Introduction

Buildings deliver the fundamental function of fulfilling the requirements and desires of users by offering a pleasant, secure, and healthy indoor setting for a wide range of activities, including leisure, study, work, family life, and social interactions [1]. Globally, there is a growing demand for enhancing indoor environmental quality aspects, such as lighting, which can favour occupants’ enjoyment, job productivity, and health [2]. Multiple studies have shown that daylighting has an impact on visual comfort [3], moods [4], health [5, 6], functioning, productivity [7], performance, and emotion of occupants [8] and also enhances their pleasure [5]. In addition, daylight positively impacts human behaviour [4]. Therefore, daylighting has emerged as an essential design approach for engineers and academic researchers in architecture that emphasises effective design solutions for building envelopes and openings. Within this particular framework, the main objective is to enhance the quality of environmental interior daylighting by achieving energy efficiency and user comfort [7].

Building laws and environmental assessments set criteria to encourage designers to use natural daylight as the most effective attainable source of indoor lighting [9]. Luminous comfort refers to the level of contentment that individuals have with the lighting conditions in their environment, as assessed by the inhabitants themselves [10]. Several design standards and laws regarding daylight provision rely on a quantitative methodology. Nevertheless, human response to daylight is consistently influenced by past encounters in which meteorological conditions, lifestyles, and sociocultural factors significantly shape perceptions and behaviours towards daylight. In order to address the need for more understanding of the relationship between daylight and user reaction in qualitative investigations, it is necessary to conduct a comprehensive analysis and study of the inter-relationship between quantitative and qualitative studies [11]. A recent study has been conducted on post-occupancy evaluation (POE) to provide valuable insights to designers and architects and enhance the overall user experience. However, the authors believe that POE would provide the necessary qualitative characteristics to create a design framework for an improved living environment.

Research Problem

In Algeria, only some research was conducted to evaluate the luminous comfort in multi-unit residential buildings, except for two research; the first was conducted by Derouiche [12], who surveyed the residents of the city of Mostaganem, characterized by a Mediterranean climate. Derouiche [12] found that the general design of the living room and the window typology only complies with some occupants’ needs. The perception of natural light and the behaviour of users towards natural light are driven by multiple reasons, such as social, cultural, or quite simply religious (such as privacy), with negative repercussions on internal comfort. Similarly, Nadji [13] surveyed the housing estate occupants of dwellings in the Commune of Soumaa in Blida City, Algeria. The author found that the unfavourable orientation, the external masks, and the bad design of the windows affect the luminous comfort level, increasing energy consumption as previous researchers have demonstrated that the interplay of human conduct, human perception, and the quality of daylighting influences luminous comfort. It is evident from the reviewed literature that POE is amongst the best research techniques to help assess the residents’ lighting comfort. However, none of these studies addressed the POE of luminous comfort in multi-unit residential buildings in Algeria’s hot and dry region.

Furthermore, previous research has studied only some human perception and behaviour factors relating to daylighting in the living environment. However, the design approach of residential buildings in the city of Biskra presents a notable difficulty during summer. The primary strategy focuses on cooling by minimising openings and windows without considering visual comfort. Unfortunately, that has resulted in an uncomfortable lighting environment and excessive electricity usage for lighting, particularly on hot summer days. Hence, it is the first post-occupancy evaluation of residents’ luminous comfort in hot and dry regions in Algeria; this investigation aims to evaluate by collecting an experimental dataset (onsite measurements and survey) the interior luminous atmosphere of Multi-Unit Residences in different orientations and during different hour of the day under typical sky condition of Biskra. This research can help architects design daylighting for residential buildings in the same climate and luminous conditions.

Post-Occupancy Evaluation (POE)

POE, or Post-Occupancy Evaluation, is a research technique that involves gathering and analysing data on user satisfaction, space utilisation, and resource consumption in a completed facility. The goal is to discover significant concerns about the occupants and the building itself [14].

