AIB Grid-Connected is a market-driven descriptor for certain Guarantees of Origin that meet the following criteria: Firstly, they're EECS-GOs, which is where the "AIB" prefix is earned - adhering to the EECS Rules overseen by the Association of Issuing Bodies (AIB) . Secondly, they are readily transactable between two countries with a physical interconnection in the European grid, hence "Grid-Connected". As all AIB certificates can be transferred across borders between AIB member countries , grid-connected is frequently used as a modifier (and potentially coined) by traders and corporates to immediately anchor a conversation about certificates back to a geographic reality. An example use case would be a GO issued in Norway that was later cancelled by a buyer in Germany - with neither counterparty having to deal with any other technical infrastructure besides their own national registry or a Soldera account. Contrastingly, an Icelandic-issue EECS GO, whilst AIB-Hub transferable, would not be considered grid connected due to a lack of physical connection infrastructure with any European mainland country.
AIB-Hub Connected refers to national registries that follow the European Energy Certificate System (EECS) standards and are connected via the AIB Hub - registries with this status can transfer Guarantees of Origin (GOs) electronically through the hub. In practice, that means buyers can procure and cancel Energy Attribute Certificates across borders without logging into each country's registry separately.
For companies doing market-based reporting for Scope 2 under the GHG Protocol , AIB-Hub connectivity is what confirms a certificate is legitimate within AIB Market Boundaries and hasn't been counted twice. Compliance teams rely on this status for verified documentation backing their renewable energy claims.
One thing to watch: Icelandic GOs carry AIB-Hub Connected status, but Iceland has no physical grid link to mainland Europe. Some corporate buyers and auditors treat that differently. The related adjective AIB Grid-Connected adds a market-driven physical interconnection requirement on top of the EECS registry standards, and that distinction matters when sourcing for stricter procurement policies. Each country runs its own registry with its own procedures. Certain platforms like Soldera handle cross-border GO transactions through a single interface via integrations, so you don't need accounts for multiple national systems yourself.
The balancing market is a real-time system run by Transmission System Operators (TSOs) to match electricity supply with demand, typically in 15-minute settlement windows under ENTSO-E rules. It exists to keep the grid physically stable, and nothing more.
Don't get mixed up - the Energy Attribute Certificate market is a completely different thing. The two worlds occasionally get confused, but they solve different problems: balancing markets keep supply and demand matched in real time on the grid, while certificates are an accounting layer that lets sustainability teams prove where their electricity came from.
ENTSO-E defines a Bidding Zone as the largest geographical area where market participants can trade electricity without needing capacity allocation. The CACM Regulation introduced this concept to manage structural congestion across European electricity markets. Relevance to EACs is multifaceted: if you work in sustainability, bidding zones are worth understanding because they are a frequent presence in discourse around higher-precision boundaries for market-based Scope 2 instruments, specifically Guarantees of Origin (GOs) in Europe. The key idea within certain schemes, such as RE100 , is to prioritise regulatory alignment and physical interconnectivity between regions - precise geographic matching via bidding zones is a highly adjacent topic to this discussion. When GO procurement aligns with the bidding zone where the electricity is actually bought and delivered, reporting a strong and credible claim via locally matched GOs becomes easier. Tracking all of this happens across separate national registries, one per country, which gets messy quickly when you're operating across borders. Soldera pulls these into a single platform so you're not logging into five different registries to manage certificates.
BREEAM In-Use is an assessment scheme for rating the environmental performance of existing buildings. It covers energy, water, waste, and other categories. Buildings score higher on energy when they can prove their electricity comes from renewable sources, and the way you prove that is with Energy Attribute Certificates (EACs). In the UK these are REGOs , in Europe they're Guarantees of Origin , and in other markets they're called I-RECs . Buy the right certificates, retire them against your consumption, and your building's BREEAM In-Use energy score goes up.
Bundled procurement means delivering electricity and EACs through unified transactions, as opposed to separate or independent transfers of unbundled EACs . The mechanism often describes a scenario whereby a producer sells power and certificates simultaneously to the same buyer through unified commercial mechanisms, such as PPAs . However, "bundled" does not strictly require that EACs originate from the exact same generator as sold energy, nor that they must correlate with the generation period of the electricity delivered. Rather, it only matters that energy and EACs are part of the same contract.
