Those questions that are essential in the development of collective housing begin with Existenzminimum rationalist approaches typical of the interwar period and the later review and critique by the modernist movement. According to Mies van der Rohe’s conception in the Weissenhofsiedlung (1927), housing—understood as a unit of aggregation that determines the social fabric and urban development—constitutes an early experimentation into the definition of a habitat that can accommodate new ways of living. After periods of intense research and debate that share the critical exploration of the legacy of modernity, housing architecture has been reinterpreted in several ways depending on its social role, its condition as an open and flexible system, its relationship with the place, memory and history, and the idea of community.
These approaches are currently more intense and, in the light of developmental trends and requirements related to the international stage, the domestic habitat needs to address a complex network of factors that entail a need for new housing solutions. Their application is not only accepted in the planning of future projects, it is also necessary in order to combat the obsolescence of the existing housing stock, which sometimes might have historical-cultural or architectural values but its technological, functional or spatial shortcomings make it inadequate. Social circumstances (a falling birth rate, an ageing population, migration, new ways of living together and gender roles, modern working lives, post-Covid habits and routines, etc.) join questions related to well-being and the green transition (a healthy lifestyle, security, integration, accessibility, care for the environment, energy saving, etc.), driven by the United Nations in the context of Sustainable Development Goals (SDGs) to promote inclusive, resilient, safe and sustainable urban settlements.
The complexity of the factors that condition the habitat, with a specific focus on collective and accessible housing, grants it a new meaning. The architectural and urban planning spheres complement each other in a multidisciplinary way in historical, socio-economic, political, philosophical, anthropological and environmental aspects. In this sense, Amos Rapoport  argued in 1969 that purely functional or technical reasoning cannot explain housing typologies; instead, culture, social patterns and shared public preferences express themselves in domestic spaces. Therefore, an approach using these complementary perspectives favours the advance in new models that fulfil the needs, wants and concerns of human beings.
Martin Heidegger’s 1951 essay  Building Dwelling Thinking also shows, in an up-to-date manner, the phenomenological character of the inhabited space, where the idea of protection and identity becomes especially important. The habitat acquires the sense of protection of the human essence through an emotional connection with the space. In this search for a receptive architecture, the Smithsons  outlined a network or system that can trigger the senses and adapt to people’s interpretations and needs. A house, understood as a home, takes on meaning when the inhabitants intervene and read the space, making it partly theirs. It is therefore essential to be aware of the contemporary determining factors and recover the timeless values of human beings in order to design their environment and release appropriation mechanisms based on emotional values connected to the memory.
This issue of ZARCH proposes a perspective approach to aspects that represent a consideration of the habitat based on current and critical reflection in order to contribute to the debate about contemporary collective and accessible housing alternatives for a broad section of the general public according to the following points:
- Experiences, models and policies for access to housing that exemplify the new ways of the habitat, which are constantly evolving. The major challenges of the Green Deal, the aims of post-Covid recovery and the global energy crisis are involved, along with spatial, functional, organisational, technological, cultural, environmental, social, phenomenological and psychological aspects of housing and its context. This also includes the cross-scale relationship between the living unit and aggregation systems, which leads to the housing - building - neighbourhood sequence and defines the response to new public demand for connection and community life.
- Theoretical reflections and historical-critical reviews of relevant projects in the observation and questioning of modernist principles, which open up new avenues of research into emerging questions in the field of collective housing. The recovery of and support for key proposals and experiences regarding housing, fostering the recognition of historical value and the relevance of its contributions are useful to create new solutions that contribute to improve the quality of life of human beings.
- Typological analysis methodologies based on comparative, transcultural and graphic studies that consider conceptual diagrammatic representations, used by Serge Chermayeff, Christopher Alexander and John Habraken; functional experimentations addressed by Alexander Klein and Gio Ponti; spatial perspectives prepared by Paul Rudolph; hidden planimetries that shape lifestyles designed by Atelier Bow Wow, etc. In short, research works in which graphic representation is the means for the abstraction of the living space and the encrypted expression of the habitat.
- Strategies for the requalification, transformation and adaptation of residential stock built in historical urban areas and peripheral settings, focusing on both the recognition of their historical-cultural values, which the review process cannot ignore, and current practical and environmental sustainability concerns, needs and standards. Special attention is paid to models for the restoration of buildings and the urban regeneration of residential complexes through one-off or regional interventions that improve their resilience to changes in requirements and in the living model demanded by the public.