The impact of surface aspect ratio on the embodied energy, embodied carbon, and embodied water of a building structure

Nearly 48% of the yearly global energy supply is consumed by buildings during their construction and operation in the form of embodied and operating energy, which is responsible for nearly 40% of global carbon emissions. Building materials used for the superstructure, substructure, envelope, and interiors of a building contribute to over 90 percent of the embodied energy. Concrete and structural steels are two major materials used in bulk quantities in the construction industry, which can adversely impact the environmental sustainability of buildings. Concrete alone is responsible for 5-9 percent of the global carbon emissions. The ratio of horizontal to vertical surface area of the building known as the surface aspect ratio is an important parameter for the sustainability of a building because it affects its structural design and the quantifies of materials such as steel and concrete. In this study, we analyzed how aspect ratio of a building impacts its structural design and material use in the foundation, framing, and slab of the building, and how it eventually affects the embodied energy (EE), embodied carbon emission (EC), and embodied water (EW). Five different building configurations of a generic reinforced concrete building with 12, 9, 6, 3, and 1 floor/s are modeled, and input-output based hybrid (IOH) models are used to determine the total EE, EC, and EW requirements for concrete and steel for different surface aspect ratios. The results show that for a 12-story building, there is ca. 34% increase in EE and EC and ca. 27% increase in EW as compared to a 1-story building. These results signify the importance of selecting horizontal vs. vertical building configurations in urban areas to potentially help reduce the environmental footprint of the building construction sector.