Another good piece on recycling at the scale of buildings: Pass the Leftovers! by Matt Burgermaster looks at the issue of reuse of building materials during demolition, using the ongoing demolition of the Union Carbide Building as an example. The statistic that jumps out at you: NYC produces 6 million tons of construction and demolition derbies per year.
There are all sorts of reasons that so much material is thrown away. Part of it is the culture of architectural and interior fashion: for example, when you move your office, it’s expected that you will demolish the existing space down to the bare structure and build a new interior. (We didn’t when we moved in 2016, partially because of reuse philosophy, partially because of cost, and partially because the existing office worked just fine for us. Purity of motive is less important than the outcome.) Part of it is the cut-to-fit waste inherent in on-site assembly rather than prefabrication. But a large part of it is the nature of our materials and assemblies.
The ultimate in construction reuse is LEGO. Each brick is complete unto itself and can be used thousands of times in different assemblies without alteration. The LEGO company is moving, slowly, towards plant-based plastics, which would make even the initial fabrication of the bricks much greener. That is not how full-sized construction proceeds. The removal of gypsum board (or its predecessor gypsum block and plaster) destroys the assembly, leaving a pile of unusable junk. The material is recyclable – gypsum is gypsum – but only if the assembly is refabricated. The great recycling success story in construction is steel, where a large percentage of the material used is recycled, but again it’s recycled as raw material not as fabricated pieces.
To change the existing system would require (a) acceptance of much higher costs for disposal, which would make recycling material relatively the less expensive option, (b) a large-scale change in how we specify materials and systems to increased standardization and those make reuse of whole assemblies feasible, or (c) top-down control over designs to force increased standardization. Options b and c are not only extraordinary unlikely, they are unpalatable. Few engineers and fewer architects want to see themselves as assembling LEGO blocks someone else has created. Option a, on the other hand, may happen all by itself: prices for large-scale garbage disposal are going up. There’s a fourth option, of course, which is to stop demolishing viable buildings without a good reason.