NetZeroCities

Currently, at the end of a building’s life the majority of its materials are sent to landfill or down-cycled into products of much lower value. To maximize the recovery and valorisation potential of existing materials in buildings and minimize waste in construction, optimal waste management at the end of life of buildings is essential. The right treatment and disposal of materials at the end of life can significantly reduce the construction sector’s environmental footprint.

There are several approaches to better manage materials from demolition of buildings:

Urban mining – the process of recovering and reusing a city’s materials – can offer a viable solution to improve waste management in the construction sector. The aim is also to increase the value of waste, so that recovered materials can be used in applications similar to those for which they were originally designed.

Using the recovered materials for new building projects has environmental advantages. By keeping the materials in the city/district, long supply chains can be prevented and emissions thereby reduced. Urban mining also limits the demand for new building materials, which in turn reduces greenhouse gas emissions.

Building phases (BAMB project) [6]

Urban mining can be facilitated by the use of material passports, which offer information about the types of materials present in a building. Material passports were successfully piloted in BAMB, where material passports where used in designing and constructing a new office building [11]. The use of innovative technology-enabled solutions can further facilitate the recovery of used materials, such as the BIM-based “smart pre-demolition audits and waste management” tested in the HISER project [13].

In addition, designing buildings for deconstruction and reuse allows better access to materials at the end-of-life of a component or a building. Design for de-construction or disassembly (i.e., a reverse construction process) allows the building to be de-constructed as much as possible, without damaging the remaining functional parts and components [BAMB]. This increases potential for renovation and reduces landfill waste [Houseful]. The design should allow simple disassembly and preferably avoid multiple types of structural systems [12]. In designing for reuse, a BIM (Building Information Model) can be a useful digital tool to store the information for the lifecycle of the building. For instance, the design for re-use was piloted in BAMB and in Houseful.

Life cycle of building [5]

Lease contracts and buy-back agreements for materials encourage recycling and re-use of materials. Suppliers conclude a contract with the buyers, committing to eventually buy back the product. The benefit for buyers lies in overall reduced prices; for the suppliers, the material flow for recycling is guaranteed. The lease contracts are still in early piloting phase.

MATURITY:

Examples of solutions that are already available:

Cradle-to-Cradle® certified products were used in Venlo City Hall in the Netherlands. The lease contracts and buy-back agreements with suppliers were typically 15-25% of the original prices, for office furniture and indoor finishing. Overall, a 10% residual value was estimated for the building in 40 years and the bank has reduced mortgage interest accordingly [BAMB][7].
In a hospital renovation in Sweden, the use of circular materials increased the costs of only 0.33%, compared to the investment that would have been necessary if non-circular materials were used. Additionally, the maintenance costs are estimated to be lower [BAMB].

Demonstration stage:

The demonstrated dismantling process includes the selection of safety procedures for disassembly and reuse of non-hazardous materials in construction elements, aiming to achieve a potential reduction of 30% in CDW (Construction and Demolition Waste) currently produced during building dismantling/demolition [Houseful].
Different renovation options were demonstrated in 4RinEU. A cost-effectiveness rating system explains the level of risks and failures in the renovation chain, allowing different stakeholders (e.g. investors) to evaluate risk of investment, responsibilities, achievable performance results and relative uncertainty, as well as related costs. The aim is to decrease primary energy consumption by 60-70% [8].
Following a demonstration in London, CIRCUIT produced a guide for sourcing the reclaimed construction materials, helping to use the reclaimed materials in new construction developments. The guide was produced with project partners to help practitioners in the real-life projects [9].

Pre-conditions

Technical aspects/infrastructure:

Technical knowledge on the correct recovery of materials in end-of-life buildings.
Data management of the materials, e.g. through BIM and online registers. Data platforms provide a useful tool, as well as the material bank approach used in BAMB. Similarly, CIRCUIT provided a guide to locate reclaimed materials [10].

Policy and legal/regulatory framework:

End-of-waste legislation: EU [14] and national legislation needs to allow and enable material recycling and reuse in new buildings and renovation projects. Particularly important are National and Regional Waste Management Plans establishing prevention, reutilization, recycling and recovery of C&D waste [HISER] [15]. Guidance and regulation should clearly state what material properties need to be tested before reused materials are employed in new buildings. However, this process should not be too time consuming or costly in order to speed up the recycling of materials.

Enabling conditions

Funding and Financing:

Securing funding for the set-up of enabling platforms (e.g. Building Information Modelling, material banks) can increase and speed up the process of using waste materials.
Incentives for material recovery/recycling and disincentives for waste production [15], e.g. subsides supporting new actors who are creating recycling solutions for construction sites and material logistics and taxes for waste materials or new materials.

Project governance and implementation modalities:

Building owners and investors play an important role, since they set the requirements for renovations or for new buildings. Therefore, awareness campaigns are needed to increase the take-up of the recycling practices in end-of-life buildings and promote materials reuse in renovations or new constructions.
Engaging stakeholders in the development of new solutions and approaches is crucial, as it allows to adapt the solution to local needs but also to ensure take-up and circulation of good-practices even after the end of the project. For instance, models involving the use of digital tools and platforms (e.g. BIM, online registers) [FISSAC] [HISER] often require a critical mass of users to be effective.

