Cradle-to-Gate — Definition and GHG Accounting Context
Every carbon footprint has to draw a line somewhere: what to count, and where to stop. For a manufactured product, the most common line is drawn at the factory door — everything that happened to make the product is counted, and everything that happens to it afterwards is left for someone else. It is a pragmatic boundary, because a maker can measure its own operations but not how a customer will use and dispose of what it sells.
That boundary has a name. Cradle-to-gate is the life-cycle assessment boundary that counts a product’s emissions from raw-material extraction up to the point it leaves the factory gate — under EN 15804, the modules A1–A3.
Cradle-to-gate is a life-cycle assessment system boundary covering a product from raw-material extraction (the “cradle”) to the factory gate. Under EN 15804 it is the product-stage modules A1–A3 — the number quoted on most Environmental Product Declarations. It stops before distribution, use and end-of-life (which cradle-to-grave would add). It is the standard boundary for the embodied carbon of materials, and a supplier’s cradle-to-gate footprint becomes the buyer’s factor for Scope 3 Category 1.
Definition — From the Cradle to the Gate
Cradle-to-gate is a partial life-cycle assessment (LCA): it accounts for a product’s environmental impacts from the extraction of raw materials — the “cradle” — through to the moment the finished product leaves the manufacturer’s gate. It deliberately stops there. What happens next — shipping the product to a customer, using it, and eventually disposing of or recycling it — is outside the boundary. The alternative, cradle-to-grave, extends the same assessment all the way to end-of-life.
The boundary is popular for a practical reason: a manufacturer can measure and control the emissions up to its own gate, but cannot know how any given customer will transport, use or dispose of the product. Drawing the line at the gate produces a stable, comparable number that a maker can publish and a buyer can rely on. That number — usually expressed per functional or declared unit, such as per kilogram or per cubic metre — is the foundation of the embodied carbon data used across construction and manufacturing.
Definition at a glance
| What it is | An LCA system boundary from raw-material extraction to the factory gate |
|---|---|
| EN 15804 modules | A1 (raw material supply) + A2 (transport) + A3 (manufacturing) = the “product stage” |
| Covers | Extraction, upstream transport, and manufacturing of the product |
| Excludes | Distribution to customer, installation, use phase, end-of-life (the “gate-to-grave” part) |
| Reported per | A functional / declared unit — e.g. kg CO₂e per kg, per m³, per m² |
| In accounting | Basis of EPDs, product carbon footprints, and Scope 3 Cat 1 factors |
The A1–A3 Modules (EN 15804)
The construction-sector standard EN 15804 divides a product’s life cycle into modules labelled A to D. The first three — the product stage, A1–A3 — are exactly the cradle-to-gate boundary, and their sum is the “A1–A3” value on an Environmental Product Declaration:
| Module | Stage | What it covers |
|---|---|---|
| A1 | Raw material supply | Extraction and processing of the raw materials and any recycled input |
| A2 | Transport | Transport of those raw materials to the manufacturer |
| A3 | Manufacturing | Production at the factory — energy, process emissions, on-site waste |
Later modules cover what a cradle-to-gate figure omits: A4–A5 (transport to site and installation), B1–B7 (the use phase), C1–C4 (end-of-life), and D (benefits beyond the boundary, such as recycling). A study that adds selected downstream modules to A1–A3 is often described as “cradle-to-gate with options”.
Cradle-to-Gate vs Cradle-to-Grave
Cradle-to-gate is one of several life-cycle boundaries, distinguished by where they start and stop. Choosing the wrong one — or comparing figures drawn to different boundaries — is a frequent source of error:
| Boundary | Covers | Stops at |
|---|---|---|
| Cradle-to-gate | Extraction → factory gate (A1–A3) | The manufacturer’s gate |
| Cradle-to-grave | Extraction → end-of-life (A–C) | Final disposal |
| Gate-to-gate | A single process or facility only | That facility’s outputs |
| Cradle-to-cradle | Full life, with materials recovered into a new product (+ D) | Reuse, not disposal |
The same idea appears in fuel accounting under different names: well-to-tank is the upstream, cradle-to-gate-style boundary for a fuel (extraction to the pump), and well-to-wheel is its cradle-to-grave counterpart (adding combustion). Whatever the sector, the rule is the same — only compare footprints drawn to the same boundary.
Where Cradle-to-Gate Is Used
Cradle-to-gate is the default boundary for the embodied carbon of materials, published through Environmental Product Declarations and databases such as ÖKOBAUDAT and the ICE database. In corporate accounting it has a specific role: a supplier’s cradle-to-gate product carbon footprint becomes the emission factor a buyer applies under Scope 3 Category 1, purchased goods and services. The buyer’s “cradle” is the supplier’s whole cradle-to-gate chain.
