The five accounts
Every joule that enters a system is assigned to one of five accounts. That is what lets the ledger be checked.
The accounts
| Account | Records | Measured as |
|---|---|---|
| Intake | All energy entering the system, from any source: grid, battery, light, heat, motion or fuel | Integrated energy at the meter point |
| Reserve | Energy held in storage: battery, capacitor, fuel or nutrient medium | The change between the start and end of the period (ΔReserve) |
| Work | Energy that produced completed useful decisions or tasks | Energy at the compute or actuator during passing tasks |
| Overhead | Energy that keeps the system able to work: cooling, life support, idle draw, power conversion | Sub-metered where possible |
| Waste | Energy that left as heat without doing work or overhead | Measured (for example, heat removed) or calculated |
Work means useful work
Only energy that produced completed useful decisions counts as Work: tasks from a versioned task set that pass a stated quality gate. Energy spent on tasks that fail the gate is not Work. This is what makes Decision Yield hard to inflate.
Reserve is a change, not a level
Reserve records the change in stored energy over the period, measured at the terminals with matched start and end temperature and rest. State-of-charge percentages are not accepted, because they are estimates.
Overhead and Waste are different
Overhead keeps the system able to work, such as cooling and power conversion. Waste left as heat without doing either. Keeping them apart shows whether a system is losing energy to support functions or to nothing at all. The Overhead Ratio compares facility energy with system energy.
Questions
Does all energy end up as heat?
Almost all of it, eventually. The accounts record what the energy did before it left: useful work, support, or nothing.
Keep reading
Take the next step.
The five accounts of the Joule Ledger: what each records, how it is measured, and why every joule entering a machine must land in exactly one of them.