Circular construction

• Use existing building stock when possible.
• Minimise energy and resource (material) consumption.
• Extend the life of products through, for instance, proper maintenance, repairs, and renovations.
• Design new products so that they are durable but also can be easily repaired and, eventually, reused.
• Avoid multi-material items that are more difficult to recycle.
• Avoid harmful substances.
• Use as many materials and elements that can be reused as possible.
• Improve processes and products continuously.

To be able to talk about circular construction, it is necessary to develop a definition of a circular building, especially since there is no such definition in the current state of the law. It is why the following definition was created:

A circular building is a building that, throughout its life cycle, does not deplete the Earth’s non-renewable resources and does not degrade the ecosystem.

To achieve this, the building should:

• be designed, operated, and dismantled following the above principle;
• be made entirely of materials that were already in use;
• be energy efficient in the construction and use phases, and be based on renewable energy that does not deplete the Earth’s non-renewable resources over its entire life cycle;
• minimise waste generation during the construction and use phases;
• allow for its flexible use and expansion;
• allow its reuse in whole, in parts, or as individual materials.

Constructing a 100% circular building is very difficult and downright impossible with the current state of the construction sector. Nevertheless, the goals set out in the above definition, which should be pursued, should guide the actions taken throughout the building’s life cycle.

Adaptability is the ability to easily modify a building or part of it throughout its life cycle, depending on changing needs and future circumstances, without requiring major construction work. It is necessary to accommodate changes in the type of use, demographics, and user needs or because of the need to adapt to external factors such as climate change. Over time, users’ needs may also change regarding their physical capacity limitations associated with advancing age. In the case of residential buildings, adaptability features can allow users to adjust their dwellings to meet their needs as they change with age.

The ISO 20887 standard provides an overview of design for disassembly and adaptability principles and strategies for integrating these into the design.

General design principles for adaptability are:

• versatility (floor space having multiple uses throughout the day, week, or month without requiring changes to the building’s design, for instance, space with a width of doors and no thresholds enabling to manoeuvre a wheelchair);
• convertibility (floor space designed so that it can be easily repurposed, e.g., an office building can be designed and built so that it is possible to convert it into a residential building in the future);
• expandability (the ability to add additional floors or floor space without significant changes to the building structure).

The design of the building should also take into account elements and components that can be easily disassembled and reused in the future. According to the ISO 20887 standard, the general principles of design-for-disassembly are:

• ease of access to components and services (easily (with minimal damage) approachable material/elements/connectors, especially those with shorter anticipated lifetime, and exposed connections with room left on all sides to enable disassembly);
• independence (ability to remove/upgrade elements/connectors/modules/systems without negatively affecting the connected and adjacent systems through designing a building in layers standing independently, for instance, following the Brand’s Theory of Layers^[5]);
• avoidance of unnecessary treatments and finishes, which might hinder future reuse or recycling;
• supporting reuse (circular economy) business models by adapting circular solutions wherever possible;
• simplicity (elements/connectors/modules/systems designed to be straightforward with the reduced number of subcomponents materials to the minimum required to execute the intended function);
• standardisation (using elements/connectors/modules/systems with standardised dimensions, components, connection types, and modularised);
• safety of disassembly.

• reducing consumption of materials/elements by optimising their delivery (thus avoiding over-ordering) and sourcing them from local suppliers (thus avoiding long-distance transport);
• reducing consumption of materials/elements and waste generation (off-cuts) by cooperating with manufacturers supplying ready-for-assembly products to the desired size;
• properly sorting construction waste;
• actively cooperating with design teams to provide hands-on knowledge on circular solutions within the construction stage.

• performing selective demolition, properly separating and segregating waste into reusable and recyclable.

• increasing the share of secondary and sustainable materials in the design;
• including design-for-disassembly and design-for-adaptability aspects in the project;
• cooperating with contractors and manufacturers to form multi-disciplinary teams working on the most efficient ways of including circular solutions in the design;
• cooperating with the project owner/investor to spread knowledge on circular solutions and their positive environmental and social aspects.

• providing important support in managing risks to reconcile security requirements with sustainability.

• creating new, more durable, easier-to-repair products from secondary materials as much as possible.

• creating regulations enhancing circular construction;
• creating appropriate rules to include circular solutions relevant to public procurement.

• properly maintaining the building and its elements.

The documents providing transparent information on the environmental characteristics of manufactured construction materials and elements are crucial in circular construction. The Type III Environmental Product Declaration (EPD) is a good example of such a document. EPD is not a typical certificate but a testimony to the environmental impact of a product throughout its life cycle, i.e., from the sourcing of materials, through the production stage, transportation, assembly, and use, ending with disposal and recycling.

EPDs are prepared following relevant standards, i.e., ISO 14040/14044, ISO 14025, EN 15804, or ISO 21930, and are usually issued for five years from the date of preparation.

The practical use of EN 15804 for environmental declarations has shown that EPD issuing bodies in Europe interpret many areas in the standard differently, often within the selection of appropriate data, data quality and availability, methodological details and assumptions, use scenarios, handling of Module D (recycling), or exclusions of certain life cycle stages^[[i]]. The ECO-Platform association was formed in response to these issues, bringing together EPD issuing bodies for European construction products and ensuring a unified interpretation of EN 15804 and its harmonised implementation into national practices.

Currently, valid EPDs vary in terms of their scope. Some contain information only on the product phase (A1-A3 according to the LCA method), while in the context of circularity, product information in phases C and D, related to the end of product life, is relevant.

In BREEAM, the most premium is given to the efficient use of materials throughout the life cycle. As part of this, measures to minimise the use of materials, increase the proportion of reused materials, and use materials with higher recycled content are evaluated.

The certification also evaluates the durability of materials found in exposed building components, intending to reduce the frequency of their replacement and thus reduce material consumption. Therefore, appropriate protective measures must be taken to prevent damage to internal and external building elements.

Additionally, the possibility of functional adaptation of the building is also taken into account through the use of solutions proposed in the criteria, such as systems that facilitate the replacement of major installations, modular construction, and the possibility of expanding the building vertically or horizontally.

DGNB certification has introduced a bonus point system for circular measures within selected areas. Additional points can be earned for reusing building materials or using recycled materials, reducing waste, minimising material inputs, and increasing building shareability and intensity of its use. Bonuses can also be received for improving the environmental performance of heavily contaminated land and implementing systems that allow using greywater and rainwater. In addition, the certification assesses the consideration of building adaptation in the context of structural modifications during use, as well as the origin of materials certified with the appropriate certificates and responsible planning for the dismantling of the building at the end of its life, which should be taken into account already at the design stage, along with the selection of building materials.

DGNB certification can be considered one of the most advanced systems in the context of the implementation of circular economy objectives.

LEED certification also features assessment areas that fit the circular economy concept and a premium point system for implementing measures in this direction. One of the prerequisites to be met is preparing a waste management plan (including construction and demolition waste) to monitor waste reduction and increase recycling or reuse. In this regard, premium points can be earned for reducing the generation of construction waste to a maximum of 50 kg/m²  of building floor area and increasing the recovery of materials from construction waste to a minimum of 50% or 75%.

LEED certification also places a premium on reusing historic or abandoned buildings in case of renovating a minimum of 50% of their floor area. Additional points can also be earned for reusing building components.

Last but not least, the LEED system enhances using environmentally certified materials or those with information on their source, such as C2C or EPD Type III certification.