The assessment of post-occupancy performance requires the examination of several aspects at different levels, including thermal comfort, which relies on heating, ventilation, and air conditioning systems, as well as illumination and visual comfort. Other essential aspects are the occupants’ satisfaction, physiological and psychological well-being [15]. Nevertheless, a significant number of these Performance Outcome Evaluations (POEs) prioritise objective assessments of Indoor Environmental Quality (IEQ) factors, such as temperature, sound, and lighting, instead of considering the subjective experiences of occupants, which have a direct impact on their well-being [16]. POE can comprehensively assess, examine, and enhance a facility’s performance and its occupants’ happiness with Indoor Environmental Quality (IEQ) [17, 18]. Regrettably, it is uncommon for facilities in hot and arid desert climates to undergo or exchange POEs. That is due to the numerous challenges posed by the occupancy patterns and general performance of the buildings in such contexts [19]. Historically, the related literature focused more on studies in schools, workspaces, and factories [20, 21], and few studies exist for residential buildings. The post-occupancy review for dwellings is infrequent, exacerbating the disparity between projected design objectives and the actual performance and user satisfaction [22]. Nevertheless, limited research endeavours have adopted an experience-centred methodology, specifically examining users’ diverse requirements and desires in the context of residential windows [23, 24], residential comfort and well-being [25]. Minimal field research has stressed residential windows’ physiological and psychological effects [26]. In research concerning luminous comfort, the daylighting satisfaction level should be the principal concern [27].

The focus of this research is on the multi-unit residential building; it evaluates the luminous comfort of the residents by examining the varying levels of satisfaction with daylighting circumstances based on occupants’ conduct and perceptions of daylighting, as well as the impacts of physical environmental factors. The mentioned studies used different research methods to address the problem of daylighting. Ming and Lau [11] stated that daylight impacts users physically and psychologically. The human response to daylight perception and acceptance would be affected by previous experiences such as climatic effects, sociocultural factors, and lifestyles.

At the level of residential buildings, Ziama et al. [28] found that designers, architects, and policymakers need to consider the need for a social/behavioural design approach to guarantee a healthier and sustainable living setting for the end users. Similarly, Brown [29] surveyed four high-rise residential skyscrapers in Toronto; the author demonstrated that suites with a high level of glazing can lead to discomfort and increased cooling requirements for some occupants. Furthermore, he stated that overhead lighting should be installed in suites of this particular kind, as he added that the enormous windows adversely hampered the occupants’ thermal comfort.

Gerhardsson and Laike [30] conducted qualitative interviews with inhabitants residing in multi-dwelling facilities in Sweden. This study discovered that residents need a home environment that allows them to control the level of visibility towards the outside, in order to meet their specific requirements for social interaction or personal privacy. Implementing a site layout and building design that is responsive to climate conditions, which includes features such as windows, shading devices, and natural ventilation, can effectively decrease the amount of power consumed for internal residential lighting, heating, and cooling. In the same vein, Hayashi et al. [31] surveyed inhabitants’ attitudes regarding the internal atmosphere in three multi-story dorms. Hayashi discovered that balconies offer significant overall benefits in various aspects, except for the drawback of limited seclusion. The primary role of sunshades on balconies is to prevent rain, and their shading capability is occasionally overlooked.

Xue et al. [27] administered a survey to assess the residents’ objective living conditions and subjective degrees of luminous comfort in order to investigate human behaviour and emotions related to daylighting. Xue et al. [27] realised that people’s satisfaction with daylighting is mainly influenced by the sense of homogeneity, heat discomfort, external obstacles, and solar access hours during the summer. Along the same lines, Wang et al. [5] conducted a survey among the residents of Bauhinia Garden in Hong Kong, where they asked them to subjectively assess their satisfaction with the luminous atmosphere in their flats. The study revealed a strong correlation between the tenants’ contentment with the amount of natural light in their apartments and their overall pleasure with the luminous environment.

Similarly, and with greater specificity, some design factors impact the daylighting qualities of apartment units. The variables encompassed in this study are window size, room layout, and unit orientation. Furthermore, the proximity of neighbouring structures might generate shadows that diminish the intensity of natural light entering the rooms, especially in the morning and late evening [32].

Research Methodology

The triangulation method was used as a data collection technique, and qualitative and quantitative measures were employed [33, 34]. This study employed an experimental method to collect quantitative and qualitative data that can evaluate luminous indoor environmental quality in residential buildings under hot climates and high exterior illuminance levels. The methodology had three main phases:

Gather data on measurable physical environmental elements, such as the degree of interior illuminance. Then, analyse the correlation between these characteristics and the level of satisfaction that inhabitants have with the amount of natural daylight in the space;

Examine the impact of personal behaviour habits on satisfaction with the luminous environment and determine the varying degrees of residents’ satisfaction.

