Housing Overcrowding: Relationships and Challenges in the Contemporary Era

1. Introduction

In the contemporary era, the gap between housing supply and demand within the city is becoming more accentuated. Apart from the issues that have always affected the urbanised territories, sociodemographic changes, as well as the diversification of lifestyles, have been added, leading to a demand for more varied and diversified housing solutions [1]; and the recent economic challenges have substantially changed the world of work by introducing different times and ways of working from the recent past. Studies conducted by the World Bank [2] have highlighted that about 55% of the world population resides in urban settlements and this percentage is destined to sharply increase by 2030 due to the continuous urbanisation that is taking place especially in countries with emerging economies [3].

Excluding instances connected to slums and informal settlements, the search for an adequate home within the city is usually difficult for a high number of people with both low and higher income. This is a general issue all around Europe, although it is found that among the existing buildings in an urban area, the residential ones are significantly prevalent. Out of around 131 million buildings in the countries members of the EU, 119 million are used as residential buildings, especially in the urban centres (43%) and in small conurbations (33%) [3].

It is undoubted that the residential construction industry is a determining and driving factor for the social and economic well-being of a country, but despite this, the ways and methods to determine the adequateness of housing are not based on uniform indicators and, even when present, they differ in each national context. It is a consolidated fact that at a European level, residential construction has to respond to new requirements and completely different needs from the recent past; and it is also recognised that the perception of the quality of housing varies significantly depending on specific characteristics of the occupiers such as employment, education, and gender [4]. Various factors are added to these requirements, among which the increase of the average life expectation of the population with subsequent functional limitations of the residents, new social needs due both to the demographic changes and the social changes of family relationships (an increase of separated couples and people living alone); contemporary work settings (the COVID-19 pandemic has facilitated the adoption of remote working, which has become a stable setting used by companies) which require an increasingly flexible job in time and space. Lastly, but no less important, part of the assessment criteria are all the conditions and modifications that allow the development of energetic performances for the reduction of CO₂ emissions in response to climate change [5, 6]. All these mechanisms, although known in each country, are not actually quantified and involve high heterogeneousness, which is often based on large-scale data without a global standard and a coherent base framework that allows the comparison between countries. The various global organisations, UN, UN-Habitat, and UNDESA [7], consider wider projections, which include the assessment of populations who live in extreme poverty (slums and informal settlements). Therefore, it is probable that the data referring to exclusively urban settlements perhaps underestimates the number of inhabitants and the living conditions in the cities for those who do not have access to a decent home [2].

At the European level, the issue has been taken into consideration by the World Health Organisation (WHO), which has introduced some parameters in the assessment of the quality of housing, connecting and relating age, gender, family relationship, and the living area. This way it has been possible to introduce the concept of sufficient available domestic space as a fundamental aspect in the assessment of the quality of the housing [8]. The availability of domestic space has been identified as space that needs to be sufficiently wide in order to comfortably house people of different ages, guarantee sufficient space to meet the needs of privacy of the occupiers, and that has to be accessible and usable by external users [9]. This new perspective has radically changed the view of housing from a fundamental human need for shelter to a place that must guarantee the physical and psychological well-being of the residents [8]. Several authors have examined various aspects of the quality of affordable housing in different countries, however the discussion on the housing standards [8, 10, 11, 12] and the organisation of the domestic space, as well as the supporting and/or shared spaces of the housing is still rather open and leaves room for considerations and research [13, 14]. The search for relationships of available space in a house and the influences on the daily lives of the residents is not a mere sociological problem but involves several fields and disciplines. If for example a reflection is made between the relationship that exists between the private and public space of the dwelling, it can be noted how the same rooms, considered as spaces devoted to privacy which offer personal refuge for study, work, relaxing and free time, assume a different value in relation to whom they are destined to (functions can vary depending on age and role in the family, i.e. parent, child or cohabitant). If these private spaces are essential for the individual well-being, so are the communal spaces such as the living room and the kitchen, which also allow people external to the family to socialise, creating at the same time opportunities for family interactions. Therefore, the correct proportion and relation between these spaces can create and facilitate a harmonious balance between moments of privacy and those of socialisation, improving the quality of domestic life [15, 16].

