Principles & requirements

Project Developers shall demonstrate that they comply with all principles and requirements outlined in the Rainbow Standard Rules, and described below with a specific focus on biobased construction materials.

Rainbow Standard Rules

Additionality

Project Developers shall use Internal Rate of Return (IRR) or Net Present Value (NPV) as financial indicators for any investment analyses.

For Biobased Product Manufacturing, additionality shall be assessed for the material manufacturer.
For Biobased Product Use in Buildings, additionality may be assessed at the building-level, or for the portfolio of buildings.

Project Developers shall follow the additionality requirements in the Rainbow Standard Rules and fill out the Rainbow Additionality Template.

Durability

All projects certified under this methodology shall prove carbon removals for 35, 50, 75, or 100+ years. Removal Rainbow Carbon Credits (RCCs) shall be displayed in the Rainbow Registry with a credit label defining their durability.

The durability of carbon storage shall be determined using:

For Biobased Product Manufacturing: the reference service lifetime (RSL) declared in the product's Environmental Product Declaration (EPD).
For Biobased Product Use in Buildings:
- Foundations: the RSL declared in the product's EPD.
- All other building elements: the shorter lifetime between
  - the expected service life of the building, as reported in official documents according to applicable norms or regulations, and
  - the RSL of the building element or biobased product.

If using the RSL provided in the EPD, Project Developers may justify a longer durability than the RSL based on reputable sources, including but not limited to scientific literature, industry reports, public databases, or performance tests.

For composite building elements made of multiple biobased products with different lifetimes, the shorter lifetime between the building element and the biobased products contained within it shall be used.

Reversal risk assessment

The major carbon reversal risks from biobased construction projects are reversals occurring during the use phase, driven by:

the management of the building and
natural disasters that degrade or fully release the stored biogenic carbon.

The minimum list of reversal risks to be assessed for all projects is outlined in the table below. The Rainbow Certification team or the Validation and Verification Body (VVB) may require additional reversal risks to be assessed for a given project or building. Project Developers shall evaluate the likelihood of each risk materializing within the project's defined durability horizon, and shall apply the buffer pool percent contribution according to the values in the table below for each risk and likelihood combination. The likelihood ranges are defined as:

Low: Not applicable, rare, or unlikely to happen.
Medium: Possible, with less than a 50% chance of happening.
High: Probable, more likely than not to happen within the durability horizon.
Very high: Likely to happen within the durability horizon.

A building or biobased material is not eligible for crediting if:

the likelihood of any individual reversal risk is High or Very high, or
the cumulative buffer pool contribution exceeds 10%.

Risk

Low

Medium

High (ineligible)

Very high (ineligible)

Wildfire

7.5

Fluvial flooding

Landslide

Avalanche

Subsidence

Storm surges

Coastal flooding

Coastal erosion

Glacial lake, reservoir or lagoon outbursts

Moisture ingress

4.5

For Biobased Product Manufacturing, reversal risks shall be mitigated through an elevated contribution of at least 5% of verified removal RCCs to the Rainbow Buffer Pool. Any additional buffer pool contributions identified through the reversal risk assessment shall be applied on top of this default 5%.

Project Developers shall complete the Reversal Risk evaluation template to identify any reversal risks specific to the biobased product, its intended use, building type and geography, and shall increase their buffer pool contribution according to the gradient in the table above.

For Biobased Product Use in Buildings, reversal risk shall be assessed for each building, using proof from the following sources, in decreasing order of preference: building permits, regulations, insurance policies, public geological surveys, and public hazard or risk maps. The assessment shall also account for project mitigation efforts such as reinforcements or enclosure in non-combustible lining.

Project Developers shall complete the Reversal Risk evaluation template to identify any reversal risks specific to each building. Each building shall be assigned an individual Rainbow Buffer Pool contribution percentage, based on its reversal risk score, increased according to the gradient in the table above.

For each credit issuance, the project-level buffer pool contribution shall be the weighted sum of:

the buffer pool contribution for each building credited in that monitoring period,
weighted by the number of RCCs issued per building.

The project buffer pool shall be updated after each credit issuance to reflect the cumulative weighted buffer pool across all buildings and all issuances completed to date.

If the buildings credited in the monitoring period all have a low risk level, the a default minimum buffer pool contribution of 2% shall be applied for that monitoring period.

Project Developers shall follow the post-crediting reversal monitoring procedures to monitor for reversals.

