- Email: [email protected]
Residents’ responses on indoor environment quality and energy use in apartments
G Model
ARTICLE IN PRESS
ENB-5486; No. of Pages 5
Energy and Buildings xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild
Residents’ responses on indoor environment quality and energy use in apartments Tae Kyung Lee a , Jeong Tai Kim b,∗ a b
Department of Housing and Interior Design, Pusan National University, Busan, 609-735, Republic of Korea Department of Architectural Engineering, Kyung Hee University, Yongin, 446-701, Republic of Korea
a r t i c l e
i n f o
Article history: Available online xxx Keywords: Structural equation model Indoor environment quality Overall residential satisfaction Residents’ attitude of energy using
a b s t r a c t Indoor environment quality is an essential condition to establish a healthy housing environment. Residents’ attitude about energy is critical to their living and residential satisfaction. The purpose of this study is to suggest a structural equation model regarding the relationship among the evaluation of indoor environment quality, overall residential satisfaction, and residents’ attitude of energy using. The method of this study was document research and questionnaire survey research. First, this study analyzed residents’ evaluation on indoor environment quality and overall residential satisfaction. Second, this study analyzed residents’ awareness and behavior about energy use in their home. Third, this study established a structural equation model according to the relationship among variables (indoor environment quality, residents’ attitude of energy using, and overall residential satisfaction). And this study verified the model by using AMOS18.0. The results of this study can be utilized as basic materials to develop healthy housing design manual from the perspective of psychological and managerial aspects. © 2014 Elsevier B.V. All rights reserved.
1. Introduction 1.1. Study background This study aims to design a housing environment in which residents can live healthy lives. Poor housing environments can negatively affect a resident’s overall lifestyle, and may cause physical, psychological, and social problems, deteriorating their quality of life. As such, it is critical to put increased effort in enhancing housing environments to provide everyone in the modern society with higher standards of living. As the quality of housing environments becomes more important, researchers are becoming increasingly necessary in handling the quality of environments in apartment complex. Several studies have already addressed methodologies for evaluating the quality of housing environment [1,2], and raised concerns over the need for evaluation criteria which encompass both objective and subjective assessments [3,4]. In this regard, resident satisfaction with the housing environment can be interpreted as a comprehensive evaluation result which represents the psychological status formed by the interaction between different variables within the
∗ Corresponding author. Tel.: +82 1052836838; fax: +82 312062109. E-mail addresses: [email protected], [email protected] (J.T. Kim).
environment [5]. Resident satisfaction is accordingly used as an important evaluation criterion that comprehensively measures the quality of the housing environment. Indoor environment quality (IEQ) is also regarded as an important part of building performance and generally is evaluated based on four aspects (lighting, noise, thermo, and air). While indoor environment evaluations were mostly based on objective, technical criteria [6,7] in the past, modern IEQ tests include both objective and subjective factors in order to compile a comprehensive evaluation [8,9]. As such, Cho et al. conducted subjective evaluations on indoor environment quality based on resident satisfaction in addition to objective evaluations. They also emphasized the importance of such satisfaction by discussing its affects on overall resident satisfaction. Recently, both residential space and home appliances have become increasingly larger. As a result, energy consumption has risen and building energy management, particularly in apartments that account for over 50% of the total urban residence, has become increasingly more important. Consequently, construction and engineering companies are now developing new housing designs and technologies to better converse energy; various studies have been conducted to properly evaluate their energy efficiency [10,11]. And also various studies have been conducted in energy consumption behavior of residents [12,13]. Residents’ awareness of energy conservation has been seen to also directly affect their housing
http://dx.doi.org/10.1016/j.enbuild.2014.10.084 0378-7788/© 2014 Elsevier B.V. All rights reserved.
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
G Model ENB-5486; No. of Pages 5
ARTICLE IN PRESS T.K. Lee, J.T. Kim / Energy and Buildings xxx (2014) xxx–xxx
2
management costs. Their energy-saving efforts have been shown to have a positive impact on their residential satisfaction and pride [14,15]. As such, residents’ attitudes, including awareness and behavior, can be regarded as critical factors in improving overall residential satisfaction. This study aims at suggesting and verifying a structural equation model to quantitatively and specifically identify relations among indoor environment satisfaction, overall residential satisfaction, and energy attitude. This equation model is designed to help understand the importance of indoor environment and resident attitudes to the overall quality of housing environment. 