What do the biogenic carbon and A1-A3 embodied carbon figures on an EPD mean?
Since the launch of TDUK’s EPD database, more TDUK members have taken the step to independently verify the environmental performance of their products across the full life cycle.
This transparency benefits not only individual manufacturers but also supports architects, engineers, and specifiers across the timber supply chain, enabling informed, low-carbon design decisions.
As TDUK Sustainability Director Charlie Law FCIOB, MISEP, CEnv explains:
“EPDs are essential to achieving net zero in our built environment, helping specifiers make sustainable material choices as early in the design process as possible.”
With over 40 EPDs from more than 20 members now available, understanding what the numbers mean is key:
🟢Stored carbon shows how much CO₂ is absorbed by the tree and locked into the timber product.
🟢A1–A3 (excluding biogenic carbon) shows the emissions from producing a timber product, from harvesting to manufacturing.
🟢A1–A3 (including biogenic carbon) shows the net result once biogenic stored carbon is taken into account.
Additionally, keep an eye out for our updated 2026 Embodied Carbon Data for Timber Products paper, calculated from the EPDs, due to be published soon. In the meantime, you can find the 2025 data here
