Carbon emissions during the design and construction phases of public works: a case study of council housing in Taiwan

Buildings account for around 39% of global CO₂ emissions each year. In both industrialized and developing countries, the construction industry accounts for more than a third of CO₂ emissions and total energy consumption. Most research on building carbon emissions continues the traditional focus on operational energy emissions embodied in building materials. Only a few studies investigate emissions generated from transporting materials to sites or from construction site processes. This study analyzes the carbon emissions of council housing in Taiwan based on their design and construction phases. The scope of carbon emission calculation includes the use of construction materials, construction materials transportation, construction machinery, water and electricity. The results show that the use of construction materials is the largest source of carbon emissions in both the design and construction phases, with an average of 17,585 (tonCO₂e), accounting for about 80-90% of overall carbon emissions. Water and electricity have the lowest carbon emissions, accounting for about 0.03-0.05%. The difference between the estimated carbon emission of construction materials in the design stage and the actual carbon emission in the construction stage can be reduced to 0.1-7.8%, which proves that the method of carbon emission calculation in the design stage of this study is reliable. Based on the 80%-90% range of carbon emissions, it is possible to estimate the carbon emissions from the use of construction materials in similar construction projects, which helps owners to know more accurate carbon emissions at the early stage or design stage of construction projects. This paper also demonstrates the development of generic emission coefficients, which are suited to increase the feasibility for application in the building industry. Finally, the calculation process of building carbon emission is presented, and methods for reducing carbon emissions are discussed.