Executed through registry interfaces or Soldera virtual accounts , cancellation (also known as retirement or redemption) is one of two ways an EACs lifecycle comes to an end, the other being expiration . Once cancelled, EACs are removed from circulation as they become ineligible for transfer or future use. This mechanism exists to prevent the double counting of renewable energy: multiple parties cannot claim attributes from identical certificates, because all registry protocols block duplicate retirements. Cancelling an EAC grants the user a cancellation certificate, which are essential to keep for complete audit trails and market-based Scope 2 disclosure .
Cancellation statements must be compiled into evidence packages to support claims : typically for emissions disclosures and for schemes that require proof of renewable consumption. They are accessible for download after EACs have been cancelled within a registry or Virtual Account . They contain beneficiary identification, and, similarly to EACs, relevant device metadata in full. To use the example of European GOs : statements reference unique certificate numbers, specific generation volumes, the domain of cancellation, facility names, the issuance date, production periods, technology classifications, and whether or not the device was in receipt of public support (whether investment support or production support).
Carbon Reduction Plans (CRPs) are documents required under UK Procurement Policy Note 06/21 for any organisation bidding on major public contracts. Each CRP has to state the organisation's current carbon footprint and commit to reaching Net Zero by 2050, covering Scopes 1, 2, and 3. Scope 2 , which covers purchased electricity, is where EACs come in. In the UK these are REGOs (Renewable Energy Guarantees of Origin ). Buy enough REGOs and you can report zero emissions for your electricity use under the market-based method. That clears the CRP's reduction targets and ticks the procurement box for green energy sourcing.
Claims are the public assertion of a type of energy usage, and must be backed by legitimate cancellation statements from tracking system registries. Claims are both a discussion of legality and credibility: In the EU, supplier-to-customer renewable claims are legally connected to Guarantees of Origin that are provably cancelled in official registries to prevent double counting (also the case for REGOs redeemed in the UK). In the US, the FTC's Green Guides are explicit: claims about renewable energy usage are considered unqualified if energy derived from non-renewable sources is used but corresponding RECs are not procured to match the energy usage (or "virtually all" the energy usage in the case of manufacturing processes). Credibility of claims is a different discussion topic, relating not to the legal messaging rights of an EAC redeemer post-cancellation, but to the quality criteria and guidelines that organisations should attempt to follow when procuring EACs. The credible claims document published by RE100 is a well-established example of this theme.
The Day-ahead market is a wholesale electricity auction. Participants buy and sell energy for delivery the next calendar day. In Europe, CACM regulations and the EUPHEMIA algorithm (run by NEMOs) set hourly clearing prices across bidding zones by 12:00 CET.
The physical energy trade happens on this market, but the environmental attributes don't come with it. It's a seperate market altogether. Those are tracked separately through Energy Attribute Certificates . A company doing Scope 2 reporting would buy Guarantees of Origin (GOs) independently to cover their actual consumption. To claim that energy as renewable, the GOs then get cancelled through national registries or through Soldera Virtual Accounts.
Demand response (DR) is a grid flexibility mechanism where end-users adjust their electricity consumption based on automated triggers or price signals. Regulations like FERC Order 2222 in the US and EU Directive 2019/944 govern how DR programmes operate. Unlike Energy Attribute Certificates (EACs) that represent renewable generation, but DR is about load curtailment, you're reducing what you actually consume rather than certifying how it was produced. DR brings down your gross consumption, while EACs zero out emissions on whatever load remains under frameworks like the Greenhouse Gas Protocol. They address different sides of the same problem.
Dual reporting under the GHG Protocol currently mandates two calculations and figures. Organisations calculate Scope 2 emissions twice using distinct methodologies : location-based figures that apply grid average factors from regional authorities , and market-based figures that incorporate the factors of residual mix data and contractual instruments, the latter of which only recognised as valid if meeting the quality criteria established by the GHG protocol or, where deviating, the criteria of a local disclosure regime.
Every megawatt-hour (MWh) of electricity has energy attributes. Consider these as the factual descriptors tied to a specific 1 megawatt-hour (MWh), and include generation technology, plant location, support status, facility start date, and the production period of the generation. The desirability of energy with renewable generation technology attributes is the easiest to understand, but all attributes serve a purpose, usually relating to supporting the credibility of a renewable claim .
Energy Attribute Certificate (EACs) act as the formal instrument recording those attributes per 1MWh.