Analyse the relationship between the building’s physical characteristics and the residents’ satisfaction level.

Case Study and Sampling

The investigation was carried out in Biskra, the primary urban centre in the Sahara Desert. It is located in the south-eastern part of Algeria. Specifically, it is southeast of the capital city, Algiers (Figure 1). Table 1 displays the attributes of research area 1.

Figure 1.

Overview of the case study.

Our investigation was performed in participatory residential buildings in the western extension zone of Biskra City, a district recently established in Biskra (Figure 2). The estate is chosen from a selection of housing groupings: (i) they have four different orientations, which allows comparison, (ii) exceeds two years of occupancy which allows the POE, and (iii) recently designed and built which reflects contemporary design in Algeria. Nevertheless, every single building has a height of five stories. The floor areas of the flats in these buildings ranged from 67 to 71 square metres (Figure 2). The four buildings (1, 2, 3, and 4) highlighted in red in Figure 2 have identical exterior features, including the number and size of windows, colour, and reflectivity. Additionally, these buildings are situated on the same floor level, precisely the middle level.

Figure 2.

Case study: (a) Location of the units, (b) Unit façade, (c) interior lateral view of the living room, (d) frontal perspective of the living room, (e) the standard floor layout of the case study.

Pilot study

Fifteen questionnaires were delivered randomly to the residents as a pilot study before the final draft was made to check the trustworthiness of the questionnaire and test the viability of the statistical techniques for analysing the participants’ responses. An initial examination of the results and participant feedback in the pilot study indicated that most questionnaire items were easily understood. However, specific questions required adjustments. Three additional items were included in the questionnaire.

Questionnaire survey

The triangulation method has been used as a data collection technique [34] to design the questionnaire according to the study’s objective. The questionnaire was designed based on literature and a heterogeneous purposive sample of 12 experts’ opinions (architects) from the same city as the case study. Furthermore, the questionnaire was paired with a semi-structured interview with the participants from the studied city. The survey used in this experience was conducted during the summer season, between June and August 2022. One hundred twenty surveys were personally presented, and the authors gathered 94 completed questionnaires that were deemed legitimate for study. It consisted of five sections, with the first containing the participants’ general information. Part 2 consisted of objective questions regarding the individuals’ physical living situations. Part 3 focused on the occupants’ perception of the amount of natural light in their living surroundings. Part 4 consisted of inquiries about the light-related actions of the occupants in their living environment. The residents responded to these questions using a 5-point Likert scale to assess their level of satisfaction, with one indicating highly unhappy and five indicating very satisfied (Figure 3). This study poses multiple questions, precisely 10 out of 17, as indicated in Table 2.

Figure 3.

Structure of the Questionnaire.

Statistical analysis

The data collected from our field measurements and survey was carefully coded and analysed using the software SPSS V 25.0. The statistical reliability was initially evaluated to determine the overall consistency of the questions. The Cronbach’s alpha coefficient was employed to assess the internal consistency of two scales: the human perception of daylighting and human behaviour about lighting. The chi-square test compares two statistical data sets that demonstrate bivariate correlations. The study was conducted to assess the impact of personal information on lighting comfort. Spearman’s rank correlation coefficient is a non-parametric statistical measure that quantifies the magnitude and direction of the relationship between two ranked variables. The correlation coefficient was utilised to examine the association between inhabitants’ contentment with daylighting and the other evaluated characteristics.

Results and discussion

Survey results

Questionnaire’s reliability

The questionnaire’s reliability in assessing sentiments towards daylight was validated using Cronbach’s alpha coefficient, including perceptual assessments of ten items. Furthermore, Table 3 displays the eight components that represent human behaviour. The Cronbach’s alpha coefficient was used to assess the internal consistency of the scales. The values obtained for sentiments towards daylight and human behaviour were 0.81 and 0.79, respectively. Various researchers have found that the acceptable range for Cronbach’s alpha coefficient is between 0.60 and 0.95 [36]. The coefficients in our investigation exhibited a level of reliability that surpassed 0.60, as indicated in Table 3.

