Action timing
An internal action has a start year and, optionally, an end year. The start ramp sets how the activity effect phases in. After the end year, the effect can continue, stop, or decay. Annual opex always stops after the end year.
Start year and end year
The start year is the first year the action can change activity. Capex is a one-off in that year, unless you match capex to a ramp.
The end year is when annual opex stops. If you omit the end year, opex continues to the projection end year.
The activity effect after the end year is a separate choice. Locked-in equipment can keep saving energy after the programme budget stops.
There is no automatic replacement action. If the effect stops, activity returns toward the plus-external-trends pathway plus any other actions that are still in force.
How the effect starts
- 100% in the start year — the full activity effect applies from the start year.
- Linear over years — the effect increases evenly from 0% in the start year to 100% at start year plus N years.
- Exponential ease-in — the effect uses progress squared and reaches 100% at start year plus N years.
- Milestone percentages — you enter year and cumulative percent pairs. Values interpolate in a straight line. The last milestone must be 100%.
You can keep annual opex at full from the start year, or match opex to the same start ramp. Capex stays a start-year lump unless you match it.
After the end year
- Effect continues — activity impact stays at full strength. Annual opex still stops.
- Effect stops — from the next year the action no longer changes activity. Balancing transfers stop in lockstep.
- Effect diminishes — remaining effect halves every half-life years after the end year.
Effect scale in each year is start scale times end scale. If you omit the after-end choice, the effect stops.
Example: ramp and after-end
This example starts in 2027 and ends in 2035. Linear and exponential ramps use four years. Decay uses a five-year half-life.
Related: NPV and EAC, balancing activities, and MAC.