In addition to all this, there is the matter of the global carbon footprint, as the construction sector is one of the main contributors [17]. The construction sector is responsible for a third of the global CO₂ emissions, and this value stems from the energy of the production processes (around 8%), the electricity and heat consumption (about 18%), and also from other processes quantified in a further 7% of the total emissions. Therefore, the construction sector appears to be highly energy-consuming when considering both the energy spent in the operating phase of the building and the energy employed in the phase of production of the building structures. If, on the one hand, the recent norms imposing the adoption of standards of low energy consumption have facilitated a slight reduction in the consumption during the production phase, on the other, an increasing demand for energy consumption is recorded during the operating phase of the building (about 1%), which highlights the necessity of an increasing demand for functional use of the buildings.

Focusing on the case of Italy, it can be noted that residential buildings contribute significantly to national energy consumption. It is estimated that the construction sector in Italy represents about 40% of the total, while 36% of the emissions are related to the existing buildings. These circumstances are determined by the phenomenon of the great reconstruction post-World War, which led to massive construction, with around 60% of the current building stock constructed before the 1970s, prior to the implementation of critical legislation addressing seismic performance and energy consumption reduction [18]. This reconstruction represented one of the largest investments in public housing, in terms of square metres built, and profoundly shaped the majority of residential buildings, particularly public housing in the outskirts of Italian cities. This model is currently undergoing a profound crisis and re-evaluation, driven not only by urban planning considerations but also, more importantly, by construction techniques and typological-functional issues related to the organisation and usability of living spaces, including per capita dwelling area and the functional distribution of housing layouts [19]. This severe crisis, determined by the lack of alignment between the requirements of the occupiers and the performance of the buildings, poses several challenges and actions. Starting from a general inadequateness of living conditions and energy insufficiency to scarce if not absent maintenance accompanied by obsolete services, these all represent unsatisfactory living conditions with subsequent lower quality of living [20].

In 2008, analysing the matter of public residences, Di Biagi [21] stated that the great reconstruction post-World War allowed 9–15% of the population to dwell in public popular housing. About 2.2 million inhabitants were housed in about 840,000 apartments of public economical housing. But what were the characteristics of these dwellings? Overall, it can be stated that the housing that took shape was founded on two important principles: on the one hand, it was the scene for the first rational experiments rooted in Alexander Klein’s existenzminimum [22]; on the other, it had to respond to specific demographic demand of the time which saw the family mainly composed of numerous households and the union of several families within the same dwelling (it was common to have the coexistence of elderly parents and related children with their own family) [23]. It was a period of great experimentation and research on housing. Therefore, there were two coexisting souls: on the one hand the search for rationality and optimisation of the domestic spaces, which aimed at creating minimal and standard surfaces to satisfy the needs of the new users; on the other hand, almost in contrast, the prevalent necessity to create apartments for numerous/complex families. The result of this combination led to the creation of large-size apartments structured with a high number of bedrooms and often equipped with minimal living areas and accessory services. Often, the hygienic services were inadequate and insufficient for the resident family [22]. In any case, this approach has led to the definition of standardised rules and housing modules, which could be replicated and applied on a large scale in the Italian territory regardless of the geographical position and needs [24].

In light of what was expressed above, the typological transformation of housing, the energetic requalification, and the adjustment to the restrictive structural norms of economical and popular construction currently represent one of the most interesting and complex challenges in the housing theme. Together with the need to improve the architectural and environmental quality (appropriate ventilation of the spaces, correct balance of the winter and summer temperatures) of the housing/domestic space, there is also the matter of reducing the average surface of the dwellings in order to balance the housing density in relation to the existing buildings. Lastly, an additional focus is the slowdown of the Italian demographic dynamics, which has seen a substantial change in the model and number of components per family, and therefore per dwelling [25].

With these premises, this short essay examines the matter of public residential and social construction under a new interpretation relating to the new housing discomforts/needs of the population. The investigation is developed through different levels of analysis and constitutes the basis for an alternative research approach on the theme of housing. It aims to widen the scope towards different perspectives, which is useful for redefining formal technical and functional models with a holistic and more resilient approach.

