The architectural design process encompasses innumerable possibilities for inserting models. They can be used to imagine, interpret, represent, calculate, and simulate existing or future ideas or reality (Fiandanese, 2019; Klaasen, 2002). Its production can assist in the qualitative, functional, and formal representation of objects (Jonassen; Strobel; Gottdenker, 2005) and in the transmission of ideas, structures, and relationships between the elements of this issue (Imai, 2007; Vasilenko, 2020). A literature review was carried out to discuss the model concept from the perspective of scientific-academic production in architecture. This discussion included the following: reviews on the concept and application of models in architecture (Fiandanese, 2019; Imai, 2007; Jonassen; Strobel; Gottdenker, 2005; Klaasen, 2002; Koch; Carranza, 2014; Vasilenko, 2020); and the use of conceptual models to evaluation processes related to architectural design process in the Brazilian context (Caixeta, 2015; Logsdon, 2019; Pandolfo, 2001; Romano, 2003; Saft, 2021).

The models are usually classified by their formal structure and their relationships with the represented reality (Klaasen, 2002). In general, they are known as: representational, mathematical, physical, or conceptual (verbal or mental). In terms of the study developed, the conceptual model proved to be the most appropriate for this research, whose main objective was to understand the phenomenon of housing privacy considering existing theoretical and empirical studies. The conceptual model represents activities or processes that visually portray the concepts and theory implicit in each reality or phenomenon (Adriaenssen; Johannessen, 2015). This allows to adequately relate the different aspects of the investigation, especially when there is an interest in also grounding the work on empirical studies (Elangovan; Rajendran, 2015).

The literature (Adriaenssen; Johannessen, 2015; Caixeta, 2015; Elangovan; Rajendran, 2015; Jonassen; Strobel; Gottdenker, 2005; Logsdon, 2019; Pandolfo, 2001; Romano, 2003; Saft, 2021) points out that to create a scientifically valid model, researchers must: raise theories regarding the phenomenon to be understood; define models’ limitations; formulate an initial validation proposal; guarantee its replicability (flexibility of adaptations). Supported by these guidelines, the construction of the model in focus was anchored in preliminary analytical diagrams, that identified indicators, requirements, and performance criteria3 for housing privacy, and in methodological procedures which were considered essential for its evaluation.

From an architectural perspective, privacy regulations are critical in shaping the design and functionality of home spaces. The spatial arrangements of homes often reflect cultural standards and social norms surrounding privacy. Perrot’s (1991) insights reveal that the boundaries between public and private spaces around homes often overlapped, implying ways of living that balance individual needs with societal dynamics. This complexity calls for a deeper understanding of how houses, especially apartments, can support privacy while reflecting the broader cultural frameworks in multifamily housing.

To understand the main constructs and relationships essential to housing privacy, a systematic literature review was carried out (Macedo; Ornstein; Elali, 2022), showing that it involves complexities inherent to the scales and dimensions evaluated. Regarding the first, three main scales were identified (Altman, 1975; Magi, 2011; Newell, 1995; Westin, 1967): individual – desired and perceived in a particular way, by each person, and protected, as a right; collective – governed by cultural standards and social norms, which establish the rules of coexistence and the sociodemographic context in which the individual lives; environmental – places where events and interpersonal interactions take place. About the dimensions, four are considered (Burgoon, 1982; Leino-Kilpi et al., 2001): physical – regulates the physical accessibility (tactile, visual, auditory, olfactory) of one person (or group) in relation to another; social – ability to control (participants, frequency, duration and content) social interactions, which define contact among people; psychological – the individual’s ability to control stimuli from the environment and people; informational – right to determine how, when and how much information is available to other individuals.

The literature (Altman, 1975; Burgoon, 1982; Dienlin, 2014; Hall, 1966; Westin, 1967; Margulis, 2011; Solove, 2006) also demonstrates that the balance of the privacy regulation system depends on aspects4 related to territoriality, personal space, perceptions of crowding and loneliness. Thus, considering the process for regulating the physical, social, and psychological barriers of individuals and among them, housing privacy is expressed by human socio-spatial relationships (Pinheiro; Elali, 2011), affective relationships (Bomfim; Delabrida; Ferreira, 2018) with the environment and other relationships that qualify such approaches (Coelho, 2011).

