Life Cycle Assessment of a Steel-Timber Composite Structure Comparison to an Established Structural System

Abstract

The building and construction industry drives 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 examined comparative life cycle assessments on the superstructures of functionally equivalent steel-timber composite and steel-concrete composite office buildings at 7-story (28,800 m2 nominal floor area) and 18-story (74,000 m2 nominal floor area) heights. Life cycle assessments were conducted in accordance with ISO 21931 and outputs quantified environmental impacts associated with each structural systems, creating meaningful and valid comparisons of sustainable merit associated with each structure and the materials within. Results indicate steel framing mass and environmental impacts are comparable between systems of the same height. As a result, environmental benefits attributed to steel-timber composite 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.