We must Cut Carbon out of Construction – NOW!

By Paul Dowsett, OAA, FRAIC, LEED AP
Principal Architect — Sustainable. Architecture for a Healthy Planet.

We have only five months to transform the construction industry.
There is no option – or planet – B.

The act of city building needs the literal city builders — the entire construction industry. In response to the climate crisis, our roles as “city builders” must change.

We must cut carbon out of construction – NOW !

Massive amounts of carbon dioxide are emitted into the atmosphere during the construction of a building (embodied carbon) and during the lifetime operation of a building (operational carbon). These massive carbon emissions must stop, we as an industry must change, and here’s why and how.

Why we must change

In 2017, the World Green Building Council (WorldGBC) stated that the global construction industry (emitting 30% of global greenhouse gases (GHG) — similar to China) must operate at “net zero carbon” by 2050 for global warming to remain under 2°C — as per the Paris Agreement.

“Every building on the planet must be ‘net zero carbon’ by 2050”. Every building … whether new and existing.

How can we transform both the operation of existing buildings, and the construction of new buildings, to emit no carbon

How we will change — existing buildings

We can’t reduce the embodied carbon in existing buildings, as it has already been emitted during construction.

But we can retain the building’s existing structure “as-is” or transformed through adaptive reuse. The alternative? Demolish that structure, send its component parts to landfill, and emit more carbon to construct a replacement building.

Additionally? Retrofit that building to be optimally energy-efficient — reducing its ongoing operational carbon.

We know that retrofitting existing buildings is urgent, because they are such huge contributors to a city’s GHG emissions. In Toronto, for example, the 2017 TransformTO study reports that, “In the baseline year

[2011], buildings account for 56% of GHG emissions in the City of Toronto” (p. 26) Buildings — our sector — were the number one cause of emissions, and caused more than half of the city’s total emissions! And this is, again, likely only looking at operational carbon.

Embodied carbon is becoming significant

Embodied carbon is significant, especially as we develop more and more energy-efficient buildings.

In Lloyd Alter’s blog post in Treehugger, he outlines that he dislikes the term “embodied carbon” — it hides the urgent need to address the carbon that is emitted through construction. Instead, he suggests we all use “upfront carbon emissions” (UCE) — because that’s what they are.”

Anthony Pak states that, “ The importance of embodied carbon becomes even more evident when you consider that, according to the IPCC, to limit global warming to 1.5°C, carbon emissions would need to peak next year in 2020 and then go to net zero globally by 2050. Given that embodied carbon will make up almost half of total new construction emissions between now and 2050, we cannot ignore embodied carbon if we want to have any chance of hitting our climate targets.”

2020 is 5 months from now — to peak our global carbon emissions!

(17 months if we’re being generous, giving ourselves to the end of 2020.)

We can no longer ignore that the manufacturing processes for concrete, steel, and asphalt — the assumed foundations of our construction industry — are huge emitters of carbon.

Writing in The Guardian, Jonathan Watts calls concrete, “the most destructive material on earth”.

What to use instead ?

A forest — the “wood factory” — is a carbon-sink, drawing down carbon from the atmosphere, and moving our carbon emissions in the right direction. Project Drawdown cites a 2014 study: “Building with wood could reduce annual global emissions of carbon dioxide by 14 to 31 percent.”

The construction industry can, and must, change

Getting designers and builders in the construction industry to convince the concrete, steel, and asphalt industries to give up their predominant position will be on par with getting the petroleum industry to give up theirs. They are all big, and powerful, and not terribly willing to change.

But there is hope!

A promo piece by Skanska, the world’s largest construction firm, encourages us to: “Think of a world where fantastic buildings …are created …giving [people] great places to live and work in, and where the CO2 impact during construction is …well, there isn’t one.”

Attention: city REbuilders !

Bringing buildings’ embodied and operational carbon to zero is hard — and also necessary for our survival.

We must embark on a program of city Rebuilding — now !
It is time for all of us to do something.

Medium writer Marta Brzosko says it best: “We are all on this sinking ship together — and we are afraid. That’s only natural. But this is precisely why it’s the time to find courage. The courage for acting and speaking about the climate crisis, no matter how uncomfortable it may be. Because, as Greta Thunberg says, our house is on fire. And to ignore the fact that your own house is burning is just ridiculous.”