Assessment of the embodied carbon in precast concrete wall panels using a hybrid life cycle assessment approach in Malaysia

There is currently growing interest in quantifying the direct and indirect carbon emissions embodied in construction materials and their components production. Previous research shows that indirect emission could be higher than direct emission for energy intensity materials such as cement and steel reinforcement. Quantifying direct emissions alone would underestimate the carbon emissions associated with a material and in turn its environmental impact. The assessment of indirect emissions is a challenging task involving upstream processes of material production. This paper investigates the existing literature on the quantification of embodied carbon by both direct and indirect emissions as well as demonstrating the application of a hybrid life cycle assessment method in building construction. The focus of this paper is the Malaysian context however the principles apply universally. A typical 2-storey residential building has been investigated to determine the total carbon emissions when comparing two construction techniques: conventionally reinforced concrete and precast concrete panels. This paper demonstrates the application of hybrid life cycle assessment by expanding the boundaries of process methods and reducing the sensitivities of I–O life cycle assessment to the raw material price fluctuation for product manufacturing.