The impact of IEQ on occupants’ satisfaction in Malaysian buildings

Abstract

This paper focuses on the importance of occupant satisfaction with indoor environmental quality in buildings as well as the effect of indoor environmental quality towards occupants’ satisfaction. This research applied post-occupancy evaluation as a method to indicate the building occupants’ needs, their satisfaction and comfort level. The research is based on a case study approach whereby a questionnaire survey was conducted among 25 organizations involved in managing office buildings. A total of 115 questionnaires were returned for evaluation of occupants’ overall satisfaction from aspects of indoor environmental quality in these buildings and to determine the occupants’ satisfaction level within these buildings. The findings revealed that indoor environment factors that could contribute to occupants’ satisfaction consists of lighting, air quality and aesthetic perception. These classifications were made based on the factor analysis done with 22 attributes of the indoor environment. The majority of occupants are satisfied with their health conditions and do not face any serious health problems. However, occupants highlighted that some environmental conditions, health effects, air movement, ventilation and air freshness are important criteria for their satisfaction and comfort. This study provides insights into how occupants perceive their indoor environment and comfort, and identify problems that could arise in buildings.

Keywords

Indoor environment quality Occupants Satisfaction Building Comfort Malaysia

Introduction

A building is a fundamental component which provides shelter and facilities for individuals to perform daily task. The quality of indoor air is very important for human health and well-being because most people spend their time indoors; in offices, schools and homes.¹ The health risks of exposure to indoor air pollution are greater than those caused by outdoor air pollution. Various aspects of the indoor environment could affect human well-being and performance. The air and environment can be affected by chemical, biological and physical agents resulting from occupants’ activities and the presence of volatile organic compounds (VOCs) from other contaminants and pollutants released by certain building materials or from the ambient environment.² Other factors affecting the indoor environment quality (IEQ) are lighting, natural ventilation, thermal quality and indoor air quality (IAQ). However, high-performance design and green buildings can provide a better and healthier environment for occupants.³

Some research studies have been conducted to determine the role of indoor environment on occupants’ productivity and efficiency.^3–6 Occupants’ opinion towards building indoor environment can be obtained through questionnaire survey. Kamaruzzaman et al.³ stressed that findings from the questionnaire survey should be able to assist in identifying particular aspects of the environment that require adjustment and improvement and aim to provide a better internal environment for occupants.

The most prevalent and established data collection method across diverse disciplines including psychology, social, health and building sciences, is an occupant survey which results in post-occupancy evaluation (POE). Previous studies that adopted this method include Kamaruzzaman et al.³ and Huang et al.⁴ In 2013, Kim et al.⁵ carried out a research, which studied the relationships between the indoor environment and behaviour, perception and comfort of building occupants. Kim et al.⁵ found that female respondents are less satisfied with all IEQ factors, with the lowest satisfaction scores for IEQ factors given to temperature, followed by air quality and acoustical conditions (noise and sound privacy).

Occupant satisfaction can be defined by various perspectives, depending on the scope of the study. Frontczak et al.⁷ stated that occupant satisfaction is associated with IEQ (thermal, visual, acoustic and air quality) and workspace as well as building features (including size, aesthetic appearance, furniture and cleanliness). These authors have highlighted the degree of importance of the indoor environmental parameters which could vary between studies, but thermal environment is generally ranked slightly higher compared to air quality, acoustic environment and visual environment. Sound privacy and IEQ (temperature, noise and air) are ranked highest in term of level of dissatisfaction. The most important factors for workplace satisfaction among occupants are the amount of space, noise level and visual privacy.

IEQ is an important quality aspect for office buildings. From the occupants’ perspectives, the ideal situation is an indoor environment that satisfies everyone. Bluyssen and Cox⁸ noted that unhealthy indoor environment can affect building occupants’ health. Several factors can contribute to a healthier indoor environment including:

Source control: reducing emissions from sources of indoor pollution

Ventilation: reducing exposure to pollution sources

Maintaining comfortable physical conditions: temperature, humidity and lighting.

A number of factors have been found to affect the indoor environmental quality (IEQ) of a building. These are summarized in Table 1. These factors would need to be addressed as they could significantly contribute to occupants’ health, productivity, performance and their well-being.

Table 1.

Factors relating to indoor environmental quality.

