5. Analysis of the results

The quality of different CDW determines the recycling and reuse possibilities. To ensure good quality of the CDW for recycling, the different fractions should be dismounted and sorted separately when possible. The on-site separation is considered a better alternative as it results in cleaner waste fractions, although it has more limitations like higher costs or limited amount of space on the site. The treatment and separation technologies for mixed CDW fractions have been developing rapidly in recent years, which also enables high-quality off-site sorting. However, upscaling of new technology and innovation is slow. Some waste materials, like plaster boards, are very difficult to separate from mixed CDW if they get pulverized during the treatment process. The pre-demolition audits make it possible to identify materials that need to be separated. The audits also help to define which order the disassembling should be done to avoid unnecessary contamination or wetting of materials.

The level of construction elements or material reuse remains relatively low across Europe, and achieving higher rates would necessitate a more standardized approach and guidance at the EU level. Presently, the Nordic countries have their own national practices regarding the verification and approval of construction elements or materials prior to reuse. The existing European Construction Product regulation and CE-marking requirement only pertains to new construction products, such as bricks.

Considerations for recyclability and reusability should be integral to the design of new buildings and construction materials. The current building stock lacks designs suitable for reuse, which complicates disassembly. Additionally, construction materials from previous decades contain numerous hazardous substances and structural complexities (e.g., composite structures), which poses challenges for recycling or reuse.

5.1 Output from the workshop

A stakeholder workshop was held to present the preliminary results and findings from the project, as well as to gather additional information from the participants for this study. During the workshop, stakeholders representing entrepreneurs, recycling companies, consultants and authorities, discussed potential knowledge gaps, challenges and opportunities for recycling and reuse in the construction sector, as well as what the Nordic countries could learn from each other.

A summary of the challenges and opportunities from the workshop discussions and findings are presented in Table 11 below. The discussions identified the need for unified ways of working to increase cooperation and opportunities within the Nordics and EU. As an example, a common terminology and more detailed statistics were seen as necessary for identification of materials which have potential for increased recycling or reuse. The terminology concerning material recycling, recovery and reuse is still regarded as difficult, as certain terms are understood differently. In the Nordic countries, this is mainly due to language differences and that the term recycling is commonly also used in all countries for recovery treatment. In addition, the need for more unified EU-wide practices and guidelines especially for construction product reuse was seen as necessary. Currently the Nordic countries have country specific practices on how construction elements or material reuse can be done or reported on. A lot of development work is going on regarding this at the EU-level e.g., Construction Product Regulation revision, Eco-design and product passports. The best practice cases and statistics from Denmark were recognized as something to learn from to increase recycling. In the long run, the focus should be more on reducing waste by demolition, only when essential and preference placed on preserving and renovating instead. In addition, the reusing of construction elements and materials have a lot of potential in waste reduction and some good examples were identified, like Cleveland Steel in UK, Brukspecialisten in Sweden and Gamle Mursten in Denmark.

The workshop discussions concluded that technologies exist to solve most of the problems, but there is a lack of drivers. The participants called for stricter requirements. Drivers for increased recycling and reuse of CDW was mentioned through legislation and regulation, e.g., climate requirements and EOW regulations, waste taxation, EPR schemes and demands in public procurement. As a good example, it was mentioned that in Norway, requirements for design for disassembly are included in the building code, which is something that could be included in other countries as well.

Opportunities

Data and statistics on the CDW at a detailed level, split into many subcategories, including data on sorting and treatment would help recognise opportunities.
Sorting of CDW into more fractions is possible and only a matter of planning. This would create new possibilities for the new business.
Climate legislation can work as a driver for reuse.
Taxes and costs are effective in driving the change in behaviour.
Process for the reusing of construction materials needs to be developed at the EU level.
Building passports and long-term routines will increase information about materials included in the buildings.
Consistency and flexibility in legislation concerning construction material reuse.
On-site separation/treatment process is possible for demolition sites. Transport costs determines if off-site or on-site treatment is carried out.
Extended producer responsibility for certain products (isolation, plaster boards) could help in closing the loops.

