Embodied carbon of concrete in buildings, Part 2: are the messages accurate?

Abstract

This paper is the second output of a project that examines the embodied greenhouse gas emissions (‘embodied carbon’) from the use of concrete in buildings. In the current absence of either regulation or widespread industry practice in quantified carbon assessment, it seems likely that messaging will play a powerful role in influencing designers’ perceptions and decisions. Using the UK as a case study, this paper considers the current messages about the carbon implications of concrete in buildings from professional institutions and the cement and concrete trade body. Three mechanisms through which it is claimed carbon emissions are significantly reduced are identified: thermal mass, durability, and carbonation. By assessing each of these in turn against the available scientific literature, it is shown that they are likely to have a far more limited effect on the total impacts than suggested. More accuracy is needed from trade organisations if real carbon reductions are to be achieved. carbon impacts The and concrete more accurate with the messages sharing. claims thermal mass, durability and carbonation effective mechanisms, suggest carbon option, reconsidered. 127 different building superstructure frames of between two and 19 stories and found that the median values for the timber, concrete and steel frames were 119, 185 and 228 kgCO 2 e/m 2 , respectively. A further study conducted a detailed analysis of a medium-rise building using dynamic LCA and found that concrete had the highest initial impact, being somewhat higher than steel and about twice that of timber (Hawkins et al. 2021).