The phrase " Energy Attribute Certificates " (EACs) is an umbrella term that refers to every type of tradeable certificate carrying energy attributes , with the majority of demand existing for the "renewable" attribute (meaning, tracking energy from a renewable source). Functionally, EACs underpin book and claim traceability mechanisms by serving as tradeable assets: EAC creation (known as issuance ) "books" the finite number of attributes that correspond with verified renewable energy production, whilst "claims" (via EAC cancellation ) represent end-of-life for an EAC, as the attribute is used permanently. The existence of market demand for EACs classes them as environmental commodities .
EAC types primarily include Guarantees of Origin (GOs), Renewable Energy Guarantees of Origin (REGOs), International Renewable Energy Certificates (I-RECs) , and Renewable Energy Certificates (RECs).
Energy origination is the process of sourcing and structuring renewable energy supply contracts (for both power delivery and Energy Attribute Certificates (EACs) . It covers everything from identifying suitable generation assets to negotiating Power Purchase Agreements and bespoke structured products . Commercially, origination sits upstream of certificate procurement. Teams looking to procure need to account for regional policy variations, registry requirements, and the specific contractual instruments available in each market, whether REGOs in the UK, Guarantees of Origin in continental Europe, or I-RECs in emerging markets.
The origination phase determines what Energy Attribute Certificates a buyer can eventually retire. Getting the contract structure right means cleaner audit trails, better price visibility, and certificates that actually match the buyer's consumption data and sustainability mandates. For Scope 2 reporting under the market-based method , strong origination is key to a a defensible and credible renewable claim . Dual-sided platforms like Soldera exist to simplify origination by aggregating thousands of renewable producers under one interface - meaning that origination is handled for most buyers who would rather focus on price quotes and customising their procurement criteria than trying to establish relationships with renewable energy producers themselves.
An environmental commodity is an umbrella term referring to any tradable instrument with market demand that carries a standardised environmental purpose within a regulatory or voluntary framework. Environmental commodities include carbon credits, emissions allowances, and Energy Attribute Certificates (EACs) .
EACs are the electricity-specific subclass: one certificate represents the attributes of 1 megawatt-hour (MWh) of generation, vary by region , and supports renewable electricity usage claims when cancelled. Whilst they are both environmental commodities, carbon credits not the same as EACs, they are different: they represent quantified greenhouse gas reductions or removals (usually 1 tonne CO₂e) and are used to offset residual emissions (Scope 1 & 3), not to evidence renewable electricity sourcing for market-based ( Scope 2 ) disclosure.
Expiry ends the period of time after production when an
EAC
can be used for an end-user renewable claim. It represents one of two ways that an EAC lifecycle
ends (the other being
cancellation)
. Expiry rules vary per jurisdiction and per EAC type:
GOs
under the
EECS framework
have a dual-deadline: certificates are tradeable for
12 months,
then enter a 6-month redemption-only window (meaning cancellation is allowed), hard-capped at 18
months (all functionality ceases).
UK REGOs
implement a
16-month rolling expiry
, with Ofgem executing automatic cancellations as per this schedule. North American
RECs
show the widest variation, ranging from 3-months in New England to
4-years
in Wisconsin.
I-RECs
have no registry-level expiry and remain technically valid indefinitely.
Note: Registry functionality is the technical maximum, but reporting frameworks can vary in vintage matching rules, causing a functional expiry separate from registry mechanics. See claims and vintage to learn more.
Granular certificate matching (more broadly conceptually referred to as "granularity") pairs generation timestamps with EAC retirement intervals at sub-annual resolutions, working to ensure that renewable energy generation and EAC retirement are occurring within highly aligned timeframes (sometimes, as aligned as hourly or sub-hourly), boosting the credibility of a claim. Groups and pacts dedicated to collaborating on the topic exist: such as SEForAll and 24/7 Carbon Free Energy , fostering conversation and dialogue. Yet, whilst "hourly matching" is emerging as a discussion point and potential standard for the market to evolve into, it's not currently clear how a shift towards granularity would impact EAC price dynamics, or if market infrastructure is currently prepared for that leap (at least in the immediate future).
GRESB Infrastructure is a global ESG benchmark for infrastructure and real assets, built around the TCFD framework and GHG Protocol. Every year, assets report environmental performance data through GRESB's assessment to give investors a standardised view of ESG risk. The GHG Protocol requires dual reporting of Scope 2 emissions, and GRESB accepts market-based figures. In practice, this means buying and retiring Energy Attribute Certificates , RECs in North America, GOs in Europe, REGOs in the UK, or I-RECs in emerging markets, allows an asset to claim zero-carbon electricity in its GRESB submission. These certificates feed straight into the fund's GRESB Score. Compliance teams have to verify them properly, because a stronger score translates to higher asset valuations and more attention from ESG-focused capital.