2. The crisis of the house system and the domestic space

The housing deprivation operates simultaneously on several levels, subdivided into three specific categories of fragility: the family, the housing space, and the urban context. In most cases, the operations aimed at facilitating the accessibility to housing focus on specific vulnerable groups of families or the adoption of functional, typological, technical, or technological solutions regardless of the specific problem.

The housing unease characterised by the highest economic instability and rapid transformation of the structure of traditional families towards new organisational models brings interesting considerations (Figure 1) [19].

Families, in their diverse compositions, often reside in housing developments that do not always support their growth or that of the communities to which they belong. In the specific context of Italian public housing, access to housing (long-term rental) grants a stable and enduring right of occupancy [26]. However, this arrangement presents two significant challenges. First, the urban setting is typically assigned rather than chosen, limiting residents’ ability to select their environment. Second, the size of the dwelling remains fixed regardless of the family’s life cycle, failing to adapt to the natural changes a family undergoes. As economically disadvantaged families are unlikely to move to a different home when their needs change, they often experience inadequate living space for a significant portion of their life cycle. In this regard, it is important to make some considerations about the evolution of the households. The rise of two different family compositions can be seen almost in parallel: the traditional families, which have seen a substantial reduction in the number of components [27, 28]; and the new family groups with various composition.

Analysing the lifecycle of a traditional family, these phases can be observed on average: the first new family is formed (single person, young couple, etc.); the family becomes more structured (birth of children) and the needs of the individual members of the family grow (the children grow and new activities and uses of the housing space appear): ageing phase (adult children leave the house) with the increase of specific needs (social, economic, of housing space) [19].

The formation of new households in Italy stems from the demographic and economic changes in the population. Among the factors that have mostly affected the change of composition of the family is the change in working conditions of women; the reduction of the “fertility rate”, that is, the number of children per woman; the increase in educational attainment, which brings to a prolonged permanence of the children within the household; the reduction of marriages and the increase in separations and divorces, which also brings about the increase of single-parent families (women/men with children) and divorced parents (mostly single parents that house the children in their dwelling in turns) [29]. Therefore, the formation of the new households in Italy includes single parents with children, divorcees, and families composed of separated parents with children, which will be defined together as complex households.

These two different family compositions (traditional family and complex household) bring about new organisational models which require flexible and dynamic housing spaces that are able to adapt to the different needs of the members of the family. For example, single parents with children require spaces that allow both privacy and the supervision of the children, while separated parents with children may need additional rooms to house the children during the visits. The fluid and interconnected planning of the housing space becomes therefore essential to respond to these new family configurations, at the same time guaranteeing the quality of life and environmental sustainability.

With these considerations, it becomes crucial to introduce a housing quality index. In this regard, the WHO has addressed the issue by introducing an indicator of housing quality, identifying overcrowding as a key determinant. The overcrowding index quantifies whether the availability of space in relation to the residents is sufficient within the dwelling. There are several ways to measure it, such as the American Crowding Index (ACI), the People Per Room (PPR), the Canadian National Occupancy Standard (CNOS), the British Bedroom Standard (BBS), and the index of floor space per person. In Italy, the method of calculation adopted considers the ratio between the number of users and the main rooms of the dwelling, excluding corridors, toilets, and other living areas. However, there are no parameters to assess the underuse of the dwellings, making it hard to quantify the oversizing of the domestic space [29].

Therefore, the research has included a base of analysis in the field of the needs of families with particular reference to the Italian case. The terms of the research have included the family lifecycle and the evolution of the housing space with the objective of identifying the premises and the positions in relation to the crisis of the house space. For the study, the compositions of the (traditional and complex) families have been observed while they change during their lifecycle and therefore correlated to the corresponding housing needs. The method of comparison was based on two aspects: the classification of the Italian Istituto Nazionale di Statistica (ISTAT), which identifies the new households, and the World Health Organization (WHO) qualitative parameters of the housing well-being, which introduces a method for calculating the overcrowding index. The analysis of the needs of families has been therefore related, in the following paragraph, to the technical construction and formal control of the housing spaces in reference to the particular context of economic and popular housing of the city of Bari and, more specifically, to the Japigia quarter.

The objective of this essay is to highlight the necessity of rethinking the traditional technical and planning concepts, going towards flexible and dynamic housing spaces. It is fundamental to plan housing that can adapt to the different phases of the family lifecycle and the new organisational models, guaranteeing at the same time the quality of life and environmental sustainability.

