A Residential Building Extension Prototype to face Post-Pandemic Needs: Foreseen Challenges and Impacts

1.

Introduction

The importance of private outdoor spaces, such as terraces or balconies, increased during the COVID-19 pandemic due to the successive mandatory confinements decreed by government institutions [1]. As people spend more time at home, the value of having a safe and private outdoor area has increased, as it enables outdoor leisure activities and connection with nature and provides a sense of physical and mental escape [2, 3]. In addition, the lack of access to public outdoor spaces has resulted in a shift of certain outdoor activities to more secluded and private areas. As a result, the idea of a balcony or terrace has emerged as both a solution, allowing people to enjoy the outdoors, sunlight, and fresh air, and a challenge for designers who must now adapt their designs to meet the evolving needs of users [2]. Therefore, this issue demands new dimensional requirements and design adjustments in new or existing balconies or terraces, mainly in highly populated urban areas [4].

However, from the research team’s standpoint, the situation of multi-story residential buildings, where architecture did not address this kind of spaces (e.g., balconies, terraces, patios) is concerning and problematic, particularly in social housing buildings (Figure 1). As stated by D’Alessandro et al. [5] a survey performed in Italy by the Istituto Nazionale di Statistica (ISTAT) in 2018 indicate that 11.4% of the apartments, representing around 2,650,000 families, were lacking outdoor private spaces like balconies, terraces, or gardens at home. This lack of provision fails to ensure user access to private outdoor spaces and the related benefits.

On top of this, several studies state that the lack of balconies or poorly designed ones, coupled with inadequate urban spaces, played a role in the decline of the population’s physical and mental health during lockdown periods. Although the affected individuals came from diverse socio-cultural backgrounds and demographics [6–8], the impact was particularly severe on the most vulnerable segments of the population [5]. Other studies, such as Moreira and Farias, conducted during the first mandatory confinement in Portugal, show that 51.3% of respondents elected “outdoor space” at home as a priority when compared to other categories like “indoor habitable area”, “location”, or “layout”. The same authors highlight the change in perception towards the domestic space and establish a new paradigm in this domain [9].

Considering this, the research team’s understanding is that dwellings lacking private outdoor spaces represent social aberrations with detrimental consequences for their inhabitants, especially during times of stress and uncertainty. To address this issue, we intend to develop a research project (RP) that explores design solutions for extending living spaces outdoors in multi-story residential buildings built between 1961 and 2000. The target is buildings where private outdoor spaces do not exist, are restrictive, or display poor design quality (Figure 1). Nonetheless, we intend to push the private outdoor spaces concept far beyond a mere “home” extension, something which is widely available.

The RP’s main goal is to develop a physical and digital architectural prototype called “X-TEND”—a lightweight, modular, permeable, adjustable, and easily dismountable structure that can be seamlessly integrated into the façade(s) of existing buildings. This exoskeleton structure will become the main element of an energy retrofit operation turning the existing building into Near Zero Energy Building (NZEB) or Positive Energy Building (PEB).

The X-TEND prototype aims to be implemented worldwide. However, its initial stage will involve the development of pilot case studies in Lisbon and Warsaw. Due to the diverse socio-cultural, climatic, economic, and legal backgrounds in Portugal and Poland, we anticipate challenges related to its development, implementation, and context adaptability. These challenges must be addressed to ensure its applicability in other geographies.

The present paper aims to describe the conceptual and programmatic foundation of X-TEND prototype RP, which is currently ongoing, focusing on its foreseen challenges, limitations, and societal impacts. Hence, the content presented here is purely qualitative.

We anticipate that X-TEND prototype will have a positive impact on society by providing secure and private outdoor spatial solutions where they do not currently exist, with the potential to enhance users’ physical and mental well-being, improve user satisfaction, and ultimately contribute to a better overall quality of life.

We foresee the development of X-TEND prototype as a pre-emptive action against the threat of future pandemics and lockdowns while contributing to developing more resilient cities in the light of the “design to anticipate” principle by Godschalk [10]. In this context, the X-TEND conceptual foundation fits on Godschalk’s “enhancing physical systems” vector, involving the preparation of buildings and human communities to endure and function even under unusual or severe circumstances [10].

2.