Factors
Noise level	Space comfort is influenced by various IEQ factors, one of which is the noise level. Noise may derived from outside such as traffic, mechanical systems, phones, or even voices of inhabitants. Although most of the time it is not at a high enough level to be harmful to human hearing, constant exposure to noise can also leave occupants irritable, distracted or dizzy. As demonstrated in Muhamad Salleh et al.'s⁹ study, the location of a building on congested streets affect the comfort of occupants
Electric lighting	Appropriate lighting level can improve productivity of occupants but poorly design lighting can cause wastage and health problems. Lighting is therefore appeared as one of the principal parameters that influence space’s IEQ.¹⁰ While no building can operate with just natural daylight alone, it is important to have electric lighting system that supports occupants’ productivity
Amount of daylight	Natural illumination of the interior from daylight forms another source of lighting that stimulates occupants’ sense of vision. As argued by Kamaruzzaman et al.,¹⁰ the concepts of the indoor environment cover both climatic and non-climatic aspects. Although day lighting enhances the quality of light indoors and decreases reliance on artificial light sources, it can also be a source of glare and thermal gain which further contribute as other factors that affect IEQ of a building
Glare level in the room and around desk	Glare is unpleasantly bright or strong light that caused by the direct penetration of sunlight. It is more often than not occur in spaces with highly reflective surfaces. Direct glare need to be reduced as it posits adverse effect on visual comfort of inhabitants
Distance to the windows	Windows are key elements of building envelopes which are designed to allow natural ventilation, admit sunlight directly into the space, reject heat and glare. The extent of windows including their size and location is therefore needed to be properly considered at the earliest possible stage of development
Temperature	Temperature of a space can have an effect on occupants’ productivity making it an important part of good IEQ.¹¹ Occupants should be empowered to control over temperature as everyone’s comfort zone is different
Ventilation	Ventilation includes both the process of exchanging air to the outside as well as circulation of air within enclosed space. Adequate ventilation or movement of fresh air is crucial to prevent build-up of odours, carbon dioxide and toxins in indoor air. This is important for maintaining acceptable IEQ of a building. However, care should be taken to prevent energy waste by over-ventilating as today’s modern buildings and lifestyles depend primarily on mechanical ventilation
Amount of air movement	Internal and external air movement assists in controlling indoor environment.¹² Adequate amount of air movement is necessary to decrease indoor discomfort especially for building in hot tropical climate
Freshness of the room	Another indoor environment attribute is freshness of a space which could be affected by air quality. Air quality is closely associated with contaminants produced outside and inside buildings. The sources of air contaminants such as dirt, dust, ash, moulds or other gaseous pollutants need to be controlled to ensure good and healthy indoor environment. This is also important to reduce the occurrence of sick building syndrome.
Humidity level in the room	Indoor environment is much affected by the level of humidity. In the context of tropical humid countries, the comfort level ranges between 59% and 65% and discomfort ranges from 65% to 75% humidity¹³
Smell in the room	Odours can be both pleasant and unpleasant, and can also be health hazards, although some are not. There are a variety of potentially hazardous smells such as smoking, cooking and cosmetic odours. Many researchers believed that smell can contribute to building occupants’ comfort^14–17
Colours of the room	Colour is another significant aspect of the indoor environment as most people respond to colours with their emotions and feelings. Colour can also be utilized to change the perception of a building. For Kamaruzzaman et al.,¹⁰ it can have an impact on illumination contrasts, which if too high may cause discomfort
Workspace	According to Kamaruzzaman and Ahmad Zawawi,¹¹ the physical workspace is one of the IEQ factors that have a massive effect on employee productivity. It plays an important role as a medium of interaction and resource, and thus essential to organization performance as a whole
Colleagues and management	Immediate colleagues and authoritative management in the workplace appeared to have an effect on worker productivity and thus making it an important parameter of IEQ. For example, although provides opportunities for social gathering, noise from colleagues may cause discomfort and affect colleagues’ concentration. Given the freedom of individual control and adjustment of indoor condition (to suit comfort zone of different individuals), this factor has been found to affect occupants’ performance and well-being¹¹
External and internal appearance	Aesthetic appearance is closely associated with occupants’ satisfaction in a building.^7,10 Keeping occupants happy is crucial in sustaining their living quality
Others	Other important parameters affecting IEQ of a building include health of the occupants, office in general, and also level of privacy provided

