> For the complete documentation index, see [llms.txt](https://docs.rainbowstandard.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.rainbowstandard.io/~/changes/226/methodologies/biobased-construction-materials/ghg-reduction-quantification.md). # GHG quantification ## General General GHG reduction quantification rules can be found in the [Rainbow Standard Rules](/~/changes/226/rainbow-standard-documents/rainbow-standard-rules.md). 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**](#user-content-fn-1)[^1]. ## Functional unit The increase in net removals 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 biobased product for the project and baseline scenario. {% hint style="info" %} Functional units for biobased product manufacturing may include, for example: * 1 m2 of flooring * 1 m2 of insulation with an R value of 3 m2K/W {% endhint %} Net removals are calculated by multiplying the **net removals per functional unit** by: * the quantity of project biobased materials delivered to construction sites over the monitoring period. for building material manufacturers, or * the quantity of project biobased materials used in all eligible buildings or structures, for building developers. ## Project scenario The Project scenario shall represent the manufacture or use of biobased construction materials by the project during the monitoring period. It shall follow the [Project Scope](/~/changes/226/methodologies/biobased-construction-materials/eligibility-and-scope.md#project-scope) and [Data Sources](#data-source) 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. It shall follow the [Baseline Scope](/~/changes/226/methodologies/biobased-construction-materials/eligibility-and-scope.md#baseline-scope) requirements described in the present methodology. The baseline scenario shall account for the use of biobased construction materials, and biogenic carbon removals, already currently used. When faced with uncertainty in defining a baseline scenario, a conservative choice shall be made. The baseline scenario shall be developed by following these steps. 1. Identify the **replaced building element:** define the application of the project biobased product that is being replaced (e.g., thermal insulation for flat roofs). * Identify building elements with a similar application, performance, lifetime, price as the project biobased product. * If the project building element 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 product**: clearly identify the type of product being replaced (e.g. stone wool or a mix of different materials) * Define the specific product/s that would make up the building element in the counterfactual (e.g. stone wool used for thermal insulation) * Identify product with a similar performance, lifetime, price as the project biobased product * By default, a mix of products from various manufacturers and Environmental Product Declarations (EPDs) shall be used to accurately represent the market mix for the specified building element. A specific product type from a particular manufacturer may only be considered with adequate justification and proof. * A product in the national market share may be omitted if it is proven to be an unsuitable equivalent for the project biobased product. 3. **Select appropriate EPDs (or full building LCA)** for the identified baseline construction product/s and building element/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 product 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 product may need to be adjusted to ensure that the scenarios have the exact same [functional unit](#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 [Baseline scope](/~/changes/226/methodologies/biobased-construction-materials/eligibility-and-scope.md#baseline-scope) section for more details. * **Lifetime:** e.g. if the project and baseline products have an expected lifetime of 100 and 50 years, respectively, then twice the amount of the baseline product is needed to fulfill the same function as the project product, since it will be replaced halfway through the project product's lifetime. {% hint style="info" %} **Baseline Example: Biobased product manufacturing — 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 building element:** * Insulation products for horizontal surface roof. 2. Identify the **replaced conventional construction products**: * 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 [ADEME (2024, p.8)](#user-content-fn-2)[^2]. 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 product, 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.) {% endhint %} {% hint style="info" %} **Baseline example: Biobased product manufacturing — 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 building element:** * Based on the product's physical characteristics, bricks are a suitable replaced construction product. 2. Identify the **replaced conventional construction products**: * 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 Île-de-France region](#user-content-fn-3)[^3], the most common similar premium product is monomer bricks, which is selected as a suitable baseline. 3. **Select appropriate EPDs:** * Numerous manufacturers offer monomer 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 38048[^4] 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 monomer bricks are required to perform the same function of hempcrete bricks. {% endhint %} {% hint style="info" %} **Baseline example: Biobased product use in buildings — Market mix** If a building developer constructs a multi-family residential building using CLT panels as structural floors, the functional unit may be **1 m****2**** of structural floor with adequate load-bearing capacity, for a reference time of 100 years**. The baseline is determined following the steps below: 1. Identify the replaced **building element**: * Structural floor systems in multi-family residential buildings. 2. Identify the replaced **conventional construction product**: * CLT floor panels can substitute several structural floor types. The market mix for this building category is therefore used. * Materials with similar structural performance include reinforced concrete flat slabs, precast concrete hollow-core planks, and timber joist floors. * Based on national construction statistics, the market mix is approximately 75% reinforced concrete slabs, 15% precast concrete planks, and 10% timber joist floors. 3. Select appropriate EPDs: * For each material, one representative EPD is selected reflecting typical performance for this floor type and building category. * Where multiple EPDs are available, the most conservative is used. 4. Ensure functional equivalence: * Performance: the thickness and quantity of each baseline floor type is adjusted to meet the same structural span and load requirements as the CLT floor. * Lifetime: the project CLT and all baseline materials share a reference service lifetime of 100 years, so no correction factor is needed. {% endhint %} ## Data source Environmental Product Declarations (EPDs) shall be the main source of information for both the project and baseline scenarios. EPDs shall be developed according to [EN 15804:2012+A2:2019](#user-content-fn-5)[^5], which itself is based on [ISO 14025](#user-content-fn-6)[^6]. Information taken from EPDs shall include the project and baseline material’s: * lifetime (Reference Service Lifetime, RSL) * product characteristics used to convert equivalent amounts of materials (e.g. density) * performance characteristics * induced emissions from A1-A5 (GWP fossil) Biogenic carbon content may be provided via the EPD for biobased products whose biomass carbon content remains stable. For biobased products **containing biomass with variable biogenic carbon content**, biogenic carbon content values shall be directly measured and regularly updated, or use the lowest biogenic carbon content across a range of reasonable values. If modules A4 and A5 are not included in the EPD, they may be estimated using project-specific data. 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](#user-content-fn-6)[^6]. ## System boundary Removal GHG calculations shall use all stages of module A (A1-A5).

