In my post titled Demolition, Deconstruction, and Discussion, I mentioned DfD expert Brad Guy. Brad has devoted his career to research on DfD, and it shows; if you look up "design for deconstruction" on the internet, chances are you will quickly come across references to his many papers and interviews.
I have actually been in contact with Brad since last year, when I invited him to speak at a green buildings panel for the 2020 Cornell Business Impact Symposium. Rather than simply continuing to read about him, I invited him to chat for an informal interview for this blog, and he agreed! The interview was 90 minutes long, so after condensing it and editing for clarity, I have decided to post it in three parts.
Without further ado, Part 1!
Luna: I see your name everywhere when I'm reading about DfD. So I was wondering— how you ended up becoming the spokesperson for DfD in the US?
Brad: I started in deconstruction around ‘95 or ’96. Salvage has been going on since there have been buildings, but we [deconstruction researchers] were trying to make it more research-oriented, more quantifiable, more rigorous, rather than just ad-hoc anecdotal. The US EPA sponsored us, so I produced several papers on deconstruction.
I was also a member of an international research group called CIB [1]. They have working groups and task groups of academics internationally, and we started a sub-group for deconstruction. The goal of that organization is to help people meet peers, produce work, get it published, have conferences, get in proceedings, and things like that. Proceedings are very helpful for any academic to just get their stuff out and get it referenced. So maybe that's why, just because papers and formal research on deconstruction was extremely rare.
I also advised on the paper for the Chartwell School DfD project in California [2]. The architecture firm EHDD did the actual project, and that helped it gain some traction. And people look towards the West Coast. It’s almost like anything you can do in California, Oregon, or Washington gets more attention, because people are interested in sustainability there. There's more of a— sympathetic population that puts the word out, and it spreads.
Yeah, and then I guess the last thing is just talking about it a lot [laughs]. Giving presentations, some teaching, and just being an advocate.
Luna: Makes sense. Some say that we should focus more on reducing operational carbon than on reducing embodied carbon because operational carbon is responsible for a larger share of total emissions in the US [3]. Have you come across a scenario in which the two are in conflict? For example, a design decision that requires prioritizing one over the other?
Brad: I was actually going to tell you that I think there are good synergies there.
If you look at the time spans of most building components, your flooring is expected to last like 5 years, most appliances and electrical devices could be anywhere from 5 to 15 years... that sort of thing. If all that stuff is only lasting 5 to 15 years, that’s stuff that you really want to be able to upgrade.
And windows, refrigerators, heat pumps too— they're constantly being innovated. Which means that if I want to maintain operational efficiency, I already know I have to be able to change building components over time. If I'm operating a building 20 years in the past in terms of efficiency, but the cost for me to upgrade operational components (like heat pumps) is prohibitive... You can't be efficient if you let buildings become obsolete like that. Clearly, making it easier to upgrade will keep you operationally efficient.
Luna: Well, for example, concrete is hard to reuse, correct? But some people argue that concrete is good in terms of operational carbon because [of its property as a thermal mass]. There seems to be a tradeoff between the embodied carbon aspect and the operational carbon aspect there, because if the building has a short lifespan the embodied carbon may account for a larger proportion of total building emissions, and if the building has a long lifespan the operational carbon may matter more.
Brad: But it would depend on which parts of it you’d build, right? Like, how many alternatives are there to concrete footings? Basically zero. Unless you did a wood piling system, which is like ancient technology.
As we get more energy-efficient with the buildings, the percentage of embodied energy will go up over the hundred-year life of the building. So when we have more energy-efficient buildings it really matters that making the material is more energy-efficient.
A presentation I got in trouble for— people were really unhappy with me, but I did a lifecycle assessment of an office building in D.C. that was built in the 1980s and was about to be renovated [4]. It’s like wow, it’s only 30-40 years old, and they're completely gutting this thing and totally renovating it. They changed all the windows and all the mechanical only after 40 years! A pretty nice office building, not degraded, it was being used up to the day...
They added photovoltaics (PV) to the roof; they were trying to get it to net zero energy. It’s like the Bullitt Center in Seattle, so the whole roof was completely covered and the PV was even overhanging the edges.
I said, well okay, here's an example where they reused the building, they saved all that embodied energy, and there's a huge benefit to that. It’s super energy efficient; like 60% more energy-efficient than it was. But they wanted to get that last percentage, so they added photovoltaics, which are extremely energy-intensive materials.
So is that really a good idea? In theory they’re going to net zero operational, but they added so much to the embodied energy with the PV. And people have different methods to calculate the embodied energy payback of PV, but the way I did it, it would take like 10 years to pay back that investment in the PV saved through the avoidance of operational electricity.
And then they got really upset with me because typically you want to put PV everywhere, all the time, right? It's like save energy now and go to net zero now, but people don't necessarily think, “well, what about the investment in additional energy put into the PV itself?” You can't really say that it’s free [laughs.] It's not free; it took some pretty precious metals and all kinds of stuff to make the PV. So if the climate crisis is... if we only have 10 years, then maybe you shouldn’t add PV, you should just renovate the building and leave it at that.
Points are (1) these things are a little bit complicated, (2) I think it's more or less worth it to reuse everything you can imagine unless it's toxic, or it's truly obsolete and operating in an extremely inefficient way, in which case you need to do that upgrade. But I would say there's a limit to how much more material you should start adding to something to increase its energy efficiency. If the carbon crisis tipping point is in 10 years or so, a 50-year life cycle is starting to be kind of long, and a 100-year life cycle may be out of scope, because most buildings don't even last that long anyway.
FOOTNOTES:
[2] Note that the Chartwell School was a case study in my previous post, What "Design for Deconstruction" Looks Like!
[3] Embodied carbon refers to emissions associated with building materials and the construction process. Operational carbon refers to emissions associated with building energy use (emissions after the building has been constructed).
[4] With this question, I was trying to play devil's advocate and see if Brad could come up with a scenario in which embodied carbon was lowered, but as a result operational carbon increased. Instead, he came up with a scenario in which operational carbon was lowered, but as a result embodied carbon increased.