Guarantees of Origin (GOs) track renewable electricity attributes across European markets via conventional book and claim, acting as Europe's dominant EAC . Producers receive one GO per megawatt-hour delivered to the grid, and issuance occurs after production data is transmitted to the respective national registry operator. Guarantees of Origin are bought and sold, and exit supply via expiry or cancellation.
GOs are regulated by EU Directive 2023/2413 , (commonly known as REDIII), and are operationalised via the EECS rules (overseen by the AIB ).
Operating via the The I-TRACK Foundation , International Renewable Energy Certificates (I-RECs) are the predominant international EAC, and can be accessed via the Evident registry or Virtual Accounts. Unlike other EACs , they never expire. They must be redeemed in the same market where the energy was generated and are equal to one megawatt-hour of renewable generation. I-RECs are issued by local issuers: all I-REC issuers are published by Evident , as well as a list of I-REC(E) participants .
ISCC PLUS is a voluntary certification that tracks whether bio-based and circular materials actually end up where companies say they do. It uses a mass balance approach, essentially accounting for sustainable feedstocks as they move through a supply chain rather than physically separating them at every step. The scheme builds on ISO 14067 and EU RED II requirements.
ISCC PLUS covers the materials side of sustainability (Scope 3), not the energy side ( Scope 2 ). But the two overlap in practice. Companies going through ISCC audits often need to prove that the energy used in production came from renewable sources as well. That means buying and cancelling Energy Attribute Certificates , either Guarantees of Origin in Europe or RECs in North America, through registries or integrated platforms like Soldera's Virtual Accounts.
The audit angle is where it gets practical. If a company claims renewable energy use but can't show cancellation certificates through a recognised registry, that claim won't hold up.
A market boundary is the geographic area, usually a single electricity grid or country-level jurisdiction, where power gets generated and used. The GHG Protocol Scope 2 Guidance (soon to undergo revision to tighten this rule further in Europe) and RE100 both require that market-based renewable energy claims stay inside these boundaries, including regulatory boundaries (regulatory regimes must be shared within a market boundary to enable a valid transfer). So a REGO bought in the UK can only back UK consumption, a Guarantee of Origin covers AIB-Hub connected countries (or, increasingly, operates via "AIB grid-connected" principles), a REC works in North America, and an I-REC applies in the country where it was issued. The certificate has to match where your actual electricity load sits. When a company operates across multiple countries, each with its own registry and rules, keeping track of all this becomes a real headache, leading teams to turn to platforms with global registry integrations and virtual accounts like Soldera .
Merit order is how electricity grids decide which power plants run first. The cheapest sources get dispatched before expensive ones, so renewables (with near-zero marginal costs) typically go ahead of fossil fuels. The EU's Electricity Market Design and the UK's Balancing Mechanism both formalize this. More renewables on the grid pushes wholesale prices down and reduces carbon intensity.
That said, merit order only covers what physically happens on the grid. It says nothing about who gets to claim that renewable energy. For that, you need Energy Attribute Certificates . Under the GHG Protocol 's market-based Scope 2 method, companies prove renewable consumption by buying and cancelling Guarantees of Origin through registries like AIB , or through platforms such as Soldera Virtual Accounts . These certificates work independently of what's actually flowing through the wires at any given moment.
This means sustainability teams are managing two separate things at once. The grid might be running clean because of merit order effects, but your company's renewable claims still depend on having the right certificates cancelled against your actual consumption. You need both the physical dispatch story and the contractual evidence to line up, otherwise your carbon accounting has gaps.
The NHS Net Zero Supplier Roadmap lays out the timeline every NHS supplier has to follow to meet the health service's Net Zero target of 2045. It rolls out in stages. Since April 2024, any company bidding for NHS contracts needs a Carbon Reduction Plan (CRP). The next milestones hit in 2027 and 2028, when suppliers will have to report their full global Scope 1, 2, and 3 emissions and provide carbon footprints at the product level.
