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What computing costs, in watts and in pounds

Climate and computing done with a plug meter and a grid API instead of a position — starting with the machine on your own desk.

Almost everything written about the energy cost of computing is an argument. Very little of it contains a figure the writer measured, and the figures that do get quoted are usually a data centre's, divided by a number nobody can check.

A £15 plug meter settles most of it for your own machine in an afternoon: idle draw, draw under load, watt-hours per task, and — with a grid carbon API — what that came to in grams of CO₂ at the hour you ran it. These posts do that, and are careful about which conclusions the measurement actually supports.

Writing on this

  • What your machine actually costs to run — A £15 plug meter settles the energy question for your own hardware in an afternoon: idle draw, load draw, watt-hours per task, and what that comes to per year. (2026-07-07, 4 min)

Courses that take it further

  • Where the energy actually goes — Joules, not vibes. Measure what your own work costs before joining an argument about data centres. (3 lessons, 65 min, 3 free)
  • The economics of automation — Why one job gets automated and the near-identical one next to it does not. (3 lessons, 65 min, 3 free)
  • Local or nothing — Run open-weight models on hardware you own, and know what they cost you in watts and seconds. (5 lessons, 6 min, 2 free)