Assessing the adequacy and sustainability performance of multi-family residential buildings in Anambra State,Nigeria

Peter Uchenna Okoye,Chukwuemeka Ngwu

aDepartment of Building,Nnamdi Azikiwe University,Awka,420007,Nigeria

bDepartment of Quantity Surveying,Nnamdi Azikiwe University,Awka,420007,Nigeria

ABSTRACT

The proliferation of multi-family residential building in Anambra State of Nigeria due to increasing demand without recourse to performance has brought concerns about the adequacy and sustainability of this housing type.This study therefore,assessed the adequacy and sustainability performance of multi-family residential buildings in urban areas of Anambra State.The study sampled the opinions of 384 households living in multi-family residential buildings through a questionnaire survey.We conducted data analysis based on 214 responses that were useful for analysis.The study found that internal and building component variables and supporting neighborhood variables were adequate,but the surrounding environment variables were inadequate based on Mean Score Index.However,based on Sustainability Performance Index,the occupants perceived social sustainability performance of the buildings as satisfactory,while environmental and economic sustainability performance were perceived as fairly satisfactory.The Pearson correlation coefficient result further established that adequacy of internal and building component variables was significantly and positively related to the residents’perceived social sustainability performance.Adequacy of the surrounding environmental variables was also found to be positively and significantly related to the residents’perceived environmental sustainability performance,whereas adequacy of supporting neighborhood facilities was found to be negatively and significantly related to the residents’perceived economic sustainability performance.This suggested that investors and owners of multi-family residential buildings should direct more efforts towards improving the surrounding environment to supplements other facilities and increase the economic benefit of the renters or occupiers with increasing economic sustainability performance in terms of value for money.

ARTICLEINFO

Keywords:

Adequacy level

Economic sustainability

Environmental sustainability

Social sustainability

Multi-family residential building

Residential building

1.Introduction

New urban configurations are frequently evolving due to constant changes in urban forms(Schmid et al.,2018).Currently,dramatic urban transformation is going on in the Nigerian developmental history(Farrell,2018).The United Nation’s report shows that world population could rise from the estimated 7.7 billion people in 2019,to around 8.5 billion in 2030,9.7 billion in 2050,and 10.9 billion in 2100(United Nations,Department of Economic and Social Affairs,Population Division,2019).In Nigeria,population and urbanization are also rapidly growing,with increasing shortage of residential housing stock(Dukku,2018;Ajayi,2019;Ekpo,2019;Moore,2019;Sanusi,2019;Gardner et al.,2020).Accessibility of land,infrastructure,and building materials are some of the market variables that aggravate the gap between housing supply and demand in Nigeria(World Bank,2018).Socioeconomic variables such as deficiency in housing finance,poverty,and unemployment also have significant effects(Makinde,2014;Akinyode et al.,2018;Ezennia and Hoskara,2019).For example,an estimated 17.0 million housing units were required to meet the housing needs of Nigerian populace(World Bank,2016).World Bank(2018)estimated that it would grow at approximately 20% per annum.The increasing urban population and excruciating economic conditions have therefore,put more pressure on urban infrastructure,especially residential houses(Makinde,2014;Dizdaroglu,2017).

In specific term,the sustained security challenges in the northern Nigeria has increased the volume of people drifting southward for safety(Saidu and Yeom,2020).The cumulative effect has increased the demand for residential buildings with depleting effect on existing housing stock in the urban centers of southern Nigeria,Anambra State in particular.The incessant depletion in the number of residential accommodation witnessed in the state is further due to increasing level of industrial and commercial activities.Consequently,this creates imbalance in the demand/supply interface(Iheme et al.,2015).

Although several efforts have been made to bridge the gap between housing supply and demand by the government through publichousing provision schemes (Adenikinju, 2019), these efforts are yet to yield the desired results (Obi and Ubani, 2014; Iheme et al., 2015;Nicholas and Patrick, 2015; Oni-Jimoh et al., 2018). Further efforts through private investments in building new towns or satellite cities,residential estates, and single family houses to complement the efforts of the government have not been yielding significant result (Blochet al., 2015). Even when about 90% of urban housing are built by the private sector in Nigeria (Makinde, 2014), the reality indicates thatit is difficult to achieve an adequate and sustainable housing in Nigeria (Yoade et al., 2018), due to the nature of housing investmentclimate, housing strategy, and problem of housing finance in Nigeria (Igbinoba, 2019; Gardner et al., 2020).

Besides the needs and demands for adequate housing,the popularity of multi-family housing as a housing choice has been amplified by the desirable features of multi-family housing such as freedom from the responsibility of maintenance costs and repair time,mobility of workforce and convenient locations;and changing demographics of the urban dwellers(Zietz,2003;McMillan,2013).Another incentive for choosing multi-family housing include: avoidance of property taxes and other homeowner costs(Zietz,2003;Mehrotra and Carter,2017).In view of this,many private real estate developers have keyed into the opportunity of investing in multi-family residential building due to its high investment return(Hardin III,2014),and many of Nigerian cities(including Anambra State)are witnessing astounding and incremental housing stock than in the past decade(Bloch et al.,2015).These actions have therefore,resulted to proliferation of multi-family residential buildings mainly in form of block of flats.The scenario is more pronounced in urban areas due to pressure of the growing urban population(Giyasov and Giyasova,2018),externally generated industrialization and dynamic urbanization processes(Ogunshakin and Osasona,1991;Docampo,2014);as well as to accommodate the middle and low class urban population(Zietz,2003).