Energy Attribute Certificates (EACs) are how suppliers deal with Scope 2 emissions, which covers electricity use. In the UK, these certificates are called REGOs . Buying them lets a company use the " market-based " reporting method, meaning their renewable electricity purchases actually show up in the numbers. That brings down the reported carbon footprint and keeps the company eligible to supply the NHS.
Power Purchase Agreements bind electricity buyers to specific generation facilities through contracts spanning 10-25 years, occasionally longer, allowing for long term hedging and predictability regarding the cost of power. Physical PPAs deliver electricity, typically via the grid. Financial PPAs (termed virtual PPAs or contracts for differences) settle the differential between contract strike price and wholesale market indices. Renewable PPAs are contractual instruments under market-based Scope 2 because environmental attributes transfer: typical PPA structures explicitly include certificate transfers.
RE100 functions as a private corporate electricity procurement standard & initiative. Member companies source 100% renewable electricity, aligned with their self-declared deadlines. The initiative defines eligible sourcing instruments and credible claims via technical specifications and guidelines that are maintained by The Climate Group.
RE100 uses "reasonably close to the reporting year", and GHG protocol uses "redeemed as close as possible" to set how old an Energy Attribute Certificate (EAC) can be when matched against your energy consumption. It's a core requirement for Scope 2 market-based accounting, and the specific rules depend on where you're operating.
In the EU, national regulations under the RED III framework govern when Guarantees of Origin (GOs) can be issued and cancelled. We did an overview article on this topic here .
Outside the EU, the GHG Protocol sets a twenty-one-month vintage window: generation from six months before to three months after the reporting period. This window applies to whichever EAC type you're procuring, whether that's North American RECs , UK REGOs , or I-RECs in emerging markets. Cancellation (or redemption, in REGO terminology) happens through the relevant registry or via Soldera Virtual Accounts to streamline the process across different certificate types. The vintage timing is worth getting right. Certificates outside this window simply won't count toward your Scope 2 claims. Auditors check vintage dates, and getting this wrong means your renewable energy claims don't hold up, or worse, you get flagged for double-counting.
NYC's Local Law 97 lets building owners use Renewable Energy Certificates (RECs) to offset electricity-related carbon limits. Rule 103-06 spells out how this works. The key restriction is geographic: your RECs have to come from generators on the NYC grid (Zone J), or through NYSERDA's Tier 4 program. Buying a certificate from a wind farm in Texas won't cut it. This is where Local Law 97 differs from other certificate systems around the world. REGOs in the UK, Guarantees of Origin in Europe, and international I-RECs all let you claim renewable energy without proving it was delivered to a specific grid. Local Law 97 doesn't. If it wasn't generated in or delivered into Zone J, it doesn't count. On the compliance side, eligible RECs need to be cancelled through the NYGATS tracking platform to count toward the 2024 targets. Get this wrong and you're looking at penalties, so it's worth double-checking that any certificates you're buying actually meet the locational requirements before assuming they'll cover your building's obligations.
Renewable Energy Certificates track renewable electricity generation across North American markets. Each REC represents one megawatt-hour of renewable energy generation from qualifying facilities. The certificate unbundles energy attributes from physical electricity for market-based claims because the grid mixes all power sources physically. For carbon accounting, valid RECs can provide Scope 2 emissions reductions under the GHG Protocol's market-based method.
Residual mix represents the attribute profile (the renewable status of procured energy) left after certificate retirements remove tracked generation from regional pools. Calculated annually by organizations like AIB (European Attribute Mix) , DESNZ (United Kingdom's Residual Mix Data) , Green-e (North American residual mix methodologies ), these organisations use the residual mix to, in-effect, assign market-based emissions factors to those who consume electricity, yet who do not retire certificates.
Residual Mix is not to be confused with the grid-average emissions factors used in location-based reporting. Read more in our residual mix guide here.
Scope 2 emissions quantify indirect greenhouse gases from energy procurement (purchasing). These figures are disclosed by reporting organisations. Unless following a different standard, disclosure practices obey the GHG Protocol Corporate Standard and Scope 2 Guidance . Companies are required to calculate and report two separate figures: location-based emissions using grid average factors , alongside market-based emissions reflecting an emissions figure calculated by applying the emissions factor of contractual instruments (required to avoid using the emissions factor from the residual mix ). Final market figures are typically disclosed after valid use of contractual instruments like EACs or PPAs , deemed valid if they meet the quality criteria established by the GHG protocol.
