Calculation method and model of carbon sequestration by urban buildings: An example from Shenyang

Owing to the carbonation of concrete, urban buildings can continuously absorb carbon dioxide in the air and have carbon fixation functions. Buildings, greenbelts, soil, etc. constitute the artificial and natural carbon sequestration system in a city. However, owing to the complexity and heterogeneity of buildings, a quantitative method for determining and understanding the spatial distribution of carbon sequestration in urban buildings is still needed. This study explored whether the neglected carbon sequestration capacity of buildings can act as a natural carbon sink in the carbon balance process and alleviate the adverse impacts of urban carbon sources on the environment. Shenyang city in China was chosen for building a concrete carbon fixation model using a regression analysis and spatial distribution map. The results showed that the carbon sequestration of the urban buildings in the Third Ring Road of Shenyang was about 1,701,600 tons, which was higher than that of natural carbon sinks of the same scale, such as soil and aboveground vegetation, and equivalent to 4.39% of the annual city carbon emissions. The average carbon density of urban buildings is 119.45t/hm2, and the carbon density gradually decreases from the center to the edge. In addition, different types of buildings showed large differences in carbon storage capacity and carbon density, with residential buildings having the highest carbon storage capacity and commercial buildings having the highest carbon density. These results can be used to evaluate the actual role of urban buildings in reducing atmospheric CO 2, visually reveal the spatial pattern of carbon storage in urban buildings and provide a reference for spatial planning.