1. Introduction
Apartment buildings are proliferating in almost all major cities in subtropical and tropical countries globally. In Brisbane, a large Australian city in the subtropical zone, apartments are predicted to increase dramatically as a proportion of Brisbane’s housing stock over coming decades [
1]. This presents problems for the city’s key urban sustainability and greenhouse gas emissions reductions policies [
2]. Firstly, compared to other multiple-housing types, apartment buildings are intrinsically energy-intensive and may actually contribute to greater overall urban energy consumption and increased greenhouse gas emissions [
3,
4,
5,
6]. In recent decades there has also been an inexorable trend toward air-conditioning becoming the default climate control solution despite the subtropical climate requiring few energy inputs for thermal comfort. Secondly, Australians prefer the relative autonomy and spaciousness of a detached house and are likely to choose apartment living for transitory periods of their lives, rather than long-term [
5]. This may be because apartment buildings currently fail to provide suitable accommodation for various demographic groups, and ultimately outer urban expansion is stimulated rather than dampened by inner-urban construction of apartment buildings that meet a narrow market band [
6]. These issues confirm that congruity between people and their living environments is important for sustainable development [
7]. The challenges of designing comfortable and healthy residential environments that can better meet residents’ expectations of desirable places to live, and minimising energy consumption must be addressed urgently in Australia’s cities and cities in other warm climate countries, almost all of which are experiencing rapid growth in high-density residential environments.
The limited long-term appeal of apartments may be due to a mismatch between available housing stock and people’s expectations of liveable attributes of dwellings [
8] rather than apartment living itself. Several studies of multi-storey residential environments have identified privacy and building quality as important influences on residents’ perceptions of liveability [
9,
10,
11,
12,
13]. Privacy is measured by the extent to which residents can control the intensity of their interaction with neighbours, and is indicated by the amount of ambient noise, noise from neighbours and the amount of outside space for personal use [
14]. Building quality indicates a physically healthy residential environment and is measured by standard of construction and energy efficiency [
11,
14] alluding to a focus on thermal comfort.
Climate-related lifestyle needs are frequently overlooked in residential environment satisfaction research, but are an important aspect of subtropical cities where the climate is conducive to outdoor living all year round. The subtropical humid climate zone has no distinctly dry season [
15] and though summers are hot and humid, and winters are cool, the ambient outdoor temperatures (19–29 °C in summer and 9–21 °C in winter) are within a comfortable range for much of the year [
16,
17]. Humidity is the main factor affecting thermal comfort in subtropical settlements, and is most noticeable when air temperature is high and wind velocity is low [
18]. Thus ways of generating air movement or capturing breeze are sought after when these conditions prevail in summer, and sometimes on autumn and spring days. In principle, MSABs can be designed to respond to the climate, by effective use of solar orientation of buildings and external shading devices to admit or exclude direct sun when seasonally appropriate, and siting of openings to effectively generate air movement to reduce the effects of humidity in summer [
16,
19], yet thermal comfort for dwellings is increasingly provided by air-conditioning. Despite the advantages and disadvantages of the mild subtropical climate, the climate zone is relatively under-researched, in terms of the relationship between climate, multi-residential building design and residents’ perceptions and experiences of this relationship. For example, many domestic activities are conducted in exterior private spaces such as verandas, balconies and terraces [
20] and are a characteristic feature of multi-storey apartment buildings (MSABs) in subtropical cities like Brisbane (
Figure 1). Residents occupying such spaces in dwellings in are potentially exposed to noise discomfort. Noise from external sources such as traffic and roof-top air-conditioning plant is prevalent in urban areas where MSAB are located. Residents using balconies may also be exposed to noise from neighbours, and may generate noise that could bother their neighbours.
Figure 1.
Multi-storey apartment buildings (MSAB) in Brisbane typically feature balconies on their facades. Source R. Kennedy.
Figure 1.
Multi-storey apartment buildings (MSAB) in Brisbane typically feature balconies on their facades. Source R. Kennedy.
This purpose of this paper is to explore residents’ experiences of liveability in apartment dwellings in the subtropical climate. In particular, we focus on residents’ perceptions of privacy and comfort, and their satisfaction with the extent that their dwelling modulated the external environment and met their privacy and comfort expectations in subtropical conditions. This research on the impact of apartment building design on liveability and on urban energy needs more broadly is much-needed in the context of Australia’s subtropical cities, and will have resonance in almost all major cities in subtropical and tropical zones globally where high-density apartment living is a fact of contemporary society.