1.2. Study contents and methodology This study is designed to explain the affects of resident indoor environment satisfaction and energy attitude on overall resident satisfaction by creating a structural equation model. Ultimately, this model is to serve as groundwork for ways to create a healthy residential environment of apartments where residents can continuously reside and be satisfied. To this end, this study conducted both literature reviews and empirical surveys. Details are as follows: (1) As for the document research, we identified the characteristics of indoor environment quality and residents’ attitude of energy using in regard to overall housing quality. (2) And we reviewed the outline and characteristics about a structural equation model as a statistical method. Additionally, we suggested a structural equation model according to the relationship among variables (the indoor environment quality, overall housing quality, and residents’ attitude energy using). As for the survey research, questionnaire survey was conducted on the residents of apartments in Pusan. Survey tool was developed to evaluate the overall residential satisfactions, indoor environment quality, and attitude of energy using, all of which previous studies and papers identified as important variables. (1) We analyzed residents’ evaluation on indoor environment quality and overall housing quality, and examined the importance of indoor comfort for housing environment quality. (2) And we analyzed residents’ awareness and behavior about energy using in their home. (3) Lastly, this study verified the structural equation model by using AMOS18.0, so that we analyzed correlations among variables. The questionnaires were designed to be easily comprehensible for the respondents. Evaluation items of the indoor environment quality encompass general conditions such as thermal, noise, light, and air in both summer and winter (Table 2). Evaluation items of the attitude of energy using encompass general awareness of residents about energy saving, energy-saving activities, and energy consumption patterns. The survey questionnaire included questions on overall housing satisfaction in order to comprehensively address housing environment quality. Five-point scale questionnaires were adopted to examine residents’ evaluation through their satisfaction level about indoor comfort; ‘Not satisfied at all’ = 1, ‘Generally not satisfied’ = 2, ‘Neutral’ = 3, ‘Generally satisfied’ = 4, and ‘Highly satisfied’ = 5. The questionnaire survey was conducted on the wives in apartments from February 5, 2012 to February 10 as a preliminary research. A total of 298 out of 350 distributed (85.0%) were collected and analyzed. SPSS program 18.0 (T-test, ANOVA) and Amos
Table 1 Characteristics of subjects. Items
Details
N (%)
M (SD)
Age of housewife
30s or under 40s 50s 60s or over Total High-school graduate Over college Total Employed Full-time housewife Total Two persons or under Three persons Four persons Five persons or over Total Under 300 300–400 400–500 500 and over Total 79 m2 –95 m2 105 m2 –119 m2 135 m2 –148 m2 Total Own Rent Total
44 (15.4) 129 (45.3) 94 (33.0) 18 (6.3) 285 (100.0) 112 (39.4) 172 (60.6) 284 (100.0) 117 (43.0) 155 (57.0) 272 (100.0) 40 (13.4) 73 (24.5) 151 (50.7) 34 (11.4) 298 (100.0) 67 (22.7) 97 (32.9) 64 (21.7) 67 (22.7) 295 (100.0) 86 (28.9) 143 (48.0) 69 (23.2) 298 (100.0) 242 (81.2) 56 (18.8) 298 (100.0)
47.2 (8.2)
Education level of housewife Employment of housewife Number of family
Average monthly income (ten thousand won) Housing size
House ownership
–
–
2.6 (0.9)
–
109.3 (7.6)
–
18.0 (structural equation model) were utilized to analyses of the survey results. 2. Residents’ evaluation of indoor environment in their apartments 2.1. General description of respondents According to demographic surveys shown in Table 1, the wives are 47.2 years old on average (SD = 8.2). Of the wives, 57.0% are fulltime, and most were highly educated (60.6% were college graduates or higher). With regard to family composition, most were nuclear families having three to four family members (75.2%). Approximately half (54.6%) of the respondents reported a monthly income of 3 million–5 million Korean won, and 22.7% have a income of over 5 million won. With regard to housing size, the proportion with areas of 105 m2 –119 m2 was high and the size is 109.3 m2 on average (SD = 7.6). Regarding the ownership of the units, 81.2% of the respondents owned their apartments. 2.2. Residents’ evaluation of indoor environment quality Indoor environment quality was assessed by residents’ satisfaction levels. Residents presented a moderate satisfaction level about the overall indoor environment. To demonstrate item by item, subjects rated heat, air, and light conditions as moderate or better, while they were dissatisfied with noise conditions (N1, N2, and N3 in summer season, N2 in winter season). Evaluations on the noise conditions also differed between two seasons, when summer season (N1, N2, and N3) showed more dissatisfactions than winter season. And overall housing quality was assessed by residents’ satisfaction of overall residential environment (Question: “I and my family are satisfied to residential environment and want to live here continuously.”). The satisfaction level of overall residential environment is 3.5 (0.7). It means that residents were very satisfied with their residential environment.
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
G Model
ARTICLE IN PRESS
ENB-5486; No. of Pages 5
T.K. Lee, J.T. Kim / Energy and Buildings xxx (2014) xxx–xxx
3
Table 2 Satisfaction of indoor environment quality M (SD). Items
Details
Summer season
Winter season
Total
Thermal
T1—Thermal sensation T2—Humid A1—Air current A2—Ventilation N1—Noise(supply, drainage facilities) N2—Noise(life between neighborhood) N3—Noise(outdoor) L1—Sunshine, natural lighting condition L2—Illumination(dark, dazzle) L3—Privacy
3.3 (0.7) 3.2 (0.7) 3.3 (0.8) 3.3 (0.8) 2.9 (0.9) 2.8 (0.9) 2.8 (0.9) 3.3 (0.8) 3.4 (0.7) 3.1 (0.9)
3.2 (0.9) 3.2 (0.8) 3.2 (0.7) 3.2 (0.7) 3.0 (0.8) 2.9 (0.9) 3.0 (0.9) 3.2 (0.9) 3.3 (0.8) 3.3 (0.9)
3.3 (0.8) 3.2 (0.8) 3.3 (0.8) 3.2 (0.8) 3.0 (0.8) 2.8 (0.9) 2.9 (0.9) 3.3 (0.9) 3.3 (0.8) 3.2 (0.9)
Air Noise
Lighting
Table 3 Residents’ attitude of energy using.
review, hypotheses and theoretical models were established, (Fig. 1) and verified the structural equation model by AMOS 18.0
Items
M (SD)
Attitude 1: I and my family recognize importance of energy use and saving in the house Attitude 2: I and my family are interest in energy-cost Attitude 3: I and my family recognize that life conveniences is more important than energy-saving activities
3.96(0.69) 3.84(0.74) 2.91(0.88)
‘Not at all’ = 1, ‘Generally not’ = 2, ‘Neutral’ = 3, ‘Generally so’ = 4, and ‘Highly so’ = 5.