Therefore, the following table summarises the various considerations made so far, indicating each time the need generated by a certain family condition and the related social, economic, or housing needs. The table, in particular, was produced using a parameter of calculation that was adopted by the Eurostat study [30]; we can recognise the conditions of overcrowding in relation to the bedrooms of the dwelling, identifying the following cases (Tables 1-3):

• one room for the household;

• one room per couple in the family;

• one room for every single person aged 18 or more;

• one room per pair of same-sex children between 12 and 17 years of age;

• one room for every single person aged 12 to 17 years of age not included in the previous categories;

• one room per pair of children under 12 years of age.

The table does not include the more specific cases of the complex and compound households since the situation becomes considerably convoluted and would require its own analysis.

Therefore, a widening gap can be noted between the static condition of the dwellings and the sometimes drastic changes in the needs of the families. This deviation depends on two specific physical components of the housing space: the dwelling itself, and its collocation in a specific urban context. For what regards the dwelling in particular, it can be noted that the deviation refers to its size, structure, the subdivision of the environmental units and the type of supporting services and technologies it contains. In the different phases of the lifecycle of a family that remains anchored to the same home, significant phenomena of under- or over-occupation of the living spaces can be observed. Expanding families and/or during their lifecycle enter a state of living distress, which is hard to remedy. This particularly happens in economic and popular housing [31].

The family compositions analysed so far and that form, in various ways, the most relevant corpus of urban families, undergo a substantial compression of the endogenous (connected to the characteristics of the flat) and exogenous housing well-being (connected to the choice of living in an unpleasant urban context but economically accessible), and lack a response to the individual, family, and social needs. This brings to a significantly lower quality of life as well as expectations of growth and future of a family, which can cause phenomena of urban spatial segregation [32, 33] and could have serious repercussions on the family sphere. All this completes and further clarifies a scenery in which many European countries including Italy register a progressive worsening of the conditions of “subjective well-being”, and a marked increase in the “risk of poverty” of an ever-growing number of urban families.

3. The crisis of the house system and the domestic space

At the end of the First World War (WWI), in Bari, there was a high demand for housing which could not be satisfied by the existing public and private buildings heritage. This was due to refugees, displaced people, and the population coming back into the city. The municipal administration and the relevant institutions implemented a series of temporary and emergency operations, which determined the birth and initial development of the peripheral quarters and, among those, the Japigia quarter. This way, from the late 1940s of the last century, a brisk transformation process began from a rural area into a settlement designed for emergency, and lacking overall planning. The Japigia quarter in Bari has recent origins in this historical context, and therefore it dates back to the spontaneous formation of small housing agglomerates. It was not until the first measures extended to the whole national territory that the creation of housing agglomerates with diversified construction typologies and techniques occurred, following a logic of higher quality both on the urban level and the building one. The measures in question belonged to the INA-Casa period and constituted an intense and significant time for the construction and reconstruction of important economic and popular buildings in the whole Nation [34].

The two 7-year INA-Casa programs initiated several popular quarters, such as San Paolo, Carbonara, Libertà, San Pasquale, and Japigia. It was the law n. 43 of 1949 to give start to the first operations in the Japigia quarter in an area of about 13 ha, with a construction impact of about 3000 lots over the total 7000 planned for the whole city. Popular buildings, in this first stage, were mainly erected in the newly-formed national institution for housing, set up in 1949, which had the duty of building low-cost housing for families with low income. This institution was flanked by the Public Building Society, set up in 1948, which notably contributed to the erection of popular housing, and realising in Bari around 3200 dwellings between 1948 and 1953 [35]. In the urban system logic indicated by the INA-Casa guidelines, this first settlement of popular housing was conceived as a small citadel. This was closed to the rest of the quarter through a first building layer which composed the external margin of the building quadrilateral and allowed the view through transversal visual axes of a complex internal organisation [36]. These first housings continued to be built in a simple and fast way, mirroring the “INA-Casa process guidelines,” and therefore, for the structures, the load-bearing masonry was mainly used with economical materials such as brick, tuff, and reinforced concrete. The ground floor was covered with reconstructed stone tiles, while traditional plaster was used for the remaining floors. The buildings (a total of about 2500 dwellings) were terraced isolated blocks with the same number of floors, four: a mezzanine floor and no more than three floors without lifts. Of reduced size and restricted by the rigid structural frame, the dwelling included a hall, a sufficiently spacious kitchen with a dining area, a living room, and a varied number of bedrooms, depending on the shape of the dwelling. Sometimes the shortage of housing led to these dwellings being shared by several households belonging to the same family group (married children with their family frequently lived under the same roof as their own parents).