Technical aspects/infrastructure [4]:

Lack of availability of used materials on local markets results in long-distance transportation, increasing costs and environmental impact significantly.
Increased time needed for deconstruction and careful packing of reusable items can cause additional costs and be a disincentive; problems can arise also in relation to expiration of planning permits.
Lack of local facilities for material stocks storage would require resorting to long-distance supply of used/recycled materials, increasing transportation costs as well as the environmental footprint, and making the solution less attractive.
Health and safety risks of manual deconstruction compared to mechanical demolition techniques
Consolidated building methods and technologies can cause challenges in further reuse, e.g. cement mortar used in brick and block construction.
Low or negative incentive in reuse of low value/cheap products and materials.
Lack of skills, among C&D waste practitioners, on sorting and recovery processes [15].

Funding and financing:

There are not enough incentives to recover materials from buildings and not produce waste [15], as the costs of producing material waste is still rather low. The challenge could be addressed through the adoption of appropriate financial and fiscal tools.

Policy and legal/regulatory framework:

EU Waste Framework Directive [15] and related national legislations on end-of-waste criteria (i.e. when waste ceases to be waste and becomes a secondary raw material) [14]. There is a general lack of support in national and regional legislations, as well as lack of standardisation, and restrictions on use of recycled materials [15].
Quality certifications of recycled materials [15].
Time constraints linked to planning permissions expiration [4].

Economic and social context:

Due to lack of knowledge and awareness, there is reluctance to use products without certification of tested performance (especially in terms of structural capacity), which hinders reuse of building materials; submitting the materials to testing would entail additional costs, making it disadvantageous [4].

Examples

CIRCUIT (Circular Construction in Regenerative Cities) aims to create a value chain that will allow cities to become fully smart, eco-friendly, regenerative, and circular. Demonstrations are located in Copenhagen, Hamburg, the Helsinki region, and London. Two demonstrations will reuse building elements, interior or exterior components such as windows, wooden parts or bricks. Two other demonstrations will recycle building materials such as concrete or gypsum in a new building. Partners will expand and automate the calculation of embodied energy and resource use in existing buildings by carrying out life-cycle assessments (LCAs) and cost analyses on demonstrations. This will include validating the recyclability of a new construction (and its components) and the integration of the reuse of components and recycled building materials into the Level(s) certification system (Horizon 2020, 2019-2023).

4RinEU (Robust and Reliable technology concepts and business models for triggering deep Renovation of Residential buildings in EU) managed different stages of the deep renovation process – from the preliminary audit, up to the end-of-life – and provides information on energy, comfort, users’ impact, and investment performance. One part of the project resulted in guidelines and technology for managing buildings’ end of life. The demonstrations were located in Norway, Netherlands, Spain and Italy (Horizon 2020, 2016-2021).

HISER (Holistic Innovative Solutions for an Efficient Recycling and Recovery of Valuable Raw Materials from Complex Construction and Demolition Waste) aimed to develop and demonstrate novel cost-effective technological and non-technological holistic solutions for a higher recovery of raw materials from complex construction and demolition waste (C&DW). It considered circular economy approaches throughout the building value chain (from the end-of-life of buildings to new buildings). The following solutions were demonstrated: (1) harmonized procedures complemented with an intelligent tool and a supply chain tracking system, for sorting at source; (2) advanced sorting and recycling technologies; and (3) development of optimized building products. The project has five case studies (Horizon 2020, 2915-2019).

BAMB (Buildings as material banks) aimed to create solutions to increase the value of building materials. Dynamically and flexibly designed buildings can be incorporated into a circular economy – where materials in buildings sustain their value, leadingto waste reduction and the use of fewer virgin resources. The project implemented the principles of the waste hierarchy: the prevention of waste, its recycling and reuse. To improve the value of materials used in buildings and allow easy recovery, the project developed and integrated two complementary value adding frameworks:(1) materials passports and (2) reversible building design (Horizon 2020, 2015-2019).

FISSAC (Fostering industrial symbiosis for a sustainable resource intensive industry across the extended construction value chain) project partners manufactured innovative eco-cement and concrete, ceramic wall tiles, and rubber-wood-polymer composites for decking, cladding and fencing – all at industrial scale. These products utilised different types of second raw materials and techniques based on eco-design concepts that include life cycle considerations from procurement, manufacturing, and use to disposal. The project has four pre-industrial scale demonstrations and five real scale demonstrations. (Horizon 2020, 2015-2020).

Houseful focuses on local building materials and their circular use in housing. The aim is for the solution provider to guarantee the waste streams. The main principle followed is Design for Disassembly, by using simple and modular building structures. The project has four demonstrations, two in Spain and two in Austria. (Horizon 2020, 2018-2022).

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