Valorising the existing situation
The expectations of residents and the performance requirements placed on a building evolve regularly. During their lifetime, buildings therefore inevitably have to undergo certain changes. Here, we distinguish between two major change strategies: demolition and renovation (or better, disassembly). When the building can no longer be adapted, it is demolished (or better, disassembled). In all other cases it is (extensively) renovated.
Regardless of the chosen strategy, the decision to deal with a building is a complex process with environmental- and energy-related as well as cultural and economic considerations. From a circular economy point of view, it is better to preserve existing buildings and structures as much as possible and to build on them using creative solutions in order to create added value.
Meaning and importance
In order to consider waste as raw materials and the built-up environment as a potential source of materials, a change of approach is needed within the construction and demolition sector. When considering the demolition of a building, enough time, space and workforce must be provided to selectively disassemble the building components and materials. In addition, you need to first make an inventory of the elements and materials to be disassembled.
Creating a demolition follow-up plan is an essential step before starting to selectively disassemble building elements. This plan includes an inventory with the aim of assessing the valorisation options for each type of material and/or product in the building. Better preparation for selective demolition can be achieved by quantifying and identifying the different material flows and their possible treatment (landfill, incineration, recycling or reuse).
In the case of reuse, the preparation of a detailed reuse inventory is recommended. This kind of inventory identifies all elements with a certain reuse potential. This is done based on an analysis of all available building-related documents and the findings during site visits. The preparation of demolition and reuse inventories requires a certain expertise and a good knowledge of the market. This is because the disassembled materials need to be able to be put back on the market as recirculated or recycled materials, and it is not always as easy to find suitable sales channels for all materials. At the same time, care must be taken to ensure that hazardous substances such as asbestos are removed from the chain. Nowadays there are companies that specialise in the preparation of these documents and can offer this as a service.
How was this included in the Circular Built tool?
In recent years, the BBRI has built up expertise in the selective demolition and reuse of construction materials through projects such as BBSM (La Bato Bruxellois source de nouveau matériaux), FCRBE Facilitating the circulation of reclaimed building elements in Northwestern Europe), Proeftuin Circulair Bouwen, Digital Deconstruction and Protocole de construction pour la Région de Bruxelles-capitale. Based on these practical experiences and insights, in the tool we have listed the main options for valorising construction materials in existing buildings. Here, too, we made a distinction between must-haves and extras.
In addition, the tool allows you to quantitatively specify your ambitions in terms of reuse on the site, reuse elsewhere, recycling and processing in the linear economy.
How can you measure this?
Based on a demolition and/or reuse inventory, you can estimate the amounts of material that will be retained or reused on site, how much will be reused or recycled elsewhere, and how much will be processed in the linear economy. Some key points here:
- It is important to distinguish between the theoretical potential and a realistic ambition. There are often practical or economic circumstances that make the valorisation of certain material flows more difficult (lack of space for correct sorting on site; too small quantities, making separate disposal too expensive; damage during disassembly, etc.)
- The unit for expressing valorisation has an important influence on the presentation of the results. For example, choosing tonnages will mean that light materials (such as insulation and wood) will weigh little compared to stone-like materials (such as brick or concrete). In some cases you might therefore want to measure in m³ or another unit (primary cost price, environmental cost, CO2 equivalent, etc.).
- Buildings that are currently being demolished or extensively renovated, were not built with a view to easy disassembly into material streams that are then separated for reuse or recycling. As a result, today it is very difficult to exceed 1.5 – 2% reuse (expressed in tons) in demolition projects.
Real-life examples
Which tools can help us here?
- Within the Level(s) framework, there is a calculator for construction and demolition waste that can be used to map out and follow up on the various waste flows and their destination during disposal within a construction project: UM3 Indicator 2.2 excel-file
- The Tracimat website collects a lot of information, templates, manuals, checklists about creating demolition follow-up plans, handling hazardous substances (including asbestos), and legislation.
- Practical guide for setting up a reuse inventory
- Handbook for reuse beyong the construction site: A practical guide with template documents to make the recovery of construction materials from public buildings feasible.