REGO certificates and SECR: what a green tariff really does to scope 2

What a REGO certificate is

A REGO — Renewable Energy Guarantee of Origin — is a certificate issued by Ofgem for every megawatt-hour (MWh) of eligible renewable electricity generated in the UK. Suppliers use REGOs to evidence the renewable share of the electricity they sell: a "100% renewable" tariff is, in regulatory terms, a tariff backed by enough REGOs to match the supplier's sales.

The certificate travels separately from the electricity itself. The physics doesn't change — every grid-connected building receives the same mixed electricity — so a REGO is an accounting instrument: proof that somewhere on the grid, a megawatt-hour of renewable generation matched your consumption.

Location-based vs market-based scope 2

The GHG Protocol recognises two ways to calculate scope 2 emissions:

Under the location-based method, everyone on the UK grid uses the same average factor, whatever their tariff. Under the market-based method, a REGO-backed renewable tariff can support a scope 2 figure at or near zero for the electricity it covers.

What this means for your SECR report

The practical convention for SECR is:

1. Report location-based scope 2 using the current DEFRA grid-average factor. This is the figure your year-on-year comparison and intensity ratio are built on, and it's what reviewers expect to see.
2. Optionally disclose a market-based figure alongside it, stating that it reflects a REGO-backed renewable tariff. Dual reporting is legitimate and increasingly common — what fails audit scrutiny is silently swapping to the flattering number.
3. Say what you did in the methodology note: which method(s), which factor set, and what evidence backs any market-based claim.

So no — a green tariff does not cut your headline SECR scope 2 figure. But it does give you a defensible second figure that shows your procurement choice, and that has real value in tenders and stakeholder reporting.

Watch-outs

• Unbundled REGOs: certificates bought separately from the underlying electricity are the weakest form of evidence and attract greenwashing criticism. A REGO-backed supply tariff is a stronger basis for a market-based claim than standalone certificates.
• Partial coverage: if the tariff covers one site out of five, the market-based figure only drops for that site's consumption.
• The grid is decarbonising anyway: the DEFRA 2026 grid factor fell 26.8% year-on-year — your location-based figure improves every year without any procurement change, which is exactly why the narrative should explain why the number moved. See what changed in the DEFRA 2026 factors.
• Scope 2 is often not the biggest lever: for fleet-heavy or gas-heavy businesses, scope 1 dominates. Run the numbers in the carbon calculator before deciding where to spend.

Getting it right in your filing

If your company is in scope for SECR and you're weighing a renewable tariff — or being asked by a parent company or tender to show a market-based figure — a specialist can set up dual reporting properly: both figures, correct factors, and a methodology note that stands up to your auditor. Speak to a specialist — free and no obligation.