Source: Adapted from Frontczak et al.,⁷ Muhamad Salleh et al.,⁹ Kamaruzzaman et al.,¹⁰ Kamaruzzaman and Ahmad Zawawi,¹¹ Jamaludin et al.,¹² Prianto et al.,¹³ Montazami et al.,^14, Puteh et al.,¹⁵ Zhang and Barrett,¹⁶ Pegas et al.,¹⁷ Kamaruzzaman et al.,¹⁸ Muhamad Salleh et al.¹⁹

The negative effects of poor IEQ are physical discomfort, such as fatigue and sick building syndrome. The poor quality of facilities and building design are associated with occupants’ performance and achievement. The building’s interior and characteristics are major influences on exposure to indoor pollutants and other indoor physical parameters. Studies conducted^3,20 have identified several criteria that could affect occupants’ health and work performance, but there is still a gap in the information about building occupants’ assessment of IEQ. Thus, this provides an impetus for us to undertake this particular study area. This paper applies POE as a method to indicate occupants’ needs in buildings, their satisfaction and comfort level. Thus, we applied systematic POE to evaluate occupants’ perceptions about their buildings or workspace.

The broad aim of this paper is to contribute to the discussion of the impact of overall occupant satisfaction from aspects of IEQ in buildings and to determine occupants’ satisfaction levels within buildings, and with particular reference to buildings in Kuala Lumpur, Malaysia. The analysis is based on survey responses directly collected from occupants. The findings of this study provide insights into how occupants perceive their indoor environment and to identify the set of problems that could arise in buildings. The findings should contribute to existing knowledge about perceived comfort and satisfaction of occupants of buildings.

Research design and methodology

A questionnaire survey was developed on the basis of extensive literature reviews. The primary aim of the questionnaire survey is to examine overall satisfaction of building occupants with aspects of IEQ in buildings. Bluyssen and Cox⁸ considered that IEQ can be treated as a part of TOBUS, namely thermal comfort, indoor air quality (humidity, pollutants and ventilation), lighting and noise. They incorporated work-related factors, personal characteristics and ergonomics in their study. On the other hand, Wolfinbarger and Gilly²¹ informed us that the type of questionnaire a researcher adopts may consist of multiple choice questions, close-ended questions and Likert-type questions. The questionnaire for the study reported in this present article is adapted from Levermore et al.,²² that was developed in the UK and is used by a number of organizations including consultancies in London.

Likert style questions were employed to rate 22 factors relating to satisfaction with offices and buildings. The questionnaire comprises important factors in the design of an ideal office and comfort of occupants in buildings. The research is based on a case study approach, with a focus on 25 organizations in Malaysia involved in managing office buildings. The office buildings selected consist of low, medium and high rise, and up to maximum of 60 m height. The main reason for this threshold is that Nguyen and Altan²³ highlighted that buildings with more than 20 storeys, or more than 60 m in height, could have dramatic effect on building processes including design, planning, construction, maintenance and deconstruction. This also supports the views espoused by the renowned architect or engineer Fazlur Khan.²⁴ In addition, it represents the typical layout settings pertain in Kuala Lumpur, the capital of Malaysia.

Through the support of top management in 25 participating organizations, building occupants were gathered and a short explanation about the survey was presented. All respondents were allowed to complete the questionnaires for approximately 1 h before collecting back the questionnaires.

The questionnaire was divided into three main sections. Section A deals with the demographic profile of the occupants; section B deals with comfort levels, using semantic differential rating questions; and section C asks about the ‘degree of likeness’ and ‘importance’ in their offices. These are needed to determine occupants’ satisfaction with their building. According to Lai and Yik,²⁵ it is important that attributes such as indoor environmental factors should be understandable by all levels of respondents, not only professionals but also end users who may have little knowledge of some technical terms. In other words, jargon must be avoided in order to gain responses about IEQ attributes without doubt or confusion. The length, structure and design of the questionnaire were short and straight forward so that it was easy to complete and did not cause fatigue to respondents. This could significantly motivate and encourage respondents to become involved in the survey and indirectly increase the response rate of our survey.²⁶