The main shortcoming of these first buildings was the absence of technological systems such as heating, boiler, and lift. After this initial period, entirely subsidised by the State, the following construction periods were characterised by only 5–10% of the houses with investments from public initiatives, in the form of subsidised buildings.

This marked another passage that modified the setting of the new constructions and the settlement logic [37].

By the late 1950s and early 1960s, the Economic and Popular Housing Projects (PEEP) season started. These involved the realisation of different and quality popular housing compared to the previous, with dwellings of various kinds and sizes, which were able to respond to the housing needs of the distinct groups of population [38]. The PEEP of Japigia began in this new context, in 1962. This involved the erection of new popular buildings but also the reconstruction of some existing ones, and the realisation of public facilities such as schools, nursery schools, and places of worship, with the aim of improving the quality of life of the residents of the quarter. This stage was distinguished by the realisation of three different building complexes. The first was composed of 13 GesCal (Housing Management for Workers) buildings aimed at specific categories of workers (such as postal workers, railway workers, and police officers), and afterwards all taken over by privates.

The second public complex by PEEP was the residential complex named ex-ISESX Via Caldarola 28, currently known as “red houses.” The third public compartment to be designed was erected adjacently to the previous one (Red Houses) and constituted what is currently denominated Colour Houses. This last agglomerate was realised with a rational approach, a sequence of parallel lines, and low recognisability of the routes, accesses, and functional junctions. Therefore, the lack of formal research on the communal urban space, in contrast with the nearby INA-Casa projects (which still reflected on the formal value of the communal and semi-private urban space), determined little attention to the quality of the space open to the complex. This was often stretched, incomplete in its articulation, and, however, not recognised as a communal area by the residents until it became a non-urban place [21].

With the operations of the 1960s, the Japigia quarter became, after that of the San Paolo quarter, the biggest popular housing agglomerate of Bari, and the most strictly related to the heart of the city. Not less relevant, a new building philosophy started to identify the car as a determining element in the processes of urbanisation and definition of housing spaces. The new architectural and urban view saw the new paradigms of the urban form in the distancing of the buildings from the roads and the erection of long fences to circumscribe yards and condominium squares (for the parking), which aimed to guarantee autonomy and safety. If, at first, the idea of creating yards and gardens pertaining to single or groups of buildings was seen as an element of innovation and modernity, with time, this solution contributed to accelerating phenomena of degradation, abandonment, and isolation [37].

In the early 1970s, the municipal administration redirected some public financing towards the Japigia quarter, mainly allocating it to the restoration of some popular buildings and the construction of new ones. A new development plan for public housing policies was started, which determined the overflowing of the city from its natural boundaries. Here, a new type of urban vision took shape, which gave birth to the B2 compartment or Via Caldarola 45 zone.

The design of the area was entrusted to the architect V. Chiaia, and the engineers D. De Salvia and G. Fuzio. Two building types were used in the design of the plan: the 5- and 7-storey terraced house and the 9-storey tower house. The choice responded to the intention to attempt a standardisation and industrialisation of the construction elements from the orthogonal arrangement of the buildings and the road network. In all effect, it was an enormous high-density residential quarter. Its construction, which started in 1972, already in 1975 included 18 buildings and a total of 1200 dwellings. At the beginning of the 1980s, after the construction phase of the district, the Via Caldarola 45 zone counted 2200 dwellings and about 10,000 residents with increasing social degradation.

The Via Caldarola 45 zone, and, more in general, this new expansion of Japigia, immediately took shape as a high-density residential area and composed the extreme eastern appendage of the Japigia quarter ending in correspondence of the Adriatic SS 16 BIS. The presence of the high-speed road (Via Caldarola) represented a limit with respect to the remaining part of the quarter, isolating and separating it from the context of private residential buildings [39].

