7. Barriers to and opportu­nities within circular construction

• Strategy & planning
• Building regulations
• Culture
• Economy
• Market
• Logistics
• Knowledge and experience
• Responsibility
• Product Documentation/certification
• Digital collaboration

7.1. Strategy and planning

7.1.1. Barriers

• These arise from the broad lack of awareness of circular construction and the environmental and economic potentials therein. Public and private developers have many other considerations that must be addressed when planning a construction project, including economy, function, time frames, and other sustainable construction approaches such as sustainable certification (DGNB, BREEAM, etc.). These factors are currently more deeply engrained in developers’ strategic processes than circular construction (Höjer, 2022).
• Circularity often enters the process too late. Even when recycling and reuse provides an opportunity to minimise the environmental impacts of a development, key decisions may already have been taken that preclude inventive or impactful circular approaches.
• Circular approaches can demand new forms of dialogue and collaboration. Adopting more comprehensive approaches to circular construction often requires dialogue and collaboration with parties throughout the construction value chain, and many developers are not used to this process or cannot fit these processes into the allotted time frame for the project.
• Circular construction demands different methods, processes, and routines compared to business as usual. Most developers, both public and private, have not yet developed these routines, and it can be difficult to find the time to develop them within already tight budgets (Grænni byggð, VSÓ ráðgjöf, 2022).
• Circular construction can demand better coordination between different authoritative bodies or different departments within an authoritative body (Steen, 2022).
• Circular construction is seen as complex and difficult compared to more conventional approaches to construction, which dissuades developers from starting out on the journey (Lunneblad, 2022).
• Insufficient investment in innovation and design within the industry, and a lack of industry focus on reuse and circular construction in general (Kristjánsdóttir, 2022).

• Lack of holistic assessments of environmental impacts from building life cycles. Specifically, existing methods seldom address issues such as whether a product can be deconstructed and reused, the maintenance required over its lifetime, or the impacts stemming from waste management at end of life (Steen, 2022).
• Lack of communication and cooperation throughout the construction value chain is seen as a barrier to implementing circular practices in the construction industry, and one that is very ingrained in the way the industry has functioned until now.
• Circular construction is difficult. It can be quite attractive at the start of a project, but later in the process, the difficulties become apparent, and enthusiasm and ambition wanes (Seilskjaer, 2022).

7.1.2. Opportunities

• Embedding circularity at the core of the planning and decision-making process. Circularity must be there from the start since it can be difficult to integrate it later. This means considering not only recycled materials or reused building products, but also how best to meet demand with existing structures through renovation and modification while considering multi-use projects which can fulfil multiple needs with one building (Steen, 2022) (Höjer, 2022) (Lunneblad, 2022) (Laurikainen, 2022) (Brix, 2022) (Jacobsson, 2022).
• Promoting designs targeting flexibility, adaptability, and disassembly. Buildings should be able to be extended, moved, deconstructed, and converted into a new building. This means ensuring that the buildings we build now will not be torn down in thirty years but can be adapted to address a new demand and fulfil a new function. This maintains the value of the building stock and ensures that they have a longer useful life (Kilvær, 2022).
• Focusing on better management of existing building renovations. The best building for the environment is the one that is not built at all. At the planning stage, there must be stronger focus on how existing buildings can be transformed to fulfil a new function or updated to modern standards (Eriksson, 2022) (Kilvær, 2022) (Kjerulf, 2022) (Koch-Ørvad, 2022) (Wærner, 2022) (Lahtinen, 2022).
• Using Green Public Procurement to drive demand for circularity in construction projects. This could be achieved by making the reuse and recycling of materials an obligatory component for public procurement of construction services (Runge, 2022) (Wennerholm, 2022). This can include adopting innovative public procurement processes. For example, the city of Gothenburg engages in market dialogue by inviting selected actors to address long-term challenges that are not yet suitable for specific procurement calls. This means that the city helps support the development of product and services that it may require, without committing to a purchase (Jacobsson, 2022).
• Establishing public-private partnerships can help minimise many of the barriers experienced by stakeholders since responsibility and economic risk can be spread more widely (Kilvær, 2022).
• Improving cooperation between public departments. Several stakeholders mentioned the need for better cooperation and coordination between public departments and agencies (Dahlgren, 2022).
• Expanding consequence analysis in order to include soft factors and move beyond CO₂.
• Using multidisciplinary, multi-faceted design teams (architects, engineers, sustainability specialists, trades). Many people who work with reuse are environmental consultants and not civil engineers. To understand the performance of constructions and better map construction products, an interdisciplinary team is needed (Wærner, 2022).
• Better and earlier communication throughout the value chain and between project team members. Architects, consult engineers, contractors, and the client/developer need to communicate earlier in the process and throughout the entire value chain (Steen, 2022) (Brix, 2022).
• Synchronising timelines for different building projects would allow materials to more easily be extracted from one project and used directly in another, thus avoiding the environmental and economic impacts from the intervening storage and transport (Bjarnadóttir, 2022).