Participants’ demographic characteristics

The data received from the respondents indicated that 67% of the participants were female, while 33% were male. This outcome is attributed to the fact that the primary participants are homemakers. Ultimately, women tend to spend more time in their residences than men. Although it was not advisable to ascertain the exact ages of our main participants, the findings indicate that 24.5% are over 60. According to Figure 4, 12.8% of the population falls within the age range of 50-59 years, 35.1% falls within the age range of 40-49 years, 21.3% falls within the age range of 30-39 years, and 6.4% are under 30 years old. This outcome is attributed to the fact that most of the residences examined were built between 2006 and 2010. Most of those who had the financial means to make purchases during this period were gainfully employed and still within the working age bracket, as opposed to those who were beginning their careers or had already retired. In addition, the statistical analyses revealed that 30.9% of the participants have resided in their residences for 10-12 years.

Similarly, 25.5% have lived in their homes for 7-9 years, while 24.5% have resided there for over 12 years. Furthermore, 13.8% have lived in their homes for 4-6 years, and 5.3% have resided there for 1-3 years. This pattern indicates that the construction of these dwellings occurred in multiple stages over 12 years, resulting in a protracted process of acquiring and inhabiting them.

Most of the respondents, 81.9%, are from Biskra, while 6.4% are from southern cities, 5.3% are from Northern cities, 5.3% are from eastern cities, and 1.1% are from western cities. Moreover, more than 60% of the participants are employees in the public sector, while 24.47% are housewives,7,45% are retired, and 3.2% are university graduates. The majority of respondents are intellectual.

The Chi-square test was employed to analyse the bivariate relationships between satisfaction with luminous comfort and personal information. According to the Chi-square test (P > 0.05), no statistically significant differences in gender, career, number of years of occupation, flat, or city of origin about satisfaction with luminous comfort. Nevertheless, there was a notable disparity in satisfaction levels among all age cohorts (P < 0.05). The findings indicate that individuals of advanced age exhibit higher satisfaction levels with the light environment. Older individuals may have a greater tolerance for unhappiness with their living environment than younger individuals, who are more likely to voice their discontent more actively. Older people are less demanding than the other age groups.

Ranking of the factors influencing daylighting satisfaction

Satisfaction with daylighting is influenced by two main factors: the physical surroundings and the residents’ subjective perception of daylight. The impact of these elements on satisfaction is analysed using a Spearman coefficient, as shown in Tables 4 and 5. The magnitude of the coefficient values directly correlates with the strength of the relationship between the elements. Table 4 demonstrates a robust and highly significant positive connection (P-value < 0.01) between the window area and satisfaction with daylighting. The relationship between satisfaction/contentment with daylighting, the size and direction of the living room showed a statistically significant positive connection, with a P-value of less than 0.01. The coefficients of floor level, Sky obstruction level, and floor area were not statistically significant since their P-values were greater than 0.01. Based on the findings, optimising the orientation and increasing the size of windows and living room areas might enhance the degree of satisfaction among residents with regard to daylighting.

Most windows with superficies less than 1.2 m² are West-oriented at 25.53% of the total number of windows, the East-oriented windows are at 23.40%, and the Southern windows are at 19,15%. A minority of 15.96% are North-oriented. The windows with superficies between 1.2 m² and 1,6 m² are primarily oriented to the North with 6.38%, the southern windows are 4.26%, and the Eastern windows are 3.19%. A minority of 2.13% are West-oriented. Generally, a majority, 54.25%, of the windows have a grim orientation (East and West), and a minority, 45.75%, of the windows have a good orientation (South and North) (Figure 4). Generally, a majority of 54.25% of windows have a terrible orientation (East and West), and a minority of 45.75% have a good orientation.

Figure 4.

Window Area Across Building Orientation.

The living rooms with less than 12 m² area are primarily oriented to the North, with 6.38% of the total living rooms. The South-oriented living rooms are 4.26%, and 3.19% are oriented to the East. A minority of 2.13% are West-oriented. Also, the living rooms, which are between 12 m² and 14 m², are majority oriented to the West with 14.89% and the same percentage for the East, and 13,83% are North-oriented. A minority of 12.77% of living rooms are South-oriented. The living rooms within 14 m² and 16 m² are mainly oriented to the West, with 10.64%. 8.51% are oriented to the East, and 6.38% are South-oriented. Finally, a minority of 2.13% are North-oriented (Figure 5). Generally, a majority of 54.25% of living rooms have a grim orientation (East and West), and a minority of 45.75% have a good orientation.

Figure 5.

Living Room Area Across Building Orientation.

