Circular Wood for the Neighborhood (CW4N)

With an increased awareness and need to change from a linear to a circular economy, in which waste no longer exists but is reused for new applications, the building sector is increasingly developing solutions for the circular reuse of materials. Circular endeavors involving wood have been initiated by different stakeholders: housing corporations, the construction industry, cities and research institutes. Already in 2017, TNO together with partners of the construction industry investigated the circular reuse of wooden doors and window frames. Their research highlighted that reusing wood is a challenging process, and that processing it manually is too time consuming and expensive. Versatile robotic solutions could help, in replacing the manual work which is currently needed for the reuse process.

Starting point for Circular Wood for the Neighborhood

Meanwhile, AUAS developed first samples of circular applications for waste wood using digital production technologies. In several opportunities AUAS met with housing corporation representatives, who repeatedly mentioned the importance of researching the potential of waste wood from their buildings, as they wondered how to process it and what could be made of it. From these conversations, AUAS learned that wood is a challenging waste stream, because it comes in fractions that greatly vary in form and quality, often ‘contaminated’ with metals (nails, hinges, etc) and finishing products (varnish, paint, laminates, etc). Digital design and robotic production processes (applied for 3D scanning, sorting, removal of non-useable parts, storage, processing, finishing, assembly or other) could offer new opportunities for reuse, which would not be available otherwise. This notion formed the starting point for the Circular Wood for the Neighborhood research project.

Research questions

The research was carried out along the following four questions.

1. What different volumes of wood waste streams can be identified within the housing corporation assets, and how are they currently processed?

Research method: A Material Flow Analysis of a selection of renovation projects from the participating housing corporations was carried out together with project partner Metabolic. Students participated with field surveys from ongoing renovations in Amsterdam and Almere.

2. From these fractions, what solutions for circular reuse can be conceived, by using digital production technologies?

Research method: A range of production processes to reuse waste wood were researched: metal detection and removal, sawing, milling, material packing to create larger wood volumes. To assemble wooden elements to one another, different connection systems were researched (dry fit joints, dowels, etc). To carry on this work and explore the potential of robotic production, wood from ongoing renovation projects was harvested and made available for the project.

Dedicated student internships and graduate projects on these developments were carried out by AUAS interns and graduates and HMC interns (Hout- en Meubileringscollege Amsterdam (MBO).

3. Can concrete applications from reclaimed wood, conceived for specific housing corporation projects, demonstrate the potential of digital production to transform cities into more circular ecosystems?

Research method: Three case studies were carried out (involving design and prototyping):

Case study 1: Once my door, now my coffeetable – A small, valuable object for tenants, made from harvested wood of the same house. This case study helps both to raise awareness on societal challenges, and create a sense of belonging to their building - which can even be enhanced by involving tenants in the design.

Case study 2: Once their windows, now our playground – In larger renovation projects, circular wood can be harvested in bigger volumes because many standard doors, doorframes and window frames come available at the same time. What if wood can be destined to upgrade the common areas of a building or the public space in its neighborhood? In this case study circular wood is used to make an objects for a community, to strengthen the social fabric of tenants and influence them to take care and cherish of their common living environment.

Case study 3: Once burned wood, now shared value - Harvested wood from building renovations comes in different volumes and types. What if a shared material bank could be organized, to store large volumes of circular wood from different sources? This case study proposes the (digital) design and production, of a room divider system made of wood from this material bank, which - based on various parameters - is adaptable to specific room sizes and/or various aesthetic choices. This model can thus be applied to various buildings, by any corporation connected to the bank.

4. What could be the impact of using reclaimed wood, for specific types of wood and for specific applications? How can this impact be measured?

Research method: A series of Key Performance Indicators was developed specifically for the project. KPI’s were collected in a series of two workshops with the partners, leading to a selection of the eight most relevant KPI’s. To calculate the KPI’s, an excel-based tool was developed and graphically presented for an easy understanding. This KPI-framework was then used to evaluate the environmental, economic and social impact of the three case studies.

Project results

The project worked on concrete and tangible answers to these questions. The wood survey used the actual data from renovation projects from Ymere and Rochdale. Wood from ongoing renovation projects was harvested to work on, at the Robot Lab at AUAS. For the three cases, prototypes were fabricated at the Robot Lab, demonstrating in practice the potential of digital design and robotic production for circular wood applications.

An exhibition of project findings (containing texts, image renders, videos, prototypes, and full-scale AR models) was developed and displayed at the three public organizations connected to the project: the municipality of Amsterdam (at the Stadstimmertuin) and at the headquarters of housing corporations Rochdale and Ymere. Special tours and organized meetings with groups of project managers from the housing corporations were held in conjunction of the exhibition.

In September 2022, the exhibition moved to the AUAS' Jakoba Mulderhuis, where it stayed on display until the end of 2022 and was integrated in a number of public events (such as the official opening of the building, the new Robot Lab inauguration, and various open days).

Conclusions

Main conclusive question in the project was: Which strategies can housing corporations apply to reuse wood waste from their own buildings, in order to create beneficial circular applications? And what can city authorities do to encourage and help increase wood reuse, in their transition towards a fully circular economy?

To answer these questions, individual interviews were held with all project partners. The findings from these interviews were synthesized into ten critical recommendations for housing corporations:

1. Create awareness

Raw materials are not enough for all housing demands: it is essential to create awareness on circular wood coming available from housing assets. Corporations are currently losing valuable materials.

2. Build a database

Start building a database of materials stored in your buildings. It is money for the future. Use common protocols for surveying current assets and material passports for all new constructions.

3. Survey your buildings

Explore digital technologies to survey buildings before renovation or demolition. This inspection can help implement sustainable solutions (like repair instead of replacement) or provide data on future available circular wood.

4. Organize collaboration

Organize collaboration between corporations, their co-makers and other parties in the value chain, so that there is sufficient circular wood for applications, and its processing costs can be collectively supported.

5. Create pilot projects

Create big pilot projects, involving several buildings and even various corporations. Test a shared material bank and applications with sufficient scale for digital production to be a real game changer.

6. Inform and engage citizens

Use pilot projects to take a front-runner role, informing and engaging citizens about circularity and sustainability in their direct environment. This contribution can help negotiate more flexible regulations for circular applications.

7. Explore alternative business models

Explore alternative business models, based on circular values and financial opportunities connected to circular wood. Start shifting from ‘paying for wood to be removed’ to ‘monetizing wood that is available’.

8. Automate wood processing

Invest in automation for circular wood processing, and apply digital design and production processes. It will pay out, given the increase of virgin wood prices and shortage of skilled workers.

9. Use parametric design systems

Use computational design systems which are adjustable to available wood, and various building typologies. Even if material input and dimensions of products slightly change, design/production costs can remain almost unaffected.

10. Investigate certification schemes

Explore the gaps and limitations of current certification schemes for ‘new’ vs. ‘circular’ building components. Which requirements -related to material quality, safety and durability- can be met by circular wood?