3.1 Design and typology

A term of comparison among some of the most significant architects and planners of the 1970s and 1980s, the Via Caldarola 45 area saw the experimentation of building techniques that were innovative for the time and mostly focused on the experimentation of systems with prefabricated surfaces for the external vertical closure. One fundamental characteristic of this building phase was certainly connected to the typology of attachment to the ground. It was a real public experiment in which the free portico floor was introduced in Bari. Although it freed the ground floor of the buildings with the objective of imagining a new dimension of public space, such a condition actually rejected the idea of an urban podium in which commercial and service businesses could appear and rendered this area completely devoid of these functions.

For what regards the buildings, this area was conceived as and composed of several building cores, of a wide variety of typology and morphology, which articulated around a central space destined for public gardens and meeting areas. Composed and organised according to a free urban plan, the buildings were installed on pilotis systems, which aimed to facilitate a deep social and physical interaction between the residents and the wide open spaces. The building structures, organised in an L and C-pattern, exploited a non-repetitive orthogonal arrangement and formed clusters characterised by a sequence of alternatively open or semi-closed courts. With the clear aesthetic intention aimed at breaking the monotony of the whole complex, each of these clusters presents similar technical and architectural characteristics. Lastly, the 15 identifiable categories of cluster proposed diversified sizes of the dwelling surfaces with the specific idea of responding to the needs of differently-sized households (Figure 2).

3.2 Study cluster, street via G. Appulo house numbers 6 to 26

From this initial situation with a high residential density, the Via Caldarola 45 zone (currently almost exclusively occupied by the properties’ first assignees) has seen a gradual decrease in the density of residents. This is due both to the natural process of adult children leaving the original households and the current demographic situation, which sees increasingly smaller households, even in social classes with traditionally large families. For the case study, a cluster composed of a core of 11 buildings with the same constructive, functional, and typological distributional features has been taken into consideration. The buildings belong to the “terraced multi-storey” type (Figure 3), 7 buildings of which are 5-storey, and four buildings are 7-storey tall. The buildings are arranged in a C-shape, creating an open and public internal court, mainly dedicated to the parking area. All the buildings present the following characteristics:

• Partially closed buildings, with two external facades (nine buildings with north–south orientation and two buildings with east–west orientation) with alternating facades adjacent to the surrounding buildings.

• Stairwell and lift shaft located at the centre of the building and serving two flats per floor.

• Internal layout of the flats generally including a sleeping area and a living area, not always clearly divided, and not always sufficient and adequate hygienic services.

• Bearing structure with reinforced concrete casing, non-insulated external walls made of prefabricated panels with intermediate air cavity, and internal walls made of tuff.

• Non-insulating cover composed of a brick-concrete structure covered in concrete and bitumen waterproof finishing.

• Single-glass windows and aluminium structure without thermal break, with external shutters as covering.

The buildings include a total of 124 housing units which are currently occupied by 353 residents (Figures 4 and 5).

Important consideration: the term family will refer to variously aggregated family groups, that is, both the traditional kind and the complex one, as per the definition at the beginning of the paper.

The age groups have been divided in such a way that they can be combined with those with similar needs. The subdivision is not exhaustive of a complex matter; however, it represents a useful starting point to make a more specific reflection of the case study. Therefore, the subdivision presents the following age groups:

1. Youngsters with ages between:

   1. 0–5 years of age with no scholarisation, therefore there are few needs related to a space exclusively dedicated to the child;

   2. 6–18, age of mandatory schooling. This wide age group has different needs according to the specific period of time going from primary to secondary school. It was decided to consider it as a single category with needs related to a space dedicated to studies and more;

   3. 19–25, age group in which a university course or job hunting should begin;

   4. 26–30, age at which independent life and the search for autonomy should start.

2. Adults with ages between:

   1. 31–45 years old, formation of a family with the search for stable housing and job, a dynamic stage in the life of a young adult. In this stage, a demand for domestic space emerges, varying according to the components of the household;

   2. 46–67 years of age, second stage of the family and adults in which life begins to stabilise and invest in the growth of all the members, maximum need for space for the household.