3. Residents’ attitude of energy using in their apartments Residents’ attitude of energy using was investigated by three items (Table 3). Residents recognized importance of energy consumption and saving in their apartments (mean = 3.96). They were very sensitive to energy charge and apartment maintenance (mean = 3.84), while participation level of energy saving activities was relatively low (mean = 2.91). 4. Structural equation model In this chapter, relations between overall resident satisfaction, indoor environment satisfaction, and energy attitude are examined by utilizing a structural equation model. Based on the literature
4.1. Outline of structural equation model (SEM) A structural equation model (SEM) is an advanced statistical methodology widely used in the social sciences and able to produce more informative results than any other statistical tool to date. An SEM overcomes the limitations of previous statistical models (such as multiple regression, factor analysis, ANOVA, and discriminant analysis) which show only one side of relations between variables. Path coefficients delivered by an SEM demonstrate the relative influences of causalities and correlations, and thus can be used to verify the causalities of variables produced by other statistical methods. It is necessary to assess to what extent a model can be accepted to verify hypotheses; the following coefficients and indexes are used as criteria for such assessment. Among the many fit indexes, CMIN/DF (mormed 2 ) and GFI (Goodness of Fit Index) are frequently used as absolute fit indexes and NFI (Bentler–Bonett Normed Fit Index), TLI (Turker Lewis index) and CFI (Comparative Fit Index) are used as incremental fit indexes. RMSEA (Root Mean Square Error of Approximation) is also often utilized among others. Fit indexes are not statistics which can be interpreted as official results of statistical verification; rather, they are empirical numbers which explain the goodness or fitness of a model. In order words,
Fig. 1. Structural equation model.
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
G Model ENB-5486; No. of Pages 5
ARTICLE IN PRESS T.K. Lee, J.T. Kim / Energy and Buildings xxx (2014) xxx–xxx
4 Table 4 The validity of the model according to model fit-index. Evaluation of pats
Unstandardized coefficients
Standardized error
Path 1—Indoor environment quality affects to overall residential satisfaction positively. 0.23 0.03 Indoor environment quality → overall residential satisfaction Path 2—Residents’ attitude of energy affects to overall residential satisfaction positively. 0.16 0.17 Residents’ attitude of energy → overall residential satisfaction Path 3—Residents’ attitude of energy affects to indoor environment quality. 1.21 0.55 Residents’ attitude of energy → indoor environment quality 2 (df) 858.23 (18) * **
p value 0.00
CFI 0.92
C.R.
p
Standardized coefficients
7.36
**
0.52
0.89
0.37
0.07
2.20
*
0.25
NFI 0.89
GFI 0.95
AGFI 0.91
RMSEA 0.08
p < 0.05. p < 0.01.
since they cannot be used for statistical verification, numbers delivered by fit index models can be used as absolute criteria for only limited occasions. Accordingly, the indexes are used to decide a model’s acceptance [16]. This study also comprehensively taps into different indexes to verify the fitness of the proposed model.
4.2. Research hypothesis and modeling Previous studies found that indoor environment quality had significant influences on overall resident satisfaction. Studies also found that resident energy awareness affected energy behavior and ultimately overall resident satisfaction. For this study, three theoretical hypotheses and a structural model were built based on the aforementioned findings. Energy attitude was assumed to be the most important variable affecting overall residential satisfaction. This was done in order to examine the influences of indoor environment satisfaction on overall resident satisfaction (paths of hypothesis 1), energy attitude on overall resident satisfaction (paths of hypothesis 2), and energy attitude on indoor environment satisfaction (paths of hypothesis 3). The model analysis found that the paths of hypotheses 1 (p < 0.01) and 3 (p < 0.05) were meaningful whereas that of hypothesis 2 was not. It turned out that indoor environment satisfaction had positive influences on overall resident satisfaction and resident energy attitude positively influenced indoor environment satisfaction. However, energy attitude did not have a direct influence on overall residential satisfaction. This result implies that indoor environment satisfaction is a parameter. In other words, energy attitude does not have a direct impact on overall resident satisfaction, but rather has an indirect impact on it via indoor environment satisfaction. The more residents that were aware of the importance of energy saving and energy costs, the higher their indoor environment satisfaction was. This led to higher overall resident satisfaction. In the examination of influence coefficients, path 1 delivered a path coefficient of 0.52 (p < 0.01), implying that indoor environment satisfaction has a 52% influence on overall housing satisfaction. Specifically, among the indoor environment evaluation factors, lighting environment (beta-coefficient = 0.76) and thermo environment (beta-coefficient = 0.75) had greater influences on overall housing satisfaction. Path 3 delivered a path coefficient of 0.25 (p < 0.05), demonstrating that energy attitude has a 25% influence on indoor environment satisfaction. Specifically, the more residents were aware of the importance of energy usage and conservation (beta-coefficient = 0.51) as well as energy costs (beta-coefficient = 0.51), and the more value they put into energysaving behavior ahead of convenience (beta-coefficient = −0.21), the higher their indoor environment satisfaction became.