Cradle-to-gate embodied carbon, common materials (live)
| Material (A1–A3) | Cradle-to-gate carbon kg CO₂e per kg · live, ÖKOBAUDAT/EPD |
|---|---|
| Aluminium — recycled | 0.26 |
| Steel — reinforcement | 0.47398 |
| Cement — Portland (CEM I) | 0.665 |
| Aluminium — primary | 10.1 |
The gap between primary and recycled aluminium — the same metal, from the same database — shows what a cradle-to-gate figure captures: primary aluminium carries the enormous energy of smelting ore in module A1, while recycled aluminium skips it. For bio-based materials the accounting can even turn negative: cradle-to-gate figures for timber products can come out below zero, because the biogenic carbon the tree absorbed while growing is counted as stored in the product (reported on a different, per-volume basis).
Worked micro-example
An assembly uses 1 tonne (1,000 kg) of structural aluminium. Its cradle-to-gate (A1–A3) embodied carbon depends entirely on the source (live per-kg factors, snapshot):
- Primary aluminium: 1,000 kg × 10.1 kg CO₂e/kg = 10,100 kg ≈ 10.1 t CO₂e
- Recycled aluminium: 1,000 kg × 0.26 kg CO₂e/kg = 260 kg ≈ 0.26 t CO₂e
Snapshot using the live A1–A3 factors above. The steel & aluminium embodied-carbon calculator applies these by mass and recycled content; the concrete & cement calculator does the same for cementitious materials.
Common Confusions
- Comparing cradle-to-gate with cradle-to-grave figures. They stop at different points. A cradle-to-gate number is always lower than the cradle-to-grave one for the same product, because it omits distribution, use and end-of-life.
- Treating cradle-to-gate as a product’s full footprint. It is the embodied carbon up to the gate only. For products with a big use phase (a car, a boiler), the operational emissions can dwarf the cradle-to-gate figure.
- Mixing materials on different units. A1–A3 values are per functional unit, and the unit varies by product — per kg, per m³, per m². Never compare a per-kg figure with a per-m² one.
- Forgetting recycled content. Cradle-to-gate carbon swings enormously with recycled input — primary versus recycled aluminium differs roughly forty-fold. Always check the declared recycled content behind a factor.
- Assuming “gate” means your gate. In a Scope 3 Category 1 factor, the cradle-to-gate boundary ends at the supplier’s gate — your own transport and processing are additional.
Frequently Asked Questions
Cradle-to-gate is a life-cycle assessment boundary that counts a product’s emissions from raw-material extraction (the “cradle”) up to the point it leaves the factory (the “gate”). Under the construction standard EN 15804 it corresponds to the product-stage modules A1 (raw material supply), A2 (transport to the manufacturer) and A3 (manufacturing) — the A1–A3 total shown on most Environmental Product Declarations. It deliberately excludes what happens after the gate: distribution, installation, the use phase, and end-of-life. Those downstream stages are added by a fuller cradle-to-grave assessment.
The difference is where the assessment stops. Cradle-to-gate ends at the factory gate — it covers extraction, upstream transport and manufacturing (EN 15804 modules A1–A3). Cradle-to-grave continues all the way to end-of-life, adding transport to site and installation (A4–A5), the use phase (B), and disposal or recycling (C). For the same product the cradle-to-grave figure is always the larger of the two, because it includes everything cradle-to-gate leaves out. The two must never be compared directly: a like-for-like comparison requires both footprints to be drawn to the same boundary.
A1–A3 are the three “product stage” life-cycle modules defined by EN 15804, and together they make up the cradle-to-gate boundary. A1 is raw material supply — the extraction and processing of the materials, including any recycled input. A2 is the transport of those raw materials to the manufacturer. A3 is manufacturing itself — the energy, process emissions and waste at the factory. An Environmental Product Declaration reports these separately and as a combined A1–A3 total, which is the cradle-to-gate embodied carbon of the product per its declared unit.
Cradle-to-gate is the natural boundary for Scope 3 Category 1, purchased goods and services. When a company buys a material or component, the supplier’s cradle-to-gate product carbon footprint — everything from raw-material extraction to the supplier’s own gate — becomes the emission factor the buyer applies to what it purchased. In effect, the supplier’s entire cradle-to-gate chain is the buyer’s upstream. The buyer then adds its own downstream stages (transport, processing, use) under the relevant scopes and categories. This is why high-quality, boundary-consistent cradle-to-gate data from suppliers is so valuable for a credible Scope 3 inventory.
For most materials, no — extraction and manufacturing emit greenhouse gases, so the A1–A3 figure is positive. But for bio-based products such as timber, the cradle-to-gate figure can come out negative. This is because the biogenic carbon a tree absorbs from the atmosphere while growing is counted as stored in the finished product within the product stage, and that stored carbon can outweigh the processing emissions. It is an accounting outcome, not free carbon removal: the stored carbon is released later if the product is burned or decays, which a full cradle-to-grave assessment captures in the end-of-life modules. It is also why bio-based A1–A3 numbers must be read alongside their end-of-life treatment, not in isolation.