Table 5 indicates a strong positive correlation between the perception of uniformity, the degree of importance of daylighting, contentment with window size, window position, sunshine difficulties (overheating and glare), and satisfaction with daylighting. This relationship is statistically significant (P-value < 0.01). Meanwhile, characteristics such as preferred lighting type, contentment with view, satisfaction with window area, and privacy show a negative correlation with P values (P-value >001), suggesting they are insignificant.

The participants who are very satisfied with daylighting indicate that daylighting is very important, presenting a majority of 5.32% of the total number of participants, and a minority of 1.06% attest that daylighting is essential. Furthermore, the satisfied participants in their apartments indicate that daylighting is very important, representing a majority of 13.83% of the total participants. In contrast, a minority of 7.45% are satisfied with daylighting and attest that daylighting is essential. Additionally, the participants who are unsatisfied with daylighting in their apartments indicate that daylighting is very important, presenting a majority of 30.85% of the total number of participants, 22.34% of unsatisfied participants attest that daylighting is important, 6.38% of unsatisfied participants confirm that daylighting is somewhat essential. A minority of 2.13% of unsatisfied participants attest that daylighting is unimportant. The participants who are somewhat satisfied with daylighting indicate that daylighting is vital, presenting a minority of 1.06% of the total participants. The same percentage is somewhat satisfied with daylighting, indicating that daylighting is unimportant. Also, the participants who are not at all satisfied with daylighting but indicate that daylighting is essential, presenting a majority of 3.19% of the total number of participants, 2.13% who are not at all satisfied attest that daylighting is not essential, the same percentage are satisfied, and a minority of 1.06% attest that daylighting is somewhat essential (Figure 6). Generally, 85,12% of participants attest to their consciousness of the importance of daylighting.

Figure 6.

Daylighting Satisfaction Across Importance of Daylighting.

All inhabitants who are very satisfied with daylighting have very uniform illuminance distribution in their living rooms. Also, the participants who are satisfied with daylighting and have very uniform illuminance distribution in their living room represent 12,77% of the total participants. Furthermore, the participants who are somewhat satisfied with daylighting and have weak uniformity in their living room present 1.06%, and the other half have uniform illuminance distribution in their living room. The participants who are not satisfied with daylighting and have weak uniform illuminance distribution in their living room present a majority of 27,66%, and the participants who are not at all satisfied with daylighting and have not uniform illuminance distribution in their living room present a majority of 6.38% (Figure 7). Generally, all very satisfied participants have uniformity in their living rooms. Most participants who are unsatisfied with daylighting have no uniformity, which allows us to deduce that the higher the degree of uniformity, the higher the satisfaction with daylighting.

Figure 7.

Daylighting Satisfaction Across Uniformity of Daylighting.

The participants whose sunlight always brings the glare in their living room and are somewhat satisfied with window dimensions represent a majority, 18.09% of the total participants. The participants whose sunlight often brings glare in their living room and who are somewhat satisfied with the window dimension present a majority of 22.34%. The participants whose sunlight sometimes brings glare in their living room and who are satisfied with the window dimension present a majority of 7,45%. The participants whose sunlight rarely brings glare in their living room and who are satisfied with the window dimension present a majority of 6.38%. The participants whose sunlight does not bring glare in their living room and who are very satisfied with the window dimension present a majority of 5.32% (Figure 8). Generally, almost all participants who are not satisfied with daylighting have the problem of glare in their living room. That makes us deduce that the greater the glare, the lower the degree of satisfaction with the window dimension.

Figure 8.

Glare Across Satisfaction with Window Dimension.

The participants whose sunlight always brings glare in their living room and who are not satisfied with the window location present a majority of 9.57% of the total number of participants, and the same percentage are satisfied. The participants whose sunlight often brings glare in their living room and are not satisfied with window location present a majority of 20.21%. The participants whose sunlight sometimes brings glare in their living room and who are satisfied with the window location present a majority of 7,45%. The participants whose sunlight brings glare in their living room rarely and are satisfied with window location present a majority of 6,38%. The participants whose sunlight does not bring glare in their living room and who are satisfied with the window location present a majority of 6,38% (Figure 9). Generally, most participants who are not satisfied with daylighting have the problem of glare in their living room. That makes us deduce that the greater the glare, the lower the degree of satisfaction with the window position.

Figure 9.

Glare across Satisfaction with Window Location.

