A Comparative Sustainability Study of a Steel-Timber Composite Structural System

The building and construction industry is one of the major drivers of global energy use and emissions. With climate change mitigation being a forefront topic of concern, the building and construction industry has a responsibility to alleviate its environmental impact. Therefore, there is a need for more sustainable structural systems that explicitly consider environmental impact. This study performs comparative life cycle analyses on the superstructures of functionally equivalent steel-timber composite and steel-concrete composite office buildings at 7-story and 18-story heights. The environmental impacts associated with both structural systems are quantified, creating equivalent comparisons of sustainable merit of each structure and the materials within. The scope of the assessment was cradle-to-gate and included end-of-life impacts. Results indicate steel framing mass and environmental impacts are comparable between systems of the same height. As a result, environmental benefits attributed to STC structures stem primarily from floor assemblages. Overall, the steel-timber composite systems had less severe environmental impacts than the steel-concrete systems, averaging 46% lower global warming potential and 27% lower energy demand.