Matching your electricity use with renewable certificates is the standard way to drive market-based Scope 2 emissions toward zero — but the cost depends entirely on volume and the certificate price. This calculator converts your MWh consumption and a per-MWh price into a total procurement cost and the resulting emission factor.
How it works
Certificates are denominated per megawatt-hour, so the math is direct:
certificates needed = annual consumption (MWh) (1 cert = 1 MWh)
total cost = certificates × price per MWh
match % = certificates bought / consumption × 100
market-based Scope 2 = consumption × certificate emission factor (≈ 0 for renewables)Matching 100 percent of consumption with retired renewable certificates reports a market-based Scope 2 of roughly zero, while your location-based figure (the grid average) is unaffected.
Worked example
An office consuming 1,200 MWh per year buys UK REGOs at a hypothetical market price. The number of certificates needed equals consumption: 1,200 REGOs. At any given price per certificate, the total cost is simply 1,200 times that price. The market-based Scope 2 after 100% matching is effectively zero, even though the grid the building is physically connected to is not 100% renewable.
Certificate types and markets
| Instrument | Market | What it covers |
|---|---|---|
| REC (Renewable Energy Certificate) | United States | 1 MWh of eligible renewable generation |
| GO (Guarantee of Origin) | European Union | 1 MWh, verified by national issuing body |
| REGO (Renewable Energy Guarantee of Origin) | United Kingdom | 1 MWh, issued by Ofgem |
All three certify the same fundamental thing — one megawatt-hour of eligible renewable electricity was generated and injected into the grid. The issuing body, eligible technologies, and market liquidity differ by region.
What to watch out for
Certificate quality and vintage matter more than the headline price. A certificate issued in the same country, in the same year, from a new project carries stronger environmental claims than an old certificate from a grandfathered plant. The GHG Protocol’s guidance on market instruments encourages buyers to consider these quality dimensions, not just cost.
Unbundled vs. bundled. Unbundled certificates are purchased separately from the electricity supply and are cheaper but offer less additionality. Bundled certificates come attached to a physical power purchase agreement (PPA) with a named generator, which typically guarantees temporal and geographic matching and funds new capacity — generally considered the gold standard.
Partial matching is allowed under market-based accounting: buying certificates for 80% of consumption reports a proportionally lower Scope 2 figure, not zero.
When to use this calculator
Use it to estimate annual procurement budgets before entering a certificate purchasing program, to model the cost of different match percentages, or to compare the expense of certificates against a direct PPA in rough terms. Always use a live market price from a broker or exchange, as certificate prices are volatile and vary by vintage, technology, and country of origin.