7.2. Building regulations

7.2.1. Barriers

• Technical demands. In some cases, environmental and structural demands cannot be met with reused materials (Wennerholm, 2022). This can be particularly true when dealing with fire safety and the structural integrity and acoustic properties of construction products, but it can also be related to accessibility and safety for example (Eriksson, 2022) (Kristjánsdóttir, 2022).
• Rigidity of regulations. The rigidity of the regulations in the national building codes prevents the use of reused products (Eriksson, 2022) (Kilvær, 2022) (Kjerulf, 2022) (Hippinen, 2022).
• Interpretation of regulations. The way in which regulations are interpreted and implemented by the authorities and certified engineers can hinder novel applications of materials and prevent reuse. In Denmark, for example, fire certification is carried out through certified private consultants, and they are understandably risk-averse in the case of used and bio-based products (Gate21, u.d.). While some stakeholders are subject to the regulatory demand that products have a CE-marking and documentation (Kjerulf, 2022), others indicate that although building regulations rarely prohibit the application of reused materials and circularity, they can still function as a barrier since they more easily facilitate the continuation of work as usual (Koch-Ørvad, 2022).
• Gearing towards linear construction with new products. Overall, there is a broad understanding within the industry that current building regulations are not geared towards circularity but rather are optimised for linearity and the use of new products (Kjerulf, 2022) (Seilskjaer, 2022) (Steen, 2022).
• Building regulations can have conflicting criteria. For example, the Danish building regulations have stringent requirements for product properties such as acoustics, fire safety, and emissions. However, the acoustic and fire safety requirements call for more material per area, which will increase the environmental footprint, thus contradicting the requirements for emissions (Gustafsson, 2022).
• Lack of a standard or guide for resource mapping existing buildings, and no common platform for dissemination. This results in either ad-hoc resource mapping actions or different practitioners following different methods, thus generating different outcomes. It reduces certainty in the process, and makes it more costly (Runge, 2022). Resource mapping results are rarely in the public domain, which limits the availability of materials and construction elements to those commissioning the resource mapping (Kilvær, 2022).

• Inflexible planning and zoning. A major consideration for circularity is repurposing existing structures. This is made more difficult by building plans and zoning regulations, which may restrict the types of activities permitted at a given location. This in turn limits the flexibility of reusing existing structures (Laurikainen, 2022).

