How to model a replacement mid-way through the assessment period

Purpose

Let a building product be replaced one or more times over the course of the assessment period, the normal, non-offset replacement cycle.

Prerequisites

The building product has been added to a construction in the building model.

Steps

1. Find the building product in the building model tree.
2. Set a lifespan (RSL) in years, see How to set lifespans.
3. Leave offset start empty: the replacement then happens automatically every time the lifespan runs out, starting from the project’s beginning.

Result

The replacements in module B4 happen every time the lifespan runs out, spread evenly across the whole period, not just once mid-way. If the lifespan runs out exactly when the period ends, that does not count as a replacement.

Number of replacements=assessment period / lifespan, rounded up, minus 1

For example, a lifespan of 25 years gives one replacement over 50 years (year 25), not two.

See also

• How to set lifespans
• B5 Renovation as a life cycle module: if the replacement should be registered as a renovation action in its own right