Literature review

The act of designing solutions for extension of living space when it is restrictive or unqualified predates the pandemic period. We highlight the projects that transform and retrofit existing buildings developed by the Lacaton & Vassal studio (www.lacatonvassal.com): the Quartier du Grand Parc in Bordeaux; Saint-Nazaire in La Chesnaie and la Tour Bois le Prêtre in Paris. In these projects, the architects aimed to prevent the demolition of existing buildings by adopting an upgrading strategy extending them beyond their boundaries through the addition of a light and transparent element (a set of balconies). A trait of Lacaton & Vassal architecture is improving the dwelling spatial quality resorting to bioclimatic strategies aiming not only to improve the users’ visual and thermal comfort [11] but also to address today’s environmental requirements without ignoring social issues. For instance, the residents were allowed to stay during the construction works, and their projects often renovate the urban image of the neighbourhoods [12]. This works and their approach constitutes a source of inspiration for X-TEND projects. However, these projects lack the integration of renewable energy source (RES) technologies and, consequently, lack an environmental and energy assessment that would align these with the qualitative standards of NZEB and PEB.

Another related approach is the ProGETonE research project [13, 14], which aims to integrate a set of technologies into an exoskeleton that embrace a pre-existing building, with the primary goal of enhancing its seismic resistance. This project has successfully been implemented in pilot projects, demonstrating its potential

. Despite its high quality, ProGETonE is presented as an architecturally rigid solution and lacking environmental considerations regarding the bioclimatic suitability for a specific location or even the selection of applied materials, resorting mostly to metals.

On a smaller, one-off scale, the Bloomframe [15], and VELUX Roof Balcony [16] solutions enable the transformation of a “window” element into a “balcony” and vice versa. However, Bloomframe is technologically more complex, automated, and consequently, more expensive. Despite the quality of the construction and the customisation possibilities offered by these brands, they are solutions for specific and individualised applications that do not consider the environmental and energy dimensions that we foresee for X-TEND prototype.

During the pandemic in 2020 the STAYHÖME was launched by Spanish architect Luís Quintano [17]. It is a modular balcony solution which can be attached to the façade and adjusted to the dimensional requirements of users and their activities. It is a low-cost solution having a wide range of applicability; however, it is ephemeral as well, and does not include RES technologies, bioclimatic optimisation or even energy and environmental consideration.

Another point worth highlighting is that, except for ProGETonE, all the other solutions lack the digital dimension, as they are unable to operate and communicate between different Building Information Modelling (BIM) software. It is also not known how they contribute to increasing the building’s thermal and energy performance, and whether they have been designed with a cost-benefit logic. This is an aspect we address in the development and design of X-TEND prototype.

From an architect’s perspective, well-designed private outdoor spaces such as balconies/terraces can offer numerous benefits, including solar shading, ensuring privacy, preventing glare, providing acoustic insulation, enhancing indoor thermal comfort and ventilation, improving air quality, and decreasing energy consumption for both heating and cooling purposes [18]. Given that these spaces ease the transition between indoor and outdoor, they should be designed not only to enhance a building’s environmental performance but also to serve as multifunctional areas throughout the year [19]. Therefore, we must balance form, function, and composition, including their harmonious integration into the building façade [20]. The potential of these spaces to accommodate different functions defines them and makes them reprogrammable [21] not only for isolation but also for working, studying, playing, and exercising, highlighting its spatial and functional flexibility as witnessed during the lockdowns [22]. X-TEND prototype is envisioned to address all this concerns.

3.

Methodology

The RP’s methodology is qualitative due to its ongoing nature, and it aims to address the challenges, limitations, and societal impacts of the X-TEND prototype. The project’s intentions and goals are to extend living space outdoors, design user-friendly eco-spaces, update environmental conditions, and incorporate energy production to achieve NZEB/PEB standards.

The X-TEND prototype design is based on Lean-Agile Management (LAM), which allows the project core aspects to be implemented without strict waterfall model milestones [23]. Thanks to LAM, the RP is divided into six main phases, which will be adjusted while each subsequent phase is completed. Figure 2 presents the designed workflow and phases for the X-TEND prototype project. To promote the healthier lifestyle it is needed to design a cost-effective and environmentally sustainable structure. The RP incoporates the psychological and technological aspects of designing the final stage of the X-TEND. The main aspect of the methods used in the RP was to incorporate generative processes for structural and bioclimatic optimisation.

Since the X-TEND prototype RP revolves around community engagement it started with a comprehensive survey phase (questionnaires and observations) to determine societal priorities and needs in Lisbon and Warsaw regarding the current perception and significance of outdoor private spaces [24]. The questionnaires were conducted using Qualtrics software (to ease responsiveness) and subsequently analysed with SPSS software (a widely used program for statistical analysis in Social Sciences). Hence, the LAM method is used in this RP, and SPSS, one of the most comprehensive software was used, since it can handle large amounts of data and perform various analyses. The survey phase involved questionnaires and observations to gather data from the chosen community to analyse their main habits and needs. The representational community chosen for the survey enabled statistical analyses of how the balconies are used: the frequency, function, and how people design those spaces.