2. Physical and Social Characteristics of Multi-Storey Apartment Living
A defining aspect of multi-storey apartment living generally is the extent to which everyday lifestyles are affected by proxemics and sharing [
21,
22,
23]. In the home environment, proxemics are linked to privacy, and concern notions of personal space, particularly the preference or desire for a place that is identified as one’s own [
24,
25]. An important part of this feeling of ownership is autonomy, the right to personalise, and the freedom to adapt one’s personal space to one’s own needs or desires. Another critical aspect of proxemics is that being separate from others is preferred to sharing [
25]. Privacy is an expectation of exclusion from intrusion and preventing the world from encroaching [
26]. King’s notion of a private place as a thing kept “apart” (p. 54) is an appropriate description for the private dwelling in a multi-residential building—the apartment. People desire both connection with the community, and privacy. They want reciprocal relationships that include living privately with “polite indifference” (p. 57) with their neighbours, and to be able to call on each other for help in a crisis [
26]. Thus, privacy is associated with peace of mind and with the freedom of personal space.
However, residents of MSAB share walls, ceilings and floors with their neighbours adjacent, above and below them [
27], as well as collective entries and circulation spaces, parking garages and communal facilities such as swimming pools, washing lines, gardens and barbeques. They also share the hardware (ducts, pipes and wires) delivering services such as energy, water, drainage, waste management and communications to their dwellings. Furthermore, because most apartment buildings in Australia are generally multi-title (strata title) developments and owners form a “body corporate” entity, residents share governance and management arrangements as well [
28,
29]. In order to avoid or manage social issues that these sharing circumstances could generate, resident cohesion is very important and a level of familiarity on which to base positive interrelationships is essential [
30]. However, there is an overall impression of social withdrawal among residents of apartment buildings [
31]. A level of anonymity may permit privacy in a setting where physical proximity makes it otherwise difficult to achieve [
32], and the careful balance of privacy and territorial control is a key factor in the success of MSAB design.
Resident Perceptions of Comfort
Residents’ comfort is situated on a spectrum where their physiological and psychological needs are met [
11,
33,
34] and are in balance [
35]. Comfort parameters comprise both quantifiable factors, (for example, thermal comfort, acoustics, air quality and illumination) and qualitative considerations (for example, perceptions of privacy and personal control over the comfort of one’s private space). All elements interact and influence the way occupants use a dwelling and a building, and consequently their appreciation for how the overall design functions or is best modulated [
36]. For example, in Singapore, a tropical city, residents on lower floors of MSAB were concerned about noise from passers-by and street traffic, as well as view obstructions, lack of privacy, and odours from garbage, [
13,
37,
38,
39,
40,
41] while dwellings on higher floors were sought-after for cleaner air [
42] less noise, more privacy and better views [
13]. In Vancouver, a city in the Temperate Zone, residents of MSAB valued large windows for views, much-needed natural light and a sense of spaciousness, but also reported overheating and visual privacy issues [
43].
The climatic variables, air temperature, humidity, radiation and air movement influence an individual’s sensation of thermal comfort simultaneously with many subjective factors such as level of clothing, age, gender, health and personal preferences. Ventilation may be perceived to be adequate for thermal comfort when velocity of air movement is appropriate for level of activity, and [
44,
45] and acceptable when air quality is not marred by unpleasant odours or stale air [
46].
Various studies have identified noise in the urban residential environment as the greatest source of annoyance to residents [
10]. Aural comfort is experienced when sound levels are acceptable for the prevailing spatial-temporal conditions, including perceptions of acoustic privacy, and stressful or annoying or loud noises are absent [
47]. Natural lighting and views to natural surroundings are associated with beneficial social and psychological effects [
48,
49].
Generally, people are not overtly aware of ambient physical conditions and tolerate a range of variation [
50] unless comfort limits are exceeded. The design challenge is to utilise the physical attributes of building design and performance (construction quality) to create an environment that is acceptable to most building users and conducive to human comfort and well-being. Focussing solely on objective measures (such as thermal comfort) does not ensure good design and does not necessarily account for occupants’ well-being [
51]. Therefore, a well-designed dwelling is one which provides a diverse range of conditions that enables individuals to meet their personal sensory requirements when and where desired, for example noise at night in bedrooms is not desirable, but well-ventilated bedrooms are recommended for sleep health. Resident’ understandings of what makes a good environment in the domestic setting is influenced by the relative importance they place on the need for personal control with other social and cultural influences [
51,
52]. Currently, few researchers have specifically examined the relationship between privacy and comfort of the individual dwelling within the MSAB and residents’ everyday dwelling practices in the subtropical climate and lifestyle context.