‘Liking’ score

Section C of the questionnaire, which is the main feature of the questionnaire, explores questions involving noise, lighting, temperature, humidity and ventilation. The control of ventilation, temperature and lighting are important elements of the comfort index in the evaluation of IEQ by the building’s occupants.⁸ Therefore, occupants were asked to offer their views by rating on a seven-point Likert scale for ‘User satisfaction’ and ‘Degree of importance’. By combining all 22 factors relating to the internal environment of building, the questionnaire was used to elicit an occupant’s level of satisfaction and a benchmark for building satisfaction. These 22 factors are listed below:

Q1	– Noise Level	Q12	– Smell in the room
Q2	– Electric lighting	Q13	– Health when in the room
Q3	– Amount of daylight	Q14	– Colours of the room
Q4	– Glare level in the room	Q15	– Attractiveness of the room
Q5	– Glare level around desk	Q16	– Control over local environment
Q6	– Distance to the windows	Q17	– Workspace
Q7	– Office temperature	Q18	– Privacy
Q8	– Ventilation	Q19	– Immediate colleagues
Q9	– Amount of air movement	Q20	– Management
Q10	– Freshness of the room	Q21	– Office, in general
Q11	– Humidity level in the room	Q22	– Outward appearance

Section C used a double Likert scale for the construct of ‘liking’ and ‘importance’ of a number of factors relating to the indoor environment and organization. The seven-point scale for ‘like’ and ‘dislike’ used in the questionnaire is as shown below:

These types of scale were used to increase the ease of understanding, which is important for a self-administered questionnaire. The seven-point like or dislike scale is another option for the respondents to offer their views on the importance of factors in designing their ideal office or room. Note that, even though few respondents considered that any of the stated factors were unimportant and thus of negative value, this scale was still used and was not reduced in order to maintain consistency and avoid confusion. The ‘importance’ rating was defined as follows:

Scale	Definition	Explanation
1	Extremely unimportant	The evidence favouring one attribute over another is of the least possible order of affirmation
2	Unimportant	The attributes are perceived as unimportant
3	Slightly unimportant	Experience and judgment slightly unfavourable
4	Moderately important	Experience and judgment moderately favour one attribute over another
5	Strongly important	Experience and judgment strongly favour one attribute over another
6	Very strongly important	An attribute is strongly favoured and its dominance is demonstrated in practice
7	Extremely important	The evidence favouring one attribute over another is of the highest possible order of affirmation

Furthermore, occupants’ level of satisfaction with the building, using the 7-point Likert scale, ranged from −3 (strongly dislike) to +3 (strongly like) for the indoor environmental factors.

Scale	Definition	Explanation
−3	Extremely dislike	The evidence favouring one attribute over another is of the least possible order of affirmation
−2	Dislike	The attributes are perceived as disliked
−1	Slightly dislike	Experience and judgment slightly unfavourable
0	Neither like nor dislike	Experience and judgment moderately favour one attribute over another
+1	Strongly like	Experience and judgment strongly favour one attribute over another
+2	Very strong like	An attribute is strongly favoured and its dominance is demonstrated in practice
+3	Extremely like	The evidence favouring one attribute over another is of the highest possible order of affirmation

The questionnaire consists of both occupants’ ratings of their satisfaction with the internal environment and their ratings on how important they find these environmental conditions. The first part of the analysis is to find the satisfaction score. The satisfaction score of a building (an overall rating for a building’s indoor environment) can be determined using equation (1)^22,27,28

OLS = [\frac{\sum_{k = 1}^{n} \sum_{j = 1}^{m} i_{j, k} l_{j, k}}{{mni}_{max} l_{max}}] 100

(1)

where j = questionnaire number; k = question number; i = importance rating 1 <i> 7; i_max = maximum value of i, (7); l_max = maximum liking rating l (+3); l = liking rating −3 <l> +3; m = number of filled in questionnaires; n = number of questions in the score.

The second part of the analysis provides a graphical representation of the totals for each answer. This is called a fingerprint, which normalizes each question to a score between +100% and −100%,^22,27,28 as described by equation (2) as follows

FLS = 100 [\frac{\sum_{j = 1}^{m} i_{j, k} l_{j, k}}{{mi}_{max} l_{max}}]

(2)

The third part of the analysis is similar to the second. However, by using equation (3) as given below, a normalized individual score, between +100% and −100%, for each person can be calculated.

