The use of LCAs related to buildings and building materials is increasing. When implementing LCA, the analyst should collect all input data and output data. However, because data collection requires significant effort, the analyst normally concentrates on collecting the foreground data. In contrast, background data is normally collected from a background database. Consequently, differences between the functional units of the foreground and the background data are frequently required commonly a need for unit conversion.
We assert that the promulgation of LCA in the building industry is hindered by the scale of the variety among materials utilized in construction; consequently, LCA data analysts are frequently overwhelmed. To ameliorate this situation, it is indispensable not only to enhance the content of the background data but also to provide proper means of unit conversion. Based on the above, our study clarified as follows:
1) We examined 11 building (LCA) cases and selected materials requiring unit conversion, based either on the scale of data or environmental loads. As a result, the proportion of items requiring unit conversion was required from approximately 70 to 90 percent in the former to 50 to 80 percent in the latter.
2) Assuming several stages in the design of the building, a list of used items was created by researching various documents and examining expert opinions. The list consists of approximately 1000 items.
3) Through a questionnaire survey of experts and the analysis of 11 buildings, we selected the data to be examined in this work with a priority for items from the list proposed in 2).
4) We propose a method to create unit conversion database. This method refers to the descriptors utilized when creating inventory database (IDEA). We scrutinized the information that should be recorded when creating a unit conversion database. The descriptor for each item in the unit conversion database includes our proposed descriptors.
5) Based on the above contents, a unit conversion database was developed from documents, statistics, and public information on the Internet. This database is a compilation of unit conversion values for more than 100 high priority items and was published on the website of the Architectural Institute of Japan.