Steel-timber hybrid buildings: a comparative life cycle assessment study of global warming potential impacts

Mass timber buildings are gaining momentum, as they are seen as an environ-
mental alternative to conventional concrete and steel structures, and they are also being
used for mid- and high-rise buildings. This study conducted a comparative LCA analysis
of 20- and 40-story building structures made with different combinations of steel and
mass timber. The results show that, even disregarding the environmental benefits of the
sequestered biogenic carbon by using a 0/0 approach, timber-based structures result in a
roughly 25% lower Global Warming Potential (GWP) impact than steel- or hybrid-based
equivalent solutions. The results show that the contribution of steel does not bring any
GWP advantage (an average increase of 20% is reported); however, steel–timber hybrid
structures may still be the only viable solution to attain greater heights. This study also
evidences that materials with lower GWP in their production phase can present a viable
solution even when long transportation is required, highlighting the importance of the
production phase to reach environmental targets.