Keywords

1 Introduction

The construction sector adopts practices and application of constructive techniques that make excessive and ineffective use of natural resources, typical of the linear economy model. The sector is the largest consumer of raw materials in the world [1] and one of the major emitters of greenhouse gases (GHG) [2].

There is an urgent need to revise the way the built environment is produced since the linear model has been shown to be inefficient. As an alternative to reduce the impacts, a model that preserves the raw resources, maintains the materials in use as long as they can be, and seeks to reuse and recycle the components of a building is more in line with sustainable development, and the circular economy (CE) emerges as a possibility for this pathway to the construction sector.

The concept of urban mining asserts that cities contain the essential materials for your own renovation, and some authors consider buildings to be material banks. In this way, adaptations of existing buildings can reduce waste, preserve natural resources, and extend the life cycle of buildings [3]. Cities have a massive stock of existing buildings that do not match increasing changes in market demand [4]. European Union data show that 85% of the existing building stock (more than 220 million) was constructed before 2001 and the majority (between 85 and 95%) of the buildings standing today will remain in 2050 [5].

Most cities are composed of residential buildings, and they store most of the construction materials [6]. A dwelling is estimated to have an average lifespan of around 100 years [7]. During the housing’s life cycle, in the occupation and maintenance phase, modifications of various natures are requested. This is due to the dwelling meeting the basic needs of domestic activities according to the way of living of a person or household, which is dependent on the structure of values of a society. Therefore, as this structure changes, the needs and requirements for housing also change, generating the need for rehabilitation of its spaces [8].

A research verified, quantitatively, the construction and demolition waste (CDW) of three housing projects, considering the different stages of the building’s life cycle, and concluded that the amount of waste at the end of life is 40% greater than the materials used in construction, due to the replacement of materials and components during the building’s life [9]. These data show the importance of studying how the circular construction model can be applied to existing housing.

It is in the design phase that the main choices are made, and it includes circular decisions. This makes it possible to foresee some future scenarios for the buildings [10] and minimize or eliminate the need for using new materials [11]. Housing buildings are more susceptible than others to variables that require changes in spatial structure. Circular renovation can extend its useful lifespan, besides benefiting the surrounding area, such as economic and social development [7].

Some circular economy research focuses on design strategies, aiming to give concept professionals support in project decisions [12]. However, as the ideal is to apply the strategies in the early stages of designing a new building [12], it is not clear which parameters of the strategies apply when it comes to renovation projects.

This article aims to analyze how strategies can be applied in dwelling renovation projects. To achieve this purpose, the objective of this research is exploratory, for a better understanding of the subject, and carried out a bibliographic review, searching for publications about circular economy design strategies. In addition, the study uses a qualitative approach to provide context about the theme [13]. As a result, this study is expected to provide analysis that crosses data on the possibilities and characteristics of dwellings’ renovation and what is suggested by design strategies of ecodesign methodologies. This can guide future research directions, as long as it will contribute to implementing CE for enhancing sustainability in refurbishing existing buildings.

The paper is organized into 3 parts. The first is the introduction, the second explains the method adopted for a systematic literature review, and the last one discusses and reports the research results gathering the circular design strategies found in the literature studied, the characteristics of the dwellings, and circular design possibilities that can be applied in renovation projects.

2 Literature Review Methodology

To a comprehensive and critical overview of academic studies on CE strategies applied to renovation design, this study developed a systematic literature review. It leads to a better understanding of the subject and identifies research gaps and potential directions.

Aiming to answer the article’s question titled ‘how circular economy strategies can be implemented in the dwelling renovation design phase’, the literature review adopted a search (Fig. 5.1) with 6 steps: search terms, excluding duplicate articles, title analysis, abstract analysis, full-text analysis, and further research of relevant articles.

Fig. 5.1
A chart includes search terms, AND building AND refurbishment, AND building AND renovation, AND building AND existing, AND flexibility, AND adaptability, AND disassembly, and AND deconstruction. The total duplicates, title analysis, and abstract analysis are at the bottom.

