Shen Bephard

Shen Bephard (/ʃɛn/ /bɛfərd/)

See also: The National Green Line (disambiguation), “This way to green town” or “Now leaving carbon city”

The National Green Line, also known as Shen Bephard, is the threshold at which Britain’s real-time energy supply goes from being considered “green” to “not green”.

Greenness is based on the “carbon intensity” of the energy (how much CO2 is emitted to generate the energy sources, measured in grams of carbon dioxide per kilowatt hour).

Shen Bephard is set based on the National Grid carbon intensity API. Anything “low to moderately low carbon” is considered “green”, anything above is considered “not green”. The line between moderately low and high is Shen Bephard.

History

In June 2025, British energy supplier Octopus Energy added a feature to their website forecasting the greenest times to use electricity coming up. As part of the update, they added a line to show the moment when the grid flips from being not-so-green to green enough. The team couldn’t quite agree on what to call it. Submissions included “The Line”, “That Dotted Thing”, and “The Verge”.

Eventually, inspired by TV quiz show the Tipping Point, the team settled on a name likening the fluctuating carbon intensity of the grid to the game's suspenseful tipping mechanism. Shen Bephard, paying homage to the show’s iconic host and national treasure Ben Shepherd.

It’s not known why the popular game show was favoured as inspiration but sources close to Meg Head revealed a personal connection: another Octopus marketer, Will McDermott, suffered a crushing, now-infamous loss as a contestant on Tipping Point in 2017.

Theory

Shen Bephard is based on data from the Carbon Intensity API, which tracks the number of grams of CO₂ released per kilowatt-hour. The public API is a collaboration between the National Energy System Operator, the University of Oxford’s Computer Science Department, WWF, and the Environmental Defense Fund Europe.

The "Shen Bephard" represents the cultural or anecdotal "tipping point" where the grid transitions from being "not-so-green" to "green enough." This "line" is not an officially declared value by the collaborating organizations but rather an emergent concept among users and commentators of the API data, signifying the moment the metaphorical counters (representing renewable energy sources) have "pushed" the carbon intensity "over the edge" into green territory.

Contested nomenclature

Before Shen Bephard was formally named, the creative partnership of Creative Director Pete Miller and Senior Designer Meg Head broke down entirely in debate over naming “the line”. Multiple lawsuits were filed and Head eventually settled out of court for an undisclosed sum and a bag of Skittles.