Forget About Life-Cycle Analyses, We Don't Have Time.

Elm street Toronto

The CO2 emissions from making stuff like concrete, plastic, aluminum and steel matter right now.

This TreeHugger has always loved concrete for its plasticity, you could form it into anything. I love Brutalism, I love Paul Rudolph and Le Corbusier, even Uno Prii's "Nightmare on Elm Street" that I show pieces of here. For years, every spring I photograph "Blossoms and Brutalism" when the cherry trees bloom in front of Toronto's Robarts Library. I hope all of these buildings last forever.

Lots of architects and designers are still building with concrete, even though it is responsible for as much as 8 percent of our CO2 emissions. Writing in the Architects Journal, Will Hurst picks up on his tweet:

Until now, many have also argued that concrete is a sustainable material because of its relative longevity and high thermal mass. When assessed purely in ‘whole life’ terms, they have a point. But if you accept the scientific consensus that we have little more than a decade in which to keep global warming to a maximum of 1.5°C, then embodied energy becomes the most pressing requirement for a construction industry responsible for 35-40 per cent of all carbon emissions in the UK.

Uno Prii's dinosaurs on Elm Street

Uno Prii's dinosaurs on Elm Street/ Lloyd Alter/CC BY 2.0

We have been saying this for years on TreeHugger, but Steve Webb of Webb Yates Engineers puts it more bluntly:

It’s absolutely outrageous that an architect goes out and buys locally grown tomatoes at the supermarket, gets on their bike to work and thinks they are an environmentally conscious person while designing a concrete or steel-frame building. Architects and engineers are the ones making decisions, so why don’t they engage with this?

I would respond by saying it is because they still don't get it. The second comment to the article reads:

It's always a good idea to reduce CO2 emissions where possible, but making choices between materials needs a life-cycle analysis to be sure the reductions are real. We have used concrete structures on many occasions so that their thermal mass can help to stabilise internal temperatures and, in consequence, save energy in the long term. Various studies comparing timber or steel with concrete show a range of results, so it's not as simple as it sounds.

It sure seems simple to me: We don't have a life-cycle to analyze, we don't have a long term; The IPCC laid it out when they said We have 12 years to limit climate change catastrophe. That means we have the here and now to stop putting CO2 into the atmosphere. As I noted in my recent post, High fiber diets are good for buildings, too, the chemistry of making aluminum, steel, plastic and concrete produces almost 25 percent of global CO2 emissions; the chemistry of making wood absorbs CO2 and produces oxygen.

But for those who are not convinced, engineer Chris Wise suggests just using less of everything, and going lean. "Lean design principles mean not only are you using less material and less embodied energy, but it’s also potentially cheaper, although it does require more collaboration between team members and costs more in fees." This is not too far off what Paula Melton suggests on BuildingGreen in her article, The Urgency of Embodied Carbon and What You Can Do about It. Melton is not totally convinced about wood, but she is about optimizing structural systems, and bringing engineers in early to reduce embodied carbon by reducing the amount of material involved, no matter what it is. She concludes: "What’s good for steel and concrete is good for wood: use only what you need."

Chris Wise also suggests a form of a carbon tax on building materials, which is a very interesting idea.


Lloyd Alter/ Cherry blossom time at the Robarts Library/CC BY 2.0

Samuel Johnson wrote “Depend upon it, sir, when a man knows he is to be hanged in a fortnight, it concentrates his mind wonderfully.” We have to concentrate our minds on reducing our carbon dioxide output by half in the next dozen years. That is our life-cycle, and in that length of time the embodied carbon in our materials becomes very important indeed.