Challenges

Mixing of waste streams prevents further recycling/reuse. Technical challenges occur especially when the mixed materials are needed to be separated.
Material availability. Demand for circular construction products, for certain product categories, is larger than the current availability.
Ease and low costs of landfilling or energy recovery of CDW.
Good availability and low cost of virgin raw materials partially prevents the use of recovered materials.
Quality demands, e.g., CE-certifications in construction, needs clarification when using recovered materials.
Obtaining behaviour change is harder than the treatment techniques.
To scale up start-ups is expensive and not incentivised.
Insufficient statistical information of CDW is a challenge. More detailed data would help to show low hanging fruits and where improvements could be made.
The reuse of construction products needs a uniform process and criteria in EU.
High cost of recycling, especially due to long transportation distances.
Timing and local availability of reused materials to meet the demand.

Table 12: Summary of discussion points from the workshop.

5.2 Challenges and impact drivers

The EU Waste Frame Directive (WFD) and the Waste Hierarchy set the tone in waste legislation through all the Nordic regions. Differences in how they are implemented can be found, and they often depend on regional factors. There are slight differences in the requirements for sorting CDW materials, including the number and nature of fractions sorted. Discrepancies in the fractions to be separated may stem from different building techniques.

This study finds that despite the sorting requirements for CDW in all countries, waste statistics indicate that not all materials are separated but instead culminate as mixed CDW. Consequently, the study concludes that while regulations for on-site sorting exist, they are not consistently adhered to, potentially due to a lack of adverse consequences for companies. Moreover, the sorting requirements are not reflected in publicly available waste data from the sector, as the data is aggregated in reporting. This can be seen for all Nordic regions.

The definitions for the different treatments, fractions, and recovery targets are established within the WFD. One prevalent challenge observed across the sector and in all countries is the lack of consistent interpretation of the terminology. While the official terminology between 'recycling' and 'material recovery' differs in English, the term 'recycling' is often used interchangeably in the Nordic languages. In some cases, backfilling is considered a part of recycling, as it falls within the recycling and material recovery target (frequently referred to as the CDW recycling target). Among the Nordic countries, only Denmark publicly reports the ratio of backfilled or recycled mineral waste.

Waste statistics vary across the different Nordic regions, and the sorting requirements stipulated in the legislation are not reflected in the available waste data. Denmark stands out as the Nordic country with the most comprehensive publicly available CDW data, encompassing statistics for various fractions and information on treatment methods. In contrast, Sweden's waste data was accessible solely through a designated contact person.

Most countries present aggregated CDW data, which combines all waste from the sector, often including soils and excavation masses. This could stem from variations in how the source data of the CDW is generated, that is, waste companies might categorize waste fractions differently. Additionally, most countries and regions also report on mineral waste at the required EWC-Stat code level, where e.g., code 12.1 for mineral waste includes concrete, asphalt, plaster and mineral wool. However, totals for plastics and glass often includes packaging materials, which do not accurately represent the construction sector.

The aim of this study was to focus on recycling and reusing techniques for CDW, uncovering both new and established methods for recycling, reuse, or preparing for reuse that are currently available. These techniques exhibit variations across countries, for instance, in the case of reuse of bricks with lime-based or concrete-based mortar, yet this variation seldom hinders increased recycling and reuse rates. The technical aspects are mostly in place, except for mixed and dirty demolition waste such as plastics, combination materials, and for some mineral wastes. The study has investigated interesting case examples in chemical plastic isolation recycling, sorting facilities, mineral wool recycling, and potential concrete recycling methods. The obstacles for expanding these techniques or implementing them in various regions appears to be economic, legislative, cultural, and, in some instances, geographical.

The economic aspects are the main drivers in this sector, as it is in other businesses as well. What is profitable or not, on the other hand, can be adjusted and influenced by policy and regulation. A higher waste tax on disposal or low value recovery can guide the material flows to recycling processes. This can lead to limitations where producers or companies providing recycling or reuse techniques, such as for flat glass or bricks, have trouble getting enough material to cover demand of their circular product. In Denmark, where the cost of landfill is high, it is less expensive to sort and recycle CDW, which is reflected in better recycling rates. Quite often it can also be the case that the recycling process leads to higher costs, and this in combination with other aspects of recycled or reused material, such as uncertain or fluctuating availability and quality assurance, can lead to a limited demand. Both cases can be helped by policy changes, making it more profitable to buy circular products due to e.g., regulation demanding climate or material saving option, or making it much more expensive to dispose of waste or producing mixed waste. Especially for rural and vast areas, the potential recoil effect of raised fees should be considered, where unethical disposal could increase.