With about 62% of the population of Anambra State living in the urban centers(UN-Habitat,2012),the state is one of the mostly built-up states in Nigeria that is witnessing increasing number of multi-family residential buildings.Chunwate et al.(2019),Ezeomedo and Igbokwe(2019),and Igbokwe et al.(2019)revealed that urbanization is rapidly spreading across the length and breadth of the state and it is expected to spread even at faster rate in the near future.Particularly,the Awka-Onitsha-Nnewi urban corridor or field which is one of the urban/metropolitan regions in Nigeria that have consolidated interdependently through a poly-nucleated structure and stretched beyond a single urbanized entity(Bloch et al.,2015).It is also associated with strong demographic pressures and rapid urban growth(Bloch et al.,2015).

Amidst this development and investment,there is growing problem of adequacy and sustainability of these multi-family residential buildings as expressed by the occupants(Addo,2016).Just as in the developed countries,most of the multi-family residential buildings are privately owned and mainly for renting and commercialization without recourse to their performance,adequacy,sustainability,and serviceability(Turcu and Persson,2015).In some cases,these buildings are poorly built(Muhammad and Bichi,2014;Agboola and Ayanlade,2016)and thereby raising more concerns about the sustainability of the multi-family residential buildings.In extreme cases,there can be building collapse as can be seen in many Nigerian cities without exception of Anambra State.

Despite the growing number of multi-family residential buildings vis-‵a-vis the prevailing conditions and concerns of the occupants over the adequacy and sustainability of the buildings,studies on adequacy and performance of multi-family residential buildings were mainly from foreign countries(Zietz,2003;Mehrotra and Carter,2017;Gan et al.,2019).McMillan(2013)noted that multi-family development has remained an overlooked aspect of research in terms of urban growth and morphology.Studies in Nigeria have focused mainly on public buildings(Ibem and Amole,2011,2013;Eni,2014;Jiboye,2014;Ibem and Alagbe,2015;Olotuah,2015a;Ishiyaku,2016;Bello and Egresi,2017),low-income housing(Ibem et al.,2012;Olotuah,2015b),slum housing(Okoye et al.,2017;Odufuwa et al.,2018),students’hostels(Sawyerr and Yusof,2013;Ajayi et al.,2015;Philip et al.,2018),or traditional housing system(Yetunderonke,2015).

Interestingly,the importance of adequate and sustainable residential housing,more particularly,multi-family housing units,has become more obvious in the face of the COVID-19 pandemic,when everyone was made to stay at home due to stringent lockdown regulations applied across the world(Carey and Tshangana,2020).Consequently,for a residential building to be adequate,it is important that it should also meet sustainability requirements in terms of environmental,economic,and social performances(Poston et al.,2010;Ahmad and Thaheem,2017;Zarghami et al.,2019;Zarghami and Fatourehchi,2020).Environmentally,the building should consider energy and water efficiency,indoor environment,etc.Socially,cultural identity,health and physical comfort,local heritage,social integration,accessibility,economy and participation,and safety and privacy of the occupants are dominant sustainability requirements(Poston et al.,2010;Zarghami et al.,2019;Almahmoud and Doloi,2020).In the same vein,economic sustainability should consider local material choice and life cycle cost(Poston et al.,2010;Zarghami et al.,2019).In this sense,a sustainable building should contain the following features:ecologically and socially suitable;high resource efficient;inexpensive;accessible and flexible;healthy,secure,and safe;long-lasting;and architecturally appealing(Roshanfekr et al.,2016).Therefore,evaluating the adequacy and sustainability performance of residential homes would enhance occupants’wellbeing and dignity and offer environmental,social,cultural,and economic benefits(Janjua et al.,2019).

This study therefore,was aimed at investigating the adequacy and sustainability performance of multi-family residential buildings in Anambra State through a survey of the occupants of multi-family residential buildings in urban centers.The result of this study would be a guide to determining the occupants’preferences so as to incorporate them into future housing projects as well as improving the existing housing stock to meet the needs of the occupants.It would also provide basis for future research especially those concerned with profiling the trends of multi-family residential housing in relation to urbanization trend and population growth.Leung et al.(2012)argued that the knowledge as well as the investment drive of owners and developers of residential buildings increases when the adequacy and performance of residential building facilities are evaluated to identify the key components of buildings that impact user satisfaction.Furthermore,ˇSpalkov′a andˇSpalek(2014)pointed out that the family’s place and location of living,its adequacy,the housing type,the privacy of household members,socio-economic status as well as other factors all affect the family’s quality of life.

