Hi CLF Community!
I’m aware that this is a “carbon” forum, but other impacts behind GWP should be also taken into account such as AP, EP, POCP, if we really want to adress the whole environmental issue. Hopefully you will find interesting this topic, I’d love to hear some feedback!
I’ve noticed that in a reinforced concrete structure builidng, PoCP impact is not nearly as important as in a CLT structure building, see graph bellow
Blue colums: Reinforced Concrete Structure
Red columns: CLT structure
Note that in previous graph, proposed building (CLT) demonstrates always a better environmental performance if compared with a baseline building (concrete) except in one impact category: Formation of ozone potential in lower atmosphere (PoCP)
When digging in for answers I could confirm that in the CLT structure building, indeed the CLT structure material was the most representative material contributing to the PoCP impact
Why PoCP is higger in CLT if compared with reinforced concrete?
In the following LCA “https://www.americanhardwood.org/sites/default/files/download/2017-11/Endless_Stair_LCA_final%20report.pdf” it’s mentioned that:
“The large percentage of PoCP during material production (wood) is due to emissions of terpene, a type of volatile organic compound (VoC) released from wood resins during kiln drying”
The Terpene issue
Terpene literacy is not as extensive as I would like, but the following report (from 2007) identifies interesting topics: https://www.researchgate.net/publication/271450371_Wood_processing_as_a_source_of_terpene_emissions_compared_to_natural_sources.
"Sawing and lumber drying are equally important terpene emitting processes. Emissions during pellets production can be as important as emissions from sawdust drying, although emissions during drying can also be considerably larger depending on drying technique.
The importance of natural versus anthropogenic emissions depends on the environmental issue. Climate change is global. The importance of the terpene contribution depends on the total amount of emitted terpenes. Natural sources of terpenes would therefore be more important than anthropogenic sources. Formation of photo-oxidants is a regional problem. Terpenes contribute in accordance with their concentration. Hence anthropogenic emissions would be more important. Effects on insects are local, with bark drying an interesting anthropogenic source”
Other reports have been found such as: Underestimation of terpene exposure in the Nordic wood industry - PubMed
While it seems that “Wood Structure buildings” are being accepted as a general strategy to reduce GWP (and other environmental impacts), other strategies may be required to reduce PoCP.
Formation of ozone of lower atmosphere (PoCP) is measured with kg Ethenee, which contributes in connection with UV radiation to the formation of ozone in the lower atmopshere (summer smog) which is damaging to the respiratory system → not only environmental but also health issue
How do we adress the PoCP impact in CLT buildings?
Is the CLT industry aware of this?
Is there any “low PoCP CLT” available in the market?