The global image of recycling—the familiar triangle of arrows—conjures an idea of continuous cycles, yet open-loop recycling is better described as delayed disposal .
When, for instance, timber joists are chipped for chipboard, this open-loop recycling still requires trees to be felled, milled, and produced when we want new joists.
However, the failure to retain materials as high-utility construction components means that the industry’s enormous resource extraction continues more or less unabated.
Current systems of waste management do not satisfactorily support mitigation of the construction industry’s environmental impacts.
BRE’s SMARTWaste data , derived from thousands of individually reported projects, indicated a recycling rate of 91% in 2012.
However, national and EU legislation does not set separate targets for reuse and recycling, and the main route for waste streams diverted from landfill has been recycling into lower value products—downcycling—often in an open loop.
A joist retained in its existing form may be able to displace new, kiln-dried sawn wood, and perform the duty of supporting a floor for many decades.
Utility also drops in the case of end-of-life concrete.
Extraction of these resources causes environmental damage, loss of habitat and biodiversity, and changes in land use patterns .
Processing and transporting those resources to supply useful building materials depletes reserves of non-renewable energy, and, in the UK, represents 8% of total greenhouse gas emissions [3,4].