2.Literature review

According to Ogunshakin and Osasona(1991),a multi-family building is a kind of housing system associated with the dynamics of urbanization such that there is a need to rationalize the use of available land,infrastructural organization,and the promotion of social integration in space.Hardin III(2014)defined multi-family housing as the subdivision of a single building or group of buildings into multiple space units allowing for individual unit use,occupancy,and possibly ownership.On the other hands,Ibem and Amole(2011)described adequate housing as a building that considers the physiology,psychology,health,and security of the occupants and aspires to meet the intended requirements.UN-Habitat(2014)recognized adequate housing as a fundamental human right of persons enshrined in the International Human Rights Law and Habitat Agenda.Other basic needs of life such as good health and education depend on adequate housing(Terminski,2011).For ease of evaluation of user satisfaction and flexibility in assessing survey data,attributes of adequate housing and users’requirements are classified into physical,environmental,and external factors(Seshadhri and Paul,2017).However,a quality and sustainable housing project would depend on a converging point of accessibility,community interaction,privacy,safety,security,provision of adequate space,and availability of right services(Department of the Environment,Heritage and Local Government,2007).

Furthermore,the theory of adequate multi-family building was motivated by its recent popularity and increasing choice as a form of housing choice for the middle,low,and even high-income earners in Anambra State.Unfortunately,research into the adequacy and sustainability of multi-family building is scarce and almost non-existent in Nigeria.For example,Jiboye(2014)examined the influence of house-types on the residential quality in Osogbo,Nigeria and found that the residential quality was significantly influenced by the house-type.In Ogbomoso,Nigeria,an investigation into the adequacy of multi-habited houses with respect to spaces and privacy of residents by Yetunderonke(2015)showed that houses were deficient with regards to meeting the expectations of the occupants especially in toilet,bathroom,kitchen facilities and general spaces.While Jiboye(2014)studied housing quality of different house-types,Yetunderonke(2015)focused on the spaces and privacy of the occupants which did not reflect completely the attributes of multi-family residential buildings nor a holistic sustainability performance of buildings.

In Busan,South Korea,Kang et al.(2014)investigated the quality of four multi-family housing complexes constructed and finished at different time.The study found that health quality of multi-family housing unit with the age is 10 a only shows a decrease in managerial aspect.However,as the age increases up to 25 a,the health quality of the house begins to decrease in all aspects of housing quality(i.e.,physical,mental,social,and managerial).In S～ao Paulo,Brazil,a study on the adequacy of high-rise residential apartment buildings by Ornstein et al.(2011)showed that the recent apartment buildings focused on the aesthetic features than the end-users’real needs.The study suggested that in the domestic space,a closer link should be established between the needs of the people and human behavior.It also suggested that the users’level of satisfaction and design performances of the building should be boosted by the quality of the building’s architecture.These two studies focused on the effects of time on the quality of buildings and the components of residential apartments,respectively.

Addo(2016)examined the influence of the dwelling unit characteristics,social networks,and neighborhood facilities on the multi-habited households’residential satisfaction in Accra,Ghana.It was found that the dwelling characteristics negatively influence the satisfaction level of the households.The study also found that the greatest satisfaction level derived by households was from the community support,whereas moderate satisfaction was derived from the neighborhood characteristics.Similarly,in Ogun State of Nigeria,Ibem et al.(2013)revealed that the overall performance of public housing estates residential buildings in urban areas was generally satisfactory in term of privacy and size of living and sleeping areas,but less satisfactory in the provision of water and electricity.In addition,the study dealt with the occupants’level of satisfaction in public housing residential buildings.

Generally,the extant literature has suggested that it is imperative to evaluate the adequacy and sustainability of residential environment on the basis of housing occupants’perceived level of adequacy of housing situations with regards to meeting their needs,anticipations,and desires(Ibem and Alagbe,2015;Gan et al.,2019).Studies have also shown that adequacy and performance of residential buildings is greatly associated with the level of satisfaction of the occupants(Jiboye,2012;Okoye et al.,2020).In China,Gan et al.(2019)who explored the level of adequacy of massively constructed public housing and found that the three most influential factors affecting the overall housing adequacy were housing unit,neighborhood environment,and affordability.They further revealed that the overall level of housing adequacy and components were also significantly affected by the family income,socioeconomic characteristics of age,residence length,family members,and housing types.Ibem and Alagbe(2015)observed that the residents of housing estate and experts in housing differ in their understanding of housing adequacy.Based on the perception of the residents,Ibem and Alagbe(2015)pointed out that the four dimensions of housing adequacy(ambient condition of interiors spaces,security,utilities and neighborhood facilities;social infrastructure;level of privacy and size of sleeping areas;and living and dining areas in the residences)identified by the residents were inadequate.Meanwhile,both Ibem and Alagbe(2015)and Gan et al.(2019)have appraised factors affecting the housing adequacy and dimensions of housing adequacy,respectively.