FLS = 100 [\frac{\sum_{k = 1}^{n} i_{j, k} l_{j, k}}{{ni}_{max} l_{max}}]

(3)

Results

Demographic profile of occupants

A total of 115 occupants completed questionnaires that were sent to them, and useable questionnaires were obtained from 25 participating organizations involved in managing these office buildings in Malaysia. Thus, the findings of this research were based on the 115 questionnaires returned by occupants of these buildings. The descriptive analysis of the general information is illustrated in Table 2, including the gender, profession, age, hours spent using visual display unit (VDU), hour spent at desk and hours spent in buildings.

Table 2.

Building occupants’ information.

Variables	Descriptions	Percent
Sex	Female	57.4
	Male	42.6
Occupation	Clerical/Secretarial	23.5
	Professional	31.3
	Managerial	19.1
	Other	26.1
Age	<20 years	4.3
	21–30	49.6
	31–40	26.1
	41–50	12.2
	51–60	6.1
	>60 years	1.7
Hours spent using visual display unit (VDU)	0–1 h	7.8
Hours spent using visual display unit (VDU)	1–2 h	4.3
	2–3 h	10.4
	3–4 h	15.7
	4–5 h	34.8
	>5 h	27.0
Hour spent at desk	<5 h	55.5
	<8 h	37.4
	<10 h	5.2
	12 h	1.7
Hours spent in building	<8 h	56.5
	8 to 12 h	38.3
	>12 h	2.6

The findings of this study revealed that the majority of respondents are professional females (57.4%) aged between 21 to 30 years old. Most of these respondents stay in the building for less than 8 h but spent most of their time using visual display unit (VDU) for around 4–5 h per day.

Satisfaction levels of occupants

The audit satisfaction score revealed that the majority of occupants are satisfied with their indoor environments as shown in Figure 1. Occupants who are very satisfied with their office environment gave a score of +1.27 (highest positive score). In contrast, occupants who are not satisfied with the distance from the window gave a least positive score, +0.54, followed by glare level in the room (+0.55) and glare level around desk/VDU (+0.57). The lowest ranking of all satisfaction attributes are related to glare. Thus, the glare level is an important consideration in determining building occupants’ satisfaction and comfort. Providing an optimum and good environment is essential to increase the productivity of occupants, as majority of respondents spend almost 8 h a day in their building.

‘Importance’ factors of IEQ

Figure 2 illustrates the ranking of IEQ factors according to building occupants’ perceived level of importance. The distance from the window was by far the least important factor, followed by room glare, desk/VDU glare and daylight. The glare level may result from the lighting and being carefully designed for VDU use. The most important factors are control over the environment, health, air movement, ventilation and freshness. These results suggest that the environment and ventilation systems of the indoor environment are critical to ensure the comfort of building occupants.

Figure 1.

Occupant satisfaction score.

Figure 2.

Importance factors of occupants score.

Comfort level of occupants

The comfort level of occupants was measured using a 7-point Likert scale. Factors considered in identifying comfort level include: aesthetics, relaxing, colour, brightness, glare, draught, heat, noise and dryness. Figure 3 illustrates comfort levels of male and female respondents, showing that both male and female respondents are in the comfort zone, since the mean values of all elements are above 3.00. The respondents are therefore satisfied and comfortable with all aspects of their current room environment.

Figure 3.

Comfort level.

Factor analysis

The variables were adequately defined by this factor solution. Simplicity of structure was assessed by inspection of the factor loading; this revealed some very high correlations and many low correlations between variables and factors as demonstrated in Table 3. Thus, variables were ordered and grouped according to factor loadings and interpretative labels suggested:

Factor 1 is labelled as Lighting. It is associated with noise, lighting, daylight, glare level in room, glare level at VDU, distance from window and temperature.

Table 3.

Grouped variable according to factor loading.

Factors	Questions	Factor loading
Factor 1	Lighting
Q1	Noise level	0.705
Q2	Electric lighting	0.645
Q3	Amount of daylight	0.661
Q4	Glare level in the room	0.851
Q5	Glare level around desk or VDU	0.888
Q6	Distance to the windows	0.625
Q7	Office temperature	0.632
Factor 2	Air quality
Q8	Ventilation	0.888
Q9	Amount of air movement	0.885
Q10	Freshness of the room	0.856
Q11	Humidity level in the room	0.720
Q12	Smell in the room	0.632
Q13	Health when in the room	0.683
Factor 3	Aesthetic
Q14	Colours of the room	0.676
Q15	Attractiveness of the room	0.691
Q16	Control over local environment	0.651
Q17	Workspace	0.732
Q18	Privacy	0.843
Q19	Immediate colleagues	0.747
Q20	Management	0.759
Q21	Office in general	0.627
Q22	Outward appearance	0.679

Factor 2 is labelled as Air Quality. It is associated with ventilation, air movement, freshness, humidity, smell and health.