The second and third phases focus on refining the conceptual Idea and cross multidisciplinary optimisations based on structural, architectural, and environmental algorithms. These stages involve conducting optimisation studies in a parametric digital environment, applying the “Design–Analyse–Evaluate–Adapt” approach outlined by de Luca [25]. This is followed by evaluating the X-TEND’s energy generation potential through renewable energy systems and assessing its environmental and financial feasibility using Life Cycle Assessment (LCA) and Life Cycle Cost (LCC) analyses [26], respectively. Subsequently, a stabilised digital version of the prototype will be developed based on the insights gained from these evaluations and modifications. The X-TEND optimization tool will be developed using digital building models chosen to represent multi-story residential buildings in Lisbon and Warsaw constructed between 1961 and 2000. To implement X-TEND, designers need to provide a digital building model specifying architectural features such as the size and positioning of openings, building height, depth, shape, location, and solar orientation.

The fourth phase focuses on creating the physical and digital prototypes and assembling all the necessary construction technical documentation. This phase includes 3D printing of main nodes, fittings, and system components at scales of 1/1 and 1/2 to test and evaluate the design thoroughly. The digital prototype will be designed to be open-source and accessible to designers worldwide within a BIM ecosystem, utilising a 100% parametric tool. The aim is to achieve “ease of use” and enable automated generation of technical drawings, bills of quantities, and context-specific costs, leading to substantial time and cost savings.

The last two phases involve securing intellectual property protection for the X-TEND prototype through patenting its digital and physical format. This includes identifying potential challenges and obstacles, and seeking financial assistance for the patent application, submission, and ongoing maintenance processes. Finally, the last phase focuses on ongoing community engagement, presenting, discussing, and gathering feedback from residents to assess their receptivity to implementing the X-TEND prototype in their neighbourhoods.

The research design of the X-TEND prototype is comprehensive and multidisciplinary, involving community engagement, digital and physical prototyping, and environmental optimisation. The data collection methods are based on surveys analysed with SPSS, and the project follows a LAM approach to ensure adaptability and responsiveness to the needs identified during the research process.

4.

Results

5.

Discussion

6.

Conclusion

This study delves on the issue of inadequate or non-existent private outdoor spaces in multi-story residential buildings and its adverse effects, which became evident during the COVID-19 pandemic lockdowns. To address this issue and embrace the new paradigm in balcony design, we present a currently undergoing RP consisting of a balcony system prototype named “X-TEND”, which expands living spaces outdoors.

Grounded on a LAM approach, the X-TEND prototype RP envisions the development of both a physical and digital prototype, representing a lightweight, modular, permeable, adjustable, and easily dismountable exoskeletal structure that can be integrated into existing building façade(s). Apart from the extension of the living space, its primary objective is to serve as the cornerstone of an energy retrofit operation, transforming existing buildings into NZEBs or PEBSs, while simultaneously enhancing indoor environmental conditions. X-TEND prototype is grounded by a set of intentions and goals (Figure 4) and its potential extends beyond the architectural scope, inspiring interdisciplinary collaborations in fields such as transportation, urban planning, and renewable energy technologies.

The current RP will inevitably face a series of limitations and challenges. On the limitation side, we foresee the restricted scope of application, centred on multi-story residential buildings of up to 9 floors, and the narrow timeframe (1961–2000). On the challenges side, the most prominent are the compatibility between diverse design goals and intentions, material certification issues, funding constraints, and the complexities of construction and implementation of a structure of this scale.

From our perspective, the X-TEND prototype has the potential to impact the European housing landscape by addressing social housing issues and contributing to economic growth and post-pandemic recovery. Moreover, it aligns with six UN SDGs by incorporating sustainable design principles, aiming to reduce energy consumption, enhance indoor air quality and improve user comfort.

In summary, the X-TEND prototype represents a step forward towards the creation of more resilient and sustainable cities with the potential to improve living conditions and foster a sense of community among urban populations.

Acknowledgments

This work was supported by the FCT - Fundação para a Ciência e a Tecnologia, IP (grant UIDB/04008/2020); and CIAUD - Research Centre for Architecture, Urbanism and Design, Lisbon, Portugal (embryo project B4F_PTPL).

Declaration of Generative AI and AI-assisted technologies in the writing process

During the preparation of this work the authors used ChatGPT 3.5 in order to improve the writing process, namely, readability and language. After using this tool, the author reviewed and edited the content as needed and take full responsibility for the content of the publication.

Conflict of interest

The authors declare no conflict of interest.