Assessment of CO₂ Emissions Reduction in High-Rise Concrete Office Buildings Using Different Material-Use Options

This study applied the Monte Carlo method to generate probabilistic distributions for describing the CO2 footprint of the superstructure of a high-rise concrete office building. The distribution profile was constructed with the material-use data collected from 13 high-rise concrete office buildings in Hong Kong. Results indicated that the average carbon footprint of the superstructure of an office building was 215.1kg CO2/m22. External walls and upper-floor construction had the highest CO2 footprint, followed by suspended ceilings and finishes. These three elements altogether accounted for an average of 84.2% of the CO2 footprint associated with the superstructure. Also, this study evaluated the emissions-reduction impacts of five different material-use options over a 60-year lifespan. Among all the studied options, the most effective option was to maintain 15-30% of the existing structural and nonstructural building elements as this could reduce the CO2 footprint by 17.3%. Diverting construction wastes to recycling could reduce the CO2 footprint by 5.9%. Reusing resources and importing regional materials could only reduce the CO2 footprint by 3.2% and 3.1%, respectively. In contrast, the CO2 footprint would be increased by 5% if offsite fabricated materials were used in facades, slabs, and partition walls.