For example, for a Biobased Product Use in Buildings project:

A project issues credits for three buildings in Year 1.

Building 1 generates 100 removal RCCs with a 2% buffer pool contribution (100 × 2% = 2 RCCs),
Building 2 generates 200 removal RCCs with a 2% contribution (200 × 2% = 4 RCCs) and
Building 3 generates 100 removal RCCs with a 5% contribution (100 × 5% = 5 RCCs).

The weighted buffer pool for the Year 1 issuance is $\sum (Buffer\ Pool) ÷ RCCs\ issued = (2 + 4 + 5)÷400 = 2.75\%$ , resulting in 11 RCCs contributed to the Rainbow Buffer Pool against 400 RCCs issued.

In Year 2, three additional buildings are incorporated into the project.

Building 4 generates 100 removal RCCs with a 2% buffer pool contribution (100 × 2% = 2 RCCs),
Building 5 generates 300 removal RCCs with a 2% contribution (300 × 2% = 6 RCCs), and
Building 6 generates 100 removal RCCs with an 8% contribution (100 × 8% = 8 RCCs).

The weighted buffer pool for the Year 2 issuance is $(2 + 6 + 8)\div 500 = 3.2\%$ , resulting in 16 RCCs contributed to the Rainbow Buffer Pool against 500 RCCs issued.

After Year 2, the project buffer pool is updated to reflect all six buildings across both issuances: 27 RCCs contributed to the Rainbow Buffer Pool out of 900 RCCs issued in total, for a cumulative project buffer pool percentage of 3%.

Reversal risk evaluation template

Project Developers shall fill in the Reversal Risk evaluation template at the link below to evaluate the risk of carbon storage reversal.

Project Developers shall assign a likelihood and severity score to each risk, and provide an explanation of their choices. The Rainbow Certification team shall evaluate the assessment and may recommend changes to the assigned scores.

The Project Developer, Rainbow Certification team, or the third-party auditor may suggest additional risks to be considered for a specific project.

Each reversal risk with a high or very high risk score is subject to a risk mitigation plan, developed by the Project Developer, that details the long-term strategies and investments for preventing, monitoring, reporting and compensating carbon removal reversal.

Risk assessment template

Post-crediting reversal monitoring

For Biobased Product Use in Buildings, Post-crediting reversal monitoring shall be conducted at least once every 5 years to ensure the ongoing carbon storage, either remotely or in-person, and submitted to Rainbow. This monitoring shall last the entire duration of the durability claim (e.g. 35 years for 35-year durability claims, 100 years for 100-year durability claims...). The post-crediting monitoring period begins for each building upon issuance of its corresponding RCCs. Project Developers shall submit a post-crediting monitoring report even if there is no reversal event, and confirm that the carbon remains stored in the building.

The Project Developer is responsible for conducting post-crediting period monitoring, and shall commit to following the procedures outlined herein upon project validation.

The Project Developer shall remain liable for the post-crediting reversal monitoring of removal RCCs unless liability is formally transferred and accepted by a new party. Upon transfer of liability, the new party shall be registered under the Rainbow certification scheme and assume the role of Project Developer and all associated responsibilities, including the submission of future post-crediting monitoring reports. The Project Developer shall inform Rainbow of any transfer of liability, provide proof of the agreement, and provide the name and contact information of the new Project Developer.

If a reversal has occurred during the post-crediting monitoring period, Project Developers shall follow the Cancelation procedure outlined in the Rainbow Procedures Manual.

No double counting

Project Developers shall sign the General Terms of Arc Platform (Certification Platform) and Terms of Use of the Rainbow Registry, committing to follow the requirements outlined in the Rainbow Standard Rules, including not double using or double issuing RCCs.

For Biobased Product Manufacturing, Project Developers shall communicate to the final users of the project biobased material (e.g. building developers) that credits have been issued for the biobased products. This shall be done via packaging labels, EPDs, disclaimers on invoices, and/or sales contracts, and shall disclose the following information to ensure traceability:

Type of biobased product and building element
Reference to the Rainbow registry and the project ID
Site registration for the site manufacturing the given biobased product
Start and end date of the monitoring period, for which credits have been issued for the given biobased products

The corresponding information shall be tracked in a database managed by Rainbow to allow for cross-checking for Biobased Product Use in Buildings projects.

For Biobased Product Use in Buildings, Project Developers shall prove that biobased products used were not already issued carbon credits by the manufacturer, by screening for relevant carbon credit registries and the above-mentioned Rainbow database, confirming no overlapping crediting activities.