In Ogun State,Ibem and Amole(2011)investigated the residents’perceived adequacy levels of conditions of public housing and found that housing conditions were generally inadequate in meeting the residents’needs.Specifically,the attributes of a housing unit were perceived as the most adequate,whereas neighborhood facilities were perceived as the least adequate housing components.However,Ibem et al.(2012)conducted another study,and revealed that about 50% of the residents of workers’housing estate in Abeokuta,Ogun State,which indicated that the environment within the housing estate adequately met their needs.The study further found that the adequacy of housing unit characteristics adequacy level was greater than that of housing services,social infrastructure,and housing estate management.In these studies,public housing other than private multi-family apartments were considered.

Some other studies have examined the sustainability of residential buildings.Unfortunately,most of these studies focused on the sustainability assessment frameworks,models,or rating systems(Poston et al.,2010;Ahmad and Thaheem,2017;Zarghami et al.,2018,2019;Zarghami and Fatourehchi,2020).While a holistic sustainability performance is being promoted(Poston et al.,2010;Roshanfekr et al.,2016;Ahmad and Thaheem,2017;Janjua et al.,2019;Zarghami et al.,2019;Zarghami and Fatourehchi,2020),Zarghami et al.(2017)revealed that there was a focus on social aspects of sustainability while implementing daylighting design strategies in residential houses in Iran.A study by Almahmoud and Doloi(2020)identified five underlying factors(health and physical comfort,accessibility,integration,economy,and participation)that enhance the social sustainability of neighborhood community of a new construction project.

From the foregoing,the extant literature further shows that the adequacy and sustainability performance of multi-family residential building in Nigeria has not been holistically investigated in spite of its increasing demand and supply.Based on identified housing quality variables,this study would investigate the adequacy and sustainability performance of multi-family residential buildings in Anambra State.The result of this study will serve as a basis for future investment drive in the housing sector and a means through which overall residential wellbeing of majority of urban residents of Anambra State can be improved.

3.Study area

Anambra State has the second highest population density(862.5 persons/km2at 2006)in Nigeria after Lagos State(National Population Commission,2009).In 2006,the population of the state was 4,177,828 with males making up 2,117,984 and females 2,059,844(National Population Commission,2010).It has a total projected population of 5,527,809 in 2016,which grows at 3.2% annually(National Bureau of Statistics,2018).The National Bureau of Statistics social statistics report shows that Anambra State is also one of the states with highest residential block of flats in Nigeria(National Bureau of Statistics,2020).The state has about 882,875 regular households in 2006(National Population Commission,2009).However,with the current average household size of 4.61(National Bureau of Statistics,2020)and projected population of 6,084,786,the number of households in Anambra State in 2019 was approximately 1,319,910.Out of this,26.4%(approximately 348,456)are living in apartment/flat dwellings(National Bureau of Statistics,2020).Thus,the population of this study are all those living in apartment/flat dwellings and residing in Anambra State according to the National Bureau of Statistics(2020)report.Since majority of apartment/flat buildings are found in the urban areas,the population of this study would be 348,456 households.However,this figure is far from the true reflection of the number of households living in multi-residential apartments in Anambra State. For example, Obosi, an urban town in Idemili North Local Government Area and a neighboring community to Onitsha can boast of more than 5000 fully occupied block of flats alone.Furthermore,about 51.4% and 36.6% of the households live in their own buildings and rented buildings,respectively(National Bureau of Statistics,2020).As earlier noted,one of the mostly built-up states in Nigeria is Anambra State (UN-Habitat, 2012), with urbanization growth rate from 33.67% to 37.24%, between 2008 and 2017 in the state capital Awka(Igbokwe et al.,2019).On this basis,Anambra State was chosen for this study.

4.Methodology and data

Fig.1.Flowchart of research methodology.

A housing and household survey research was conducted on privately-owned multi-family residential(block of flats)buildings in Anambra State.The survey was carried out across urban cities in Anambra State.These cities are witnessing an increasing number of block of flats due to their status and nature of activities going on in them.Questionnaires were administered to heads or representatives of households living in multi-family residential buildings.The researchers employed the services of helpers who were residents of the areas where the survey was conducted.These helpers assisted the researchers by accompanying them in distributing and retrieving the questionnaires due to their familiarization with the areas.Fig.1 shows the flowchart of the research methodology.

Ordinarily,one wouldn’t have been expected to study the entire population,rather a representative of the population upon which inferences could be generalized was sampled and studied.However,four approaches of determining the sample size have been suggested by Israel(2013):(1)using census of a small population;(2)using sample size from a similar study;(3)using published tables;and(4)using formulas to estimate.The sample size of this study was therefore estimated using Cochran’s sample size formula which is suitable when a large population is involved in the study as it is with the present case(Cochran,1977).In the first instance,the sample size would be estimated using Equation(1).

where n0is the sample size;t is the value of alpha(0.025)in each tail(t=1.96);p is the estimate of variance(p=0.5);q is 1–maximum possible proportion(maximum possible proportion=0.5;q=0.5);d is the margin of error(d=0.05);and N is the population size.However,if n0>5% of the population size,the actual survey sample size would be computed using Equation(2)(Cochran,1977);else,n0remains the sample size.

