Life Cycle Assessment of a typical new Swiss construction

Abstract

Climate change concerns us more and more in our daily life and the consequences are noticeable in Switzerland as well. This is forcing the construction industry to rethink the origin of their resources, since they are a main cause for greenhouse gas emissions. A crucial amount of those emissions is emitted in connection with the construction of the building structure. The goal of this thesis is to therefore analyze different types of building structures and materials for a residential building by using a case study. For the evaluation of this objective, a life cycle assessment is done where all the emissions of the relevant process steps are collected and compared to each other. For building owners and investors, not only the carbon footprint, but also the investment costs are considered for the choice of the building structure. By calculating the investment costs, it is examined if the environmentally friendly and sustainable building materials can also compete with regard to their investment costs.
To begin, different building materials, which are suitable as structural elements, are introduced. The focus is thereby put on concrete types with different shares of recycling aggregates and varying cement types, masonry, steel fiber concrete, wooden board stack elements and wood-concrete composites. The dimensions and material thicknesses for the materials are then calculated and defined with values found in the literature. The materials are applied to the case study, whereby different building methods and scenarios are defined that are later compared to each other. The carbon footprint and the investment costs are then calculated with values from the KBOB, expert surveys and other sources and applied to the building methods.
The results have shown that the carbon footprint of a wooden construction can be drastically lowered in comparison to a concrete structure if the wood is not transported over long distances. By comparing the different concrete types, a larger recycling amount has almost no influence on the carbon footprint. In terms of circular economy, it is still advantageous to increase the share of recycling aggregates in new products. Despite of the higher investment costs for wooden constructions, it can be an attractive building method due to the reduced construction time of prefabricated elements.