The participants whose sunlight always brings overheating in their living rooms and are somewhat satisfied with window dimensions represent a majority of 20.21% of the total participants. The participants whose sunlight often brings overheating in their living room and who are somewhat satisfied with the window dimension present a majority of 14.89%. The participants whose sunlight sometimes brings overheating in their living room and who are satisfied with the window dimension present a majority of 6,38%. The participants whose sunlight rarely causes overheating in their living room and are satisfied with window dimensions present a majority of 6.38%. The participants whose sunlight does not bring glare in their living room and who are very satisfied with window dimension present a majority of 5.32% (Figure 10). Generally, almost all participants who are unsatisfied with daylighting have the problem of overheating in their living rooms. That makes us deduce that the greater the glare, the lower the degree of satisfaction with the window dimension.

Figure 10.

Overheating Across Satisfaction with Window Dimension.

The participants whose sunlight always brings overheating in their living room and are not satisfied with window location represent a majority, 17.02% of the total participants. The participants whose sunlight often brings overheating in their living room and are not satisfied with window location present a majority of 9.57%. The participants whose sunlight sometimes brings overheating in their living room and are satisfied with window location present a majority of 7,45%. The participants whose sunlight rarely brings overheating in their living room and are satisfied with window location present a majority of 5.32%. The participants whose sunlight does not cause overheating in their living room and who are very satisfied with the window location present a majority of 5.32% (Figure 11). Generally, most participants unsatisfied with daylighting had the problem of overheating in their living room. That makes us deduce that the greater the overheating, the lower the degree of satisfaction with the window dimension.

Figure 11.

Overheating Across Satisfaction with Window Location.

Individuals often behave in their living environment in a way that creates their luminous indoor environment.

Table 6 demonstrates a robust and statistically significant positive association (P-value < 0.01) between the amount of time artificial lighting is used and daylighting satisfaction. That indicates that artificial lighting usage has the most significant impact on daylighting satisfaction. The link between the modification of windows and the regulation of solar light access and contentment with daylighting was considerably positive (P-value < 0.01). That suggests that these parameters indirectly impact satisfaction with daylighting.

Results presented in Figure 12 indicate that all the respondents who use artificial lighting fewer hours per day are satisfied with daylighting. A majority, 13.83% of inhabitants who use artificial lighting for 1-3 hours are unsatisfied with daylighting. A majority of 11.70% of inhabitants who use artificial lighting for 3-5 hours are unsatisfied with daylighting. A majority, 26.60% of inhabitants who use artificial lighting for 5-7 hours are unsatisfied with daylighting. All inhabitants who use artificial lighting for 5-7 hours are unsatisfied with daylighting. Upon analysing the average degrees of satisfaction depicted in Figure 12, it becomes evident that prolonged exposure to artificial lighting has a detrimental effect on luminous comfort. This discovery implies that individuals experience more significant discomfort when using artificial lights excessively. This outcome further substantiates the significance of daylighting as a crucial determinant of luminous comfort.

Figure 12.

Daylighting Satisfaction across the Number of Hours employing.

On the other hand, Figure 13 shows that a majority of 5.32% of inhabitants who have carried out significant transformations in their apartments are very satisfied with daylighting. At the same time, the same percentage are satisfied with daylighting. A majority of 7.45% who have made significant transformations are satisfied. A majority of 21.28% who have made average transformations are not satisfied. Most inhabitants, 21.28%, who performed a few transformations are unsatisfied (Figure 13). All inhabitants who do not make transformations are unsatisfied with daylighting. By comparing the results, more considerable transformation on windows increases luminous comfort. This finding suggests that inhabitants feel more comfortable when the transformation is over-operated.

Figure 13.

Daylighting Satisfaction across the Transformation.

Figure 14 demonstrates that 5.32% of the participants who habitually use solar light control in their living room are always satisfied with daylighting. The majority,13.83% of inhabitants who habitually use solar control in their living room, often are unsatisfied with daylighting. The majority, 11.70% of participants who use solar control in their living room, sometimes are unsatisfied with daylighting. The majority, 26.60%, of Inhabitants who use solar control in their living rooms are rarely satisfied. All inhabitants who habitually do not use solar control are not satisfied with daylighting(Figure 14). The habit of controlling sunlight access impacts satisfaction with daylighting. Therefore, the more solar light access is controlled, the more satisfaction with daylighting.

Figure 14.