7.2.2. Opportunities

• Revising building regulations to better accommodate reuse is a common theme in the literature and when speaking to stakeholders. In general, current regulations implicitly assume building with new products, which makes building with reused products a challenge (Kilvær, 2022) (Laurikainen, 2022) (Bjarnadóttir, 2022).
• Developing guides to help stakeholders who adopt a reuse strategy navigate the existing building regulations. This seems to be particularly pertinent to those actors who do not see intrinsic barriers in current regulations (Höjer, 2022) (Seilskjaer, 2022) (Runge, 2022) (Lahtinen, 2022) (Fjeldheim, 2022) (Hippinen, 2022)(Falk, 2022) (Lunneblad, 2022).
• Demanding pre-demolition resource mapping is seen as a fundamental necessity if valuable resources are to be successfully identified and removed from buildings flagged for demolition. Swedish (Sveriges Riksdag, 2010) and Norwegian (DIBK, 2022) building regulations already demand pre-demolition resource mapping, while a similar demand is anticipated to be implemented in Denmark in 2023. Developing a standard methodology could provide a significant increase in the quality and supply of construction materials, products, and elements for reuse (Kilvær, 2022) (Lindholm, 2022) (Steen, 2022).
• Minimising demolition through regulatory procedures could provide an incentive for developers to consider renovation and other alternative solutions rather than demolition. This could be achieved through a regulatory request for authorisation before demolition, whereby the developer must justify the demolition of the building (Kjerulf, 2022) (Kilvær, 2022).
• Enforcing the existing separate-collection waste regulations for construction and demolition waste could provide a significant boost to the quantity and quality of material for reuse and recycling (Kilvær, 2022) (Lahtinen, 2022).
• Demanding material passports for all new buildings would enable easier disassembly and utilisation of the materials currently being used in construction at end of life, as well as facilitate maintenance and renovation throughout the life cycle (Lahtinen, 2022).

7.3. Culture

7.3.1. Barriers

• Organisational momentum. The construction industry and related value chains are mature, with deep-rooted processes that tend to change incrementally rather than categorically. The processes involved in circular construction can be a significant departure from existing practices throughout all parts of the value chain. This manifests in an (perhaps healthy) aversion to risk, resistance to change, and highlights the lack of knowledge and experience within the industry and thus its hesitancy to commit.
• Sustainability discourse. There are already well-known and well-used sustainable construction paradigms focusing primarily on certification based on sustainability criteria. The existing schemes—DGMB, BREEAM, LEED, Nordic Swan etc.—all fulfil a market role and drive sustainability for some actors in the construction industry. Certification is often associated with a premium project/product, and most efforts to date have focused primarily on minimising energy consumption during a building’s life cycle (which comes with an economic bonus to the final user), minimising hazardous substances, and improving indoor climate. Broad demand for sustainable buildings has yet to filter down to end consumers.
• Ownership rather than stewardship. Within the construction sector, materials and components are still considered linear—they are bought and installed with the expectation that they will be discarded. The concept of material stewardship and buildings as material banks is still relatively unknown (Wittrup, 2022).
• Conservative attitudes in the industry. The building sector works with complex projects with significant unknown elements and across many groups of actors that form new constellations for each project. The competition for projects is considerable, and the net gains are very small. By following the established structure, everyone is secure in their roles; therefore, any challenges to the established structure are a threat to the value chain actors since their role may change or disappear. In addition, there is a deep and deserved respect for safety and health within the industry, which often trumps environmental sustainability (Koch-Ørvad, 2022).
• Demand from developers and end users for clean and new products. There is a broad expectation from developers and end consumers alike that new buildings should be ”new”; therefore, there is a lingering scepticism about the aesthetic and quality attributes of buildings containing reused or recycled materials (Jacobsson, 2022).
• Lack of broad support for sustainability as a goal. Not everyone in the sector is concerned about or engaged in sustainability, which means that it is still a niche activity (Koch-Ørvad, 2022).

7.3.2. Opportunities

• National programmes for Circular Construction. The development of national strategies and programmes for Circular Construction would indicate a clear strategic direction for the industry and provide a clear framework for future work concerning circular construction.
• Dedicated support programmes for circular construction within industry organisations. Industry organisations are in an excellent position to help drive the circular agenda. This leadership and network provide an excellent basis to both promote circular construction practices and draw on, collect, and synthesise experiences with circular construction from the industry. Industry organisations can also help identify specific challenges and develop solutions together with industry actors. Architects and designers can be particularly strong advocates for change.

