Use a component, pass it on
Åsa Ekberg Österdahl / group manager of building physics / WSP / Sweden
We use more building materials than we need to, just because what’s popular changes — people change the colour of their walls and their carpets more often than is necessary from a technical perspective. There are a lot of developments in recycling to deal with this. For example, in Europe, we are trying to develop the plastic recycling industry to deal with decades’ worth of old PVC flooring. But we’ve not yet achieved a fully industrialized methodology for it yet.
If you count energy recycling, I would say we are very close to recycling all construction waste in Sweden. We don’t send any organic materials to landfill. The most ambitious companies have set a goal to send just 2-3% of construction waste to landfill. They are achieving at least 5%, but that final 5% is very hard because there are some parts of the waste that we don’t want to be recycled in any way because they might include substances that are toxic or hazardous. We don’t want those materials in the recycling loop — we want them out of it.
From a chemical engineering point of view, materials such as brick and glass are quite easy to reuse or recycle. The most difficult are polymeric materials, such as PVC. There has been such rapid development and there are many additives — softeners, for example. Over time, we’ve learned more about their toxicity. To reach 100% recyclability, we need to avoid using these toxic elements in new construction projects.
But the dream is not just to recycle materials but to maintain them at the same value level. To achieve that, we need to look not only at the choice of materials, but at ways of connecting different parts of a building without using glue or nails, so we can take them apart without destroying them.
I think we will also need some kind of digital solution to find new users for the materials that we take out from buildings as they’re demolished. So if you’re in a big city and you’re taking down an office block, you need to find a user for every single element. Perhaps a customer who is not too far away, so there isn’t a high carbon footprint from transporting the components.
Construction companies already do this when it comes to stone and earth — when they’re digging out the ground and they have to get rid of it, they try to find another project that needs filling. When you’re about to demolish a house, there are companies that will come and look at what parts they could sell to another owner. They take doors and maybe windows, toilets and sinks and so on. There are companies that take the bricks from old houses and remove the mortar and sell them on. I think this market will grow, but there will be challenges — for example, concerns about quality, harmful substances and what kind of building the material has been used in before.