3. Research Design and Method
This paper on residents’ experiences of privacy and comfort and the actions they take to modify the effect of the external environment on their dwelling’ comfort performance, presents a subset of qualitative and quantitative data obtained from an extensive study investigating the positive and negative social, environmental and economic impacts that residents associate with higher density (HD) living in a subtropical environment. At the outset it is important to note that the founding study investigated residential satisfaction [
53] and the findings indicated quite a high degree of congruity between these residents and their HD environments. Most residents were extremely satisfied with the overall HD residential environment, when taking into account their neighbourhood, neighbours and dwelling. Overall, the findings indicate a strong sense of belonging and security with most residents indicating that they would regret it if they had to move (p. 334). Nevertheless, several environmental aspects that depreciated their living experience, including traffic noise, dust and sirens, were identified. These data indicate that there is a difference between the predictors of residential satisfaction and the attributes that residents perceive to be important indicators of environmental quality.
Procedure and Participants
The inner city urban area of Brisbane was identified using the boundary defined by the Australian Bureau of Statistics. Within this boundary, six precincts demonstrating the following characteristics were purposively selected: they support residential densities greater than conventional Brisbane suburbs (based on 30–45 dwellings per hectare compared to 8–12 dwellings per hectare); have diverse land uses and services; have multi-dwelling housing typologies diverse in design and age; have a culturally diverse population; and have an engaged community. As well, these precincts represent areas with and without obvious amenity impacts (such as, heavy traffic generating noise and air pollution). Within each precinct, all multi-dwelling buildings and the total number of apartments within each building were identified, representing the HD population of the sample. A proportionate sampling technique was applied to select one third of the dwellings within each building, within each precinct. 2311 households received a postal questionnaire on “Living in the City”, to be completed by the household member (18 years or older) who had most recently had a birthday. There was a 28% response rate, with 636 questionnaires returned by post. While most addresses included in the survey were in MSAB, it is possible that some respondents lived in other types of multi-residential buildings such as walk-up flats, duplex, boarding houses, or warehouse/lofts.
Participants answered approximately 140 open and closed questions about their current dwelling, neighbourhood and neighbours, quality of life and social capital. Standard socio-demographic categories drawn from the Australian Bureau of Statistics 2006 census [
54] were used to obtain relevant data on respondents’ personal characteristics. Data for this paper were obtained from questions on design characteristics such as spatial properties of the dwelling, access to breezes and natural light, indoor climate of the dwelling, view from the dwelling, privacy, construction quality, and whether the dwelling is designed to suit the local Brisbane climate. A variety of Likert scales (typically scales with one to five response alternatives ranging from “not at all” to “extremely”, with “fairly” being the midpoint on the scale) allowed residents to circle the appropriate response indicating their level of agreement with a statement, level of satisfaction with a dwelling element and level of awareness about an issue or design aspect. Binary “yes/no” responses were also included. Open ended questions allowed participants to add an extra response. Analysis of the questionnaire was conducted using the Statistical Programme for Social Sciences (SPSS), with basic descriptive statistics such as frequencies, percentages and means calculated for all residents. The open-ended questions were analysed thematically to identify key terms that were regularly invoked by the respondents.
In addition, follow-up repeated semi-structured qualitative interviews with 24 residents, explored issues in more depth and covered their likes and dislikes of their current dwelling and neighbourhood, social contacts within the dwelling, opinions on sustainability, and design perceptions. Interviews, which were recorded and transcribed verbatim, provided rich narrative data. A thematic analysis identified key themes expressed by interviewees. More men (14) than women responded to the invitation to be interviewed, while most interviewees were owners (19). Survey respondents were predominantly aged between 25 and 59 years old (71%) and female (60%). Households were predominately one (31%) or two people (54%). The low number of households with children under 18 years old (7%) was a critical difference between the respondents and the resident population of the local statistical area (21%) [
53]. The number of renters in the study sample (44%) was higher than the ABS 2006 Census data for Brisbane area (30%), possibly illustrating the more transient nature of this population [
53]. The remainder were either owners (27%) or paying off their mortgage (28%). Participants had been living in their present dwelling for an average of 3 years and 5 months. The longest period of residency was 39 years, while the shortest was one month. Respondents lived on various floor levels, ranging from below ground (one respondent) to the 19th floor (one respondent), with the majority located on floors 1–3 (68%).
