Reference period and service lives

How the reference period for a calculation relates to the service lives of building products and building elements.

The assessment period is the period over which the calculation follows the building’s impacts. It is used, among other things, to calculate how many times a building product is replaced in module B4. The period is not the same as the product’s lifespan.

Assessment period and lifespan

A building product with a lifespan shorter than the assessment period may be replaced once or several times. Replacements include the relevant impact from the new product. A lifespan equal to or longer than the assessment period normally results in no replacement during the period.

The lifespan must describe the selected product in the specific building element. Use the BUILD lifespan table as a guide, and choose a material-specific value when it fits. If the lifespan is missing, the replacement is left out of the calculation; this is not the same as setting lifespan to 0.

See also How to set lifespans and How to set the assessment period and year of occupancy.