Stark divide in UK energy sustainability rankings, Which? reports

A major divide has been exposed in how UK energy companies approach the green transition, according to a comprehensive sustainability audit by Which?

While official government data shows that renewable generation now accounts for over half of the National Grid’s electricity output, the consumer watchdog’s assessment of 15 major providers reveals a stark gap between industry leaders and companies taking minimal action.

The analysis evaluated firms across three critical metrics: renewable energy sourcing, operational greenhouse gas emissions and the practical support provided to help households reduce their carbon footprint.

Which? Eco Providers

At the top of the table, Good Energy and Octopus Energy emerged as the joint highest-scoring suppliers, both achieving impressive overall scores of 85% and earning the coveted Which? Eco Provider endorsement for 2026.

Both firms secured a perfect five-out-of-five rating for assisting households in lowering their carbon footprints. Octopus was highly praised for its extensive green tech installations and flexible tariffs, while Good Energy stood out by matching 90% of its customers’ electricity usage with renewable power generated within the same half-hour window.

Rounding out the top tier, Ecotricity secured a 75% overall score, notably logging the highest individual renewable energy mark at 11 out of 12 points, while 100Green followed closely at 70% as the only evaluated firm offering 100% green gas alongside a unique tariff tailored to protect fragile ecosystems.

Wild differences

Conversely, some of Britain’s largest household brands languished in the middle of the rankings. British Gas and EDF Energy both finished with scores of 55%, hampered by high operational emissions and direct corporate ties to fossil fuels. Parent companies for both firms continue to maintain contracts with or operate gas-fuelled power plants.

The bottom of the table saw a total collapse in scores, with Scottish Power and E (Gas & Electricity) both registering 0%. Scottish Power’s bottom-tier finish was a result of the company choosing not to participate in the research questionnaire.

Meanwhile, E (Gas & Electricity) dropped to zero because it does not generate or buy renewable energy, failed to provide requested emissions data, offers below-average solar export rates and does not provide green gas or time-of-use tariffs to its customer base. Outfox Energy finished marginally higher at just 5%.

The findings highlight that despite broad industry marketing, real corporate action varies wildly across the market.

“Our research shows there are big differences in how energy firms are approaching green initiatives,” said Emily Seymour, Which? Energy Editor. “If this is something you care about, it’s worth checking how your supplier performs against its competitors. Some providers are taking far more action than others, so don’t assume they’re all the same.”

Seymour added that consumers hold significant leverage in driving sector-wide change: “If your supplier isn’t performing as well as you’d like, switching to a top-performing company sends a clear message to the market.”