Embodied GHG emissions of reinforced concrete and timber mid- and high-rise structures: Driving factors and target values

Nuno Bernardo Abreu Machado

Key information

Authors:

Nuno Bernardo Abreu Machado (Nuno Bernardo Abreu Machado)

Supervisors:

José Dinis Silvestre (José Dinis Silvestre); Rolf André Bohne

Published in

07/04/2022

Abstract

In order to deliver on the commitments made on the Paris Agreement and limit global warming to 1.5ºC, it is necessary that greenhouse gas (GHG) emissions have been limited to net-zero by 2050. Monitoring and regulating life cycle emissions will be an important step in this direction, especially those considered as embodied. This study investigates the influence that different factors have on the embodied GHG emissions from material production of reinforced concrete and timber mid- and high-rise structures, through a meta-analysis with 62 cases, and establishes reference and target values for them. The results show the structural weight of buildings being the driving factor of embodied emissions. The benchmark comparison of the cases with the SIA 2040 targets further revealed that reinforced concrete buildings material production consumes most of the budget for embodied emissions. Opting for a timber structure can increase the available budget for the other components and life cycle stages of the building and, in some cases, can make the difference between meeting and not meeting the benchmark. Based on the 50th and 5th percentiles of modelled distributions, the reference and target values are, respectively, 3.7 and 1.7 kgCO2-eq/m2.y for reinforced concrete structures, and 1.2 and 0.4 kgCO2-eq/m2.y for timber structures. In addition, the creation and introduction of a ‘carbon’ label was also demonstrated to be a clear way of informing the environmental performance of buildings in terms of Global Warming Potential.