The crux of disassembly at the end of life
In the case of the demolition of a building, the various component materials are divided into categories which corresponds, for each, to a selected disposal. In this way, recyclable materials are divided into those that can be recycled and those that will end up in landfill. While, for example, demolished reinforced concrete structures undergo the separation of the inert part from the metal parts, for demolished coats the situation is very different.
Cement, sand and gravel aggregates, in fact, can no longer be separated, at least today, but once crushed, they will become filling material, while all the ferrous parts can be re-melted to create other metal products, even if for a different use. For thermal insulation, however, the situation is very different, especially for those that have undergone the gluing, fixing and smoothing treatment and are clinging to the facades of buildings.
The problem with these thermal systems, in the demolition phases, is the action of recovering and disposing of the insulation, rather than the recovery of the metal anchoring elements, easily identifiable and mechanically separable from the plastic of the anchors. The insulating panels, in fact, are coated with an adhesive and smoothing product, which is generally a cement or hydraulic lime mortar, integrated with a reinforcing mesh on the external surface and, in this way, they are not recoverable for possible recycling. While carrying out selective demolition and therefore admitting the successful separation of the metal part from the insulation, the inert element aggregated to the insulation is difficult to separate and ends its life directly in the landfill, without the possibility of recycling.
The fate of insulating materials after demolition
But what does landfill disposal mean? It essentially means that the insulating panels “contaminated” by the mortars undergo a crushing and shredding process, to better manage the disposal volume, and are transported to a final place, where they will remain forever, buried under a blanket of earth, covered – together with many other similar materials – by waterproofing membranes.
Unfortunately, all the insulation that made up a glued coat was given to this unfortunate destination, without any distinction. Expanded polystyrene, natural cork, polyurethane, wood fibre, etc., all have this purpose in common at the end of their life, as, in the phase of dismantling a thermal coat, carrying out the separation of the various components, however feasible, is uneconomical and does not justify the final yield.
But then is there a disposal alternative? Without prejudice to the economic difficulty of recovering the insulators, the other alternative is the so-called thermo-energization, which, translated into simple words, means burning the disused materials in an incinerator or in an industrial oven, to produce energy.
The environmental impact of dispersed materials
However, there is another unfortunate aspect to consider: the risk of dispersion of the potentially polluting insulating material, which is released during the demolition phase. This is a big problem, which mainly concerns those materials of synthetic origin, chemically manipulated and which struggle to degrade in the open air, as well as in the soil and in the aquifers or in the beds of waterways, where they can remain for a long time, gradually releasing macro-micro and nano components, impacting on an environmental and organic level.
A different matter, however, for insulators of vegetal and animal origin, whose organic component favors easier environmental disposal, without risks of pollution.
Dry systems as an alternative: designing with the end of life in mind
Having said this, another question arises spontaneously: is there an alternative to thermal insulation for insulating buildings, which can avoid disposal problems? Of course yes!
There are thermal coats that can be created entirely dry, both on the external facades and inside the homes, mainly adopting low-density insulating materials, easily maneuverable and deformable, which obviously must necessarily be protected from the elements and from the risk of fire with non-combustible supports.
When dismantling a dry coat, each component material is more easily disassembled and recoverable for other uses. Thermal insulators, which do not suffer any contamination from glues and smoothing compounds, can be reused in their entirety, or recovered by the manufacturer to be recycled or, at worst, more easily thermo-energized without burdensome residues.
As? With various methods that differ according to the category of the insulation involved. But this is another matter.
