scope 1 through 3 combined.
The two accounting methods
The GHG Protocol allows two approaches, and picking the right one matters:
Direct use-phase emissions, for products that consume energy or fuel directly (vehicles, appliances, machinery). The calculation is, at its core:
units sold × expected lifetime use × energy consumption per use × emission factor of the energy source
A carmaker selling a combustion vehicle multiplies units sold by an assumed lifetime mileage, fuel economy, and the emission factor of the fuel. An appliance maker multiplies units sold by expected years of operation, annual energy draw, and the local grid emission factor for the markets where it sells.
Indirect use-phase emissions, for products that don't themselves consume energy but whose use causes emissions elsewhere — fertilizer that off-gasses nitrous oxide when applied, or refrigerants that leak from equipment over its service life.
Where the estimates get shaky
Three assumptions drive most of the uncertainty in a Category 11 number, and each is a legitimate point of scrutiny from investors and auditors:
- Expected lifetime. A vehicle assumed to last 12 years produces a very different number than one assumed to last 15. Companies should disclose the lifetime assumption, not just the final tonnage.
- Use intensity. Real-world fuel economy and rated fuel economy diverge, sometimes significantly. Regulatory test-cycle figures tend to understate real driving emissions.
- Grid factor over time. For electric products, the relevant question isn't today's grid mix — it's the grid mix over the product's entire service life, in every market where it's sold. A refrigerator sold today in a market decarbonizing its grid will have a materially lower true footprint than a static assumption would suggest, and most companies do not currently model this correctly.
Why this category resists easy reduction
Categories 1 through 8 respond to supplier engagement — you can switch a supplier, redesign a component, or shorten a shipping route. Category 11 responds to product design and to forces largely outside the manufacturer's direct control: how customers actually use the product, and how fast the energy grid they draw on decarbonizes.
That's precisely why Category 11 is increasingly where climate strategy and product strategy converge. For an automaker, the lever isn't supplier engagement — it's the pace of electrification. For an appliance maker, it's efficiency ratings. For a software or cloud company whose "product" is compute, the equivalent category is often reframed as customer energy use of the service, which is why hyperscale data center operators now report customer-side emissions with almost as much rigor as their own operations.
The disclosure expectation
Under both CSRD/ESRS E1 and the GHG Protocol's own guidance, companies with a material Category 11 are expected to disclose not just the final number but the lifetime, usage, and grid assumptions behind it — because those assumptions, not the arithmetic, are where the real judgment calls live.