Functional/Declared Unit

In building life cycle assessment or EPD declared/functional unit is the unit per which the results are provided.

The functional unit defines the impact results for certain service level the product provides. For instance, for insulation products, it could be 1 m2 of insulation which ensures a thermal resistance of 1.5 m2/WK

during 50 years. It is normally used in product EPD calculations when impacts related to the product use phase are also given. If the function of the product in the building level is not known (e.g. if the product has several applications in the building) or when the study does not consider all the life cycle modules declared, a unit is used instead of a functional unit. It represents the physical quantity of the product such as 1 m2 of 50 mm thick insulation or 1 kg insulation.

Which units does One Click LCA support?

For product level calculations, the unit can be freely chosen based on the product and life cycle stages studied.

For buildings, most of the LCA tools of One Click LCA provide results as a total for the whole building and per 1 m2 of building area (different area definitions can be used). Additionally, other units such as impacts per 1 m2 of building/year of building use or impacts per user amount may be available for some tools.