“I’m pretty sure wood is better than steel”: Revisiting rules of thumb and perceptions in AEC industry

SE literature café (5): a quick look at “Saade, M. R. M., Guest, G., & Amor, B. (2020). Comparative whole building LCAs: How far are our expectations from the documented evidence?. Building and Environment, 167, 106449.

There are certain observations (or “rules of thumb” if you would like) in each industry that “supposedly” have been made so many times, they become common knowledge: “customers will be interested in buying your product, and you benefit from sales in the long run” (link), “Avocado goes well on a crunch toast” “, etc.

In the AEC industry, the same goes for “environmental” performance: ”wood is better than concrete and steel”; “renovation is better than construction”; and “operational impacts are more important the embodied impacts” (environmental impacts of energy use in a building is larger than the impacts from materials and process of building them).

 A curious mind might challenge this status quo; the stronger the belief is, the more rewarding the challenge becomes.  The paper selected this week takes an intuitive yet interesting approach: Does the wealth of research supports these perceptions? The authors examined 577 documents on AEC life cycle assessment (LCA) and came up with 37 papers (a total of 223 case studies) to revisit common beliefs. Life cycle assessment is a quantitative method to monitor and sums up the process and material feed into a system (AKA a functional unit) and the resultant emission and impacts during different stages of its existence.

What is this paper addressing?

How LCA research supports common perceptions of environmental performance in the building industry

A wrap-up of the results

1. Is wood better than steel and concrete? GWP-wise? Probably. Primary energy-wise? Probably not.

The numbers show the papers advocating for the material represented with its color adopted from Saade et al (2020)

2- Is renovation better than demolition and construction? It seems so. But the sample is not large enough to make a general conclusion

3.are operational impacts always larger than embodied? It depends on whether you are referring to regular buildings or advanced construction with decreased energy deman

Operational versus embodied energy demand for different building constructions adopted from saade (2020)

What I like about this paper

This paper synthesizes literature to challenge the status quo in construction-related LCA. Also, section 3.4 of the paper provides an in-depth analysis of how these trends change for papers using advanced LCA (dynamic LCA, inclusion of concrete carbonation)

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