What is a REGO certificate?

Quick Answer: A Renewable Energy Guarantee of Origin (REGO) is an electronic certificate issued to UK renewable electricity generators that proves one megawatt-hour (MWh) of electricity came from a renewable source. Businesses use REGO certificates to support a zero-emission Scope 2 claim under the market-based method of carbon accounting. Without cancelled REGO certificates as evidence, no GHG Protocol-aligned carbon report can treat a renewable electricity tariff claim as zero-emission.

What is a Renewable Energy Guarantee of Origin (REGO)?

A Renewable Energy Guarantee of Origin (REGO) is an electronic certificate issued by Ofgem, the UK energy regulator, to generators of renewable electricity. One REGO certificate corresponds to one MWh of electricity generated from a qualifying renewable source, such as wind, solar, hydropower, or biomass.

The EU Renewables Directive introduced the scheme in 2003, and it remains in force in the UK. Its purpose is to create a transparent, auditable record of renewable electricity production and prevent anyone from claiming the same unit of generation more than once.

REGOs are separate from the physical electricity supply. A generator produces electricity, feeds it into the grid, and receives a corresponding REGO certificate. The generator can then sell, transfer, or retire that certificate independently of the electricity itself.

How REGOs work in practice

An official registry tracks REGO certificates. When a business wants to claim that its electricity consumption was renewable, it must cancel the relevant certificates (also called retiring them) in that registry against the volume of electricity consumed. An uncancelled certificate does not support a valid renewable energy claim.

The process typically works as follows:

1. A renewable generator produces electricity and receives one REGO per MWh generated.
2. The generator sells the certificates, either bundled with the electricity supply or separately on the open market.
3. An energy supplier retires the certificates on behalf of its customers, or a business purchases and retires them directly.
4. The retired certificates serve as evidence that the electricity consumed came from a renewable source.

Each REGO certificate is valid for 12 months from the date of generation. A certificate not cancelled within that window expires and is void.

Why do REGOs matter for Scope 2 carbon accounting?

Scope 2 emissions cover the greenhouse gases associated with purchased electricity. The GHG Protocol requires organisations to report Scope 2 emissions using two methods: the location-based method and the market-based method.

Under the location-based method, organisations calculate emissions using the average carbon intensity of the electricity grid. REGOs have no role here.

Under the market-based method, emissions reflect the specific electricity a business has chosen to purchase. If a business holds cancelled REGO certificates covering its full electricity consumption, it can report a market-based Scope 2 emission factor of zero, or close to zero, for the electricity those certificates cover. This is the mechanism that lets a renewable electricity claim lower a reported Scope 2 figure.

There is an important condition attached. The GHG Protocol requires both the location-based and market-based figures to be disclosed side by side. A business cannot drop the location-based number simply because it holds REGOs. That figure reflects the physical grid and does not move with your purchasing decisions, so it remains the more conservative view of your electricity emissions.

It is also worth being clear about what a REGO does and does not prove. A cancelled REGO substantiates that a volume of renewable electricity was generated, and that the attribute has been assigned to you and to no one else. On its own, it does not prove that your purchase caused any additional renewable generation to happen. That distinction sits at the centre of how credible a zero-emission claim looks to an auditor or a reporting framework.

What makes a REGO claim valid under the GHG Protocol?

Holding a REGO is not the same as holding a REGO that meets the GHG Protocol's market-based quality criteria. To apply a renewable emission factor, the certificates behind the claim should meet a set of conditions:

• Retirement (cancellation): The certificate must be cancelled in the registry against your consumption. An uncancelled, traded, or expired certificate does not support a claim.
• Temporal matching: The certificate should relate to the same reporting period as the consumption it is matched against, rather than generation from several years earlier.
• Geographic matching: The generation should sit in the same market as the consumption. For UK consumption, that means UK-based renewable generation evidenced by REGOs.
• Uniqueness: Each MWh of renewable generation can be claimed once, and the attribute cannot sit with both the generator and the consumer.

Where a claim cannot meet these conditions, the GHG Protocol's principle is to fall back to a residual mix factor for the market-based figure, reflecting the grid mix left over once everyone else's claimed renewable attributes have been removed. The practical takeaway for UK reporters is simpler: a claim you cannot evidence with cancelled, in-period, UK-sourced REGOs is not a claim you should be reporting as zero.

Bundled versus unbundled REGOs: why the distinction matters

Not all REGOs reach the end user in the same way, and the difference has a real bearing on how defensible a claim is.

• Bundled REGOs are sold together with the underlying electricity. The certificate and the power it represents stay linked, giving a clearer line between what was generated and what was supplied.
• Unbundled REGOs are sold separately from the electricity, on the open certificate market. A supplier can buy unbundled REGOs cheaply and use them to label an otherwise conventional supply as renewable.

Because unbundled REGOs are inexpensive and widely available, a green tariff backed only by unbundled certificates can meet the letter of the market-based method while doing little to drive new renewable capacity. This is the main reason REGO-backed claims attract questions, and why stakeholders increasingly ask not just whether a business holds REGOs, but where those certificates came from.

How does a REGO differ from other certificates?

A REGO is the UK's energy attribute certificate. Equivalent instruments exist in other markets:

• Guarantees of Origin (GOs) are used across the EU and work on the same one-certificate-per-MWh basis.
• Renewable Energy Certificates (RECs) serve the same function in the United States.

The principle is consistent across all three. One certificate evidences one MWh of renewable generation, and it must be retired against consumption to support a market-based claim. The differences lie in the registries, the markets they cover, and the rules on geographic matching. A UK business reporting UK consumption should be substantiating its claim with REGOs, not with certificates issued in another market.

What does this mean for your carbon reporting?

For most businesses, the practical position is clear. If your supply is on a renewable tariff, find out whether the REGOs behind it have been cancelled against your consumption, whether they relate to the right period, and whether they are UK-sourced. If they are, you have the evidence to support a zero or near-zero market-based Scope 2 figure. If you cannot confirm those things, reporting a zero figure is a risk worth avoiding.

At Seedling, we report both location-based and market-based Scope 2 emissions in line with the GHG Protocol's dual reporting requirement, and we keep the basis of every figure transparent, including the REGO evidence behind any renewable electricity claim. That is what makes the output usable when it is shared with auditors, investors, or frameworks such as SBTi, B Corp, and SECR, rather than just a number on a page.

‍