Since n0was 384,lower than 5% of apartment/flat dwellings population(17,423),than the survey sample size n1=n0=384.

Although the sample size was less than 5% of the apartment/flat dwellings population which may limit the generalization of the result,Siddiqui(2013)argued that the appropriate sample sizes depend on the number of items available for analysis.Taherdoost(2016)also suggested the important factors in determining the appropriate sample sizes:the absolute size of the sample selected relative to the complexity of the population,the aim of the researcher,and the kinds of statistical manipulation that will be used in data analysis.Based on the above position,the sample size for this study was sufficient.

无线通信用电信息采集系统适合应用在用户密度低、电表安装分散、对数据实时性要求不高的情况。特别是农村、城市边缘、乡镇等地区的用户分布情况和无线信道情况都非常适合使用无线通信采集系统。

A simple random sampling was adopted in selecting the desired samples for the buildings and households in the survey.This is because the buildings are not sequentially located or clustered in a particular area.However,the selection was based on certain specified criteria.

The respondents must be the head of the household or a designated representative who must be an adult,who have lived in the building for at least one year.Only one respondent could be selected per building since a multi-family building is assumed to have the same form,shaped,size and facilities in each apartment.The building must be housing more than two households and have more than one floor.Only respondents who consented to the survey request in the course of the survey were included.

Based on the sample size,we distributed 384copies of questionnaire to 384 households living in the same number of buildings across the study area.Consequently,226 questionnaires were retrieved,out of which 12 were found to be invalid and discarded because they were either return empty or partially filled with vital parts missing.Therefore,214 representing about 55.73% were found to be adequate,suitable,and used in the analysis.

Meanwhile,the questionnaire was made to investigate the adequacy and sustainability performance of multi-family residential buildings in urban centers of Anambra State,on account of certain housing adequacy and sustainability performance criteria.To ensure that the questionnaire items are representative of all aspects of the constructs being measured in the study,an in-depth review of extant literature was carried out from which variables for the study were extracted.Firstly,the assessment measure was matched to the aim of the study.The questionnaire was compared with other questionnaires used in related studies.Further assessment was carried out by the researchers for troublesome wordings and other difficulties associated with the understandings of respondents on the subject matter of the study.For adequacy and suitability,the questionnaire was presented to two academic experts in the field of study for expert evaluation.Through the input of these experts,the questionnaire was modified,and irrelevant items were discarded with inclusion of few other items especially as it relates to sustainability performance.The questionnaire consists of three sections.Section 1 captures the demographic characteristics of the respondents. Section 2 contains 32 variables measuring the adequacy of facilities within and around a multi-family residential building.Whereas,Section 3 comprises 28 variables measuring the sustainability performance of buildings.To ensure the effectiveness of score,a universal scale of measurement for the questionnaire items was employed to obtain valid scores from the respondents.Here,5-point Likert scale was adopted as the measurement scale.Based on the assessment variables,respondents were asked to express their perceptions on the adequacy and sustainability performances of multi-family residential buildings(1=very inadequate/dissatisfied,2=inadequate/dissatisfied,3=neutral,4=adequate/satisfied,and 5=very adequate/satisfied).

The Cronbach’s alpha was used to determine the reliability of the total responses.The uni-dimensionality of the questionnaire was assessed using the mean inter-item correlation.In this case,a Cronbach’s Alpha of>0.6 would imply that the instrument for collecting data for this survey is reliable(Tavakol and Dennick,2011;Adeniran,2019;Ekolu and Quainoo,2019),in consideration of Panayides(2013)and Taber(2018)concerns about the acceptable Cronbach’s Alpha benchmark.

According to the nature of this survey data,the margin of error(ME)and confidence interval(C.I)were±5% and 95% respectively(Bartlett et al.,2001;Ahmad and Halim,2017).The ME was derived from Equations(3)and(4).

where CV is the critical value;SE is the standard error;SD is the standard deviation;n is the sample size.

In this case,the Alpha level α =1–C.I/100=0.05;and since the test was a two-tailed test,we determined the critical probability(p＊)as follows:p＊ =1–α/2=1–0.05/2=0.975,and the degree of freedom(df),as follows:df=n–1=384–1=383.

Descriptive and quantitative analyses were carried out on the data generated from the survey.The buildings’level of adequacy and sustainability performance were computed following the perceived responses from the respondents using Mean Score Index(MSI)and Sustainability Performance Index(SPI),respectively.MSI was computed using Equation(5).

where fiis the number of response for each weight;wiis the weighting given to each variable by the respondents(from 1 to 5);and N is the total number of response.

Similarly,SPI was computed using Equation(6).

where wiis the weighting given to each variable by the respondents(from 1 to 5);fiis the number of response for each weight;A is the highest weight(A=5);and N is the total number of response.

