Indicators in EPD for building products EN 15804
This section discusses the common approaches regarding the GWPs of different greenhouse gases, considering that the EPDs formulated at different timepoints have applied different values. Other environmental indicators defined in EN 15804 are handled and commented on in the next section related to the CPR Acquis process.
The EPDs published in different databases can be based on either of the two versions of the standard European standard EN 15804. EN 15804:2012+A1:2013 says that the global warming potential (GWP) shall be calculated based on the GWP for a 100-year time horizon as in IPCC: Climate Change 2007 (AR4). However, the current version of EN 15804 + A2 2019 refers to the IPCC 2013 (AR5). The GWP values for a 100-year time horizon for greenhouse gases somewhat differ in accordance with AR4 and AR5 for carbon dioxide, methane, and nitrogen oxide. At this stage, many EPDs that follow the previous version are still available.
According to EN 15804 A2 (2019), the GWP indicators are defined as follows:
GWP-fossil - This indicator accounts for the GWP from greenhouse gas emissions and removals to any media originating from the oxidation or reduction of fossil fuels or materials containing fossil carbon through their transformation or degradation (e.g. combustion, incineration, landfilling, etc.). This indicator also accounts for the GWP from GHG emissions, e.g. from peat and calcination, as well as GHG removals, e.g. from the carbonation of cement-based materials and lime. The indicator also includes the emission of laughing gas (N2O) from renewable sources.
GWP-biogenic - All biogenic emissions of carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4) from different processes are included, as well as biogenic carbon stored in the product and, potentially, its packaging material. This stored carbon accounts for the sequestration (uptake) of CO2 into biomass from all sources except native forests. Harvesting wood from native forests and its emitted GHG is treated as a fossil emission, including its origin, from the stored biogenic carbon in the product.
Biogenic carbon stored in the product or its packaging must be balanced out over the life cycle when the material is recycled or energy recovered to fulfil the requirement in EN 15804 that inherent properties cannot be allocated away. Therefore, GWP-biogenic also accounts for the GWP from the transfers of any biogenic carbon from previous product systems into the product system under study. This indicator also covers biogenic emissions to air from biomass from all sources except native forests due to oxidation or degradation (e.g. combustion, solid waste disposal). It also covers all transfers of biogenic carbon from the biomass from all sources, except native forests, into subsequent product systems in the form of biogenic CO2. The amount of CO2 in the product or packaging material from the biomass at the point of complete oxidation results in zero net CO2 emissions, when biomass carbon is not converted into methane, non-methane volatile organic compounds (NMVOC), or other precursor gases. Note that all other biogenic stored in any other auxiliary material is directly balanced out to support the modularity approach.
GWP-luluc - The indicator accounts for GHG emissions and removals (CO2, CO, and CH4) originating from changes in the defined carbon stocks caused by land use and land-use changes associated with the declared/functional unit. This indicator includes biogenic carbon exchanges resulting, e.g. from deforestation or other soil activities (including soil carbon emissions). Calculation rules for GWP-luluc shall follow the latest available version of the PEF Guidance document. For native forests, all related CO2 emissions are included and modelled under this sub-category. The CO2 uptake related to the carbon content of biomass entering the product system from native forests is set to zero. Any biomass-based net increase in carbon stocks, including soil carbon uptake (accumulation), shall not be considered in GWP-luluc and is set to zero. Soil carbon storage may be included as additional environmental information when proof is provided. NOTE: For example, proof of soil carbon storage is provided when legislation provides modelling requirements for the sector, such as the EU greenhouse gas accounting rules from 2013 (Decision 529/2013/EU), which indicate carbon stock accounting. GWP-luluc shall be included in the GWP-total. If the contribution of GWP-luluc is < 5% of the GWP-total over the declared modules, excluding module D, GWP-luluc may be provided, as an indicator not declared.
