Detailed Assessment of Embodied Carbon of HVAC Systems for a New Office Building Based on BIM

Abstract

The global shift towards embodied carbon reduction in the building sector has indicated the need for a detailed analysis of environmental impacts across the whole lifecycle of buildings. The environmental impact of heating, ventilation, and air conditioning (HVAC) systems has rarely been studied in detail. Most of the published studies are based on assumptions and rule of thumb techniques. In this study, the requirements and methods to perform a detailed life cycle assessment (LCA) for HVAC systems based on building information modelling (BIM) are assessed and framed for the first time. The approach of linking external product data information to objects using visual programming language (VPL) is tested, and its benefits over the existing workflows are presented. The detailed BIM model of a newly built office building in Switzerland is used as a case study. In addition, detailed project documentation is used to ensure the plausibility of the calculated impact. The LCA results show that the embodied impact of the HVAC systems is three times higher than the targets provided by the Swiss Energy Efficiency Path (SIA 2040). Furthermore, it is shown that the embodied impact of HVAC systems lies in the range of 15-36% of the total embodied impact of office buildings. Nevertheless, further research and similar case studies are needed to provide a robust picture of the embodied environmental impact of HVAC systems. The results could contribute to setting stricter targets in line with the vision of decarbonization of the building sector.Sustainability 2020, 12, 3372 2 of 18 annual global emissions [4]. Furthermore, it has been estimated that embodied carbon in buildings can contribute up to 80% of lifetime GHG emissions for energy efficient building [5].These developments indicate the need to assess the embodied carbon of the whole building. The importance of reducing embodied carbon is underlined in many recent studies [6][7][8][9][10][11] as well as in the most recent World Green Building Council's report "Bringing Embodied Carbon Upfront" [12], which outlines the vision of zero operational and embodied carbon for new buildings by 2050. In the same report, the importance of life cycle assessment (LCA) as a consistent and globally accepted method to assess and communicate environmental impact through the lifecycle of the building is clearly stated and structured according to the lifecycle stages or modules defined in the widely-adopted European standard EN 15978.In new buildings, reduction of operation energy has usually been achieved through better insulation of houses and improved technical systems [13]. The embodied energy of energy efficient buildings is usually equal to, if not higher than, a less energy efficient building, but usually, this increased embodied emission during the construction is quickly paid back during building operation [13]. However, most LCA studies have the tendency to reduce the system boundaries to the main construction materials of a building, leaving on the side the heating, ventilation, and...

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