7.4. Economy

7.4.1. Barriers

• Higher costs of circular construction processes and products, even if material is free at source. The addition costs are not limited to a single part of the process since planning, designing, and the construction process itself all involve additional steps that add to total costs (Kjerulf, 2022) (Kilvær, 2022) (Lunneblad, 2022) (Grænni byggð, VSÓ Ráðgjöf, 2022). This is a key challenge for demolition companies. The disassembly process is more labour intensive than demolition, especially given the current lack of experience in the practice. This factor is aggravated by the uncertainty about the demand for and pricing of reused goods (Bjarnadóttir, 2022) (Hippinen, 2022).
• High labour costs are a significant factor in making new products more cost effective than reused products. New products are well understood, can be used directly in the construction process, and satisfy a well-defined application. Reused products can be more difficult to handle, often require some level of preparation for reuse, and construction workers have little experience working with reuse products in general. All of this means that the process of reuse can be more labour intensive and consequently more costly. This is not unique to the construction industry—it is often more cost effective to replace mass-produced products than to repair them, especially when the product was not designed to be deconstructed.
• Relatively inexpensive new construction products. Utilising reused materials and products is more expensive than using new products despite the increasing costs of materials (Dahlgren, 2022). In one building project, for example, reusing hollow core slabs was 5 times more expensive than using new slabs, which are not only cheap, but also easier to order and have delivered within a tight schedule (Wærner, 2022).This is heavily linked to the high labour demands for reuse, which is exacerbated by a lack of knowledge about the processes involved. In some cases, and for some product groups, it is also linked to the ability to outsource production of new products to locations with lower labour costs and often lower environmental standards (Wittrup, 2022).
• Uncertainty about payback. When sustainability is seen as a premium, it only appeals to a certain market segment. Circular construction, with its additional costs, can potentially be sold as a premium product, but that approach only addresses a limited share of the total construction market (Wittrup, 2022). What’s more, other sustainability approaches—for example certification according to one of the recognised schemes—can provide a proven premium for a developer, while the direct financial benefits of circular construction are less clear.
• Lean margins. There is rarely room in the economy of a construction project for innovation, experimentation, or taking on extra risks. This means that that there is rarely room for circular approaches given the uncertainties involved and the related additional costs (Gustafsson, 2022). Sustainability is often the first expense to be minimised to maintain budgets (Kjerulf, 2022).
• Environmental externalities are not priced in to the construction products market, which helps to keep the price of new products and materials low enough to outcompete reused products (Wærner, 2022).
• Requires investments. New investments may be required for a company to engage in circular construction—in equipment or training for example—and technical solutions might be seen as expensive and complicated; it is thus not clear how and when this investment will be recouped (Eriksson, 2022).
• Demolished material (not deconstructed) is a profit for demolition companies since they can sell the recovered material fractions as material for recovery (wooden chips or scrap metal, for example). Disassembly demands that the demolition company must rethink their business model (Lunneblad, 2022).

7.4.2. Opportunities

• Lowering VAT on reuse and recycling. This would also help make reused products more economically attractive compared to new products. This could be applied to reused products at points of sale, and/or to the services involved in generating products: dismantling, preparing for reuse, or even building with reused products (Lahtinen, 2022) (Wærner, 2022).
• Implementing a broad Carbon Tax. A carbon tax that included all carbon emitting activities and imports associated with carbon emitting activities would see an increase in the price of raw materials, including cement and steel. This would have a direct positive effect on the relative competitiveness of reused components, although the magnitude of that impact is uncertain (Wittrup, 2022) (Bjarnadóttir, 2022).
• Modulating property and utility taxes for circular buildings. This would help make circular buildings less expensive to run than conventional buildings, making them more attractive to investors (Bjarnadóttir, 2022).