Based on the MSI and SPI,we determined the weighted average of each of the building adequacy parameters and sustainability performance criteria,respectively.Accordingly,five adequacy levels are transformed from the MSI values as:very adequate(VA;4.5≤MSI≤5.0),adequate(A;3.5≤MSI<4.5),fairly adequate(FA;2.5≤ MSI<3.5),inadequate(IA;1.5≤MSI<2.5),and very inadequate(VIA;1.0≤MSI<1.5).Likewise,the five performance levels from the SPI values are as: very satisfactory(VS;0.8≤SPI≤1.0),satisfactory(S;0.6≤SPI<0.8),fairly satisfactory(FS;0.4≤SPI<0.6),unsatisfactory(US;0.2≤SPI<0.4),and very unsatisfactory(VUS;0.0≤MSI<0.2).

Subsequently,the nature and extent of relationship between the adequacy and sustainability performance of multi-family residential buildings was established from the Pearson’s correlation coefficient(γ)through testing of null hypotheses.Decision on whether there is a significant relationship between the adequacy level and sustainability performance of multi-family residential building was taken through the result of Pearson’s correlation coefficient.In this case,if P<0.05,H0(no significant relationship between the adequacy level and sustainability performance of multi-family residential building)would be rejected,otherwise it would be accepted and conclusion would be drawn.The whole analysis was done using SPSS version 22 and results are presented in succeeding section.

5.Results

Table 1 presents the respondents’demographic data.It showed that majority(82.71%)of the respondents are male,indicating that most of the heads of households are male.Out of this number,most of them fall within the middle ages of 31–60 a.Likewise,majority(75.70%)are married,while about 16.82% are still single hand.More than half(67.76%)of the respondents have a household size of five persons or more.It also revealed that all the respondents are lettered at least up to primary school level.This implied that the respondents have the requisite knowledge to respond to the questions for the study.Interestingly,most(89.25%)of the respondents live in a rented house which is an indication of the challenges of housing ownership in the state.

Table 1Respondents’demographic data.

Table 2Level of adequacy of multi-family residential building.

Generally,majority of the respondents are gainfully employed,either employed in white-collar job/private(50.93%)or selfemployed(36.92%).This suggests that majority of the multi-family residential building occupiers are middle-income earners.It is an indication of the changing status of urban residents.The survey result further revealed that most of the respondents have lived for at least 2 a(89.72% cumulative)in the building they are currently occupying,thus in good position to measure the adequacy and building performance level.

In terms of building form,all the surveyed buildings are of 2 floors and above.Majority of the buildings contain between 5 and 10 apartment/flats each.Most(87.85%)of the buildings contain 2 flats per floor.This shows that the buildings met the criteria for multifamily dwelling.Similarly,majority(70.09%)of the buildings are of 3-bedroom apartments.This could be likened to the demand or choice of the people due to the size of households.

Table 2 shows the MSI result of multi-family residential buildings’adequacy in Anambra State.The overall adequacy level revealed that the internal and building component(IBC)variables(3.82)and supporting neighborhood(SN)variables(3.76)were perceived as adequate,while the surrounding environment(SE)variables(2.25)were perceived as inadequate.However,the three most adequate facilities under IBC variables are size and layout of bedrooms,roof type and condition and size,and number and layout of openings.Whereas the three most adequate variables under SN facilities are place of worship,education facilities and commercial and business facilities.Although the SE variables are generally inadequate, telecommunication network and power supply were found to be adequate.Meanwhile, out of a total of 32 variables considered, none was perceived as very adequate, 19 as adequate (10 from IBC variables, 2 fromSE variables, and 7 from SN variables), 6 as fairly adequate (2 from IBC variables and 4 from SN variables), and 7 as inadequate (from SEvariables).

This suggested that the owners or investors of multi-family residential buildings pay a greater attention to forms,shapes,and attributes related directly to building units rather than other facilities that would supplement the comfortability of the residents living in and around the buildings.However,the result revealed that there is a total lack of commitment in the public infrastructure provision such as access roads,public water supply,refuse disposal,and open spaces for parks.Even within the building surrounding,there is lack of space for parking and for other outdoor activities as shown by the results.

Table 3 shows the result of SPI of multi-family residential buildings’performance level in Anambra State.The overall environmental sustainability(ENV)performance(0.57)and economic sustainability(ECO)performance(0.43)levels revealed that the buildings wereperceived as fairly satisfactory.However,the overall social sustainability(SOC)performance level(0.68)was perceived as satisfactory.The three most environmentally performing aspects of the building component variables are in the form of visual comfort,natural lighting and ventilation,and healthy internal environment.Economically,the buildings mostly performed in maintenance and serviceability,economic value,and utility rate.Whereas,three most socially performing aspects of the buildings are visual privacy between apartments/buildings,social image and reputation,and durability and safety.Out of 28 performance criteria considered,3 were perceived as very satisfactory(2 from environmental sustainability performance and 1 from social sustainability performance);9 as satisfactory(2 from environmental sustainability performance and 7 from social sustainability performance);12 as fairly satisfactory(4 from environmental sustainability performance,6 from economic sustainability performance,and 2 from social sustainability performance);and 4 as unsatisfactory(2 from environmental sustainability performance and 2 from economic sustainability performance).