The fit index analysis on the structural model (Table 4), RMSEA (Root Mean Square Error of Approximation) was 0.08, lower than the recommended value of 0.10. Absolute fit indexes of GFI (Goodness of Fit Index) and AGFI (Adjusted Goodness of Fit Index) were 0.95 and 0.91, respectively, both higher than the recommended value of 0.90. Incremental fix indexes of CFI (Comparative Fit Index) and NFI (Normed Fit Index) were 0.92 and 0.89, respectively. CFI was above the recommended value whereas NFI was slightly lower. However, a comprehensive analysis on the different fit indexes confirmed the proposed structural model was valid. 5. Conclusion This study is to examine the relationship among the indoor environment quality, residents’ attitude of energy using, and overall housing quality by suggesting a structural equation model, in order to establish sustainable and healthy housing environment. This study evaluated the indoor environment quality and overall housing quality of their apartment via a survey of residents’ satisfaction, and investigated residents’ attitude of energy using on the apartment environment. The following conclusions are derived: • According to the residents’ evaluation on apartment environment, residents were satisfied with overall housing quality (mean = 3.48) and indoor environment quality (mean = 3.37) generally. Concretely they were satisfied with thermal, air, and light conditions, while residents were not satisfied with noise condition. • Residents recognized importance of energy consumption and saving in their apartments (mean = 3.96). They were very sensitive to energy charge and apartment maintenance (mean = 3.84) and residents recognized that energy saving activities are more important than life conveniences (mean = 2.91). • As the structural equation model, indoor environment quality has mediating effects in association between attitude of energy using and overall residential satisfaction. Improvement of attitude of energy using does not only have a direct influence on the improvement of indoor environment quality, but also the improvement in overall residential satisfaction by enhancing indoor environment quality. Indoor environmental quality (IEQ) could regard as a critical part of the entire housing quality. And residents’ attitude of energy using considered in enhancing the indoor environment quality and overall housing quality. This study is expected to serve as a practical guideline of apartment management in order to enhance housing environment quality and ultimately establish healthy housing environment. Both
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
G Model ENB-5486; No. of Pages 5
ARTICLE IN PRESS T.K. Lee, J.T. Kim / Energy and Buildings xxx (2014) xxx–xxx
nationally and domestically, this study also could contribute to reducing energy consumption and saving resources. Acknowledgments This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2008-0061908) and Pusan National University Research Grant, 2012. References [1] S.H. Cho, T.K. Lee, A study on the evaluating indicators of the level of deterioration in high-rise and high-density apartments, J. Korean Hous. Assoc. 20 (2009) 131–142. [2] T.S. Hyun, B.T. Lee, A case study on the evaluation of residential performance for deteriorated multi-family housing, J. Korean Hous. Assoc. 17 (2006) 77–86. [3] Y.M. Lee, S.W. Kim, A study on the correlation analysis between the qualitative indicators of the outdoor spaces and the residents’ satisfaction in multi-family housing for constructing useful qualitative indicators, J. Archit. Inst. Korea 19 (2003) 69–78. [4] S.H. Cho, T.K. Lee, J.T. Kim, Residents’ satisfaction of indoor environmental quality in their old apartment homes, Indoor Built Environ. 20 (2011) 16–25. [5] J.R. Anderson, S. Weidemann, Developing and utilizing models of resident satisfaction, advances in environment, Behav. Des. 4 (1997) 287–314.
5
[6] S.H. Lee, H.R. Kim, A study on the improvement of indoor air quality with application of finishing materials in newly-constructed apartment houses, Archit. Inst. Korea 27 (2011) 249–258. [7] Y.K. Oh, Y.W. Cho, M.K. Chu, A study on the outdoor noise conditions and its regulation scheme, Korean Inst. Archit. Sustain. Environ. Build. Syst. 4 (2010) 61–65. [8] N.N. Kang, T.K. Lee, J.T. Kim, Characteristics of the quality of Korean high-rise apartments using the health performance indicator, Indoor Built Environ. 22 (2013) 157–167. [9] C.M. Chiang, C.M. Lai, A study on the comprehensive indicator of indoor environment assessment for occupants’ health in Taiwan, Build. Environ. 37 (2002) 387–392. [10] G. Kim, L. Schaefer, J.T. Kim, Development of a double-skin fac¸ade for sustainable renovation of old residential buildings, Indoor Built Environ. 22 (2013) 180–190. [11] G.Y. Yun, H.Y. Jung, J.T. Kim, Energy-saving potential of LED lighting systems, Indoor Built Environ. 22 (2013) 235–241. [12] A. Verma, Y.K. Jaiswal, K.A. Wani, Energy consumption behaviour of an urban residential sector in the northern province of Madhya Pradesh (India), Indoor Built Environ. 21 (2012) 703–709. [13] O.A. Nisiforou, S. Poullis, A.G. Charalambides, Behaviour, attitudes and opinion of large enterprise employees with regard to their energy usage habits and adoption of energy saving measures, Energy Build. 55 (2012) 299–311. [14] N.N. Kang, S.H. Cho, J.T. Kim, The energy-saving effects of apartment residents’ awareness and behaviour, Energy Build. 46 (2012) 112–122. [15] I.Y. Choi, S.H. Cho, J.T. Kim, Energy consumption characteristics of high-rise apartment buildings according to building shape and mixed-use development, Energy Build. 46 (2012) 123–131. [16] B.R. Bae, AMOS Structural equation modeling, Chung-ram, Seoul, Korea, 2011.