If part of the building's biobased components have already been issued carbon credits, the remaining portion of biobased components are still eligible. Signed agreements do not exclude a project from issuing RCCs for all of their biobased components — only for the components that have already been issued carbon credits in another project.

Co-benefits

Projects should support at least two quantifiable and verifiable environmental or social co-benefits, aligned with the UN Sustainable Development Goals (SDGs) framework. Any co-benefits claimed by the Project Developer shall be quantified, monitored, and audited for each verification and credit issuance.

Common co-benefits under this methodology are detailed in the table below. Project Developers may suggest and prove other co-benefits not mentioned here.

SDG 13 on Climate Action by default is not considered a co-benefit here, since it is implicitly accounted for in the issuance of carbon credits. If the project delivers climate benefits that are not accounted for in the GHG reduction quantifications, then they may be considered as co-benefits.

Table 1 Common co-benefits that projects under this methodology may provide are detailed, including types of proof that can be used to justify each co-benefit.

UN SDG

Example

8.4 Resource efficiency in consumption and production

Projects using waste biomass instead of raw materials such as concrete and steel use less raw, non-renewable resources.

9.4 Upgrade infrastructure and retrofit industries to make them sustainable, with increased resource-use efficiency and greater adoption of clean and environmentally sound technologies and industrial processes

Biobased construction may have better performance in the use phase, or may require less energy in the manufacturing phase.

12.2 Achieve the sustainable management and efficient use of natural resources

If waste biomass is used, projects give value and a second usable life to the organic waste.

Project Developers shall prove that the project does not contribute to substantial environmental and social harms.

Forestry certificate requirements

Biobased products containing biomass originating from forests shall be certified under at least one of the following forestry sustainability certificates:

FSC (Forest Stewardship Council)⁠
PEFC (Program for the Endorsement of Forest Certification)⁠
RSB (Roundtable on Sustainable Biomaterials)⁠
SFI (Sustainable Forestry Initiative)⁠
SBP (Sustainable Biomass Program)⁠

These certifications are used to prove:

Legal and transparent chain of custody
Proper forest regeneration
Safeguarding biodiversity and soil health
Historically stable or increasing forest carbon stocks
Sound socio-environmental practices in forestry operations⁠

Project Developers shall demonstrate that all forest-derived biomass used in, or incorporated into, the biobased products they manufacture or use in buildings is covered by a recognized forestry sustainability certificate. This may be evidenced by any credible documentation establishing chain of custody between the biomass and a valid certificate, such as invoices, supply agreements, technical specifications, or the certificate itself.

Project developers shall fill in the Rainbow biobased construction risk evaluation, to evaluate the identified risks of biobased construction. The identified risks include:

Forest management, land use and deforestation
Intensive cultivation of biomass with fertilizers, irrigation and pesticides
Use of dedicated crops, competition for food and agricultural land
Distant transport of biomass
Chemical treatment of construction materials
Energy intensive processing
Worsened energy or other performance in the use stage

The risk evaluation shall be completed for all biobased products.

Biobased Product Manufacturing projects shall submit the risk evaluation upon project validation, and only update it if the project activity changes (e.g. new material sources).
Biobased Product Use in Buildings shall submit the risk evaluation for all biobased products used upon project validation, and update it in future monitoring periods if any new biobased products that were not previously reported are used in the buildings constructed during the monitoring period.

For Biobased Product Use in Buildings projects, the environmental and social risks that vary by building site shall be assessed for each site individually. Risks that remain constant across all buildings within a project may be assessed only once, and then proven to remain unchanged for subsequent buildings.

All risk assessments must also address the Minimum ESS risks defined in the Rainbow Standard Rules.

Project Developers shall assign a likelihood and severity score of each risk, and provide an explanation of their choices. The VVB and Rainbow’s Certification team shall evaluate the assessment and may recommend changes to the assigned scores.

Any identified material risk (defined as issues with a risk score of moderate or higher) shall be subject to a Risk Mitigation Plan, which outlines how Project Developers will mitigate, monitor, report, and if necessary, compensate for any environmental and/or social harms.

Additional proof may be required for certain high risk environmental and social problems.

The Project Developer, the Rainbow Certification Team, or the VVB may suggest additional risks to be considered for a specific project.

Note that the life-cycle GHG reduction calculations account for the climate change impacts of most environmental risks. Nonetheless, Project Developers shall transparently describe any substantial and sensitive GHG emission risks in the risk evaluation template.