Factor 3 is labelled as Aesthetic Environment. It is associated with colour, attractiveness, control, working space, privacy, colleagues, management, office and outward appearance of the building.

Relation between IEQ and occupants’ level of satisfaction

Three factor scores were generated from occupants’ responses, using the regression analysis.

Assessing the impact of IEQ on occupants’ satisfaction

The majority of the variation in occupants’ satisfaction (58%) was accounted for by the IEQ lighting, air quality and aesthetics. The standardized β values also explain the importance of the socio-psychological factors in the model used in this study. It gives a measure of the contribution of each independent variable to the model. The findings in Table 4 shows that aesthetics is the most influential factor for occupants’ satisfaction (β = 0.593, t = 6.46, p < 0.05) while lighting and air quality did not significantly influence satisfaction within the building.

Table 5 illustrates the strength of the relationship between IEQ and occupants’ satisfaction. The significance value for the correlation of this study is p < 0.01, which is an acceptable significant level of the study at p < 0.1, p < 0.05 and p < 0.01. Therefore, all factors of IEQ have a positive significant relationship with occupants’ satisfaction in the building, with lighting (r = 0.351, p = 0.01), air quality (r = 0.402, p = 0.01) and aesthetics (r = 0.405, p = 0.01). Therefore, our findings revealed that occupants are satisfied with all the criteria of IEQ in the building. Furthermore, this study explained that the stronger the lighting, the higher the level of occupants’ satisfaction. In short, occupants’ satisfaction increases when occupants are satisfied with the lighting, air quality and aesthetic environment in the building.

Table 4.

Influence of indoor environment quality on building occupant’s level of satisfaction.

Construct Variables	ERP System Usage		t value	Sig.
Construct Variables	b Value	Standardize β	t value	Sig.
Lighting	0.104	0.104	1.43	0.16
Air Quality	0.132	0.143	1.55	0.13
Aethestic	0.526	0.593	6.46	0.00
R	0.76
R ²	0.58
Adjusted R²	0.57
F	51.55
Sig F change	0.00

Table 5.

Association of indoor environment quality and occupant’s satisfaction.

No	Construct variables	1	2	3	4
1	Satisfaction	1	0.351^a	0.402^a	0.405^a
2	Lighting	0.351^a	1	0.501^a	0.493^a
3	Air Quality	0.402^a	0.501^a	1	0.729^a
4	Aethestic	0.405^a	0.493^a	0.729^a	1

Correlation is significant at the 0.01 level (two-tailed).

Discussion

Our research findings revealed that the indoor environmental factors that could contribute to occupants’ satisfaction consist of lighting, air quality and aesthetic environment. These classifications were based on the factor analysis done with 22 attributes of the indoor environment. This is in line with research carried out by Groth,²⁹ which highlighted the concept of the indoor environment including all aspects of the relationship between occupants and contents of a building, as well as their surroundings, which can be considered as climatic and non-climatic aspects of indoor environment.

This study found that occupants were less satisfied with the distance from window, glare level in the room and glare level around desk/VDU. Most occupants spend almost 8 h a day in the building, so the glare level is very vital. The dissatisfaction among occupants was due to the low level of glare and distance from window. Occupants spend a lot of time inside buildings, where physical conditions could influence their wellbeing and indirectly influence their performance and productivity. The respondents ranked control over the environment, health, air movement, ventilation and freshness as important factors of IEQ. These findings support the previous study where important IEQ factors for occupant satisfaction were the amount of space available for individual to work, noise level and visual privacy.⁷ In terms of comfort level, respondents were satisfied with the condition of their ‘current rooms’. In short, occupants were comfortable with the appearance, serenity, colour, brightness, noise and temperature of their building or their room.

