A comparative analysis of embodied carbon in high-rise buildings regarding different design parameters

The building sector accounts for one third of the global greenhouse gas emissions, of which a substantial amount is embodied carbon from construction material production. While previous studies concentrated on analyzing the carbon emissions of low-rise buildings, they have overlooked high-rise buildings, which also have large impacts on the carbon emissions of a city. Moreover, high-rise buildings use different construction materials and structural forms, resulting in large variability in their embodied carbon estimates. Therefore, this study aims to evaluate the relationships between different design parameters and the embodied carbon in high-rise buildings. The results serve as a basis for making more environmentally-sustainable decisions when designing high-rise buildings in order to reduce the carbon emissions from the building sector. Different high-rise buildings are designed by varying the construction materials (namely reinforced concrete, structural steel and composite materials), recycled contents (steel scrap and cement substitutes), structural forms (i.e., core-frame, core-outrigger, tube-in-tube and mega-brace) and building heights. The embodied carbon values are evaluated and compared, by considering the carbon emissions from material manufacture and transportation. Given the same structural form and building height, steel buildings have 50-60% less total weight, but 25-30% more embodied carbon than composite and reinforced concrete buildings. If 80% of the steel used in buildings is recycled, the embodied carbon in steel buildings is reduced by around 60% and becomes the least among all buildings. The embodied carbon per floor area against building height follows a concave upward trend, indicating that each structural form has a suggested height range where embodied carbon is minimum. When the building height exceeds the suggested height range, the structural efficiency of the building decreases with considerable growths in material demand and embodied carbon.