Climate indicator
The GWP is the main indicator in CO2data. The database defines the GWP values for products, services, and systems, covering all modules of the life cycle. CO2data includes three GWP indicators: Global Warming Potential fossil fuels (GWP-fossil), Global Warming Potential land use and land-use change (GWP-luluc), and Global Warming Potential biogenic (GWP-biogenic). However, the typical values for GWP-biogenic and GWP-luluc are mainly assumed as zero values based on the following adopted approaches:
Based on the review of the environmental declarations, wood products have a low GWP-biogenic value when carbon dioxide that is binding to the growing wood and is released in the C module of the product are not considered. In Finland, in the manufacture of wood products in sawmills, the burning of wood-based fuel does not produce methane, but some carbon monoxide (emission factor of 1.57) is induced. The released nitrous oxide is attributed to fossil emissions. Thus, the GWP-biogenic share caused by wood-based fuels is largely compensated to zero within the A module, and it can be left out of consideration in the typical values of the emission database. Also, the GWP-biogenic values, which are caused by, e.g. packaging materials, are typically minimal compared to the GWP-fossil value. In summary, it was concluded that GWP-biogenic can be ignored without making a significant assessment error when choosing typical values, except for the carbon bound to and released from sawn timber.
The sum of GWP-biogenic values in modules A and C in environmental declarations for sawn timber is usually zero or almost zero. According to the standard, the procedure is such that the value of bound CO2 is negative in the A1 module, and the value of CO2 is positive when the same carbon is then released from the system either during combustion or when the product moves from one product system to the next. CO2data database defines this value based on the product’s carbon content, which is calculated as CO2. The same value is considered in module A as negative and again in module C as positive (i.e. emission). The products are also assumed to be made from timber harvested from a sustainably managed forest. GWP-biogenic values are not multiplied by a conservative factor.
Regarding other materials and based on a small review of environmental declarations, GWP-biogenic emission values are low. The typical order of magnitude is smaller than 2% compared to GWP-fossil. The current version of the database does not consider GWP-biogenic emissions for any materials other than wood, but those are marked as zero.
The GWP-luluc values of construction products, as presented in environmental product declarations, are also minimal compared to the GWP-fossil values. In general, construction materials and fossil fuel inputs contribute with an insignificant share to land use impacts in the life cycle of Finnish buildings, as mineral and fossil raw materials and fuels have low embodied land use needs (Häkkinen et al., 2013). Thus, the values are now ignored in the typical values and marked as zero.
The GWP-luluc indicator covers greenhouse gas emissions and removals (CO2, CO, and CH4) resulting from changes in carbon stocks caused by land use and land-use changes related to the functional unit under consideration. The indicator includes biogenic carbon changes that result from, e.g. the loss of forests or other soil-related changes, including soil carbon emissions. The calculation of GWP-luluc follows the latest version of the PEF Guidance document. Accordingly, the category includes biogenic carbon exchanges from deforestation, road construction, or other soil activities (including soil carbon emissions). For products based on wood from native forests, all related CO2 emissions are included and modelled under this sub-category (including connected soil emissions, products derived from native forests, and residues), while their CO2 uptake is excluded.
The principles for dealing with biogenic carbon substantially affect the emission data of wood products. According to the product category rules defined by the Finnish EPD operator (RTS PCR (Method for the formulation of building products’ EPDs following the principles of SF EN 15804 2019. RTS EPD WG PT 18 22.4.2022):
The carbon bound to the organic material is reported as a negative GWP-biogenic value in section A1 if the product’s raw material comes from a sustainably managed forest. If this biological raw material is used for energy production in manufacturing the product, the resulting CO2 emission is reported as a positive GWP-biogenic value in section A3.
If the product’s raw material does not come from a sustainably managed forest, no GWP-biogenic information is reported in section A1. If this organic raw material is used for energy production in manufacturing the product, the resulting CO2 emission is reported as a positive GWP-luluc value in section A3.
The same principle has been adopted for the CO2data database. It considers the carbon uptake for products originating from sustainably managed forests and assumes this is the case in Finland, especially based on the statistics that show that the living standing trees in the Finnish forests are still increasing. However, the current interpretation of sustainable forestry criteria does not consider the effect of harvesting levels on the net carbon sink. According to The Finnish Climate Change Panel’s (Seppälä et al., 2022) report, increasing levels of harvesting have decreased the carbon sink for decades. Calculation rules and principles regarding land use, forestry, and wood-related emissions require more research and discussion.