• Increasing waste management costs. This would help make reusing products a more cost-effective strategy for addressing end-of-life buildings. This could be achieved by specific charges like landfill gate fees (Wittrup, 2022) (Grænni byggð, VSÓ Ráðgjöf, 2022).
• Targeting funds for pilot/flagship circular construction projects and for specific technical problems in circular construction. Providing direct funding for innovative projects that seek to address specific challenges in circular construction or develop standards that can be applied in circular construction. This would help mature the circular construction industry and broaden the experience base (Bjarnadóttir, 2022). The City of Copenhagen allocates extra resources to developing circularity in the construction sector (Runge, 2022).
• Increasing the costs of virgin construction products by integrating the costs of environmental externalities. This could, for example, be implemented through targeted fees/taxes on construction products or resource taxes (Koch-Ørvad, 2022) (Wittrup, 2022).
• Reducing the financing costs of circular projects. The EU Taxonomy should itself make financing sustainable buildings more affordable in the coming years, but this could be supplemented by national measures that incentivise investments in circular projects, or more broadly in sustainable projects (Wennerholm, 2022) (Eriksson, 2022) (Wærner, 2022) (Kristjánsdóttir, 2022) (Brix, 2022).
• Increasing focus on creating employment and other social benefits from circular construction. Circular construction practices are typically more labour intensive than conventional practices. While this is associated with additional costs, it also increases employment in the local area (Jacobsson, 2022).

7.5. Market

7.5.1. Barriers

• A lack of access to both materials and services. Since demolition managers usually don’t have an interest in reusing the materials themselves, time and energy are not spent on inventory, deconstructing, storing, and selling materials (Lindholm, 2022). In contrast, new products are easy to procure and have all the necessary information. A similarly fluid market for reused products does not yet exist (Lunneblad, 2022) (Steen, 2022), and a lack of supply of products and services also serves to keep prices high through a lack of competition. This applies not only to the dismantling services, but also the packaging and transporting of those products to where they are needed and the discovery of products for reuse (Jacobsson, 2022) (Höjer, 2022).

• A lack of capacity, methods and practices. Established actors in the market need to work with different methods, and new actors and services are needed within all areas. Few actors are currently working with disassembly, preparing for reuse, reconditioning, storing, and selling deconstructed materials, and there is little reason to develop additional capacity if there is no demand for reused products (Lindholm, 2022) (Jacobsson, 2022). At the same time, a lack of actors working with, and practical examples of, reused materials in construction deters developers from requesting reused materials for their projects (Steen, 2022).
• Product discovery. Products that are available for reuse are difficult to find. A fragmented market with many platforms, all using different data standards and product descriptions, makes it challenging for developers and builders to quickly and reliable identify the products they need. No common repository for pre-demolition material audits exists (Dahlgren, 2022) (Johannesson, 2022).
• Security of supply. Even if high-quality, well-documented reused materials come onto the market, there is no guarantee that they will be on the market when they are needed, nor is there a guarantee that they can be supplied in sufficient volume within a given time frame. This is a significant problem for large construction projects and construction projects that are intended to be implemented in stages with significant time lags (Hippinen, 2022) (Kjerulf, 2022) (Brix, 2022).

• Administrative burden. The administrative processes involved with suppling, documenting, cataloguing, and marketing reused products requires new competencies and capacities, and these processes take time and money (Eriksson, 2022).
• The ease of business as usual. The building sector is used to existing practices, and incorporating new routines is hard. It is easier to order materials and products using existing practices (Höjer, 2022) (Kristjánsdóttir, 2022). This is another example of (perhaps understandably) conservative attitudes within the construction sector (Hippinen, 2022).
• Difficulty in balancing supply and demand. As the market is still in its infancy and the required tools, methods, and planning routines are still being developed, it is very difficult to establish a stable equilibrium between supply and demand.

7.5.2. Opportunities

• Mapping resources in buildings well before demolition. Pre-demolition audits are already obligatory in Sweden and Norway, and they will be obligatory in Denmark in 2023. However, circular planning would be greatly aided by having knowledge of the material content of buildings to be demolished at some time in the future, not only those buildings scheduled for imminent demolition (Wærner, 2022) (Kristjánsdóttir, 2022).
• Digital resale marketplaces and platforms. A variety of sales platforms for reused building products already exists in the Nordic countries; some are state-supported, and others are private initiatives. Broadening awareness of these platforms throughout the industry could help products flow more freely between stakeholders.
• Open standards and APIs for product data. Interoperability and open standards for product specifications and documentation can help mitigate market fragmentation. A common database for the whole sector instead of several different ones would make it easier for the client (Wærner, 2022).
• Skills, methods, and networks for disassembly. The demolition sector is already moving toward disassembly for reuse, but this could be accelerated by providing education and technical training, and developing routines and new networks for the disassembly, packaging, and transportation of products.
• Public developers can help drive both supply and demand within circular construction. They can integrate circular criteria into their procurement processes, all while also taking advantage of a large portfolio of buildings that are ripe for renovation or demolition, which represents a huge potential material bank for future construction projects (Wennerholm, 2022) (Bjarnadóttir, 2022).

