What is design for disassembly, and why is it so important in the current context of civil construction?
Design for disassembly is basically designing things, products, buildings, and infrastructure, so that it can be taken apart easily in the future, and the various materials and components can be recovered for reuse and recycling. This technique is quite well understood in industrial and product design, but is not common practice in the construction industry. Design for disassembly starts with the very first design proposition, but is a critical aspect of a project through all of its life cycle stages.
What are the main problems in the design of contemporary buildings that prevent or make it difficult to reuse their materials and components after renovation or demolition?
The main problem with contemporary construction, is that the techniques that we use are really all about making a building as if it will be a perfect thing that never needs to be changed or removed/demolished. So, we see materials and components assembled using irreversible, or difficult to reverse, techniques, such as gluing, welding, casting, nailing, laminating, coating, painting, etc. While some of these processes can be reversed and materials recovered, such recovery processes are difficult, time-consuming, and usually too expensive. We also see a lot of bespoke design happening, which can be a wonderful thing (I’m an architect and I love designing new things), but it does make components less reusable for other applications. I’m not saying we all have to design to the same standard or modular pattern, but there are times when a less customised approach would increase the potential for future reuse, when it is appropriate.
Which are the key strategies that architects could incorporate in their projects to make the disassembly and reuse of building’s materials possible? What can architects do to help increase the rates of material reuse through design for disassembly?
There are a number of very simple strategies, many of which we can see in historic examples of temporary buildings or traditional construction techniques in developing nations. Strategies would include: using reversible connections (e.g. screws), using a minimum number of different types of materials and components, using standard sized materials, sizing elements for easy handling, modularising components, avoiding coatings on materials, avoiding toxic or hazardous materials, provide realistic tolerances for disassembly, and retaining all construction information about materials and systems. These are really simple techniques and in many cases will actually make assembly easier as well as future disassembly. Architects do however need to develop these strategies with client, contractor and other consultants, to ascertain which are most appropriate for a given project.
At which stage of the design should design for disassembly strategies be incorporated into the project?
Design for disassembly should ideally be considered from the very start of a project, since even understanding the location or siting of a project can impact on the potential for future recovery. Design for disassembly can also have a financial impact on a project, since in some cases it may result in slightly higher initial costs. All stakeholders, contractors, and consultants need to be involved in developing an appropriate design strategy. It may not always be appropriate to design the whole building for future recovery, and there may certainly be issues that the contractor, the structural engineer, or other consultants will understand better than the architect. So while we talk about it as a design strategy, it most certainly does not rest just with the architect; to be really successful it needs to be a whole of team effort.
How is it possible to guarantee that the designed building will be deconstructed in the right way years after its construction?
We can never guarantee the future of our buildings, other than the fact that none of them will last forever. Design for disassembly isn’t about providing a manual or instructions for how the building should be taken apart in the future. It is about creating opportunity for an uncertain future. It’s about increasing the likelihood that some materials and components can be recovered and reused, by making such recovery easier. We don’t know what the future will be like, but we can avoid limiting the options.
Which are the main obstacles and impediments today for the application of DfD strategies? What should be improved or changed to facilitate it?
Current construction practice is driven largely by economic matters, where the owner or developer is seeking to maximise financial returns. Even for owner-occupier projects, the short-term issues of funding construction usually outweigh any long term returns to be realized through design for disassembly. Because of this, most building are assembled using the quickest and easiest method available, which means that consideration of what might be done decades into the future is a very low priority. Within our current economic context, it is those client organisations who build and occupy their own buildings for long periods of time, and who own many buildings, who should be looking to design for disassembly as a strategy for sustainability; environmentally, economically, and socially. These would be organisations such as governments, hospitals, universities, and even the military.
Which are the main benefits of DfD for the society?
Design for disassembly will obviously reduce waste and reduce future material consumption. But it can also empower building owners and users to easily modify their environments as their needs change. A simple example would be modifying the family home as children move out or aging parents move in. This supports social sustainability as well as economic and environmental responsibility. There is simply not enough material in the planet to keep making new things forever, so sooner or later we will have to all look more seriously at reuse and recycling; hopefully sooner.