In housing, these relationships can be related to characterizing the place – descriptions of the physical attributes of the unit, the building and the surrounding area; regulation of interpersonal distances – expressed by controlling physical accessibility and desired social contact with cohabitants, family/close friends and neighbors; personal relationships – reflected in family functioning, experiences with neighbors and perceived social support; environmental affective relationships – indicated by the sense of belonging to the place and community, meaning of the place, representation of identity and appropriation of spaces; balance of individuals’ spatial needs – revealed by positive or negative perceptions/evaluations of privacy.

Illustrating the complexity of this process in terms of housing, a conceptual model of housing privacy was developed (Figure 1), based on the principle that the phenomenon under analysis can be defined by the users sociodemographic and individual characteristics, including their personality traits; physical attributes of the place, which determine the needs to be translated by the space. Such characteristics are interdependent and define the individuals’ privacy needs – who will positively or negatively perceive and evaluate them.

However, the perception and evaluation are affected by requirements related to managing privacy in the home environment, which include possibilities to control the environment; user satisfaction; existing person-environment affective relationships; pre-existing personal relationships. This set of requirements determines the individual’s desire for privacy and results in forms of communication regarding the desired type and degree of contact, which are specifically expressed by demarcating territories and delimiting personal space. Through social contact, the responses given can contain coping/defense strategies against unwanted contacts.

This will result in an assessment of the situation, which will culminate in balancing (or not) the spatial needs of the different individuals involved. In positive evaluations, the domestic environment and the relationships that ensue from their experience are consistent with the individuals’ desired level of privacy. On the other hand, in negative evaluations, individuals perceive an imbalance in this relationship, which can cause stress reactions, due to a perception of crowding or loneliness; or the search to balance out spatial needs by readjusting the coping strategies used to address the stressful situation or by changing environmental control conditions, restarting the process, or readapting privacy needs.

Considering the literature review, this initial model (Figure 1) demonstrates that the process of regulating housing privacy largely depends on physical characteristics, and when modified, these can contribute (positively or negatively) to perceptions of privacy. Under this assertion, architecture and its design process can contribute significantly to balance the system by designing spaces that are compatible with the residents’ needs and, consequently, consistent with the level of privacy they desire.

It is thus understood that assessments of housing privacy must consider this set of variables to ensure their perception is adequately measured. This condition was taken as the basis for developing the preliminary housing privacy evaluation model.

The literature review demonstrated that housing privacy evaluation should consider in one hand the relationships between the characteristics of the environment and user behaviors, which include the relationships that qualify privacy (Coelho, 2011), the themes under study, the dimensions of privacy (Burgoon, 1982), and the housing privacy performance indicators related to it; and on the other hand the evaluation methods procedures, which include methodological instruments and data sources, related to physical and social assessments and user perceptions.

Regarding the evaluation variables, their correlation was identified with: the scale, such as sociodemographic context, nearby neighborhood, building, housing unit, individual; the actors involved, who serve as data sources, such as residents, building managers, real estate market agents and researchers; the focus on which the study is centered (Newell, 1995), such as the person, the environment, the person-environment relationship. The interrelationships between these findings covered the physical, social, and psychological dimensions, defined as follows:

With regards to the evaluation procedures, their choice was especially related to the research focus and the privacy qualities and themes (privacy, territoriality, personal space, loneliness or crowding). The characteristics of the place were measured mainly through walkthroughs5, questionnaires and physical and social assessments. The regulation of interpersonal distances and the balance of individuals’ spatial needs were specifically measured through questionnaires and physical and social assessments. Finally, given their degree of subjectivity, personal and affective environmental relationships were assessed using questionnaires, interviews, or walkthroughs.