Literature review process (review date: February 2023)

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Using the Scopus database, a search was made for articles published in the last 5 years (2018–2022), using relevant theme terms in the title, abstract, and keywords. The terms ‘circular economy’, ‘circular design’, ‘design for’, and ‘housing design’ were searched as phrases.

The terms ‘refurbishment’ and ‘renovation’ were chosen based on Shahi et al. [3] research which concluded that ‘renovation’ is defined as ‘the process of replacing or repairing outdated components or remodeling the interior spatial layout of existing buildings’, and this term is a subcategory of ‘refurbishment’, a wider definition that is ‘the process of improving the existing conditions of buildings and making improvements for the existing use’.

The 21 articles of the systematic literature review can be accessed through this link.

3 Results and Discussion

3.1 Circular Economy Strategies

To achieve circularity in building projects, the literature already provided numerous circular economy strategies, also known as ecodesign methodologies, besides tools, and frameworks to apply the strategies in the design phase and support decision-making [14]. The strategies differ in circularity objective and can focus for example on the circularity of the materials, aiming at the reuse and recycling of materials, the adaptability of the buildings, analyzing their capacity for spatial modification, or the components disassembly, avoiding the common end-of-life demolition solution.

Some researchers studied different ecodesign terminologies often used, related to the design stage, and found many terms employed to address the changing needs of users and external factors all over the building life cycle. There are several similarities in terms’ names and objectives, and this can be explained by the lack of standardization and interpretation of the terms, as reported by Munaro et al. [15], whose research presents the most distinct ecodesign terms. Table 5.1 shows the integration done in this research.

Table 5.1 Integration of CE strategies terms. Authors, adopted from [15]
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The terms can be summed up in two principal methods, Design for Adaptability and Design for Disassembly, to facilitate understanding and because they are considered in some studies as the main strategies to be adopted in design decisions [14, 16]. Both main methods encompass all the other strategies’ objectives.

It is essential to understand how these strategies are presented in practice to identify which strategies can be applied during the renovation design phase. This can be seen in Figs. 5.3 and 5.4, on the next topic, where some design solutions were identified for adaptability or disassembly purposes.

Design for Adaptability (DfA) aims to apply in buildings, design characteristics of flexibility, reconfiguration, or change of function, structure, space, components, systems, services, and size as a response to accommodate change throughout time and minimize demolition risk [12, 15].

Design for Disassembly (DfD) seeks to make a reversible building, instead of demolishing it, by planning in design, the possibility of disassembly of the elements, and the reuse or recycling of its parts [12].

The next section reports on the problem of the rigid layout configuration of the dwellings, the desires for modifications on the part of the inhabitants, and the possible design options for a renovation project identified in the studies.

3.2 Dwellings and the Renovation Projects

Dwelling spatial configuration models and their consequences. In the literature review, some studies examined dwelling characteristics and the relation between them and the market and its inhabitants. The configuration of housing spaces has a logic depending on the period and local culture. This can be better understood using for example, the space syntax method, developed by Hillier and Hanson [17], which evaluates spatial configurations and, when applied to dwellings, assesses meaningful information about architectural spaces, their relationship, and the connectivity between them. In general, the construction market follows a spatial configuration model and builds dwellings without flexibility possibility. Therefore, the inhabitants show dissatisfaction with the model imposed on them [18]. Griz et al. [8, 19] report incompatibility between market offers and inhabitants’ demands, causing modifications/customizations to be performed on the first resident as seen in Fig. 5.2. Gilani and Türker [20], in a survey with inhabitants, found that 64% of dwellers want to change space organizations, 62% the functions of interior spaces for functional flexibility and 54% want to change wall arrangements for privacy needs. Ollár et al. [18] report that the most frequent motivations for a renovation were dissatisfaction with the dwelling layout, a lack of workspace, insufficient floor area, obsolete furniture, or appliances, improve the appearance of the kitchen, and an increase or decrease in household size.

Fig. 5.2
Two models of the original project and the customized project. 1. It indicates QUARTO 01, QUARTO 02, QUARTO 03, three W C, varanda, estar, jantar, copa, cozinha, servico, and suite. 2. It indicates home theater, estar, social, servico, intimo, jantar, closet, home office, suite master, copa, and cozinha.

