“We need you to send us the LCA for the product.” The buyer’s email arrives like that, one line long, and by the next internal meeting nobody is quite sure what to prepare: a full Life Cycle Assessment? A carbon footprint? A verified declaration? The difference between LCA, EPD and carbon footprint is not academic hair-splitting — each one costs differently, takes a different amount of time, and answers a different question.
An LCA is the underlying study that measures many environmental impacts of a product; a carbon footprint is one slice of that study covering a single impact, climate; and an EPD is a third-party verified document that publishes those results in a comparable format. One is the engine, one is a specific reading of that engine, and the third is the sealed document you can show outside the company.
What each one measures
The confusion almost always comes from treating them as three competing products, when they are really three levels of the same chain. Side by side it reads more clearly:
| What it measures | Standard | Third-party verified | What it is used for | |
|---|---|---|---|---|
| LCA | Many impact categories: climate, water, acidification, resources… | ISO 14040 / 14044 | Not necessarily | Internal decisions: comparing materials, finding where to cut |
| Product carbon footprint | Greenhouse gas emissions only, in CO₂e | ISO 14067 | Optional, increasingly requested | Answering a customer, Scope 3, an importer |
| EPD | Several indicators, in a standardized comparable format | ISO 14025 (and EN 15804 in construction) | Always | Tenders, specification, building certifications |
Look at the third column, because it is what usually drives both price and timeline: third-party verification is only mandatory for the EPD. It is also why an EPD takes months while a product footprint can be ready in weeks.
Why do they get confused so often?
Because they depend on each other, and in one specific direction: upward.
An EPD is built on an LCA. A rigorous product carbon footprint is calculated, in practice, with the same life-cycle methodology while looking at a single impact category. Anyone who does an LCA properly has already done the heavy lifting for the other two.
The reverse does not work. Companies that start with a standalone carbon number, without defining system boundaries or a functional unit on life-cycle terms, tend to discover months later that the figure is useless for the EPD a tender ends up demanding — and the inventory has to be rebuilt.
That sequencing error is the expensive one, and it does not show up until you have paid twice.
Which one do you need, depending on who is asking?
The useful question is not “which is best” but “who is asking, and what will they do with it”. The source of the request almost always determines the deliverable:
- A corporate customer asks for “the product footprint”. They almost always need a figure per unit of product for their own Scope 3 inventory. What resolves the request is a product carbon footprint under ISO 14067, built on primary data from your operation. Ask them in writing for the scope and the unit they expect: per tonne and per unit sold are not the same request.
- A tender requires an “environmental product declaration”. No shortcut here: you need a verified and registered EPD. Check the submission date before anything else, because the process includes external verification and cannot be compressed at will.
- A European importer asks for emissions data for CBAM. They are asking for neither an LCA nor an EPD, but for embedded emissions per tonne at installation level, using the regulation’s own methodology. It is a different calculation, covered separately in our CBAM guide for exporters.
- Your management wants to know where to cut. Then what you need is the wide study, not the public document: a Life Cycle Assessment that shows the real hotspots, even if it never gets published.
- Nobody has asked yet, but you sell into Europe. Start with the inventory and the footprint. It is the base the other three are built on, and it is what will let you answer in days when the request arrives.
Common mistakes when choosing
Four that come up again and again:
- Commissioning an EPD when a footprint would have done. It multiplies cost and timeline for a requirement the customer never made.
- Calculating a footprint without defining the functional unit. Without it the number is not comparable to anything, and buyers reject it for that reason rather than for its value.
- Filling the inventory with database averages. Fast, but increasingly penalized: buyers ask for primary data from your installation, and in some cases the average looks worse than your actual performance.
- Treating the study as a finished file. A well-scoped LCA feeds the EPD, CBAM and corporate reporting. A badly scoped one serves none of the three.
Frequently asked questions
Can a carbon footprint be turned into an EPD?
Not directly, but much of the work carries over if the inventory was built on life-cycle terms and the assumptions were documented. If the footprint was done with improvised boundaries, the inventory has to be rebuilt.
Which is fastest to obtain?
The product carbon footprint. The EPD is the slowest of the three because it involves Product Category Rules (PCR), third-party verification and registration in a programme.
Does a carbon footprint have to be third-party verified?
Not as a matter of standard, but more buyers and ratings ask for it every year. If you expect to be asked, design the study to be verifiable from the start.
Can one study cover several products?
Only where they share process and materials substantially. The usual approach is to model a product family with variants, which is far cheaper than studying every reference separately.
What to have ready before deciding
Before requesting a quote for anything, have three things at hand: who is asking and in what format they expect it, what your real deadline is, and what operational data you can gather (consumption, materials, transport, waste). That is enough to decide, in a twenty-minute conversation, which of the three studies you need and in what order.
At EcoAsesoria we start exactly there: by reading the request you received before proposing anything. If you have a customer email on your desk and you are not sure what is actually being asked, tell us about it and we will tell you which evidence answers that request and which can wait.