The construction sector contributes significantly to global carbon emissions and construction waste, creating an urgent need for sustainable material selection. Formwork is a critical component in concrete construction because its material type, reusability, transportation, surface quality, and end-of-life treatment affect overall environmental impacts. This study compares the cradle-to-grave carbon emissions of plywood, plastic, aluminium, and steel formwork used in a residential project in Taoyuan, Taiwan. The assessment includes material production, transportation, reuse stages, and end-of-life scenarios such as recycling, landfill, incineration, and pyrolysis.

A detailed bottom-up approach was applied to calculate emissions for each formwork component, including panels, studs, walers, tie rods, alignment bars, push props, bolts, and other supporting elements. Process-level energy data from literature and LCA databases were combined with Taiwan-specific emission factors to produce traceable and locally relevant results.

The findings indicate that recycled plastic formwork has the lowest carbon emissions due to its lightweight properties, moderate production energy, high reusability, smooth concrete finish, and recycled material content. Recycled and primary aluminium follow, while recycled and primary steel show higher emissions. Plywood produces the highest emissions because of its limited reuse cycles and the additional cement plastering required for rough concrete surfaces. Overall, the study confirms that increasing formwork reuse and replacing primary materials with recycled feedstock can substantially reduce emissions in construction projects.