3. Senior adults with ages between:

   1. 68–80 years of age, period in which presumably the children have left the household and there is a substantial reduction of the components and related needs of space;

   2. 81+ years of age, a period in which the family has been reduced and the stage of caregiving and support for the elderly begins. The domestic space is almost exclusively required for small households and the possibility of suitable manoeuvring areas.

The following graph shows that the two age groups most representative of the situation are the 26–30 young adults and the 46–67 adults, demonstrating the complexity of managing the domestic space (Figure 6).

If the data referred to the average age of the household components is added to these, it can be noted how the situation of underuse of the complex is bound to worsen since the population is generally ageing leading to a natural decline in the number of components of the household (Figure 7).

The distribution of the typologies of households in the complex is also not encouraging. The variability of the families within also prompts interesting reflections. For better clarity of the graph (Figure 8), it should be mentioned that the initials have the following meanings:

N = household.

Number = indicates the number of members of the household.

Letter = the type of family aggregation; if with this letter there is also a number, the sub-category of family aggregation is indicated.

It can be observed that the most recurring households are N2.C, N3.B, N1.A, N4.H, N1.B, that is, the ones composed of:

• Single-parent with child, N2.C

• Couples with one child, N3.B

• N1.A Single-person households in working age, N1.A

• N1.B Single-person households in retirement age, N1.B

• N4.H Complex households, that is, composed of several households, N4.H

However, compared with the average age of each household, this data highlights a substantially progressive reduction in family units and, consequently, in their members. Moreover, it can be noted that as the number of occupants increases, the complexity of the households also rises, while the available living space is neither designed nor structured to accommodate this. Lastly, the comparison between the expected and the actual residents, along with the variability in the living areas, clearly highlights a shortfall in the housing potential for an area conceived and built for high residential density (Figure 9).

In particular, a more detailed analysis of the data referring to the surface of the dwelling between 100 and 122 sqm, which is intended to accommodate a household of 5 to 7 occupants (including complex households that require additional space), reveals that in reality there is a prevalence of households with two occupants (variously articulated). This condition highlights a clear undersizing of the housing quota, and therefore an underutilisation of the living space (Figure 10).

A completely opposite situation can be found in the data referring to the dwelling with a surface between 53 and 69 sqm, intended for a household with two to three occupants (including complex households which require more space), which sees the prevalence of households with four occupants, variously articulated and often comprising complex households. This condition highlights a clear undersizing of the living space, resulting in problems of overcrowding (Figure 11).

4. Discussion and conclusion

It is widely recognised that the processes of planning, constructing and utilising residential housing require significant improvements. Currently, the scientific literature focuses on the more general theme of building stock redevelopment, particularly in terms of energy efficiency or restoration. However, studies addressing the quality and liveability of the residential spaces have only recently begun to gain prominence, following the parameters introduced by the WHO such as the housing overcrowding indicator [29]. The present paper contributes to the body of research on housing by documenting and evaluating a new approach to the refunctionalisation of living spaces and the holistic redevelopment of affordable and public housing. The method is based on a careful analysis of existing conditions, which establish connections between the housing users, their age, to the life needs and the quality indicators established by the WHO (housing overcrowding index) and, the characteristics of dwelling in which they reside including their spaces and functional domains. This approach, while applied to a specific case, is customisable and replicable in its methodology, allowing the analysis of the issue of overcrowding or underutilisation of housing and domestic space within “Affordable housing.” In fact, the proposed methodology facilitates a more direct relationship between the identified problem and the suggested solution, since it addresses the needs of the actual users of the housing rather than those of generalised groups of families. An examination of the existing literature reveals that, although studies and analyses often delve deeply into housing-related issues, they propose decontextualised solutions which fail to respond to specific needs. Such measures, broadly associated with initiatives introduced during the era of urban regeneration processes, have, in most cases, not achieved the expected outcomes due to their inability to adequately address the actual requirements of their beneficiaries [40, 41, 42]. This article advocates an innovative approach to evaluating potential actions for the redevelopment of residential living spaces, specifically through the transformation of existing public housing into social housing, using context-specific analyses tailored to the areas under consideration. The evaluation framework described in this paper is based on a set of indicators, including the number, age, and developmental stage of households or complex family units residing in individual apartments. This analysis is supplemented by an assessment of the dwelling areas, focusing on the organisation and composition of the living spaces in relation to the overcrowding index introduced by the WHO. The methodology enables a comparative evaluation of housing situations, informed by the type and configuration of each dwelling. When applied to multiple buildings with comparable characteristics, this approach facilitates the prioritisation of interventions, targeting those buildings where issues of over- or under-utilisation are more pronounced.