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 **Project removals** are calculated by subtracting the carbon sequestration of the project biobased product from the induced emissions from producing that product. **Net removals** are calculated by subtracting project removals from baseline removals. The biogenic carbon amount reported in the EPD of the project biobased product shall be used as the basis for calculating the amount of carbon removal credits to issue.
Calculations: Removal credits Net total project removals are calculated using the following equations: $$\textbf{(Eq.1)}\ R\_{product\ i} = C\_{i} \times \frac{Q\_{product\ i}}{FU} \times C:{CO}\_{2} \div 1000\frac{kg}{tonne} \times -1$$ where * $$R\_{product\ i}$$ represents the gross tonnes of CO2eq removed per functional unit per construction product $$i$$. Its sign is negative. This equation is used for calculating both project and baseline removals. * $$C\_{i}$$ represents the biogenic carbon content of the biobased product $$i$$, in kilograms of biogenic carbon per functional unit. This value shall be taken from the EPD or measured directly, according to the requirements in the [Data source](#data-source) section. * $$\frac{Q\_{product\ i}}{FU}$$ represents the quantity of the construction product $$i$$ in one functional unit. For example, if the functional unit is 1 m2 of flooring, and * the project material's biogenic carbon content is already reported per m2 of timber flooring, then this value is 1. * if the baseline material's biogenic carbon content is reported per m3 reinforced concrete flat slabs, then this value shall convert between m3 reinforced concrete flat slabs per m2 of flooring. * $$C:{CO}\_{2}$$ is the conversion factor between carbon and CO2eq, and is calculated by dividing the molar mass of CO2eq by the molar mass of carbon = 44/12 = 3.67. * It is multiplied by -1 to obtain a negative sign. Removals are reported as a negative value. $$\textbf{(Eq.2)}\ Net\ Removal = \sum\_i((R\_{product,\ B,\ i}- \ R\_{product,\ P,\ i}\ - E\_{A1 - A5,\ fossil,\ P,\ i}) \times A\_{product\ i})$$ * $$Net\ Removal$$ represents the net removals from the project during the monitoring period, in tonnes of CO$$\_2$$eq. Its sign is positive. * $$R\_{product,\ i}$$ represents gross tonnes of CO2eq removed per functional unit, for the project ($$P$$) or baseline ($$B$$) construction product $$i$$ as calculated in Eq. 1. Its sign is negative. * $$E\_{A1-A5,\ fossil,\ P,i}$$ represent the GHG emissions for the project's biobased building product, taken directly from the biobased product EPD. Note that it **includes only the GHG emissions from the fossil fraction**, not biogenic or LULUC. * $$A\_{material\ i}$$ represents the amount of functional units of the biobased building product eligible for RCC issuance in the monitoring period.
## Uncertainty assessment An uncertainty assessment is presented below for all aspects of GHG quantification set **at the methodology level**. The findings from this assessment are then applied **at the project level**, where project-specific GHG quantification also undergoes an uncertainty assessment. The **overall project GHG quantification uncertainty** is determined by qualitatively combining both the methodology-level and project-specific uncertainties for each identified source of uncertainty. The outcome of the assessment shall be used to determine the percent of removals to eliminate with the [**discount factor**](#user-content-fn-7)[^7]. 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. For a given project, the **specific baseline scenario selected** may have more or less uncertainty, depending on the nature of the project. Equations 1 and 2 are used to calculate removals and have no **uncertainty**. They are commonly used and are 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:
ParameterUncertainty assessment

E_{A1-A5,\ fossil,\ P,i}

C_i

A conservative, default estimate of high uncertainty is used for these parameters because they are taken directly from EPDs, which may not provide information on uncertainty. Project Developers may provide information to justify lower uncertainty here.
A_{product\ i}This parameter should be known and measured for each project, so the uncertainty is low.
Q_{product\ i}The uncertainty is low because this is a basic conversion based on the size of the product.
The uncertainty at the methodology level is estimated to be moderate to high. This translates to an **expected discount factor of at least 6%** for all projects under this methodology. [^1]: ISO 14064-2:2019. Greenhouse gases — Part 2: Specification with guidance at the project level for quantification, monitoring and reporting of greenhouse gas emission reductions or removal\ enhancements. [^2]: Etude de l’impact de la mise en œuvre sur la performance d’isolation thermique de la paroi. Available at: [^3]: Baromètre Domexpo Dédié à l’habitat Individuel Neuf (2017) Domexpo. Available at: (Accessed: 23 October 2023). [^4]: [^5]: EN 15804:2012+A2:2019 - Sustainability of construction works - Environmental product declarations- Core rules for the product category of construction products, 2019. [^6]: ISO 14025:2006. Environmental labels and declarations. Type III environmental declarations. Principles and procedures [^7]: A percentage of verified Rainbow Carbon Credits eliminated from each project and never issued. This acts as a safeguard against uncertainty in GHG reduction quantifications and overestimated carbon removal/avoidance. [^8]: Marsh, E., Allen, S., Hattam, L., 2023. Tackling uncertainty in life cycle assessments for the built environment: A review. Building and Environment 231, 109941. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.rainbowstandard.io/~/changes/226/methodologies/biobased-construction-materials/ghg-reduction-quantification.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.