GHG quantification

General

General GHG reduction quantification rules can be found in the Riverse Standard Rules.

Calculations of GHG emissions for the baseline and project scenarios shall follow a robust, recognized method and good practice guidance. The overall methodological approach is a comparative life cycle assessment (LCA) at the project-scale, based on ISO 14064-2:2019.

Project biobased materials with an expected carbon storage duration of less than 100 years are only eligible for avoidance RCCs. Materials with an expected carbon storage duration of 100 years or longer are eligible for removal and avoidance RCCs.

See section Carbon storage duration determination for more details.

Functional unit

The avoided emissions between the project and baseline scenarios shall be compared on the basis of a common functional unit.

The functional unit shall describe the amount, units, lifetime, and function of the building material for the project and baseline scenario.

Some functional units for biobased construction materials may include, for example:

• 1 m$^2$ of flooring

• 1 m$^2$ of insulation with an R value of 3 m$^2$K/W

Annual avoided emissions are calculated by multiplying the avoided emissions per functional unit by the quantity of project biobased materials sold over the year (for building material manufacturers), or the quantity of project biobased materials used in a building (for building developers).

Project scenario

The Project scenario shall represent the manufacture or use of biobased construction materials by the project during the reporting period (typically 1 year).

It shall respect the Project Scope and Data Sources requirements described in the present methodology.

Baseline scenario

The baseline scenario shall represent the conditions or practices that would occur in the absence of the project. The baseline scenario depends on the project-specific context (e.g. project biobased material, country...), but shall follow the same standard guidelines:

1. Identify the replaced construction product: define the application of the project biobased material that is being replaced (e.g., thermal insulation for flat roofs).

   • Identify products with a similar application, performance, lifetime, price as the project biobased material.

   • If the project biobased material has multiple likely applications, a market mix of likely applications should be used (e.g., thermal insulation for roofs in general).

   • The market mix should be based on national construction practices/statistics, and come from reliable, recent, and transparent data sources.

2. Identify the replaced construction material: clearly identify the type of material being replaced (e.g. stone wool or a mix of different materials)

   • Define the specific material/s that composes the replaced construction product/s (e.g. stone wool used for thermal insulation)

   • Identify materials with a similar performance, lifetime, price as the project biobased material

   • By default, a mix of materials from various manufacturers and Environmental Product Declarations (EPDs) shall be used to accurately represent the market mix for the specified material type. A specific material type from a particular manufacturer may only be considered with adequate justification and proof.

   • A material in the national market share may be omitted if it is proven to be an unsuitable equivalent product for the project biobased material.

3. Select appropriate EPDs for the identified baseline construction product/s and material/s. This selection should be made conservatively and, as much as possible, should respect the geographic location of the project.

4. Ensure functional equivalence by analyzing the characteristics of the project biobased material and the chosen Baseline scenario EPDs. They should already have similar characteristics after following steps 1 and 2, but may not be equivalent. The amount of project or baseline material may need to be adjusted to ensure that the scenarios have the exact same functional unit (e.g. same amount, units, lifetime, and function). This includes, at a minimum:

   • Performance: the performance characteristics of the replaced product including but not limited to, energy efficiency, strength, mechanical resistance, reaction to fire, or insulation capacity (e.g., thermal resistance of 7 m²·K/W). See the Substitution section for more details.

   • Lifetime: e.g. if the project and baseline materials have an expected lifetime of 100 and 50 years, respectively, then twice the amount of the baseline material is needed to fulfill the same function as the project material, since it will be replaced halfway through the project material's lifetime.

When faced with uncertainty in defining a baseline scenario, a conservative choice shall be made.

The baseline scenario shall account for the use of biobased construction materials, and biogenic carbon removals, already currently used. The method below for calculating the biogenic carbon and carbon removal shall also be applied to any biobased baseline materials that have a lifetime of 100 years or more.

The baseline scenario structure remains valid for the entire crediting period but may be significantly revised earlier if:

• The Project Developer notifies Riverse of a substantial change in project operations or baseline conditions, and/or

• The methodology is revised, affecting the baseline scenario.

The specific values within the baseline scenario will be updated annually, using project data to accurately reflect the equivalent of the project’s annual operations.

Baseline Example: Market mix

For example, if a project produces cellulose insulation from waste paper in France, the functional unit may be the thermal insulation of 1 m² surface roof with a thermal resistance of 7 m²·K/W, for 50 years. The baseline is determined following the steps below:

1. Identify the replaced construction product:

   • Insulation products for horizontal surface roof.

2. Identify the replaced construction material:

   • Cellulose insulation is versatile with no specific replacement. Therefore, the market mix of roof thermal insulation is used.