5. Challenges for Privacy and Comfort Design in the Subtropics
The findings confirm that residents consider that privacy and comfort are important attributes of liveability in subtropical MSAB, and that their ability to control these factors is influenced by building design. There are multiple challenges of meeting residents’ desires for personal control over their own space, including the desire for outdoor living, in MSAB in the subtropical urban environment. The key finding is that residents overwhelmingly prefer natural ventilation but choose air-conditioning when external conditions are too noisy or dusty to leave windows and doors open. Therefore paying attention to the control of noise is a high priority design issue for the success of MSAB living in the subtropics. The inter-relationships between thermal performance, natural ventilation and acoustic privacy and comfort in architectural design integrating layout, structure and materials specifications are extremely important to resolving this issue, rather than assuming that air-conditioning can be used to mitigate design problems.
The finding that residents were not likely to use air-conditioning in winter, and were more likely to manage thermal comfort in summer by opening windows and doors is promising in terms of energy demand management, suggesting that designs that enhance air-flow within dwellings have significant potential to reduce MSAB residents’ need to use air-conditioning. The standardisation of notions of thermal comfort in affluent societies is leading to “thermal monotony” [
61] which is becoming the norm in indoor environments as air-conditioning is used in housing to replace living spaces that are designed to respond climatic variations with human intervention. Typically, the meaning of
thermal comfort commonly used in conditioned spaces is based on the approach that assumes: (1) that “comfort” is universal; (2) that thermal variation outside the band is undesirable and (3) that occupants of buildings want neutral, dry, still air [
17]. Clearly in the subtropics, residents do not want thermal monotony and they also desire greater choice and control over personal comfort in their own homes.
However, dwellings in multi-storey buildings are potentially exposed to more noise than other housing types due to more expansive views and direct lines of sight to noise sources such as rail corridors, roads, and rooftop heating, cooling, or ventilation equipment on other structures [
62,
63,
64]. Traffic noise may also reflect upwards off the facades of the structures on either side of streets [
65]. In a vicious circle, high external noise levels are often used to justify the use of sealed environments and air conditioning in commercial and residential buildings. However, conversations and other personal noises made by humans are often the most annoying sounds and some degree of ambient noise that helps mask neighbours voices and other noise [
24] may be an important part of living in close proximity, and being able to remain “private”.
Traffic noise may be less annoying than sounds from other people in the complex, or from neighbours in other types of dwellings, during the day, but becomes less tolerable at night. Avoiding the combined impacts of traffic generated noise and air pollution is not a matter of simply closing windows and utilising air conditioning, especially with compelling evidence that people prefer natural ventilation. As well as air-borne noise, structure-borne noise is also a problem in MSABs when noises of impacts and vibrations are transmitted through the buildings’ structure and services. Acoustic privacy is highly valued by residents and the
Building Code of Australia Volume 1 requires inter-tenancy walls to have a discontinuous construction (a wall must have a minimum 20mm cavity between two separate “leaves”) to reduce noise transmission between dwelling units [
55]. The need to eliminate noise annoyance and enhance privacy is imperative, but these internal linings effectively rule out exposed thermal mass as the main element of passive thermal performance in apartments. Therefore, in a sub-tropical climate-responsive design approach, maintaining the cooling effect of natural ventilation, combined with thermal mass, must be a design priority. An approach to acoustics which integrates building plans and cross-sectional design and acoustic treatments to building facades is necessary so that windows can be kept open according to residents’ preferences. Well-designed balconies can play an effective role as sound insulators in this regard [
63,
66].