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
ARTICLE IN PRESS
ENB-5486; No. of Pages 5
Energy and Buildings xxx (2014) xxx–xxx
Contents lists available at ScienceDirect
Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild
Residents’ responses on indoor environment quality and energy use in apartments Tae Kyung Lee a , Jeong Tai Kim b,∗ a b
Department of Housing and Interior Design, Pusan National University, Busan, 609-735, Republic of Korea Department of Architectural Engineering, Kyung Hee University, Yongin, 446-701, Republic of Korea
a r t i c l e
i n f o
Article history: Available online xxx Keywords: Structural equation model Indoor environment quality Overall residential satisfaction Residents’ attitude of energy using
a b s t r a c t Indoor environment quality is an essential condition to establish a healthy housing environment. Residents’ attitude about energy is critical to their living and residential satisfaction. The purpose of this study is to suggest a structural equation model regarding the relationship among the evaluation of indoor environment quality, overall residential satisfaction, and residents’ attitude of energy using. The method of this study was document research and questionnaire survey research. First, this study analyzed residents’ evaluation on indoor environment quality and overall residential satisfaction. Second, this study analyzed residents’ awareness and behavior about energy use in their home. Third, this study established a structural equation model according to the relationship among variables (indoor environment quality, residents’ attitude of energy using, and overall residential satisfaction). And this study verified the model by using AMOS18.0. The results of this study can be utilized as basic materials to develop healthy housing design manual from the perspective of psychological and managerial aspects. © 2014 Elsevier B.V. All rights reserved.
1. Introduction 1.1. Study background This study aims to design a housing environment in which residents can live healthy lives. Poor housing environments can negatively affect a resident’s overall lifestyle, and may cause physical, psychological, and social problems, deteriorating their quality of life. As such, it is critical to put increased effort in enhancing housing environments to provide everyone in the modern society with higher standards of living. As the quality of housing environments becomes more important, researchers are becoming increasingly necessary in handling the quality of environments in apartment complex. Several studies have already addressed methodologies for evaluating the quality of housing environment [1,2], and raised concerns over the need for evaluation criteria which encompass both objective and subjective assessments [3,4]. In this regard, resident satisfaction with the housing environment can be interpreted as a comprehensive evaluation result which represents the psychological status formed by the interaction between different variables within the
∗ Corresponding author. Tel.: +82 1052836838; fax: +82 312062109. E-mail addresses: [email protected], [email protected] (J.T. Kim).
environment [5]. Resident satisfaction is accordingly used as an important evaluation criterion that comprehensively measures the quality of the housing environment. Indoor environment quality (IEQ) is also regarded as an important part of building performance and generally is evaluated based on four aspects (lighting, noise, thermo, and air). While indoor environment evaluations were mostly based on objective, technical criteria [6,7] in the past, modern IEQ tests include both objective and subjective factors in order to compile a comprehensive evaluation [8,9]. As such, Cho et al. conducted subjective evaluations on indoor environment quality based on resident satisfaction in addition to objective evaluations. They also emphasized the importance of such satisfaction by discussing its affects on overall resident satisfaction. Recently, both residential space and home appliances have become increasingly larger. As a result, energy consumption has risen and building energy management, particularly in apartments that account for over 50% of the total urban residence, has become increasingly more important. Consequently, construction and engineering companies are now developing new housing designs and technologies to better converse energy; various studies have been conducted to properly evaluate their energy efficiency [10,11]. And also various studies have been conducted in energy consumption behavior of residents [12,13]. Residents’ awareness of energy conservation has been seen to also directly affect their housing
http://dx.doi.org/10.1016/j.enbuild.2014.10.084 0378-7788/© 2014 Elsevier B.V. All rights reserved.
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
G Model ENB-5486; No. of Pages 5
ARTICLE IN PRESS T.K. Lee, J.T. Kim / Energy and Buildings xxx (2014) xxx–xxx
2
management costs. Their energy-saving efforts have been shown to have a positive impact on their residential satisfaction and pride [14,15]. As such, residents’ attitudes, including awareness and behavior, can be regarded as critical factors in improving overall residential satisfaction. This study aims at suggesting and verifying a structural equation model to quantitatively and specifically identify relations among indoor environment satisfaction, overall residential satisfaction, and energy attitude. This equation model is designed to help understand the importance of indoor environment and resident attitudes to the overall quality of housing environment. 