Based on these results, it was understood that evaluating privacy would designate preliminary and sequential definitions, namely: (1) choose the key themes that will be evaluated; (2) define the research focus; (3) choose the case study: housing typology and study universe; (4) identify the actors who will participate in the evaluation process and define the scales of study; (5) choose the assessment items, considering the desired privacy relationships to study; 6) choose which procedures will be necessary to measure the data. These choices enable the researchers to define the instruments necessary to assess privacy, which would provide the information necessary to diagnose privacy in the context studied through the following steps: 7) data collection, 8) data analysis; 9) publication of results.

A preliminary model (Figure 2) was proposed based on these delimitations, which uses 9 steps and serves as a guide for preparing privacy evaluation studies.

A procedure used to validate a model is an evaluation by experts in the field (Caixeta, 2015; Logsdon, 2019; Romano, 2003), which corresponds to experts’ opinions on a topic to guarantee greater reliability of the study (Pinheiro; Farias; Abe-Lima, 2013). By bringing together different points of view and analyses, the panel can contribute to elucidating the phenomenon or situation under study, as well as to reduce possible methodological biases (Elali; Pinheiro, 2013).

The work carried out included a panel of experts that had to verify whether the objectives set were achieved; certify the quality of the model generated; analyze whether the procedures adopted would enable incorporating new knowledge in the area. This was based on seven questions (Table 1) relating to the scope, operability, precision (or simplicity), empirical validity, importance, and replicability of the model (Elangovan; Rajendran, 2015; Holton; Lowe, 2007).

The panel included 12 university professors with a background in architecture, psychology, or engineering. They were selected based on their skills in the field of housing. They received, via email, a document with the analytical schemes (Figure 1 and Figure 2) and the questions related to the model validation (Table 1) that contained spaces for comments on potentialities and difficulties encountered in the interpretation and applicability of the model.

The panel results demonstrated the comprehensive evaluation criteria of the preliminary model – but needed further details about the items evaluated and how they were evaluated, better defining their relationships and scope. Regarding operability, it emphasized the need for greater depth in the evaluation procedure and the requirements and criteria taken into consideration. The model was deemed accurate and simple for application in different housing privacy analyses by different actors. Regarding empirical validity, experts pointed out the difficulty or unfeasibility of defining such measures to delimit behavioral measures that alleviate privacy concerns. Finally, in terms of importance and replicability, the experts state is relevant for the model to support new research and project solutions, if some adaptations are made.

The apartments complex chosen – study object – are in the city of Natal (RN) on a land area measuring 39450m² and has 900 units distributed across 6 towers (Figure 3). The minimum apartment program consists of at least 2 bedrooms, living and dining room, balcony, kitchen, laundry area, circulation area, and bathroom. The differences are mainly regarding the number of bathrooms or bedrooms (which could be 2 or 3), the presence of a garden or a private leisure area. Therefore, the apartment complex selected has five types of plans distribution and spatial organization (Figure 3), with built areas of 49.61m², 55.00m², 67.35m², 89.19m² and 129.97m².

The common area of the condominium (Figure 3) is located on the ground floor and offers a leisure area with: entrance with covered access, public squares, two swimming pools and deck, sports courts, two playgrounds, barbecue area, pet area and parking. The projection areas of the towers on the ground floor include party room, gym, toy/entertainment area, youth space, auditorium, and administrative areas.

The following were methodological procedures used in the exploratory study: walkthrough, questionnaire, interview, space syntax analysis of the unit. Data collection comprised visits to the apartment complex to become familiarized with the spaces, building managers and residents; and to collect information about uses of the common areas and those responsible for the architectural design. The instruments with user participation, questionnaires, and interviews, were applied by the researcher, after the participants’ consent.

The residents, in person and online, participated in the questionnaires, and the return rate was 42 valid questionnaires. The following were the main objectives of its application: identify the residents’ sociodemographic characteristics and personality traits (Rammstedt; John, 2007); identify the participant’s concept of privacy and home; assess the level of satisfaction with privacy and inconvenience perceived inside the unit; identify strategies to combat invasion of privacy; evaluate perceptions of crowding, by checking the inadequacies of the environment and the level of stress (Campagna, 2016), as well as measuring the participants’ loneliness scale (Hughes et al., 2004).

