Quote:
Originally Posted by Keith P.
So essentially any new development is "bad" and will be decried by those inclined to wrap themselves in the climate change flag.
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While I'm sure embodied carbon calculations will be used by some people to say "new is bad", we shouldn't write them off. The reality is that up-front carbon emissions can indeed be significant, and they happen
right now when we drastically need to cut emissions. Much like money, there is a time-value to emissions.
Importantly, embodied carbon emissions vary widely based on building typology and construction methods. Concrete construction creates more emissions than wood, for example. Some forms of insulation actually create more emissions from their manufacture than they will ever save in reduced operational emissions. Per-dwelling-unit emissions also vary based on building typology and height. There's typically a decrease as you go from low density to medium and high density, but as you get into the super high range per-unit emissions actually go up because you have to have a higher percentage of the building dedicated to elevator cores and building structure.
The key to all of embodied carbon calculations though is that they're a data point that allows you to actually take a holistic look at the impact of a building or way of building. The question shouldn't just be "how much carbon does this building create in its construction?", but "how does the carbon emitted in the construction of a building compare versus building a different building, or building the same number of units elsewhere when transportation emissions are included?"
Of course, even such an analysis requires a lot of assumptions and hand waving. Are dwelling units actually fungible? E.g. if you don't build a proposed tower does that truly mean 500 single-detached units and all of their carbon impacts will be built somewhere else in the city? For such reasons I tend to find embodied carbon calculations more useful on the very high-level scale (making decisions during regional planning about the types of communities we should develop given our transportation network), and at the very small scale (making decisions about building design, such as what types of insulation to use). This mid-scale, where we use them to say "yay" or "nay" to a building in a relatively isolated decision-making process, doesn't seem all that productive to me and I would discourage any city from making it a requirement of a planning application process.