   • Materials with similar performance include rook wool, glass wool, other biobased materials, extruded polystyrene insulation etc.

   • Market shares can be taken from the study on thermal insulation in France from . The mix for the baseline is about 50% glass wool, 30% rock wool, 10% cellulose insulation, and 10% extruded polystyrene.

3. Select appropriate EPDs

   • For each material, one representative EPD is selected that represents the material with similar performance characteristics in France.

   • If multiple EPDs are appropriate, the most conservative one is used.

4. Ensure functional equivalence:

   • Performance: the amount of products is adjusted to achieve the same function of the project biobased material (e.g. if the project material's R is 2x higher than the baseline's, 2x the mass of baseline material is needed to achieve the same R.)

Baseline example: Specific product

If a project makes hempcrete blocks for construction in France, the functional unit may be 1 m² of a load-bearing wall with a thermal value of at least R=3.25 m2.kW for a reference time of 100 years. The baseline is determined following the steps below:

1. Identify the replaced construction product:

   • Based on the product's physical characteristics, bricks are a suitable replaced construction product.

2. Identify the replaced construction material:

   • The project biobased material is a premium product, due to its higher production costs and superior thermal properties.

   • Several types of brick were identified with similar technical performance to hempcrete. However, the premium price means it is likely replacing other premium products. In , the most common similar premium product is monomur-type bricks, which is selected as a suitable baseline.

3. Select appropriate EPDs:

   • Numerous manufacturers offer monomur-type bricks. Therefore, a mix of EPDs from different manufacturers with similar price and performance characteristics as the project are selected.

   • Alternatively, a single EPD (such as EPD from the INIES database) could be chosen if there is a clear justification, such as alignment with price, performance, or being the most widely sold option in the specific geographic area studied.

4. Ensure functional equivalence:

   • Lifetime: the baseline product's lifetime is 50 years, and the project biobased material's lifetime of 100 years. Therefore, 2x the amount of monomur-type bricks are required to perform the same function of hempcrete bricks.

Data source

Environmental Product Declarations (EPDs) shall provide the main source of information for both the project and baseline scenarios. EPDs are developed according to EN 15804, which itself is based on ISO 14025.

Information taken from EPDs shall include the project and baseline material’s:

• lifetime (Reference Service Lifetime, RSL)

• performance characteristics

• end of life waste treatment methods

• climate change impact (sum of fossil, biogenic, and land use change)

• biogenic carbon content

If no EPD is available for a project, then a similar document may be used instead, given that it includes the above information, is independently verified, and follows ISO 14025.

System boundary

The avoided GHG calculations shall include the cradle-to-grave impacts of the project and baseline scenarios. This corresponds to the “cradle-to-grave and module D” scope that includes all stages of modules A, B, C and D in EN 15804 (Figure 1).

If module D was excluded from either the project or baseline EPD, then the A-C cradle-to-grave scope shall be used for all products in both the baseline and project scenarios.

Figure 1 The life cycle stages of a building material are presented, according to the norm EN 15804’s terminology using modules A-D.

Calculations

Avoidance credits

The following formulas shall be used to calculate the avoided GHG emissions for all projects, regardless of the carbon storage duration:

Calculations- Avoidance credits

$\begin{aligned}\textbf{(Eq.1)}\ E_{material\ i} = &(E_{Module\ A,i} + E_{Module\ B,i} + E_{Module\ C,i} + E_{Module\ D,i})\\ * &Q_{material\ i} * \frac{FU\ lifetime}{EPD\ \ lifetime}\end{aligned}$

$\textbf{(Eq.2)}\ E_{avoided\ total}\ = \sum_{i\ = 1}^{n}((E_{material,\ baseline,\ i} - E_{material,\ project,\ i}) \times A_{material\ i}$

where

• $E_{material\ i}$ represents the life cycle embodied GHG emissions of a building material, normalized to one functional unit. For the project scenario, this includes the project biobased material, plus any ancillary materials if necessary.

• $E_{Module\ A:D}$ represent the GHG emissions per life cycle stage for a given amount of a building material defined in the EPD. These values are taken directly from EPDs for both the project and baseline materials. The corresponding Modules A through D are shown in Figure 1.

• $Q_{material\ i}$ represents the quantity of the building material in one functional unit.

• $FU\ lifetime$ represents the service lifetime of the building material as defined in the functional unit.

• $EPD\ \ lifetime$ represents the reference service lifetime of the building material as defined in the EPD. Often, this is same as the $FU\ lifetime$. However in some cases the project' biobased material may have a different lifetime than the material. In that case, a correction factor must be applied to consider the different amount of materials needed for functional equivalence.