Table 3Level of sustainability performance of multi-family residential buildings.

Of particular interest is the economic sustainability performance level. The result suggested that the choice for this type of residentialdwelling is not as a result of economic gain from the residents rather because of social benefits as also indicated in this result. The overallperformance level could be attributed to the level of adequacy of certain variables in and around the buildings that would influence theresidents’ perceived performances of the buildings.

Table 4 presents the correlation between different aspects of housing adequacy and sustainability performance levels of multi-family buildings as perceived by the residents.The result showed that IBC and SE are positively related with both ENV(r=0.073 and P=0.152,respectively)and SOC(r=0.224 and P=0.050);but while IBC is insignificantly related with ENV(P=0.288),it is significantly related with SOC(P=0.001).On the other hands,SE is significantly related with ENV(P=0.026)and insignificantly with SOC(P=0.468).However,both IBC(r= –0.032 and P=0.637)and SE(r= –0.077 and P=0.262)are negatively and insignificantly related with ECO.The result also revealed that SN is negatively related with all the three aspects of sustainability performance.Further,while SN is insignificantly related with both ENV(P=0.154)and SOC(P=0.778),it is significantly related with ECO(P=0.023).

Table 4Result of correlation between adequacy and sustainability performance of multi-family residential buildings.

This result implied that adequacy of IBC,SE,and SN variables would reduce ECO,which could be seen in the form of higher rental rate,unaffordable building,higher utility rate,security rate,etc.It also indicated that provision of SN variables either from the government or private individual has not been reflected on the buildings’sustainability performance due to the presence of other variables such as socioeconomic factors and individual status that could have strong influences on the residents’perceptions and dispositions.The result further suggested that SE variables have strong positive influences on environmental performance(e.g.,visual comfort,natural lighting and ventilation,healthy internal environment,etc.);whereas IBC variables have strong positive influence on social performance(e.g.,visual privacy between apartments/buildings,social image and reputation,mutual support among residents,etc.).

6.Discussion

Arising from the object of this study,it could be acknowledged that there is a dominance of multi-family residential building as a growing housing-type choice for urban residents in Anambra State.As suggested by this study,the reason is not because of economic value gained by the occupants but social value.However,the result indicated that IBC of multi-family residential building are adequate especially in the areas of size and layout of bedrooms,roof type,condition,and size,number and layout of openings,etc.This result is in contradiction with the finding of Yetunderonke(2015)about the adequacy of toilet,bathroom,kitchen facilities,and spaces of multi-habited buildings in Ogbomoso.The difference could be as a result of difference in the ownership of the buildings.Whereas Yetunderonke(2015)studied public building,the current study focused on privately owned buildings.The study both supports andcontradicts Ibem and Amole(2011)in term of housing unit variables and SN facilities,respectively.This could be due to the differences in the study location,setting(public housing estate vs.private multi-family building),and socioeconomic variables.It also disagrees with Ibem et al.(2012),who posited that the buildings do not adequately met the expected level of surrounding environment facilities needed by the residents.Whereas this result indicated that SN facilities of the buildings are adequate,mainly in the areas of place of worship,education facilities,commercial and business facilities,etc.The perceived adequacy of SN variables could be due to the high concentration of multi-family residential buildings which attract high population in these areas,and provision of these general facilities either privately or by the government.

Contrarily,the result indicated that SE facilities are grossly inadequate especially in terms of parking spaces within the compound,access roads to the buildings,water supply to the buildings,playing spaces for children,and fire safety facilities in the buildings.This implied that irrespective of the efforts of multi-family residential building investors in ensuring the adequacy of the building components and forms,and the complementing neighborhood facilities,SE facilities for outdoor activities are still lacking.These are expected to complement the adequacy of a residential building,and thereby satisfy the occupants.The adequacy of these variables could also be attributed to the business-driven motives of most multi-family residential building owners.

In spite of the adequacy of IBC and SN variables,the result indicated that the multi-family buildings are not meeting the ENV and ECO performance but SOC performance as perceived by the residents.Expectedly,the residents perceived the ENV and ECO performance of the buildings as fairly satisfactory but perceived SOC performance as satisfactory.This result supported the finding of Jiboye(2012)and Okoye et al.(2020).This could also be attributed to the occupancy status of the residents where majority of the respondents were renters.However,the perceived satisfaction level of the residents on SOC performance could not be as a result of economic gain or meeting of environmental criteria or adequacy of facilities,but could be associated with other benefits of multi-family residential building such as privacy of households,social image and reputation,composition and attractiveness,mutual support among residents,changing status of residents,etc.(Zietz,2003;Mehrotra and Carter,2017).Incidentally,few indicators of environmental performance which are associated with basic form and shape of building were met because the components in the buildings are adequate(see Table2).This study also agrees entirely with Addo (2016) on the satisfaction level of the supporting neighborhood facilities but partiallywith Ibem et al. (2013) on the satisfaction level of the privacy and sizes of living and sleeping areas, and provision of water andelectricity.