1.2. Study contents and methodology This study is designed to explain the affects of resident indoor environment satisfaction and energy attitude on overall resident satisfaction by creating a structural equation model. Ultimately, this model is to serve as groundwork for ways to create a healthy residential environment of apartments where residents can continuously reside and be satisfied. To this end, this study conducted both literature reviews and empirical surveys. Details are as follows: (1) As for the document research, we identified the characteristics of indoor environment quality and residents’ attitude of energy using in regard to overall housing quality. (2) And we reviewed the outline and characteristics about a structural equation model as a statistical method. Additionally, we suggested a structural equation model according to the relationship among variables (the indoor environment quality, overall housing quality, and residents’ attitude energy using). As for the survey research, questionnaire survey was conducted on the residents of apartments in Pusan. Survey tool was developed to evaluate the overall residential satisfactions, indoor environment quality, and attitude of energy using, all of which previous studies and papers identified as important variables. (1) We analyzed residents’ evaluation on indoor environment quality and overall housing quality, and examined the importance of indoor comfort for housing environment quality. (2) And we analyzed residents’ awareness and behavior about energy using in their home. (3) Lastly, this study verified the structural equation model by using AMOS18.0, so that we analyzed correlations among variables. The questionnaires were designed to be easily comprehensible for the respondents. Evaluation items of the indoor environment quality encompass general conditions such as thermal, noise, light, and air in both summer and winter (Table 2). Evaluation items of the attitude of energy using encompass general awareness of residents about energy saving, energy-saving activities, and energy consumption patterns. The survey questionnaire included questions on overall housing satisfaction in order to comprehensively address housing environment quality. Five-point scale questionnaires were adopted to examine residents’ evaluation through their satisfaction level about indoor comfort; ‘Not satisfied at all’ = 1, ‘Generally not satisfied’ = 2, ‘Neutral’ = 3, ‘Generally satisfied’ = 4, and ‘Highly satisfied’ = 5. The questionnaire survey was conducted on the wives in apartments from February 5, 2012 to February 10 as a preliminary research. A total of 298 out of 350 distributed (85.0%) were collected and analyzed. SPSS program 18.0 (T-test, ANOVA) and Amos
Table 1 Characteristics of subjects. Items
Details
N (%)
M (SD)
Age of housewife
30s or under 40s 50s 60s or over Total High-school graduate Over college Total Employed Full-time housewife Total Two persons or under Three persons Four persons Five persons or over Total Under 300 300–400 400–500 500 and over Total 79 m2 –95 m2 105 m2 –119 m2 135 m2 –148 m2 Total Own Rent Total
44 (15.4) 129 (45.3) 94 (33.0) 18 (6.3) 285 (100.0) 112 (39.4) 172 (60.6) 284 (100.0) 117 (43.0) 155 (57.0) 272 (100.0) 40 (13.4) 73 (24.5) 151 (50.7) 34 (11.4) 298 (100.0) 67 (22.7) 97 (32.9) 64 (21.7) 67 (22.7) 295 (100.0) 86 (28.9) 143 (48.0) 69 (23.2) 298 (100.0) 242 (81.2) 56 (18.8) 298 (100.0)
47.2 (8.2)
Education level of housewife Employment of housewife Number of family
Average monthly income (ten thousand won) Housing size
House ownership
–
–
2.6 (0.9)
–
109.3 (7.6)
–
18.0 (structural equation model) were utilized to analyses of the survey results. 2. Residents’ evaluation of indoor environment in their apartments 2.1. General description of respondents According to demographic surveys shown in Table 1, the wives are 47.2 years old on average (SD = 8.2). Of the wives, 57.0% are fulltime, and most were highly educated (60.6% were college graduates or higher). With regard to family composition, most were nuclear families having three to four family members (75.2%). Approximately half (54.6%) of the respondents reported a monthly income of 3 million–5 million Korean won, and 22.7% have a income of over 5 million won. With regard to housing size, the proportion with areas of 105 m2 –119 m2 was high and the size is 109.3 m2 on average (SD = 7.6). Regarding the ownership of the units, 81.2% of the respondents owned their apartments. 2.2. Residents’ evaluation of indoor environment quality Indoor environment quality was assessed by residents’ satisfaction levels. Residents presented a moderate satisfaction level about the overall indoor environment. To demonstrate item by item, subjects rated heat, air, and light conditions as moderate or better, while they were dissatisfied with noise conditions (N1, N2, and N3 in summer season, N2 in winter season). Evaluations on the noise conditions also differed between two seasons, when summer season (N1, N2, and N3) showed more dissatisfactions than winter season. And overall housing quality was assessed by residents’ satisfaction of overall residential environment (Question: “I and my family are satisfied to residential environment and want to live here continuously.”). The satisfaction level of overall residential environment is 3.5 (0.7). It means that residents were very satisfied with their residential environment.
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
G Model
ARTICLE IN PRESS
ENB-5486; No. of Pages 5
T.K. Lee, J.T. Kim / Energy and Buildings xxx (2014) xxx–xxx
3
Table 2 Satisfaction of indoor environment quality M (SD). Items
Details
Summer season
Winter season
Total
Thermal
T1—Thermal sensation T2—Humid A1—Air current A2—Ventilation N1—Noise(supply, drainage facilities) N2—Noise(life between neighborhood) N3—Noise(outdoor) L1—Sunshine, natural lighting condition L2—Illumination(dark, dazzle) L3—Privacy
3.3 (0.7) 3.2 (0.7) 3.3 (0.8) 3.3 (0.8) 2.9 (0.9) 2.8 (0.9) 2.8 (0.9) 3.3 (0.8) 3.4 (0.7) 3.1 (0.9)
3.2 (0.9) 3.2 (0.8) 3.2 (0.7) 3.2 (0.7) 3.0 (0.8) 2.9 (0.9) 3.0 (0.9) 3.2 (0.9) 3.3 (0.8) 3.3 (0.9)
3.3 (0.8) 3.2 (0.8) 3.3 (0.8) 3.2 (0.8) 3.0 (0.8) 2.8 (0.9) 2.9 (0.9) 3.3 (0.9) 3.3 (0.8) 3.2 (0.9)
Air Noise
Lighting
Table 3 Residents’ attitude of energy using.
review, hypotheses and theoretical models were established, (Fig. 1) and verified the structural equation model by AMOS 18.0
Items
M (SD)
Attitude 1: I and my family recognize importance of energy use and saving in the house Attitude 2: I and my family are interest in energy-cost Attitude 3: I and my family recognize that life conveniences is more important than energy-saving activities
3.96(0.69) 3.84(0.74) 2.91(0.88)
‘Not at all’ = 1, ‘Generally not’ = 2, ‘Neutral’ = 3, ‘Generally so’ = 4, and ‘Highly so’ = 5.