Requirements for French projects complying with FR L229-55/R229-101 🇫🇷

Projects in France satisfying the requirements of their applicable track below are eligible for compliance with FR L229-55/R229-101. Eligibility with FR L229-55/R229-101 is determined at the project-level: all project mitigation activities (i.e. all buildings constructed, or building materials produced) shall meet the requirements for the project to be compliant.

Track 1: Biobased Product Use in Buildings — New construction

Applies when the project involves the construction of a long-lived building in France (not the manufacturing of biobased materials) and falls under the scope of RE2020 (Articles R172-1 to R172-9 of the French Building and Housing Code).

The project shall comply with RE2020 and shall surpass its future performance targets, including the IC Construction threshold.

The binding threshold for each building is an adjusted maximum derived from the IC Construction Max Moyen, per Decree n° 2026-16 of 15 January 2026. Applicable adjustments account for: geographic zone, reference surface area, foundation depth, site networks, and use of default environmental data. Project Developers shall calculate and document the full adjusted IC Construction Max for each building.

The indicative base values (before adjustments) by permit date and usage type are:

Usage

Before 1 Jan 2025 (2025–2027 targets)

On/after 1 Jan 2025 (2028–2030 targets)

Individual housing

530 kgCO₂eq/m²

475 kgCO₂eq/m²

Collective housing

650 kgCO₂eq/m²

580 kgCO₂eq/m²

Offices

810 kgCO₂eq/m²

710 kgCO₂eq/m²

Attestation requirements

Project Developers shall demonstrate compliance for each building through official RE2020 attestations at two stages:

Ex-ante: upon submission of the building permit
Ex-post: upon completion of construction

Track 2: Biobased Product Manufacturing & Biobased Product Use in Buildings — renovation

Applies when the project uses biobased construction materials for building renovation, or manufactures biobased construction materials.

The Project Developer shall prove that the building's energy performance rating (DPE, diagnostic de performance énergétique) is rated B or better.

For equivalent projects outside France, this principle should be followed and assessed qualitatively in the Rainbow biobased construction risk evaluation; the strict B-or-better cutoff does not apply.

Leakage

Project Developers shall source biomass in a way that reduces leakage. Project Developers shall assess and, if identified to be material, quantify the leakage caused by the project and deduct the associated emissions from the project removals. This shall be done by first identifying the alternative use of biomass, and then assessing the leakage risks from the following identified leakage sources:

Biomass diversion and replacement
Counterfactual biomass carbon storage

Upstream and downstream emissions are accounted for in the life-cycle based GHG quantifications, and by the requirement that the baseline scenario downstream emissions be equivalent to the project scenario.

Monitoring

Monitoring Plans shall include the following information for each monitored parameter:

a description of the parameter to be monitored
monitoring frequency
emission sources and sinks
data storage and management plan, including the format, location and duration of data keeping records
Primary data
- description of measurement methods/procedures, and their level of accuracy and calibration procedures
- quality assessment or quality control procedures
- laboratory name and relevant accreditations for any measurement conducted by external laboratories
- responsible party for collecting and archiving data, including how they are assigned/selected, and how their competence to monitor the parameter is assessed
- plan in case of unexpected interruption or errors in monitoring, ensuring conservative treatment of data and an appropriate deduction of emission reductions
Secondary data
- data source and, where applicable, value and frequency of update

Biobased Product Manufacturing

Monitoring Plans for this methodology shall include, but are not limited to, tracking the following information by biobased product producers:

amount and type of biobased products delivered to construction sites for use
amount, type and source of biobased inputs
proof of adherence to the No Double Counting criterion
Co-benefits

Biobased Product Use in Buildings

Monitoring Plans for this methodology shall include, but are not limited to, tracking the following information by building owners using biobased materials:

amount and type of eligible biobased products incorporated into buildings
building permit and certificate of completion, including address, date of completion, and building typology
ESS risk assessment for the use of new building products that were not previously assessed, and used in any new buildings completed in the monitoring period
Reversal risk assessment for all new buildings completed in the monitoring period
proof of adherence to the No Double Counting criterion
updated project EPDs and carbon storage quantification, if any new biobased products are used
updated baseline scope, or confirmation of no change to the baseline
if in France, embodied and use-stage GHG emissions of the completed building (see Environmental and Social Safeguards section)
Co-benefits

PreviousEligibility and scope

NextGHG quantification

Last updated 23 days ago