Another challenge in advancing towards increased recycling and reuse of CDW relates to supply and demand dynamics. The supply of recyclable or reusable materials is inconsistent and fragmented, while the demand for these materials remains unpredictable. This pattern is typical across various recycling endeavours and is recognized as a significant barrier to establishing a circular economy in all sectors across countries. Additionally, waste materials may emerge in different locations or times than where the demand for these materials exists and knowledge gaps regarding available materials, their timing, and locations remains a significant obstacle. Limited awareness and education among stakeholders, including builders, contractors, and consumers, contributes to a lack of understanding of the benefits associated with construction waste recycling. This hinders the creation of a robust demand for recycled materials. Fluctuating demand for these materials impacts the economic feasibility of recycling initiatives. Efforts have been made to establish platforms for demand and availability of materials, with some platforms mentioned in the case examples, such as SalvoWeb, Materiaalitori, Malmö Återbyggdepå, and Ylijäämävarasto. However, some of these platforms faced challenges during the implementation phase. For instance, despite its general recognition as a valuable and necessary initiative, an Icelandic platform of this kind was discontinued due to insufficient funding and disagreements regarding ownership and operational responsibilities

Personal communications, Daði Rúnar Pétursson, Ríkiskaup. 2023.

Despite similarities among the Nordic countries, notable differences also exist. For instance, the building stock varies between countries, as does the use of materials such as wood, bricks, and insulation, and building techniques and age of buildings for demolition can differ, which affects the composition of the CDW.

Regional aspects play a crucial role in determining the treatment of CDW. For instance, in island regions like Greenland, the Faroe Islands, Åland, and to some extent Iceland, local recycling treatment for every waste fraction is often unavailable due to small waste streams and cost-benefit considerations. Consequently, waste from these areas tends to be exported or used for low-value recovery methods like backfilling or disposal. Additionally, industries within the region influence CDW treatment approaches. In Finland and Sweden, most of the wood from construction and demolition sites is incinerated for energy recovery since the forestry industry provides the particle and chipboard producers and other wood product industry with enough wood waste that is clearer and more locally generated. In Denmark, where the forestry industry is less dominant, wood waste from construction is an important material stream for the wood product industry.

Harmful substances pose a perpetual challenge in the circular economy because, while materials are meant to circulate, these substances should not. It's crucial to separate them from other materials and treat them safely. The identification and separation of harmful substances from CDW have long been a focus in all Nordic countries. The construction product categories from a certain era, which may contain harmful substances, are generally well known and considered during the demolition in all Nordic countries. Hazardous substances have been utilized in various construction materials such as mortars, jointing materials, impregnated wood structures, insulation materials, paints, and glues. Each country seems to adopt a similar approach to mapping hazardous substances in materials prior to demolition and separating them during the process. This study did not focus on the technologies which are used to treat hazardous substances, but typically, they are disposed of through incineration with energy recovery.

5.3 Potential to increase recycling and reuse of CDW

This study found that the largest fraction of CDW is mineral waste. Looking into good examples and techniques available, there appears to be significant potential to enhance high-value recycling across all countries. Particularly in the regions lacking an End-of-Waste scheme, redirecting materials away from backfilling towards recycling could be beneficial. Additionally, it could facilitate the recycling of concrete into new concrete aggregates. Establishing a market for recycled concrete could be driven by climate requirements for new buildings and waste pricing. The optimal reuse of elements is achieved in buildings designed for disassembly. It should be a requirement for new buildings to adhere to this principle, coupled with comprehensive documentation of materials used via a building material passport.

Other potential for increased recycling or even reuse can be seen for mineral wool, PVC and wood waste. These are materials that are largely recycled in Denmark, but not in other Nordic regions. For PVC, clean surplus pipes, and more from building sites could easily be sorted out. The barriers in Finland for example, seem to be the small volumes and long transportation distances to recycling plants. For mineral wool, as well as for plaster boards, there are return schemes for surplus material from construction sites, where the mineral wool and plaster boards are recycled into new products. Recovering materials from demolition sites is challenging, as the materials are often mixed, contaminated, and exposed to weather conditions.

