How to Compare Furniture EPDs: The Five-Equality Rule

An Environmental Product Declaration (EPD) presents life-cycle impacts in a standardised format. Possessing an EPD does not automatically make furniture “low carbon” or environmentally preferable to a competitor. An EPD is a verified disclosure, not a pass/fail label. Figures from two declarations are comparable only when they answer the same question.

Applying the comparability conditions published in EPD International declarations to furniture procurement produces a five-equality rule: equality of PCR, function/unit, scope, method and validity. If one check fails, the results should not enter a ranked table.

1. The same PCR and a compatible version

A Product Category Rule is the accounting policy for a life-cycle assessment. It determines the unit, reported stages and modelling rules. The International EPD System contains a “Furniture and components of furniture” c-PCR, while other routes include an external PCR for office furniture workspace products.

Declarations that appear to cover the same product family may use different programmes or incompatible PCR versions. Check the PCR name, registration number, version and validity together. “EN 15804 compliant” alone does not establish that every category-specific rule is aligned.

2. The same function, technical performance and unit

“One chair” looks clear, but two chairs may not provide the same service. A single seat, two-seat module, standard-load task chair and large-occupant chair have different functional performance. Read the distinction between declared unit and functional unit.

The current furniture c-PCR page states that a functional unit is used for furniture types with a defined reference service life, while a declared unit may be used for other furniture and components. A comparison should cover equal capacity and service duration. Ranking production emissions per item does not equalise service if one item provides ten years and another 20.

3. The same life-cycle modules

In EN 15804-based EPDs, A1–A3 cover raw materials and manufacturing, A4 transport and A5 installation. B modules cover use, C modules cover end of life, and D reports potential benefits and loads beyond the system boundary. If one supplier reports A1–A3 and another A1–C4, the smaller-looking number is not automatically better.

Module D should not be silently netted into the main total. Show core life-cycle impacts separately from recovery potential. Every comparison heading should state its scope, such as “GWP-total, A1–A3” or “A1–C4.”

4. The same method, data quality and modelling rules

Cut-off rules, recycled-content allocation, electricity datasets, transport scenarios and impact-assessment methods can change the answer. EPD International comparability language requires equivalent system boundaries, data descriptions, data quality, allocation, cut-off rules and characterisation factors. Seeing the same indicator name is not enough.

5. Declarations valid at the same time

Check issue and validity dates. An expired declaration and a current one may reflect different electricity, material recipes and method editions. Both EPDs should be valid on the comparison date, and the supplied configuration should match the product covered.

Reading a real EPD line

The OK Office 102/103 declaration published through EPD Norway offers a concrete reading example. The declared unit is one product, with a product mass of 29.20 kg and a 15-year reference service life. It reports GWP-total of 73.7 kg CO₂e for A1–A3, 1.68 for A4, 7.03 for A5, 53.9 for C3, 0.0378 for C4 and −2.29 kg CO₂e for D.

Three lessons follow:

• 73.7 kg CO₂e is not the whole-life total; it is the A1–A3 production stage.
• The 15-year reference life supplies functional context and is not a warranty.
• The negative D value is a potential outside the main system boundary; it does not make the product “carbon negative.”

The example is not used to declare another chair better or worse. It demonstrates why a lone carbon figure loses meaning when the document heading, unit and modules are omitted.

Mandatory columns in a comparison table

1. EPD number, programme operator and validity date;
2. PCR name, number and version;
3. Product configuration and technical performance;
4. Declared/functional unit and reference service life;
5. Indicator name and unit;
6. Included life-cycle modules;
7. Transport, maintenance, replacement and end-of-life scenarios;
8. Third-party verifier and declaration status.

Carbon intensity per kilogram can help inspect material efficiency, but it cannot by itself rank a heavy, long-lived product against a light, short-lived one. “kg CO₂e/kg product” is not a procurement outcome until the seating, working or storage service has been equalised.

Conclusion

Reliable EPD comparison comes from five equalities, not the smallest visible carbon number: same PCR, same function and unit, same modules, same method and the same validity period. When equality is absent, EPDs still reveal supply-chain hotspots but should not be used for a product ranking. The defensible statement is not “it has an EPD,” but “under an equal scope, this indicator differs by this amount.”

Sources

• EPD International — Furniture and components of furniture c-PCR
• EPD International — example of EPD comparability conditions
• EPD Norway — OK Office 102/103, NEPD-8853-8514