> ## Documentation Index
> Fetch the complete documentation index at: https://docs.salvidia.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Product data checklist

> The data a product footprint needs at each life cycle stage, who holds it, and why the functional unit has to be settled before you collect anything.

Product footprints differ from organisation footprints in one way that governs everything else: every figure has to be expressed per unit. A factory's annual electricity is not useful until you know how many units that factory made.

So settle the functional unit first. One bottle, one garment, one kilogram, one service use. Collecting before that is settled produces numbers you cannot combine. See [What is an LCA?](/guides/what-is-an-lca) for how to define it.

## Materials

| Data                 | Usually held by                 | Arrives as                                     |
| -------------------- | ------------------------------- | ---------------------------------------------- |
| Bill of materials    | Product or engineering          | Component list with material types             |
| Weight per component | Engineering, or a set of scales | Grams or kilograms per unit                    |
| Recycled content     | Supplier                        | Percentage recycled versus virgin              |
| Material origin      | Procurement                     | Country or region, where it affects the factor |

Weight is the number everything else depends on. If a bill of materials gives you dimensions rather than mass, weigh a unit and its components. An afternoon with a scale beats a month of supplier emails.

## Manufacturing

| Data                         | Usually held by             | Arrives as                                  |
| ---------------------------- | --------------------------- | ------------------------------------------- |
| Energy per process or batch  | Production or plant manager | kWh per batch, plus units per batch         |
| Production location          | Operations                  | Site and country, since grid factors differ |
| Yields and scrap rates       | Production                  | Percentage lost per stage                   |
| Contract manufacturer energy | Your manufacturer           | Energy per unit or per batch                |

Scrap matters more than people expect. If a process wastes 20% of input material, every unit carries the footprint of 1.25 units of material. Ask for yields at each stage, not just the finished count.

## Packaging and distribution

| Data                          | Usually held by    | Arrives as                                          |
| ----------------------------- | ------------------ | --------------------------------------------------- |
| Packaging weights             | Packaging supplier | Grams per unit for primary, secondary, and tertiary |
| Units per shipping carton     | Logistics          | Count, for apportioning transport                   |
| Transport modes and distances | Logistics          | Origin, destination, and mode per leg               |
| Warehousing                   | Operations         | Energy, where storage is long or refrigerated       |

Do not forget the packaging that never reaches the customer. Pallets, shrink wrap, and outer cartons are part of the product's footprint even though the buyer never sees them.

## Use phase

| Data                         | Usually held by        | Arrives as                                 |
| ---------------------------- | ---------------------- | ------------------------------------------ |
| Energy or consumables in use | Product or engineering | Consumption per use, and uses per lifetime |
| Expected lifetime            | Product                | Years, or number of uses                   |
| Usage assumptions            | Product or marketing   | How a typical customer actually uses it    |

For appliances, vehicles, and anything that draws power, this stage usually dwarfs everything upstream. For a product that just sits there, it may be zero. Knowing which case you are in determines where the rest of your effort should go.

## End of life

| Data                       | Usually held by           | Arrives as                                   |
| -------------------------- | ------------------------- | -------------------------------------------- |
| Disposal route             | Product or sustainability | Percentage recycled, landfilled, incinerated |
| Recyclability by component | Engineering               | Which materials are recoverable in practice  |
| Take-back or return rates  | Operations                | Percentage returned, if you run a scheme     |

End of life is almost always modelled from regional averages rather than measured. That is accepted, as long as you state the assumption and the source.

## Two traps worth knowing

**Averaging across variants.** If one product line covers three sizes, a single averaged footprint is defensible for internal use and weak for a customer claim about a specific size. Decide early which you need.

**Supplier data that is not per unit.** A supplier who sends annual totals has given you something you cannot use until you know how many units that total covers. Ask for the denominator in the same request as the numerator.

## Where to go next

* [What is an LCA?](/guides/what-is-an-lca)
* [Requesting data from other people](/collecting-data/requesting-data)
* [What good data looks like](/collecting-data/what-good-data-looks-like)