7.6. Logistics

7.6.1. Barriers

• Lack of space on building/demolition sites. Space is often at a premium on demolition and construction sites. This makes intermediate storage on either type of site impractical. This is particularly the case for fragile or easily damaged products (Kristjánsdóttir, 2022) (Kjerulf, 2022).
• Distance. The distance between the demolition site and the construction site might make transporting materials and products less economically or environmentally attractive (Johannesson, 2022).
• Storage space. There is a lack of suitable storage space for products between projects, and storage can be expensive, especially when given the relatively low value of the stored products. This is particularly a problem in urban areas. The storage space must be able to house and suitably protect the relevant recovered products satisfactorily over the long term (Dahlgren, 2022) (Kilvær, 2022) (Brix, 2022) (Eriksson, 2022) (Johannesson, 2022) (Höjer, 2022) (Kilvær, 2022) (Hippinen, 2022)(Grænni byggð, VSÓ ráðgjöf, 2022).

7.6.2. Opportunities

• Synchronizing demolition & construction across sites in order to facilitate reuse, minimise storage requirements, and begin to balance supply and demand.
• Developing local solutions and coordination so that long-distance- and long-term storage is unnecessary.
• Reusing own materials or materials on the site to minimise transaction costs (Kilvær, 2022).

7.7. Knowledge & experience

7.7.1. Barriers

• Circularity is still broadly a new concept, as are the various activities it includes (Jacobsson, 2022). Circularity requires a new way of thinking (Seilskjaer, 2022) (Eriksson, 2022).
• Lack of knowledge and experience with circular approaches in developers. Driving circular projects requires knowledge and know-how from the developer, and this is currently lacking and difficult to attain (Dahlgren, 2022).
• Lack of skills and know-how throughout the value chain in methods and techniques for circular construction:
  • Designing for flexibility, adaptability, and disassembly (Lunneblad, 2022).
  • Designing with reused products (Lunneblad, 2022).
  • Working with reused products and recycled materials (Wennerholm, 2022) (Höjer, 2022) (Wennersjö, et al., 2021) (Steen, 2022).
  • Safe and careful disassembly, packaging, and transport of products and materials for reuse (Höjer, 2022) (Seilskjaer, 2022). In existing buildings, where reuse is not a design criterion, it can be difficult to remove otherwise suitable materials or components because of the surrounding structures or the way in which they are attached; this can result in damage to the potential reuse product (Lunneblad, 2022) (Kristjánsdóttir, 2022) (Grænni byggð, VSÓ Ráðgjöf, 2022).
  • Planning and conducting pre-demolition audits. Although guides to this practice are appearing, the knowledge is not yet widespread in the industry.

• Lack of capacity and lack of time and money to develop the required new competencies. Construction projects have little leeway for learning and experimentation, which limits the ability of actors throughout the value chain to develop the required competencies and capacities (Kristjánsdóttir, 2022).
• Lack of coordination and knowledge-sharing between stakeholders. Despite the growing interest in circular construction, there is still a broad lack of experience with reuse and circular construction throughout the value chain (Hippinen, 2022) (Kristjánsdóttir, 2022) (Höjer, 2022) (Wennerholm, 2022). The knowledge that does exist is scattered and has yet to become common knowledge (Eriksson, 2022); furthermore, there are legacy incentives for not sharing knowledge in order to maintain a competitive advantage.

