Architects Have to Deal With the "Wicked Problem of Embodied Carbon."

This story is part of Treehugger's news archive. Learn more about our news archiving process or read our latest news.
CC BY 3.0. Cmglee on Wikipedia

A British critic calls two green icons, rammed earth and Passivhaus, "architectural trickery at its most cynical."

UPDATE: Critic Phineas Harper raises serious issues about the importance of embodied carbon, or as I prefer to call it, upfront carbon emissions. When I wrote this post I reacted to his paragraph linking of Passivhaus to "greenwash" and titled the post "Passivhaus is not a cult," when he did not actually call it that.

There are many buildings and architects that we have accused of being "greenwash" over the years, the poster child being the integrated wind turbines in London's Strata tower, where the developer actually wanted to put motors on them to make them turn and look like they were doing something. We have complained about the silliness of LEED certified airports and parking garages.

But there are two things I have never considered greenwashing: Passive House or Passivhaus certification and rammed earth construction. However, that's exactly what architectural critic Phineas Harper does in the Architectural Review.

Harper writes that "seeing through specious gestures like living walls and tower-top wind turbines is getting easier." It's true that almost all the building-integrated turbines are pretty much useless; we have been calling them folly for a decade. I have also questioned the contribution to sustainability of living walls, but then that's just me thinking that you should keep mud and water off walls, not build it into them.

Is rammed earth greenwash?

With rammed earth, Harper complains that much of it is made with a binder, calling it "a steel-reinforced earth composite with barely less cement than concrete." Harper insists that "there is no need to build rammed earth with cement." And it is true that you can build a rammed earth wall without it. But many building codes don't allow it; water can cause it to disintegrate and it doesn't hold together in earthquakes.

Rammed earth walls also use less cement than concrete walls, as little as 5 percent, and the other 95 percent is good old local dirt instead of sand and aggregate that has been dragged for miles. I suspect also that, now that people are finally getting concerned about embodied carbon or upfront carbon emissions, they will start using other binders like lime or volcanic ash (pozzolana). Like anything else in this world, it is not black and white, but a matter of degree.

Is Passivhaus greenwash?

Here, Harper writes:

Passivhaus – once a sensible building standard for low operational loads – now risks swelling to an almost cult-like club, its acolytes committed to defending the standard even as the, at times, dogmatic focus on operational emissions dwindles in relevance against the more wicked problem of embodied carbon.

This is an issue we have been discussing on TreeHugger for years, even complaining that they should change the standard to take upfront carbon emissions (UCE) into account. (See the Elrond Standard.) It is also true that Passivhaus buildings were often foamy, using lots of insulations with lots of UCE.

However, to be fair, concern and understanding of UCE is a relatively recent phenomenon, and many in the business are just beginning to wrap their brain around it. None of the green building standards really take it seriously; even the toughest, the Living Building Challenge, just demands carbon offsets. Even the brand new Canadian Net Zero standard just kind of says, "Measure it, and we will figure out what to do about it later."

But while Passivhaus is an operating energy standard, developed before people understood the implications of upfront carbon, many of the architects using Passivhaus are thinking seriously about UCE. Architype is a good example; I have suggested that their thatch-covered Enterprise Centre may be the world's greenest building because of its obsession with embodied carbon.

INterior of space

Passive House +/via

George Mikurcik of Architype writes in response to Harper's article, acknowledging that the Passivhaus standard has been historically "agnostic about what materials are used (the embodied carbon). It could be timber, concrete, steel, foam or marshmallow." But Architype has been a pioneer in building Passivhaus buildings with low UCE materials like wood and straw.

As a practice we love working with timber and other bio-based materials. They are healthy, renewable and have small embodied energy. They are also easy to reuse or recycle at the end of their life.

He concludes:

As Greta says, ‘Our house is on fire,’ and we don’t have enough time to mess around with reinventing the wheel. The Passivhaus community is one that personifies the opposite of greenwashing, and it works for operational energy, comfort, build quality and closing the performance gap. So let’s combine Passivhaus with an intelligent use of low impact materials to make a real difference.

Architype isn't alone in this; many architects and builders are on the embodied carbon case, and plug-ins are being developed for the big PHPP spreadsheet. As I wrote in an article for the Passivehouse Accelerator, you have to start somewhere, and I believe you need Passivhaus first.

Passivhaus First is the best shot we have at decarbonizing in a hurry. It’s not perfect (I think it should measure upfront carbon emissions, and measure carbon emissions instead of energy consumption, but this takes time) but it’s the best we’ve got.

Passivhaus is not a cult, and it is not ignoring embodied carbon. People get this now.