The life-cycle of a building project starts before any physical construction activities and ends after its usable life. Figure 2 shows an integrated LCA of the building stages.
In the first BSA methods, the concept of sustainable construction was confused with the concept “low environmental impact construction”. Therefore these methods failed to enter the mainstream sustainable development discourse. More recent BSA methods include the economic performance analysis in the evaluation. The economic assessment is an important factor in the success of any new approach in construction that includes sustainable principles. Demand for sustainable construction is influenced by buyer perception of the first costs versus the life cycle costs of sustainable alternatives [7].
At the environmental performance level, life-cycle inventory analysis (LCI) can be extremely complex and may involve a dozen individual unit processes in a supply chain (e.g., the extraction of raw resources, various primary and secondary production processes, transportation, among others) as well hundreds of tracked substances. The more rigorous the LCA methods are, the more data intensive they are. Therefore, the assessment process can involve significant costs of collecting data and keeping it updated, particularly in a period of considerable changes in materials manufacturing processes. Some data needed for the LCA is expensive and difficult to obtain, and is most often kept confidential by those manufactures that do undertake the studies. According to some authors [8], the databases do not include all the needed information for many of the relevant building products and components, nor for the construction process itself. Therefore, the researchers concluded that it is essential for LCA tools to allow the editing of existing variables and the addition of new ones according to local conditions and constant technological development.