In the specific case study analysed, the findings highlight a priority for the typological and functional redevelopment of housing units, assessed through a detailed examination of residents, their needs, and the evolution of family life cycles. A particularly noteworthy observation is the frequent occurrence of complex households—often consisting of an elderly parent living with an adult child and their family—occupying larger housing units. While these households do not meet overcrowding criteria, their configuration supports social caregiving for the elderly. In such cases, the design and organisation of living spaces significantly impact the residents’ health and well-being [43]. From a technical-architectural perspective, there is a pressing need to rethink living spaces, emphasising key characteristics such as flexibility, adaptability, the design of furnishings, and the full usability and accessibility of spaces [44, 45]. The literature on interior design offers a wealth of insights and methodologies for the requalification of domestic spaces, often based on strategies that promote shared functions and multipurpose environments. These strategies include furniture and spatial solutions that enable versatile use of a single area [4]. However, such approaches have yet to find widespread implementation or experimental validation in real-world applications.

The transformation and redevelopment of large public housing complexes represent one of the most compelling frontiers and challenges in the field of housing. Only recently has scientific literature begun to introduce transformability indicators for large public residential settlements aimed at guiding investors in selecting and prioritising interventions [46]. The public housing sector faces numerous challenges, among which the typological redevelopment of domestic spaces is no less significant than energy retrofitting. However, the issue cannot be addressed solely through the downsizing of housing units, as the slowing of demographic trends has fundamentally altered family models, household compositions, and, importantly, the organisation of living spaces to accommodate diverse lifestyles. Determining the appropriate interior layout for a residence is a complex issue, and the solution does not lie merely in the size of the dwelling. The search for adequately sized housing tailored to users’ variable needs is hindered by the inherent temporal variability of those needs. Additionally, building regulations are often rigid and inflexible, disproportionately affecting low-income groups who lack the ability to easily relocate to more suitable housing.

One potential starting point is to move away from the traditional concept of a dwelling with fully autonomous functional spaces. Instead, some functions could be transformed into semi-public spaces, designed to be shared and/or adapted to specific cases. To ensure that residents’ “basic needs” are met, it would be advantageous to aggregate and modulate spaces and surfaces, envisioning a housing organism in continuous evolution. A useful starting parameter might be the classification of needs and their corresponding residential spaces based on the levels of privacy required for specific activities. This approach would transition from highly private spaces, requiring no sharing, to more public spaces characterised by high levels of shared use. Complementary to this would be the inclusion of residential spaces designed to support functional diversity, addressing the dynamic needs of a society undergoing profound transformation.

The added value of this work lies primarily in its analytical phase, while the operational phase is deferred to further research developments. From an analytical perspective, the study enhances typological research on housing evaluation, particularly regarding the potential for the transformability of individual dwellings and, more broadly, entire buildings. It offers a methodology grounded in a comprehensive analysis of existing conditions, enabling a thorough understanding and comparison of the current state of buildings. This approach facilitates the rebalancing of housing portfolio management and the prioritisation of interventions. Applying the proposed procedure to public residential building stock—where the necessary data for this methodology is available—could further refine the set of indicators employed. One of the primary limitations of the results presented is the equal weighting given to all considered indicators. Future research phases will involve assessing key differences in terms of the transformability of dwellings and buildings in relation to the variability of family life cycles. A potential indicator could incorporate appropriate weighting procedures, increasing community engagement in the planning and design of transformative regeneration solutions at both the building and dwelling scales.

Acknowledgments

My acknowledgements go to ARCA Puglia Centrale and to all those who made it possible to acquire the technical and documentary material that was indispensable for the development of this research and, in particular, to the President, lawyer De Nicolo Piero, arch. M. Ruta of the Technical Office and Dr. F Vincenti of the CED. Finally, I would like to thank the students M Pinto and F. Ricciardi for their data collection.

Conflict of interest

The authors declare no conflict of interest.