Life Cycle Assessment (LCA) is a method used to quantitatively describe a building's total environmental impact "from the cradle to the grave". LCA calculations in the early stages are done with generic data, but the longer one gets in the construction process instead one wants to have supplier-specific LCA environmental data. These LCA-based environmental performance is obtained by manufacturers supplied Environmental Product Declarations (EPD). When EPDs are to be used for comparative purposes, there is currently no documentation on the quality of these data required, which makes it uncertain whether they really have such a quality that they can be used for a direct comparison between different suppliers. To make this possible, this document proposes a number of metadata describing the quality (Q) of the EPD has. These Q metadata complement the finished EPD.
If an EPD is supplemented with Q metadata, it is possible to ensure that an EPD has the quality required that it can be can be used for a direct comparison between two products, a so-called supplier assessment. Since EPDs can be made based on different interpretations of the standards, different levels of ambition and different representatives exists, these factors must be clarified before deciding whether an EPD can be used for a particular purpose. In simplified terms, it is possible to divide the purpose of an LCA or EPD in the following stepwise order and need for increased data quality; the first step is about to get information and to assess hotspots, the seconds step is to support on how to make environmental improvements of the same product or construction works, and the final step is the potential use of LCA to actually make an comparison on different suppliers products, different constructions solutions or constructions works made of different materials that meet the same basic function as requested. Q metadata describes the following aspects of the LCA data contained in an EPD; • Is it for a unique product or product group, • Is it for one specific manufacturer or several, • Is the environmental data based on specific process data or generic (database) data • How is the environmental indicator result verified • Are significant assumptions made in the underlying LCA • If the EPD is not certified how is the indicator result calculated • Who is responsible for establishing the Q metadata for the current product Q metadata contains documentation of methodology choices that could affect the results of an LCA as part of an EPD. Methodology choices include interpretations and assumptions for the modelling of the LCA.. In other words, Q metadata provides data on LCA data and an increased transparency of the methodology settings and assumptions made. The inclusion of Q metadata in an EPD allows for a quality assessment of the data. Thus, it facilitates the decision if it can be can be used for a direct comparison between two products, a so-called supplier assessment. In addition to these Q metadata for the EPD used, the options must have the same basic function to allow a comparison.
Coworkers: Martin Erlandsson
Keywords: metadata, EPD
Report number: C363
Authors: Martin ErlandssonDownload publication