3. Residents’ attitude of energy using in their apartments Residents’ attitude of energy using was investigated by three items (Table 3). Residents recognized importance of energy consumption and saving in their apartments (mean = 3.96). They were very sensitive to energy charge and apartment maintenance (mean = 3.84), while participation level of energy saving activities was relatively low (mean = 2.91). 4. Structural equation model In this chapter, relations between overall resident satisfaction, indoor environment satisfaction, and energy attitude are examined by utilizing a structural equation model. Based on the literature
4.1. Outline of structural equation model (SEM) A structural equation model (SEM) is an advanced statistical methodology widely used in the social sciences and able to produce more informative results than any other statistical tool to date. An SEM overcomes the limitations of previous statistical models (such as multiple regression, factor analysis, ANOVA, and discriminant analysis) which show only one side of relations between variables. Path coefficients delivered by an SEM demonstrate the relative influences of causalities and correlations, and thus can be used to verify the causalities of variables produced by other statistical methods. It is necessary to assess to what extent a model can be accepted to verify hypotheses; the following coefficients and indexes are used as criteria for such assessment. Among the many fit indexes, CMIN/DF (mormed 2 ) and GFI (Goodness of Fit Index) are frequently used as absolute fit indexes and NFI (Bentler–Bonett Normed Fit Index), TLI (Turker Lewis index) and CFI (Comparative Fit Index) are used as incremental fit indexes. RMSEA (Root Mean Square Error of Approximation) is also often utilized among others. Fit indexes are not statistics which can be interpreted as official results of statistical verification; rather, they are empirical numbers which explain the goodness or fitness of a model. In order words,
Fig. 1. Structural equation model.
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
G Model ENB-5486; No. of Pages 5
ARTICLE IN PRESS T.K. Lee, J.T. Kim / Energy and Buildings xxx (2014) xxx–xxx
4 Table 4 The validity of the model according to model fit-index. Evaluation of pats
Unstandardized coefficients
Standardized error
Path 1—Indoor environment quality affects to overall residential satisfaction positively. 0.23 0.03 Indoor environment quality → overall residential satisfaction Path 2—Residents’ attitude of energy affects to overall residential satisfaction positively. 0.16 0.17 Residents’ attitude of energy → overall residential satisfaction Path 3—Residents’ attitude of energy affects to indoor environment quality. 1.21 0.55 Residents’ attitude of energy → indoor environment quality 2 (df) 858.23 (18) * **
p value 0.00
CFI 0.92
C.R.
p
Standardized coefficients
7.36
**
0.52
0.89
0.37
0.07
2.20
*
0.25
NFI 0.89
GFI 0.95
AGFI 0.91
RMSEA 0.08
p < 0.05. p < 0.01.
since they cannot be used for statistical verification, numbers delivered by fit index models can be used as absolute criteria for only limited occasions. Accordingly, the indexes are used to decide a model’s acceptance [16]. This study also comprehensively taps into different indexes to verify the fitness of the proposed model.
4.2. Research hypothesis and modeling Previous studies found that indoor environment quality had significant influences on overall resident satisfaction. Studies also found that resident energy awareness affected energy behavior and ultimately overall resident satisfaction. For this study, three theoretical hypotheses and a structural model were built based on the aforementioned findings. Energy attitude was assumed to be the most important variable affecting overall residential satisfaction. This was done in order to examine the influences of indoor environment satisfaction on overall resident satisfaction (paths of hypothesis 1), energy attitude on overall resident satisfaction (paths of hypothesis 2), and energy attitude on indoor environment satisfaction (paths of hypothesis 3). The model analysis found that the paths of hypotheses 1 (p < 0.01) and 3 (p < 0.05) were meaningful whereas that of hypothesis 2 was not. It turned out that indoor environment satisfaction had positive influences on overall resident satisfaction and resident energy attitude positively influenced indoor environment satisfaction. However, energy attitude did not have a direct influence on overall residential satisfaction. This result implies that indoor environment satisfaction is a parameter. In other words, energy attitude does not have a direct impact on overall resident satisfaction, but rather has an indirect impact on it via indoor environment satisfaction. The more residents that were aware of the importance of energy saving and energy costs, the higher their indoor environment satisfaction was. This led to higher overall resident satisfaction. In the examination of influence coefficients, path 1 delivered a path coefficient of 0.52 (p < 0.01), implying that indoor environment satisfaction has a 52% influence on overall housing satisfaction. Specifically, among the indoor environment evaluation factors, lighting environment (beta-coefficient = 0.76) and thermo environment (beta-coefficient = 0.75) had greater influences on overall housing satisfaction. Path 3 delivered a path coefficient of 0.25 (p < 0.05), demonstrating that energy attitude has a 25% influence on indoor environment satisfaction. Specifically, the more residents were aware of the importance of energy usage and conservation (beta-coefficient = 0.51) as well as energy costs (beta-coefficient = 0.51), and the more value they put into energysaving behavior ahead of convenience (beta-coefficient = −0.21), the higher their indoor environment satisfaction became.
