Screening LCA of torrent control structures in Austria

Abstract

Purpose The purpose of this article is to find a suitable life cycle assessment (LCA) method to quantify the most important environmental burdens caused by construction processes of torrent control structures. To find these environmental burdens, 17 construction projects of the BAustrian Service for Torrent and Avalanche Control^(WLV) were analyzed using the Bcradle to gate with options^LCA methodology (CEN, 2013). Methods This article explains an LCA methodology for the product stage and the construction process of torrent control structures following existing standards. The iterative approach of LCA methodology (ISO, 2006a) was used to record all important processes of the system and to supplement missing information. The LCA methodology has been developed from existing standards of the construction and product sector. Since the production of some construction materials takes place locally, the generic data, for Austria, was adapted. Wood inherent biogenic carbon and primary energy, used as raw material, are treated as materials inherent properties (CEN, 2014). The contribution of the various processes was reproduced by hotspot. Results and discussion Hotspots of the different stages are related to the construction materials used. The emissions and primary energy inputs in the product stage are clearly dominated by concrete and steel. If these two materials are used sparingly, the focus is on machine application and transportation. Depending on the selected scenarios, the smallest share of emissions, in relation to the total result of product and construction stage emitted by transport, is 3% and the maximum share is 69%. The greatest environmental impacts in the construction stage are caused by excavation work and transportation on-site. With an average of 4% in the construction stage, the transport of workers to the construction site cannot be neglected as is done in the building sector. Conclusions The conclusion of this study is that existing LCA models can be adapted to protective structures. In contrast to conventional buildings, the construction process and transportation are much more important and cannot be neglected. Shifting the hotspots to these processes requires specific calculation rules for that particular field. There is still a need for research to find a suitable functional unit and to develop a methodology for the use and end of life stage of these structures.

Development of LCA benchmarks for Austrian torrent control structures

“…The methodological basics for the life cycle assessment of torrent control structures were created by screening the LCAs of several construction projects. Through the analysis of all relevant construction processes, it was possible to determine system boundaries, cutoff criteria, suitable data sources and hotspots of the processes (Paratscha et al 2019).…”

“…Due to the individuality and complexity of each protection system, it cannot be compared with others. However, the comparison between project variants of the protection system, which have identical performance characteristic, is possible because the same protection function can be achieved with different combinations of structures (Paratscha et al 2019).…”

“…In addition, it was necessary to treat material inherent properties in module A1 as inputs to the system and to treat them as outputs in the end of life stage C4 again. This concerns the uptake of CO 2 or energy intake of wood during the growth (Paratscha et al 2019).…”

“…In the second part of the use stage (B4-B5), the replacement of the structures is taken into account if their service life is shorter than the consideration period of the life cycle. The service lifetime of the structures was calculated using a specially developed stochastic predictive model by using a homogeneous Markov chain approach (Paratscha et al 2019).…”

“…According to EN 15978 (CEN 2011), the end of life of structures is reached when all components and materials that have to be removed from the site are finally removed. The difference between conventional buildings and torrent control structures is that the structures have reached their end of life after loss of functionality and then go directly into nature as a landfill (Paratscha et al 2019). Thus, the stored CO 2 is returned to the natural cycle and the energy contained in the material is not used any further.…”