The interviews were prepared with semi-structured scripts, open-ended questions and applied in person. A total of 6 participants were interviewed, including: 4 building managers, 1 architect and 1 resident. The focus of the interview with the building managers was to understand the use of common spaces, especially in aspects related to territoriality and perceived nuisances (Pereira, 2017); identify the most used spaces and who used them; establish which privacy complaints were most recurrent among residents and whether there were conflicts related to the use of common spaces or between units. In the interview with the architect, the main goal was to identify the most relevant criteria for designing the housing projects, and how privacy was proposed to meet the residents’ needs. In the interview with the resident, issues related to privacy, personal space and territoriality were addressed. The objective was to better comprehend the residents’ privacy needs, identifying personal spaces and the patterns of use related to them, and family functioning (Munro; Madigan, 1993), by understanding conflict management, neighborhood relations and the residents’ needs that had not yet been met (Ozaki, 2002) in their homes and common areas. The interviews addressed questions about the impacts of the COVID-19 pandemic on the participants’ perceptions of privacy. Furthermore, in the interview with the architect, technical drawings of the architectural projects were requested and in the interview with the resident, the participant described the plan and layout of her residence. This graphical information enabled physical and social assessments of the project and the built environment.

The researchers prepared the instruments for physical and social assessment, without the users’ direct participation, namely: walkthrough and space syntax analysis of the unit. The walkthrough consisted of technical visits to diagnose the physical and behavioral conditions of the nearby neighborhood and common areas of the apartment complex. The nearby neighborhood was assessed in the immediate surroundings (Day, 2000) through a research evaluation of the physical features (roads, sidewalks, and adjacent accesses), the existing facilities (urban equipment within a radius of 500m), the presence of socio-environmental problems and pathological manifestations (on the sidewalks and walls of the building of the apartment complex). The common areas of the building were assessed by the access legibility conditions, presence of green areas and places where groups gathered (territoriality). Furthermore, some interpersonal distances were measured (Pereira, 2017) such as: distances between towers and their immediate neighborhood and main noise sources; distances between windows in different towers and the ground floor windows and the passage routes (circulations of common areas).

For space syntax analysis of the unit, the plan described by the interviewed resident was converted into an access graph, externally rooted. This graph was used to quantify the movement accessibility relationships (convexity)7, measuring the syntactic measures8 of mean depth and the RRA. The design was also used for visibility analyses, in which the isovista from the entrance and the VGA were processed. These analyses allowed the understanding of the public-private relations inside the houses and contemporary trends in the use of living spaces (Ozaki, 2002).

Despite the limited number of respondents, the results of the empirical application revealed some trends regarding the participants and apartment complex under study:

Despite the limitations regarding the number of respondents, the results indicate that the apartment complex under study satisfactorily met the privacy needs of a portion of the participating residents, despite highlighting the inadequacies that could be lessened by other design solutions. This relative satisfaction was based on the positive results of satisfaction with privacy, the relatively low frequency of all nuisances, the low perceptions of stress, crowding and loneliness and the peaceful coexistence between neighbors, with apparent personal bonds between neighbors and environmental affections with the place.

However, as Munro and Madigan noted, it is true that most people have positive images of their home, which could be sometimes “[…] unhelpful as an indicator of how they live their lives” (Munro; Madigan, 1993, p. 43). So, it is noteworthy that the satisfaction detected may not necessarily reflect that the housing project fully and satisfactorily met the privacy desires and needs of all residents regarding this type of housing development. As it involves two closely related themes to the self (privacy and the home, as a primary territory), there may be biases related to the ‘social expectation of responses’ or the ‘cognitive dissonance’ of the respondents, which did not allow detecting negative opinions. This indicates that the study of the correlation between satisfaction and adequacy of the project to the needs of residents should be expanded in future research.