architecture circular economy

Building of the week: the circular building

No, not circular like the Colosseum or the Albert Hall. Circular as in the circular economy, something I’ve written a fair bit about over the past few years, but not so much in the construction sector. In a circular economy, materials are reused in a closed loop, rather than being thrown away. The only stuff that gets thrown away is stuff that’s been designed to safely biodegrade, so that it serves as nutrients to the world’s natural systems rather than ‘waste’.

That’s a problem for the construction industry, which is one of Britain’s biggest sources of waste – three times more than all the country’s household waste put together. Of over 100 million tonnes of construction waste produced every year, just half gets reused. More than a third ends up in landfill, including rubble, scrap wood, and insulation materials. Some of it is hazardous and really shouldn’t be dumped at all, such as plasterboard. Other materials leach into the environment and pollute land and water, like PVC. There’s also the embedded carbon to consider – cement is one of the most carbon intensive industries in the world, so it’s a shame to see concrete go to waste.

With this waste problem in mind, it doesn’t seem unreasonable to design buildings for a circular economy, even if that re-use comes many years down the line. One company that is pioneering the idea is Arup, and last year they built a demonstration house that could be completely re-used.

There are several key design considerations that make this possible:

  • First, the building has to be designed for disassembly, not demolition. It has to be fixed together so that it can be taken apart without damaging components, so pieces are clipped or bolted together and adhesives are kept to a minimum. (This idea was applied in the Green Solutions House that I wrote about a couple of weeks ago.)
  • Secondly, the people taking the building apart later will need to know what they’re looking at. Like Maersk’s latest container ships, every part has a tag and a scannable code showing what the material is and how it can be reused.
  • Some materials were chosen for durability and reuse. The structure is a steel frame, which can be dismantled and reused with no loss of quality at all.
  • Other materials were selected because they can be safely composted. Mycoboard insulation was used for example, which is grown by a fungus – see this post on myco packaging.
  • The ‘wet trades’ were avoided in the construction process – those are the ones where materials are mixed with water, such as concrete, plaster or mortar. Once you’ve plastered a wall, that clay and gypsum and other ingredients are only ever going to come off in useless chunks that will have to go in a skip. If you clad a wall in panels instead, those can be taken down and replaced and recycled.

Arup’s demo home was only a temporary prototype for the London Design Festival, so it’s gone now. But you can see the research that went into it in this Arup report, and get the details of how it was built here.

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