Circular construction is not about building a round house (although they can make really interesting spaces to live in). Circular construction is about applying “circular economy” principles to the construction process.
Our economic system is sometimes described as a “linear” system – we take, make, use and eventually discard things without much care about where we take from or discard to. The circular economy by comparison is about managing the full economic cycle of any product so that we minimise resource use and environmental impacts at every stage of the process, and where nothing is ever discarded as “waste” but everything is kept in a continuous loop, either reused as raw ingredients for a new product or composted back to its natural state.
The theory is simple but the application of circular economy in practice is complex, especially for buildings which are one of the most complex things to make most of us will ever have to engage with.
There is no standard currently agreed for how to assess the “circularity” of a building, but the Ellen MacArthur Foundation is one of the global leaders on the circular economy and they define three key principles:
- design out waste and pollution
- design to keep products and resources in use
- design for regenerative natural systems
These principles can be applied at any level of detail for a building project. The first big question is “do we need a new building at all” as not building something is the best way to minimise resource use. Can we adapt an existing structure instead, or can we make better use of the space we already have.
If a new building is essential, then the next question is how can that building be designed in a way that will give it as long a life as possible? This means flexibility to accommodate changing uses, and using materials that are durable or that can be easily maintained, repaired and replaced as necessary.
And if demolition is required in the future, how can the building be designed in a way to make sure the materials are recoverable? This is sometimes called Design for Disassembly (DfDA), or Buildings as Material Banks (BAMB) and means things like having bolted rather than welded connections for steel.
There are lots of other aspects to circular construction. The use of recycled and recyclable building materials is an obvious one. Less obvious but equally important is avoiding the use of toxic substances, as these have the potential to cause environmental pollution during recycling or impact on health and wellbeing of users and workers, all of which are covered by the regenerative natural systems principle.