The fit index analysis on the structural model (Table 4), RMSEA (Root Mean Square Error of Approximation) was 0.08, lower than the recommended value of 0.10. Absolute fit indexes of GFI (Goodness of Fit Index) and AGFI (Adjusted Goodness of Fit Index) were 0.95 and 0.91, respectively, both higher than the recommended value of 0.90. Incremental fix indexes of CFI (Comparative Fit Index) and NFI (Normed Fit Index) were 0.92 and 0.89, respectively. CFI was above the recommended value whereas NFI was slightly lower. However, a comprehensive analysis on the different fit indexes confirmed the proposed structural model was valid. 5. Conclusion This study is to examine the relationship among the indoor environment quality, residents’ attitude of energy using, and overall housing quality by suggesting a structural equation model, in order to establish sustainable and healthy housing environment. This study evaluated the indoor environment quality and overall housing quality of their apartment via a survey of residents’ satisfaction, and investigated residents’ attitude of energy using on the apartment environment. The following conclusions are derived: • According to the residents’ evaluation on apartment environment, residents were satisfied with overall housing quality (mean = 3.48) and indoor environment quality (mean = 3.37) generally. Concretely they were satisfied with thermal, air, and light conditions, while residents were not satisfied with noise condition. • Residents recognized importance of energy consumption and saving in their apartments (mean = 3.96). They were very sensitive to energy charge and apartment maintenance (mean = 3.84) and residents recognized that energy saving activities are more important than life conveniences (mean = 2.91). • As the structural equation model, indoor environment quality has mediating effects in association between attitude of energy using and overall residential satisfaction. Improvement of attitude of energy using does not only have a direct influence on the improvement of indoor environment quality, but also the improvement in overall residential satisfaction by enhancing indoor environment quality. Indoor environmental quality (IEQ) could regard as a critical part of the entire housing quality. And residents’ attitude of energy using considered in enhancing the indoor environment quality and overall housing quality. This study is expected to serve as a practical guideline of apartment management in order to enhance housing environment quality and ultimately establish healthy housing environment. Both
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084
G Model ENB-5486; No. of Pages 5
ARTICLE IN PRESS T.K. Lee, J.T. Kim / Energy and Buildings xxx (2014) xxx–xxx
nationally and domestically, this study also could contribute to reducing energy consumption and saving resources. Acknowledgments This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP) (No. 2008-0061908) and Pusan National University Research Grant, 2012. References [1] S.H. Cho, T.K. Lee, A study on the evaluating indicators of the level of deterioration in high-rise and high-density apartments, J. Korean Hous. Assoc. 20 (2009) 131–142. [2] T.S. Hyun, B.T. Lee, A case study on the evaluation of residential performance for deteriorated multi-family housing, J. Korean Hous. Assoc. 17 (2006) 77–86. [3] Y.M. Lee, S.W. Kim, A study on the correlation analysis between the qualitative indicators of the outdoor spaces and the residents’ satisfaction in multi-family housing for constructing useful qualitative indicators, J. Archit. Inst. Korea 19 (2003) 69–78. [4] S.H. Cho, T.K. Lee, J.T. Kim, Residents’ satisfaction of indoor environmental quality in their old apartment homes, Indoor Built Environ. 20 (2011) 16–25. [5] J.R. Anderson, S. Weidemann, Developing and utilizing models of resident satisfaction, advances in environment, Behav. Des. 4 (1997) 287–314.
5
[6] S.H. Lee, H.R. Kim, A study on the improvement of indoor air quality with application of finishing materials in newly-constructed apartment houses, Archit. Inst. Korea 27 (2011) 249–258. [7] Y.K. Oh, Y.W. Cho, M.K. Chu, A study on the outdoor noise conditions and its regulation scheme, Korean Inst. Archit. Sustain. Environ. Build. Syst. 4 (2010) 61–65. [8] N.N. Kang, T.K. Lee, J.T. Kim, Characteristics of the quality of Korean high-rise apartments using the health performance indicator, Indoor Built Environ. 22 (2013) 157–167. [9] C.M. Chiang, C.M. Lai, A study on the comprehensive indicator of indoor environment assessment for occupants’ health in Taiwan, Build. Environ. 37 (2002) 387–392. [10] G. Kim, L. Schaefer, J.T. Kim, Development of a double-skin fac¸ade for sustainable renovation of old residential buildings, Indoor Built Environ. 22 (2013) 180–190. [11] G.Y. Yun, H.Y. Jung, J.T. Kim, Energy-saving potential of LED lighting systems, Indoor Built Environ. 22 (2013) 235–241. [12] A. Verma, Y.K. Jaiswal, K.A. Wani, Energy consumption behaviour of an urban residential sector in the northern province of Madhya Pradesh (India), Indoor Built Environ. 21 (2012) 703–709. [13] O.A. Nisiforou, S. Poullis, A.G. Charalambides, Behaviour, attitudes and opinion of large enterprise employees with regard to their energy usage habits and adoption of energy saving measures, Energy Build. 55 (2012) 299–311. [14] N.N. Kang, S.H. Cho, J.T. Kim, The energy-saving effects of apartment residents’ awareness and behaviour, Energy Build. 46 (2012) 112–122. [15] I.Y. Choi, S.H. Cho, J.T. Kim, Energy consumption characteristics of high-rise apartment buildings according to building shape and mixed-use development, Energy Build. 46 (2012) 123–131. [16] B.R. Bae, AMOS Structural equation modeling, Chung-ram, Seoul, Korea, 2011.
Please cite this article in press as: T.K. Lee, J.T. Kim, Residents’ responses on indoor environment quality and energy use in apartments, Energy Buildings (2014), http://dx.doi.org/10.1016/j.enbuild.2014.10.084