EoL: Why is my net CO2 balance of wood products over entire life cycle not 0? (EN15804, EPD, +1/-1-Method)

Question

When balancing the entire life cycle of wood products according to EN15804 (EPD) with the +1/-1 method and the EcoInvent database the result should actually be 0 or almost 0 at the end of the life cycle. Unfortunately, a large part of the storage effect remains in my balancing, although I have assumed incineration for all wood components and landfilling for fossil/other components for EoL? If I assumed landfilling for the wood components, it would make sense, but with incineration, all the stored C should actually be released again in the form of CO2.

A more detailed investigation has shown that for cross laminated timber, for example, an input of 1.89m3 of wood is calculated for the production of 1m3 of cross laminated timber in the data sets. With EoL, I only calculate with this 1m3 of cross laminated timber and not with 1.89m3. Could this be the error? Is the storage effect of 1.89m3 of timber taken into account in the production and not 1m3? If so, would the system limits in the data set be incorrect? How do you deal with this?

Comments

wow, three views and two answers ;)

Answer 1

Hello Sobr,

We have had this issue as well. The EcoInvent database is great for many things, but not for consistency across lifecycles. When you do EPD's, the biogenic balance has to sum up to 0, as per EN16449.

I handle this by drawing a separate input/output table for biogenic carbon. Example:

Inputs: MDF, fibreboard, pallet as packaging, cardboard as packaging

Outputs: Recycling of packaging, incineration of MDF, incineration of fibreboard

Difference: -20 kg CO2e

I would then add a correcting factor to the outputs: +20 kg CO2e. Only this way can you be in compliance with the standard.

Good luck with the EPDs.

Answer 2

Hi, good questions ->

a, 1m3 wood at EoL is good in my view, you only have this 1m3 of product;

b, the remaining 0.89 m3 will be waste or by-product at production, and you should see some releases of biogenic C there (or, apply allocation and then lower the input of biogenic C for your investigated system accordingly).

Would you agree?

Best wishes,

Andreas