## 3 Obstacles to the Implementation of LCA in the Procurement Process of Buildings
### Methodological Obstacles
In addition, there is even a standard for the application of LCA to calculate the environmental performance of buildings [27]. The application of these standards and, therefore, the application of LCA in the construction industry is already far-reaching and, therefore, cannot be an obstacle to implementation. In addition, the lack of guidelines and handbooks was mentioned a few times as a barrier to implementation. In terms of LCA implementation in general and specifically for the calculation of embodied emissions, guidelines for designers, policymakers, and manufacturers have already been developed [69; 70; 71; 72]. Regarding the implementation of LCA within the building's procurement process, these guidelines and handbooks are lacking, as the assessment of the environmental performance of buildings in the course of tendering and awarding is uncharted territory and is still scarcely applied in practice. In this context, new approaches are currently being developed in the research project \"Paris Buildings\" [73]. For the calculation of the economic performance of buildings, i.e., life cycle costing (LCC), there are already guidelines in Austria for the implementation of LCC in the building procurement process [74; 75]. Based on these guidelines, a guidance document for the implementation of LCA in the building procurement process could also be oriented. Regarding the LCA process, its complexity was highlighted as a problem for application in the procurement process. Closely related to this, the problems of varnishing of the data and also data quality due to underlying uncertainties are also emphasized. To make the complexity manageable, the know-how on all sides of the project participants must be increased. Nevertheless, sustainability assessment experts are recommended (especially in the initial application phase) in order to support the mandatory implementation of LCA in the tendering and awarding of buildings. By consolidating these experts, the valid examination of the submitted offers is guaranteed by complete, transparent, and consistent LCA. Although numerous LCA databases such as Ecoinvent, ELCD database 3.1, GaBi Database, and Okobaudat are available, new/specific data sets will always be needed due to the uniqueness of buildings [76]. Implemented sustainability experts can also close the practical gap concerning \"data-lack,\" since new project-specific data sets can \begin{table}
\begin{tabular}{l c} \hline \hline
**Methodological Obstacles** & **Reference** \\ \hline _LCA is applied to wood windows to support procurement criteria definition_ & [66] \\ \(\rightarrow\) Lack of practical and operational tools & \\ \hline _Literature review of obstacles and drivers for sustainable buildings_ & \\ _Interviews about obstacles and drivers for sustainable buildings_ & \\ _Case studies on improving the sustainable building process and the impacts_ & \\ _and benefits of sustainable buildings_ & \\ \(\rightarrow\) No methods that enable comparisons, quality control, & \\ and monitoring & \\ \(\rightarrow\) No methods to verify the compliance of subcontract’s work with the & \\ sustainability requirements & \\ \(\rightarrow\) Lack of available information & \\ \(\rightarrow\) Design documents do not show adequate performance and capacity & \\ requirements for the products & \\ \hline _Interview series to achieve insights into application of environmental_ & \\ _preferences in construction projects_ & \\ _Survey about the application of environmental preferences in the procurement_ & \\ _of construction contracts_ & \\ \(\rightarrow\) Environmental criteria are weighted less heavily & \\ \(\rightarrow\) Environmental criteria have therefore no influence on the results & \\ of the evaluation & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: _Cont._be modeled by themselves. This is crucial in terms of time expenditure during a mostly strong limited planning phase. In the uncertainty context, this was equal for all bidders, i.e., all submitted bids, if external and independent experts were involved.