Quantifying operational-phase carbon sequestration in urban concrete buildings: A spatiotemporal analysis of Qingdao City

Abstract

Concrete structures in urban buildings act as carbon sinks, continually capturing and storing carbon dioxide. Accurate calculation of CO₂ uptake in urban concrete buildings and understanding the spatial distribution of carbon sequestration across a city are crucial. In this study, we calculated the carbon sequestration capacity of concrete buildings using an optimized Fick’s law and examined the spatiotemporal characteristics of carbon sequestration in Qingdao City, China. The results indicated that urban concrete buildings in Qingdao sequesters approximately 1.86 million tons of carbon. Carbon sequestration varies significantly by building type, with residential buildings showing the highest ratio of total carbon sequestration and carbon sequestration intensity. Lower buildings generally had a higher proportion and intensity of carbon sequestration. Additionally, carbon sequestration displayed time-dependent characteristics, as older buildings tended to show higher average carbon sequestration and intensity. The spatial distribution of carbon sequestration across Qingdao is uneven, with carbon sequestration decreasing from older to newer urban areas and county-level cities, from district centers to their peripheries, and from the city center to the suburb regions. These findings are critical for evaluating the role of urban concrete buildings as carbon sequestration on an urban scale and provide valuable insights for urban planning and development.