Furthermore,the result indicated a complex scenario.It showed that adequacy of IBC variables is significantly and positively influencing the residents’perceived SOC performance of the building.Likewise,the result indicated that adequacy of the SE variables is also positively and significantly influencing the residents’perceived ENV performance.However,the result revealed that adequacy of SN facilities is negatively and significantly influencing the residents’perceived ECO performance.This could be seen in the form of increasing rental rate,unaffordability of building,higher utility rate,security rate,etc.This highlighted the significance of SE variables on ENV performance of multi-family residential buildings.Although the result also suggested that the level of adequacy of housing variable is associated with the perceived level of multi-family residential building occupants’satisfaction,the overall result indicated that the satisfaction of the occupants about residential buildings cannot be entirely dependent on the adequacy of housing variables in all cases.Accordingly,socioeconomic factors,cultural attributes,and other factors such as convenient locations,mobility of the workforce,avoidance of maintenance costs,and homeowner costs,could play a substantial role in the determination of the perceived satisfaction level of an occupant of a building(Zietz,2003;McMillan,2013;ˇSpalkov′a andˇSpalek,2014;Mehrotra and Carter,2017;Gan et al.,2019).

7.Conclusions

The basic principle of a residential building is to satisfy the resident’s needs and expectations in terms of adequacy and performance.But as the numbers of multi-family residential buildings continue to grow,especially in urban areas of Anambra State due to increasing demands and changes in urban status,concerns are raised about the adequacy and performance of this residential housing type.This study has therefore,evaluated the adequacy and sustainability performance of the multi-family residential housing type in urban areas in Anambra State.The study found that internal and building component variables and supporting neighborhood variables were adequate,but the surrounding environmental variables were found to be inadequate.It also showed that the buildings were perceived as satisfactory in terms of social sustainability performance and fairly satisfactory in terms of environmental and economic sustainability performance regardless of the level of adequacy of internal and building component variables.This implied that the existing multifamily residential building stocks in Anambra State are not holistically adequate and sustainable.This is because for a building to be adequate and sustainable,it has to meet the internal and building component requirements,supporting neighborhood and surrounding environmental requirements.On the other hand,it has to meet the environmental,economic,and social sustainability performance criteria.

Furthermore,the study revealed that adequacy of internal and building component variables is significantly and positively related to the residents’perceived social sustainability performance.Similarly,the adequacy of this variable is positively and significantly related to the residents’perceived environmental sustainability performance.It also indicated that adequacy of the supporting neighborhood facilities is negatively and significantly related to the residents’perceived economic sustainability performance.On this basis,this study argued that the residents’satisfaction level about residential buildings cannot be entirely dependent on the adequacy of housing variables in all cases but also on other factors.

Implicitly,since multi-family residential building is an emerging residential housing choice for urban residents in Anambra State where private real estate developers are currently investing to satisfy the housing needs of the increasing urban population,and to make investment returns,this study has highlighted the needs and expectations of multi-family residential building occupiers.These include:the internal and building components,the surrounding environment,and the supporting neighborhood facilities.It has indicated where more emphasis should be placed when considering investing in multi-family apartment buildings or during design and construction of such buildings.This included:building forms,shapes and attributes related directly to building units.It has also indicated that improvements are needed in the existing buildings in the areas of environmental and economic sustainability performance,so as to meet the users’satisfaction level and expectations.Therefore,investors should direct their efforts towards improving the surrounding environment to augment the internal and building components and supporting neighborhood housing adequacy variables.This may increase the economic benefit of the renters or occupiers,thus increasing the economic performance of the building in terms of value for money.

Expressively,this study has provided appreciable information about the residential housing choice with a particular emphasis on multi-family buildings.However,major drawback of this study is its localization in one state out of 36 states in Nigeria,and the number of samples for the study.Since there may be differences in the nature and rate of development,and mode of provision and operation of multi-family residential buildings and associated surrounding facilities across states,the application of the results of this study may suffer generalization across the nation.Besides,different states may have different development control laws that guide the provision and operation of buildings of any kind.Notwithstanding,multi-family residential buildings have almost the same features and functions all over the world.Hence,the value of this study could be extended beyond the area of study especially for the investors,owners,and occupants.This study also would be a guide for future research in the areas of adequacy and sustainability of multi-family residential housing in Nigeria.It has therefore,added to the scanty body of knowledge and craves for more research interest in that direction.Undoubtedly,multi-family residential building is a trending residential housing choice for urban residents not only in Anambra State,in terms of demand and supply.Future researches should be directed toward profiling the trends of multi-family residential housing in the state and other states and in relation to urbanization trend and population growth.This study further recommended for cross-sectional studies involving more states and larger samples to examine if there would be changes in the adequacy and sustainability of multi-family residential buildings due to differences across states and sample size effects.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.