The wood waste is an interesting fraction, which would have recycling or reuse increment potential in other Nordic countries other than Denmark. However, wood waste is important and cost-effective fuel for energy production and security of supply in the Nordics and would in the case of large-scale shift towards recycling need a replacement for energy production. In the longer run, though, the energy production via combustion is declining. One potential use of wood waste from construction and demolition are programmes with companies for reuse, working in smaller scale in the UK but also as pilots in the Nordics. In addition, utilization of wood waste as material for biochar, which may be the most feasible large-scale use, is already happening to some extent.

To enhance recyclability and reuse, the significant potential lies in improved sorting, documentation, and reporting. “You can’t lead what you can’t measure” applies here, indicating new business opportunities through better-sorted fractions. On construction sites, several methods can enhance sorting, such as offering sorting possibilities and assigning responsibilities. For larger construction sites or on a city-level scale, establishing a logistical hub outside the site, similar to Bouwhub in the Netherlands or Skanska Bart Hospital logistic site detailed in Chapter 4, could be an effective solution. Regarding demolition sites, effective planning, and the dismantling of reusable and recyclable materials before demolition are crucial.

On-site sorting of demolition waste is imperative, and the implementation of requirements and economic incentives, such as procurement requirements and waste taxes, are vital for successful implementation.

Quality assurance for reusable material is vital, and schemes for CE-certification for reused material would create huge opportunities in the field. This has been seen in the case with bricks, where the demand for reused certified bricks exceeds the supply.

5.3.1 Impact drivers for reaching potential

Understanding the possible impact drivers is important to reach the potential of reusing and recycling CDW. The four main categories of impact drivers have been identified as the following: Legislative or political drivers, economical drivers, technical drivers, and social or cultural drivers. The drivers will be described in more detail in the following section.

The legislative and political impact drivers to enable the reuse and recycling of CDW have been identified as the following:

End-of-Waste regulations that makes it easier to recycle and reuse safe material will enable an increase in higher-value recycling of mineral wastes and reusable building products, for example.
Establishing Extended Producer Responsibility (EPR) schemes require producers to establish or contribute to developing systems for collecting and recycling their products. This will encourage producers to think of the end-of-life use during the design of the product, making it easier to close the loop, as the financial responsibilities at the end-of-life of the products are shifted to the producers.
Establishing more comprehensive and transparent climate and resource targets in national regulation can lead to a common understanding of the stakeholders’ roles and responsibilities in the implementation of change. The targets and goals should be easily understandable and easy to follow up and should be transparently reported on.
Design for disassembly integrated in building code.

The economic impact drivers to enable the reuse and recycling of CDW have been identified as the following:

Increasing the waste tax or other fees on the disposal practices that do not promote reuse or recycling, such as landfilling or energy recovery, will discourage the use of those treatment alternatives. This will create an incentive for waste reduction and better waste sorting for the possibility of using disposal practices such as reuse, recycling, and material recovery.

Creation of market value through other policy, e.g., obligations or procurement requirements, or benefits for climate or resource saving practices.
Investment funds for innovative practices.

The following technical impact drivers were identified to enable increase recycling and reuse of CDW:

On site sorting and technological innovations which enables production of good quality waste for recycling.
Importance of proper timing (pre-demolition audit, assorting disassembling) in demolition projects to ensure high quality recycling and reuse.
Development of uniform guidelines and approval process, reusing of construction elements and materials.
Clarify the verification process of the reusable construction elements or materials.
New buildings and construction materials should be designed so that they would be more easily recyclable or reusable.

The following social and cultural impact drivers were identified to enable increase recycling and reuse of CDW:

The public sector plays an important role in implementing a change in old ways of working as they are a significant developer in the construction and demolition sector. Implementing stricter procurement requirements to enable the use of reused or recycled materials can drive this change.
Clearer and common guidelines and practices for reuse of CDW should be developed and implemented to unify the process and make it understandable for as many actors. The guidelines could include definition on how material quality is verified for reusable materials and how waste status or End-of-waste is determined.

Refitting, refurbishing and renovation efforts before demolishing.