A Study on Life Cycle Assessment-based Tool for the Early Stage of Building Design

Sammanfattning: The responsibility of the building sector to diminish the harmful environmental impacts, locally and globally, has been extensively considered. Thus, Environmental Impact Assessment (EIA) in building and construction practices has been widely implemented. Among several available EIA methods, Life Cycle Assessment (LCA) is the only standardized method which provides a holistic overview of environmental impacts to support the decision-making process. However, there are several barriers that hinder the process of implementing the LCA-based tools in the building sector. Specifically, the demand for a simplified LCA-based tool adapted to the early stage of the building design is rather high. Recently, the Construction Sector's Environmental Calculation Tool (Byggsektorns Miljöberäkningsverktyg BM v1.0) is developed to assist non-experts without knowledge of LCA. Architects, as one of the main target groups of the BM tool, have limited knowledge about the LCA approach due to its complexities; further, the architects have their own requirements for applying an LCA-based tool towards leveraging in the early design process. Hence, it leads to scepticism whether the BM tool has been so far successful to entice the architects' attention towards employing the BM tool in that process. This master thesis aimed to investigate if the newly-developed LCA-based tool, namely the BM tool, is a desirable choice for architects to evaluate the environmental impacts of their design at the early stage of building design. To be able to perceive more deeply the BM tool, as an environmental assessment and a decision support tool for architects, two main procedures, i.e., quantitatively and qualitatively, were employed to cover different technical and functional angles of the tool: (i) an LCA-based carbon footprint assessment for two reference buildings along with comparing the achieved results with the simplified Environmental Load Profile (ELP-s) tool, plus (ii) using a framework included various criteria for LCA- based tools in the early stage of building design. The findings from the quantitative analysis were consistent so that the concrete frame building produces a greater amount of carbon footprint during the stages A1 to A4 compared to the wooden frame building. The considerable deviation was related to the carbon footprint of aluminium profile in the material production stage. This could be due to the fact that in the BM database it is not specified whether aluminium profile was recycled or not. Regarding the carbon footprint in material transport stage, the inconsistent results were mostly linked to the default values in the BM database in which values for two of the main parameters (distance and mode of transport) differed. Particularly, the absence of boat as a transport mode and an error related to an unneeded distance value for concrete transport were identified in the BM database. The framework, used to evaluate the desirability of the BM tool for architects, suggests several criteria required for an LCA-based tool implementation in the early design. The outcome indicated that the majority of criteria, not satisfied by the BM tool, were related to the geometry parameter and associated 3D model. Thus, in order to make the decision-making process, desirable for architects in the early stage of building design, the two parameters, i.e., material and geometry, should be utilized in parallel. On the one hand, the LCA methodology in the BM tool is simplified in a way that makes the process comprehensible and easy to learn for non-LCA-experts. Since the tool is under the development, minor amendments would make the carbon footprint evaluation robust for the early stage of design. On the other hand, from the requirements of the architects' point of view, the fundamental modifications are needed in the structure of the tool. If architects intend to work with such an LCA-based tool, they have to make an extra effort to translate the resulted information from the environmental assessment tool to the inputs of the modelling tool and vice versa. This leads to an undesirable and inefficient design process for architects.