Daylighting Satisfaction Across Solar Light access.

Among the respondents who wished they were very satisfied with luminous comfort, half were very satisfied with daylighting, while the other half were satisfied. 10.64% of inhabitants are satisfied with luminous comfort are satisfied with daylighting. Similarly, 11.70% of inhabitants who are somewhat satisfied with luminous comfort are unsatisfied with daylighting. Most inhabitants, 31.91%, are unsatisfied with luminous comfort and also not satisfied with daylighting. All inhabitants unsatisfied with luminous comfort are not at all satisfied with daylight (Figure 15). In general, the satisfaction level with daylighting significantly influences the overall level of luminous comfort.

Figure 15.

Satisfaction with Luminous Comfort.

Measurements results

Field measurements of indoor and outdoor illuminance levels have been carried out using a digital lux meter to validate the results of the questionnaires. The equipment used is the CA 813 light meter with a sensitivity from 20 lux up to 200000 lux (Figure 16).

Figure 16.

The Luxmeter Used in this Research.

The distribution of the questionnaire accompanies the measurement of illuminance levels on a sunny hot day with clear sky conditions on 14 July. Indoor and outdoor illuminance measurements were performed on the same day and time every two hours from 9 am to 5 am. The measurements were carried out at desk height level, which is 0.75 meters. The field measurements were based on a grid of nine measurement points spaced 1.2 m x 0.92 m.

The outdoor illuminance level distribution varies significantly from one hour to another. It was measured between 14175 lux at 9:00 am and 9875 lux at 5:00 pm (Figure 17).

Figure 17.

The Outdoor Illuminance Level Measured on 14 July Under a Clear Sky.

The illuminance level distribution varies significantly from one hour to another in the room. The available illuminance level increases until 1 p.m., then it decreases. In the facing south, the illuminance values obtained vary between 403 lux near the window at 1:00 p.m. and 58 lux at the back of the room at 5:00 p.m. (Figure 18).

Figure 18.

Distribution of Daylight Illuminance at the Points of Measurement in the Southern Living Room.

When facing North, the lighting levels differ throughout the day. At 1:00 p.m., the lighting near the window reaches 300 lux, while at 5 p.m., the lighting at the opposite end of the room drops to 46 lux (Figure 19).

Figure 19.

Distribution of Daylight Illuminance at the Measurement Points in the North.

In the East orientation, the lighting values obtained vary between 350 lux near the window at 11:00 a.m. and 41 lux at the opposite end of the room at 5:00 p.m. (Figure 20).

Figure 20.

Distribution of Daylight Illuminance at the Measurement Points in the Southern Living Room.

In the West orientation, the lighting values obtained vary between 368 lux near the window at 3:00 p.m. and 41 lux at the opposite end of the room at 9 a.m. (Figure 21).

Figure 21.

Distribution of Daylight Illuminance at the Measurement Points in the Eastern Living Rooms.

The legislation in Algeria needs to establish specific criteria for ensuring adequate levels of visual comfort; French laws were chosen due to the similarity between the light climate in France and Algeria, which can be attributed to their similar geographical positions (mean latitudes).Thus, the reference for the levels of comfort illumination by room type is derived from Table 7, provided by ADEME (French Agency for Environment and Energy Management), which works in collaboration with the Algerian APRUE (National Agency for Environment and Energy Management, Promotion and Rationalisation of energy).

Selection comfort zone (60-300 lux): Most points comprise 91.11% of the Northern façade and 64.44% of the southern façade. A minority of points comprise 46.66% in the East and 37,77% in the West. That is a reasonable result because the South and the North are the best orientations to ensure the occupants’ comfort.

Rational choice (200-300 lux): Most points comprise 55.55% of the Southern façade and 26.66% of the Northern façade. A minority of points make up 15.55% in the East and 11.11% in the West. That is a reasonable result because the South and the North are the best orientations to ensure the occupants’ comfort.

Values exceeding 300 lux: Most points above 300 lux account for 44.44% in the West, 37.77% in the South, and a minority of 31.77% on the façade. Therefore, it may be inferred that living rooms may necessitate the use of shade devices or curtains in order to restrict glare.

Values below 60 lux: Most points below 60 lux comprise 17.77% of the West, 15.55% in the East, and a minority of 4.44% in the South façade (Figure 22). That makes us deduce that living rooms may require artificial lighting to enhance their luminous comfort.