• $E_{avoided\ total}$ represents the total annual tonnes CO$_2$eq of GHG emissions avoided by the project.

• $A_{material\ i}$ represents the annual amount of functional units of the building material either 1) sold by the material manufacturer, or 2) used by the building developer, depending on the nature of the project, and the equivalent amount required in the baseline scenario to fulfill the same function.

Removal credits

If the expected carbon storage duration of the project biobased material is 100 years or more, then the project is eligible for removal RCCs in addition to the above-mentioned avoidance RCCs.

Project removals are calculated by subtracting the carbon sequestration of the project biobased material from the induced emissions from producing that material. Net removals are calculated by subtracting project removals from baseline removals.

The biogenic carbon amount reported in the EPD of the project biobased material shall be used as the basis for calculating the amount of carbon removal credits to issue.

Note that any ancillary materials required in the project scenario from avoidance calculations are not included in removal credit calculations.

Note that EPDs report biogenic carbon uptake as a negative value in Module A using the -1/+1 method (common in LCAs of construction), and this must be removed in order to consider only GHG emissions induced by production (see Equation 3).

Calculations- Removal credits

Net total project removals are calculated using the formulas:

$\textbf{(Eq.3)}E\ adj_{Module\ A1 - A3,i} = E_{Module\ A1 - A3,i} + (C_{i} \times C:{CO}_{2} \div 1000\frac{kg}{tonne}$

$\textbf{(Eq.4)}\ R_{material\ i} = C_{i} \times C:{CO}_{2} \div 1000\frac{kg}{tonne}{\ \times Q}_{material\ i} \times \frac{FU\ lifetime}{EPD\ lifetime}$

$\textbf{(Eq.5)}\ R_{net\ total} = \sum_{i\ = 1}^{n}((\ R_{material,\ baseline,\ i}- \ R_{material,\ project,\ i}\ - E\ adj_{Module\ A1 - A3,\ project,\ i}) \times A_{material\ i})$

where

• $E\ adj_{Module\ A1 - A3,i}$ represents the GHG emissions of Module A1-A3 adjusted by removing the biogenic carbon uptake.

• $E_{Module\ A1 - A3,\ i}$ is the GHG emissions from production of the biobased material. It corresponds to Modules A1, A2, and A3 in the norm EN 15804's terminology in Figure 1.

• $C_{i}$ represents the kilograms of biogenic carbon stored for a given amount of a building material defined in the EPD.

• $C:{CO}_{2}$ is the conversion factor between carbon and CO$_2$eq, and is calculated by dividing the molar mass of CO$_2$eq by the molar mass of carbon = 44/12 = 3.67.

• ${\ Q}_{material\ i},\frac{FU\ lifetime}{EPD\ \ lifetime}$, and $A_{material\ i}$ are described in section 3.6.1.

• $R_{material\ i}$ represents net tonnes of CO$_2$eq removed per functional unit.

• ${\ R}_{net\ total}$ is the net tonnes of CO2eq removed, i.e. the carbon removed by the project in addition to what is removed in the baseline.

Uncertainty assessment

See general instructions for uncertainty assessment in the Riverse Standard Rules. The outcome of the assessment shall be used to determine the percent of avoided emissions to eliminate with the .

The use of an assumption for carbon storage duration leads to high uncertainty. This duration can be estimated, using best available information and proof, but it is impossible to know with certainty what will be the fate of the material decades from now.

The baseline scenario selection method has high uncertainty. The requirements outlined here ensure that appropriate baseline materials are selected, but ultimately this remains an assumption and can not be known with certainty.

Note that this covers only the method used to select the baseline scenario. For a given project, the specific baseline scenario selected may have more or less uncertainty, depending on the nature of the project.

Equations 1-5 are used to calculate GHG avoidance and removals and have no uncertainty. They are commonly used and basic equations.

No estimates or secondary data are used at the methodology level. The following secondary data are used as parameters at the project level, and their uncertainties must be assessed for each project. Expected uncertainties, based on the data source, are provided below as a guideline:

$E_{Module A:D}$ $C_i$ $EPD \ lifetime$	A conservative, default estimate of high uncertainty is used for these parameters because they are taken directly from EPDs, which typically do not provide information on uncertainty. Project Developers may provide information to justify lower uncertainty here.
$A_{material\ i}$	This parameter should be known and measured for each project, so the uncertainty is low.
$Q_{material\ i}$	The uncertainty is low because this is a basic conversion based on the size of the product.
$FU\ lifetime$	This parameter has no uncertainty because it is defined by the Project Developer for the purpose of the GHG reduction quantification.

The uncertainty at the methodology level is estimated to be medium to high. This translates to an expected discount factor of at least 6% for projects under this methodology.