7.7.2. Opportunities

• Developing and maintaining national & regional knowledge centres can act as focal points for the entire industry or for specific parts of the value chain. They can help by building knowledge and sharing experiences, developing and distributing common practices, methods and standards, and providing a network of engaged actors within the industry (Høibye & Sand, 2018) (Karppinen, 2020) (Jacobsson, 2022) (Lahtinen, 2022) (Lunneblad, 2022) (Kilvær, 2022) (Koch-Ørvad, 2022) (Runge, 2022) (Seilskjaer, 2022). For best effect, these should include or be open to the industry in order to ensure that all needs are addressed, not just those of the actors currently engaged in circular construction (Koch-Ørvad, 2022). Working across the traditional borders of stakeholder interest and understanding the concerns of the other actors in projects is the key to change (Brix, 2022).
• Targeted Workshops: Having workshops that focus on implementation, design and material flows, including aspects from business and engineering (Kristjánsdóttir, 2022). This includes workshops with the housing authorities, financial institutions, and municipalities working on issues that currently limit circular construction.
• Using Pilot projects to build knowledge and experience (Bjarnadóttir, 2022).
  • Learn-by-doing. Hands-on experience is invaluable for learning how to work with reuse and other circular construction practices. This also helps build new relations and networks, and by starting small, it provides a base from which to scale up operations (Eriksson, 2022) (Kjerulf, 2022).
  • Dare to try. Just undertaking a project can help mitigate the expectation of circular construction being too difficult and complex (Lunneblad, 2022).

• Increasing Nordic cooperation. Harmonising collaboration between the Nordic countries regarding approaches and best practices within CC is necessary. This will create a larger and more stable market for CC materials and products (Laurikainen, 2022) (Kristjánsdóttir, 2022).
• Training in specific technical aspects of Circular construction. This is particularly relevant for disassembly methods and practices as well as working with older products in new construction.
• Preserving trade skills from older, more experienced employees. This is particularly relevant to the above potential regarding training for construction with reuse (Höjer, 2022).
• Developing standard routines for construction and dismantling processes, contract forms, data gathering, product testing, and packaging norms, so as to bring stability to circular construction.
• Using digital tools to spread knowledge within the value chain. For example, a database of important projects and contacts can be created in order to provide a useful reference and encourage direct contact with actors that have faced and overcome similar challenges (Gustafsson, 2022).
• Developing a common terminology and language around circular construction: An important part of making the transition to CC successfully is to have an agreed-upon terminology in place. The FIGBC (FIGBC, u.d.) is currently attempting to address this issue in Finland (Lahtinen, 2022).
• Integrating circular construction into national school curricula: This will help embed circularity as a concept in the next generation of experts and help provide the necessary expertise in circular approaches in the coming decades.

7.8. Responsibility

7.8.1. Barriers

• Allocating responsibility between parties. Usual building processes and contracts hand the builder responsibility for the finished building for a fixed period after completion. Should problems occur that are not the result of misuse of the building or other exclusions, the builder is held responsible for any repair and remediation. Builders are reluctant to enter into the same agreement when their control over the quality of individual elements is reduced through the application of reused products (Brix, 2022) (Gustafsson, 2022) (Höjer, 2022) (Kjerulf, 2022) (Koch-Ørvad, 2022) (Wennerholm, 2022).
• Sourcing products for reuse. Builders operate within a known supply chain, with well-known suppliers and standardised products, and are typically responsible for sourcing the products they use in construction. Builders are reluctant to engage with projects that demand reused products since these products cannot be sourced from their usual suppliers, come with less documentation, and can require non-standard methods to work with them (Gate21, u.d.).

7.8.2. Opportunities

• New forms of cooperation and dialogue. Existing relationships and responsibilities are challenged, and new arrangements can help overcome some of these challenges related to responsibility for a product’s technical capabilities and for the final construction (Brix, 2022). This can be done within the framework of existing regulations and standard practices or, if need be, by modifying or re-interpreting them to better suit the challenges concerning responsibility and risk in circular construction (Koch-Ørvad, 2022).
• New roles in product sourcing. Rather than passing responsibility on to the builder, the architects, advisors, and commissioning authorities can play a much more active role in identifying and sourcing used building components for reuse. This works together with the previous opportunity for differentiated responsibility for the products themselves (Gate21, u.d.). It is important to have trust between the developer and the contractor. This can be reinforced by the developer taking responsibility for the reused products. The developer usually has knowledge about the products, which helps to make correct decisions about how they can be used again (Höjer, 2022).