Example of the original project and the customization [19]

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Fig. 5.3
A chart includes the design strategies of Tarpio et al., 2022, Rabeneck et al., 1974, and Gilani and Turker, 2020. The strategies from Rabeneck et al. include the use of movable partitions.

Adaptability strategies possibilities for renovation projects

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Fig. 5.4
A chart of disassembly strategies includes strategies from Rabeneck et al., 1974, Dams et al., 2021, Gilani and Turker, 2020, van Stijn et al., 2022, Wouterszoon Jansen et al., 2022, and O’Grady et al., 2021.

Disassembly strategies possibilities for renovation projects [23–26]

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Le Corbusier in 1914, with the Domino system, showed to architects the possibility to separate the interior from the structure, with the ‘free floor plan’ strategy to achieve space flexibility. The De Stijl movement’s manifesto (1924) and Mies van der Rohe’s ideas (1926) also talk about adaptability in spaces and defend movable and non-supporting walls [21]. But many housings built before and after these modern concepts were designed to have a specific function, interior dimensions, and space organization, with rigid structures and non-movable dividing walls, and considered low possibilities of adapting spaces to contemporary and future requirements of environments [16, 20].

This raises the question of the role of a renovation in minimizing the impact of future modifications by different residents who will still reside in the place.

Design possibilities in renovation projects. The literature review revealed some circular design strategies for new buildings that are also applicable to renovation design, to enhance circularity, more specifically, properties of adaptability, flexibility, disassembly, and reversibility in the modified housing area.

These possibilities were recognized based on modifications characteristic of a renovation in a dwelling, such as changes in layout, which lead to demolition and construction of walls, kitchen and bathroom counter changes, furniture exchange, and a new heating/cooling system, among other services. Ollár et al. [18] report that in previous research from other authors, it is said that ‘the kitchen is one of the functions of the home, which is most often subject to renovations and adaptations’, and Stijn et al. [22] reports that domestic furniture and appliances account for 35% of building environmental impacts.

This section answers the article’s question of ‘how circular economy strategies can be implemented in the dwelling renovation design phase’. Figures 5.3 and 5.4 below show the circular design options for renovation projects, the reference where it was reported, and the relation to the specific principal strategy the design possibility belongs to.

As seen in the information presented above, there were just a few design options identified in studies that can also be applied to renovation projects, and many are common, such as modular kitchens and dry connections. It was noticed that minor-scale component modifications such as coatings, kitchen and bathroom pieces, lighting, and piping have minimal or no direction on how to be done, especially in renovation projects. Therefore, considering the literature reviewed, design decisions about other housing elements that are not addressed in the studies, are subject to the designer’s interpretation through the broad concepts of strategies.

Also, for a more sustainable renovation proposal, it is imperative to analyze the quality and impact of the materials used and the economic viability of choices through a life-cycle assessment analysis [12].

Several researchers report the importance of material choice, focusing on reused materials, bio-based materials, and recyclability possibilities [12]. For ‘Design for Disassembly’, it is also important that the material has a Material Passport to guide the path through reuse [11].

4 Conclusion

Through the literature review developed, and the definition of renovation given in Shahi et al. [3] research, this paper recognized design possibilities to be applied to renovation projects related to the principals’ circular strategies studied. However, there were difficulties in gathering this information, as it was verified a lack of definitions regarding the practical application of circular strategies by design professionals, and, in general, those possibilities were described as an example in studies texts and tables.

This shows an opportunity for future research to increase the discussion that focuses on developing documents capable of guiding the application of circular economy strategies in projects, both for new buildings and for renovation. The development of research that addresses the investigation of executed architectural renovation projects that aim to apply circular characteristics, and the analysis of assessments and tools, such as Level(s) from the European Union, and certification guides, like the ones from the Green Building Council, are important in the definition of strategies for renovation projects.

It is essential to broaden this discussion and focus on its applicability, so that there is greater harmony between the market and inhabitants, offering greater possibilities for spatial, aesthetic, and functional modifications from day one of the housing, without major environmental damage.