Assessment of CO₂emissions 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 CO2footprint of the superstructure of a high-rise concrete office building. The distribution profile was constructed with the material use data collected from thirteen high-rise office concrete buildings in Hong Kong. Our results indicate that the superstructure of an office building (i.e. it does not embrace foundation or basement), on average, had a footprint of 215.1 kg CO2/m2. External walls and upper floor construction had the highest CO2footprint, followed by suspended ceilings and finishes. These three elements altogether accounted for an average of 84.2% of the CO2footprint associated with the superstructure. Furthermore, this study also 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 is to maintain 15-30% of the existing structural and non-structural building elements as it can reduce the CO2footprint by 17.3%. Diverting construction wastes to recycling can reduce the CO2footprint by 5.9%. Reusing resources and importing regional materials can each only reduce the CO2footprint by 3.2% and 3.1% respectively. In contrast, the CO2footprint will be increased by 5% if off-site fabricated materials are used in facades, slabs and partition walls.