Scope 3 Category 15 includes indirect emissions from a company’s investments (known as 'financed emissions'), included via equity ownership, project financing, or debt issuance. C15 falls under the Greenhouse Gas Protocol’s Scope 3 standard, and is the final category within Scope 3. As is the nature of Scope 3 (indirect emissions beyond the reporting entity, located within their value chain), C15 is concerned only with emissions that are not already included in the Scope 1 (direct) or Scope 2 (purchased energy) inventories of the investor company. S3 C15, instead refers to the indirect, proportional Scope 1 and Scope 2 emissions of those portfolio companies, that become attributable to the investor via this category. Within the context of EACs (market-based Scope 2 instruments); if a portfolio company uses and retires EACs and reflects them in its market-based reporting , its reported Scope 2 emissions fall, and because Category 15 uses those reported emissions data to calculate financed emissions, effective EAC cancellaitons at the portfolio company level can indirectly reduce the financed emissions attributed to the investor in Category 15. EACs themselves are not a direct Category 15 instrument but influence the input data used in the Category 15 calculation due to their core functionality within market-based calculations .
Structured energy products are custom-designed financial or physical contracts that go beyond standard supply agreements. Think Power Purchase Agreements ( PPAs or vPPAs ) or tailored pricing structures built around a buyer's specific consumption profile, risk appetite, and price expectations.
These products often span years or even decades, giving energy-intensive industries and corporate buyers long-term price certainty while supporting their Scope 2 reporting under the GHG Protocol . They're particularly common across European and North American markets where companies need to lock in renewable supply at predictable costs.
Structured products work hand-in-hand with Energy Attribute Certificates (EACs) - the GOs , RECs , or I-RECs that provide the actual proof of renewable consumption for reporting purposes. The structured product secures the power or hedge, while the certificates handle the compliance side for renewable claims. Buyers still need to procure and cancel certificates delivered within structured products in the relevant registry or Soldera virtual accounts to make valid renewable energy claims.
For companies operating across multiple markets, managing these arrangements alongside certificate procurement across different registries gets complex fast. That's where unified certificate management platforms come in to ensure that audit trails are kept clean and all national rule deviations are automatically followed.
Temporal Energy Attribute Certificates (T-EACs) are energy certificates with hourly or sub-hourly timestamps that show exactly when carbon-free electricity was produced. For compliance teams, T-EACs give you timestamped proof that renewable supply actually matched demand hour by hour. They're issued by certain registries (with pilots and rollouts increasing as their popularity increases), operating at a finer granularity than but building on the same idea as RECs in North America, Guarantees of Origin in Europe, and REGOs in the UK. Instead of proving renewable energy was generated somewhere during the year, T-EACs prove it was generated in the same hour (or less) that the exact period in time it was consumed.
At time of writing: The Greenhouse Gas Protocol is currently reviewing whether to formally recognise these granular instruments in Scope 2 reporting, though procurement is already happening regardless. The tricky part is that each country runs its own registry with its own data formats, so tracking and cancelling certificates across borders gets incredibly messy very quickly. Soldera connects to multiple registries through a single platform, cutting through most of that friction, therefore being well positioned to handle T-EAC workflows.
Unbundled procurement of EACs refers to the procurement of energy and EACs in separate transactions, usually with the intend to cancel EACs for market-based Scope 2 disclosure. Certain entities, like traders, procure EACs with the intention of selling them rather than cancelling them, which can still understood as an unbundled purchase. Only the party that ultimately cancels an EAC can make the renewable consumption claim.
Vintage, the timestamp of electricity production, refers to the generation date or time period when the renewable energy, tracked by an EAC, was produced. It's used by reporting frameworks and compliance schemes to impose vintage matching rules that determine which certificates are eligible for use. For example, "2025 Vintage" EACs carry the renewable attributes of electricity generated in 2025. As generation metadata is carried by each certificate, expiry timelines are applied from the point of generation onwards. After that period, the certificate's vintage is too old for usage and is technically worthless, which is also why older vintage EACs fetch lower prices as they approach expiry. Certain schemes may disallow certificates before the expiry date, even if they remain technically valid in a registry. For instance, Green-e® requires certificates to be no more than 21 months old relative to the reporting period, and RE100 recommends this as a "reasonable practice" . This prevents companies from using old certificates to claim renewable energy use, ensuring claims reflect contemporary generation. Standard-driven vintage requirements like these is also what creates a functional expiry for I-RECs, despite their perpetual registry validity.