7.9. Product documen­tation / certification

7.9.1. Barriers

• No widely accepted methods or standards for the re-documentation and recertification of reuse products. Even in the unlikely event that the original documentation for a product can be found in the original building documentation, this may not satisfy current or future documentation demands, and it is not always evident whether the technical properties detailed in the existing documentation are still valid at end of life (Wærner, 2022). There are no established methods and standards for generating documentation for reused products, which reduces trust in any documentation and increases the costs of providing documentation (Grænni byggð, VSÓ Ráðgjöf, 2022) (Wittrup, 2022).
• Testing can be challenging. If materials and products need to be tested before they can be reused, this can be difficult to achieve in a non-destructive manner (Kristjánsdóttir, 2022). This is a particular problem with unique, rare, or low-count products.
• Documentation and certification are often comprehensive. Many criteria must be documented depending on the product: There is also uncertainty within the industry about which properties need to be documented for a given reuse product.
• Invalid warrantees on reused building and construction products. Warranties on building and construction products are typically not valid after first application. This creates a degree of concern relative to the reliability of reused products as well as where responsibility for the quality and technical performance lies in reuse applications (Gustafsson, 2022) (Koch-Ørvad, 2022) (Wittrup, 2022).

• Suspected presence of hazardous substances. In the absence of comprehensive documentation, testing, or resource mapping, there is no guarantee that products intended for reuse are free of hazardous materials. The presence or suspected presence of hazardous materials is a commonly cited reason for avoiding reused products in construction.
• Lack of digital information standards for generating, storing, and communicating product information. This leads to the fragmentation of the potential market for reused products and limits the potential for reusing recovered construction materials and products.

7.9.2. Opportunities

• Standardised documentation for reuse & recycled materials. Ideally, this could take place at the EU-level alongside existing construction product documentation and certification demands. Alternatively, Nordic or national standards would also help developers trust reused products, and they could be tailored to the materials and products used most frequently in each respective country.
• Developing standardised methods for CE-marking (or equivalent) reused products. This would allow reused products to re-enter the market on equal footing with virgin products. Brukspecialisten in Sweden and Gamle Mursten in Denmark have achieved this for reused bricks.
• Including a reuse guide and conditions as an additional component in existing harmonised standards for new products. This would provide clear guidance on how and under what conditions a given product can be reused at end of first life.

• Transferable guarantees. Enabling guarantees to extend beyond first life, or transferring the guarantees on to a third party, which could enable products to re-enter the market.
• Promoting take-back and re-manufacturing. This would put the onus on the original manufacturer to control the quality of and provide documentation and guarantees for products as they are remanufactured.
• State-backed guarantees for reused products. A governmental insurance pool (for example “Byggeskadefonden for genbrug”) could drive the agenda forward by removing some of the economic risks for clients, designers, and contractors. This could be particularly relevant for "non-fatal" risks such aesthetic or even premature functional failures. When looking at structural components, other measures need to be considered since there may be fatal consequences if something goes wrong (Gustafsson, 2022).

• Digital twins for new products could reduce this problem for future circular construction projects by providing comprehensive and up-to-date information on a given element or product in a building.
• Online database of (standardised) documentation for reused products. This could streamline the documentation of products for reuse and provide easier access to documentation for designers and builders.

7.10. Digital collaboration

7.10.1. Barriers

• Closed and isolated digital silos. Digitalisation in the construction industry often works within closed systems with proprietary data.

7.10.2. Opportunities

• Sharing data. It will be imperative in the future to make data on buildings and products more freely available, open, and transferable in order to enable a higher level of transparency, better utilisation of the existing building stock and construction products, and facilitate high-quality maintenance, renovation, and disassembly.