High-rise residential buildings often have large glazed areas where natural lighting levels are achieved but excessive solar heat gains or glare in both winter and summer, are introduced if orientation and external shading are inadequate [
43,
67]. These instances illustrate that objective knowledge is required to solve an array of problems simultaneously, but creative intuition is also required to provide practical solutions that respond to the human aesthetic and emotional needs of a user group (residents) with whom architects generally have no direct contact during the design process. In the subtropical humid climate, the challenge for designers is to find a balance between natural ventilation and noise, rather than designing solely for one parameter or the other. Environmentally, therefore, facilitating climate-responsive design in MSAB may help mitigate the need for air-conditioning, leading to direct reductions in apartment household energy use and contributing to the stated objectives of urban consolidation policies. In the urban environment, it seems there may be a need to provide air-conditioning as well as climate-responsive design. An ideal solution would combine the best practices of energy efficient specifications with strategically placed operable glazing that residents can adjust to capture prevailing breezes and allow daylight infiltration, exclude heat and glare, minimise unwanted noise, and provide privacy and views to the outside, according to their personal preference. Traditionally, the veranda has played this role in subtropical houses. In the MSAB, adjustable layers of external screening applied to openings and balconies may be one way of addressing multiple interrelated problems. Evidently some local apartment buildings already apply some of these principles (
Figure 4) however, concerning issues for further design research are how to provide much-needed open space and personal climate control as towers increase in height and the effects of wind conditions make cross-ventilation difficult and projecting balconies extremely uncomfortable. Further, the influences of balcony structures on the environmental behaviour of MSABs also need careful examination in conjunction with functional criteria to enable residents of various building forms and configurations to benefit from the favourable subtropical conditions.
Figure 4.
Adjustable layers of external screening applied to openings and balconies in Brisbane apartment buildings. Source: (a) Centre for Subtropical Design QUT (b) Glenn Weiss.
Figure 4.
Adjustable layers of external screening applied to openings and balconies in Brisbane apartment buildings. Source: (a) Centre for Subtropical Design QUT (b) Glenn Weiss.
6. Conclusions
This paper places multi-storey apartment buildings (MSAB) within the context of urban sustainability in the Australian urban system, and identifies the conundrums associated with the suitability and acceptance of apartment buildings as a housing type in this mix. Not only is the multi-storey building very energy-intensive in terms of both embodied energy and operational energy, but Australian residents have expressed a reluctance to transition to higher density neighbourhoods and apartment buildings. The findings contribute evidence that should help inform property developers, policy-makers, designers and residents about the key attributes that enhance the liveability of MSABs in a subtropical context, and specifically of the need for a design approach that can mitigate the environmental impact of MSABs while improving the social acceptability of MSAB dwellings as a housing type in Australia’s subtropical cities.
In particular this paper examined residents’ day-to-day experiences of their MSAB dwelling in the context of subtropical climate and lifestyle. The key findings are that residents seek flexibility and choice in how they manage privacy and comfort issues at different times of the day. Residents valued outdoor living and overwhelmingly prefer natural ventilation over continuous air-conditioning to manage thermal comfort in their dwellings. The discussion has shown the intense design interrelationships that exist between several comfort and privacy parameters in habitable apartment design (thermal comfort, acoustics, air movement, daylighting, visual and aural privacy). As well as the need to reduce reliance on air-conditioning and to deliver more nuanced personal control to residents over their private dwelling environment, the challenges of providing resident-identified liveability attributes of “openness” in the noise-laden urban environment and in taller buildings subject to windy conditions were identified, and require further research.
In mediating the surrounding environment, practical issues for MSAB design in the subtropical climate are to ameliorate the combined effects of traffic-generated noise and air pollution, and gain both acoustic amenity and the cooling effect of natural ventilation. In mediating the shared environment of the collective building, reducing noise transmission between dwellings and maintaining the moderating effect of exposed thermal mass must be addressed. Therefore maintaining the cooling effect of natural ventilation is a design priority. Achieving the right balance between thermal mass, operable openings and glazing is critical in achieving an indoor environment which is neither over- nor under-heated, is well-lit but not glary, and affords views to the outside but may not be overlooked by passers-by or other residents, and finally can be opened to breezes but is not noisy.
Another fertile area for future research is whether there are any differences in the experiences or adaptive practices of tenants when compared to owner-occupiers. Our findings suggest that residents have similar experiences whether they own or rent. Nevertheless the question is pertinent and will be addressed in a future paper because much new MSAB development in Brisbane and similar cities is speculative and is aimed at the “investor” market, meaning that most residents are likely to be tenants.
There is a clear need for further design research to be undertaken with respect to designing MSABs that perform better socially, economically and environmentally, to assist residents to interact positively with the subtropical climate and urban environment, and to control the intensity of their interaction with neighbours.