Figure 22.

Points’ Measurements across the Comfort Zone.

Results obtained from the measurements are correlated with the survey. The participants whose living rooms are south-oriented and are satisfied with daylighting represent a majority, 10.64% of the total participants. Also, most percentages of point measurements are close to the reasonable choice of comfort zone in the southern façade with 55,55%.

The participants whose living rooms are north-oriented and are not satisfied with daylighting represent a majority, 10.64% of the total participants. Additionally, an approximative percentage of 9.57% present those who are satisfied with daylighting in the North orientation. Also, most percentages of point measurements are close to the reasonable choice of comfort zone in the southern façade, with 26.66%.

The participants whose living rooms are east-oriented and are not satisfied with daylighting represent a majority, 18.09% of the total participants. Furthermore, a minority of point measurements are close to the reasonable choice of comfort zone in the East with 15.55%.

The participants whose living rooms are west-oriented and are not satisfied with daylighting represent a majority, 24.47% of the total participants. Furthermore, a minority of point measurements are close to the reasonable choice of comfort zone in the East, with 11.11%.

These results are reasonable because the South orientation is the best orientation to ensure homogeneous lighting during the year; the North orientation comes second. On the other hand, most inhabitants are unsatisfied with the East and West orientations because they are the two unfavourable orientations (Figure 23).

Figure 23.

Daylighting Satisfaction Level Across Orientation and Reasonable Choice of Comfort Zone.

Conclusions

This study aims to assess the degree of visual comfort in multi-unit residential buildings by conducting a post-occupancy evaluation of buildings (MURB) in Biskra City, Algeria, using an experimental method that relies on both objective and subjective assessments.

The findings indicated that the experience of visual comfort arises from the interplay of daylighting, human conduct, and human perception of environmental factors. Furthermore, it has been proven that the level of pleasure with daylighting is the most crucial component in determining the degree of comfort related to illumination. Based on the data analysis, the following conclusions can be drawn on the factors that contribute to luminous comfort. The results indicate no significant statistical difference between genders regarding their preferences for luminous comfort. However, age does impact it since older individuals generally experience more satisfaction with their luminous environment. The profession also has an impact.

From the results, the orientation, the window area, and the living room area are the primary physical environment factors increasing the residents’ satisfaction with daylighting. Most 51.07% of residents unsatisfied with daylighting have living rooms oriented to the East and the West. In contrast, almost all participants satisfied with daylighting had living rooms oriented to the South and the North.

Findings demonstrated that uniformity, degree of importance of daylighting, satisfaction with window dimensions and locations, overheating, and glare are the human perception factors affecting daylighting satisfaction. Furthermore, uniformity is vital in increasing the participants’ satisfaction; almost all, 92.85% of participants who are satisfied with daylighting have uniformity in their living rooms, whereas 97.36% of unsatisfied participants have a problem with illuminance uniformity. Moreover, behavioural aspects substantially impact the level of comfort provided by lighting, the utilisation of artificial lighting, the implementation of solar access control, and the adaptation and enhancement of the indoor environment’s lighting conditions. Utilising artificial lighting (based on the duration) is the most suitable approach for affecting degrees of luminous comfort. Prolonged use of artificial lighting suggests inadequate natural lighting conditions and reduced visual comfort. Participants who used artificial illumination for less than one hour expressed high satisfaction, while those who used artificial lighting for more than seven hours reported dissatisfaction.

The results obtained from the objective measurements are correlated with the subjective evaluation. The participants whose living room is south-oriented are primarily satisfied with daylighting and point measurements close to the reasonable choice of the comfort zone, with a majority of 55,55%. The participants whose living rooms are oriented to the East and the West attested as a majority that they are not satisfied with daylighting and points measurements close to the reasonable choice of the comfort zone with a minority of 15.55% and 11.11 respectively.

The study also highlights the significance of daylighting concerning people’s overall satisfaction, and this evidence can assist policy-makers in formulating suitable norms and standards. The results empower planners and architects to incorporate enhanced daylighting in their housing endeavours and provide inhabitants with acoustically and visually pleasing surroundings. Further research will evaluate the effectiveness of daylighting through the use of modelling approaches or on-site measurements. Integrating quantitative measures and qualitative assessments will yield a more comprehensive investigation, particularly about the correlation between individuals’ behavioural habits and their perception of luminous comfort.