This study found a moderate positive relationship between IEQ attributes and occupants’ satisfaction with their buildings. The extent of the influence and relationship between these attributes could be impacted by gender and type of respondents and by duration of stay in the building²⁵ (Choi et al.³⁰). The duration of stay in the building could also influence the relationship between these attributes. The factor of adaptation could affect responses given in study. The level of satisfaction with the IEQ condition among occupants in their buildings is different according to the duration of their stay. In addition, Agha-Hossein et al.³¹ pointed out that employees’ self-reported productivity, well-being and enjoyment at work increased with a higher level of satisfaction towards work environment. This means that the work environment could significantly influence the productivity and performance of building occupants. Thus, managers in organizations should provide a good working environment to ensure the greatest satisfaction level among occupants in their buildings. All IEQ factors should be assessed in order to provide comfort and satisfactory conditions for all occupants in their buildings. On the other hand, further studies are needed to ensure that occupants’ level of satisfaction would be consistently maintained.

Conclusion and policy implications

The assessment of occupants’ satisfaction towards IEQ in buildings is critical because it can affect occupants’ health, comfort, performance and productivity. This study highlighted the need for an assessment of IEQ satisfaction among occupants. The assessment acts as a pioneer in assessing indoor environment problems based on human’s view and perception. Indoor environment study is essential in order to satisfy requests linked to critical functions of occupants because most people spend their time living inside buildings rather than outdoor. The study of IEQ is complex and made up of many factors, which are intricate, inter-linked and often difficult to disentangle and study.

The paper presents the comparison of results from the questionnaire survey. The satisfaction of occupants is affected by the comfort level of the building environment. This study found that occupants are less satisfied with daylight, glare levels in the room, glare level around desks/VDU, and distance from the window. Thus, interior designers should take note and due cognizance of these in order to maximize occupants’ level of workspaces. Occupants who are satisfied with their overall working environment would have improved job satisfaction, work performance and productivity. In conclusion, occupants’ level of satisfaction depends on their satisfaction with elements of the indoor environment, but perceptions can vary depending on individual characteristics.

In addition, IEQ can also contribute to energy saving. Sarbu and Sebarchievici³² noted that the energy consumption of buildings depends on the criteria used for the indoor environment (temperature, ventilation and lighting), building design and operation. The design of rooms can reduce energy consumption and influence comfort levels.

IEQ is an important aspect of the discourse on sustainability of buildings. It is one of the assessment criteria for Green Building Index (GBI), which is implemented in Malaysia, and in which IEQ accounts for 21% of a total of 100%. IEQ is the second highest contributor after energy efficiency. Other constructs such as air quality, thermal comfort, lighting, visual and acoustic comfort are evaluated in order to achieve green building recognition in Malaysia. Elements such as day lighting, daylight glare control and lighting levels are evaluated under lighting. Thus, the satisfaction level with all factors are essential in ensuring that buildings could operate in a sustainable way, and that building occupants could perform well with optimum overall surrounding conditions. Factors suggested in this research can be applied for the GBI index evaluation to improve the health and well-being of occupants and their performance in buildings

Practical implication

This study was conducted in order to identify building occupants’ needs and satisfaction and to address key issues relating to their level of satisfaction. It is suggested that all actors, including designers, engineers, developers and facility managers need to be cognizant of factors identified in the study as these actors are directly involved in building and operation processes. This study has shown that building occupants’ level of satisfaction with IEQ can have a significant impact on creating changes needed to improve a building’s environment. It provides lessons and feedback for owners and relevant parties involved, directly and indirectly, in environmental improvement work. In addition, findings from this study could empower end users and provide a benchmark to identify building design and its environmental management to meet occupants’ needs. The study has also identified a number of issues that could lead to the disruption of building performance and deterioration of buildings.

Further studies can focus on understanding on differences and association between factors that impact occupants’ level of satisfaction, including differences in gender, type of occupants and duration of stay in the building as they relate to IEQ attributes. Exploring whether a variable is causally linked or different to a particular IEQ attribute can provide a richer and better understanding of differences between IEQ and occupants’ level of satisfaction. Therefore, these findings and knowledge can lead to further improvements in the indoor environment of buildings.

Footnotes

Authors’ contribution

SNK designed/modification of research instrument and performed, analysed data and wrote the main paper; CE supervised the project, performed data collection, analysed data and wrote the paper; NM administered the data collection, assembled input data, analysed data and wrote the paper; EMAZ gave technical support, conceptual advice, supervised its analysis and wrote the paper; SJLC analysed and interpreted the data, performed major upgrading and wrote the paper; NFA gave technical support, performed major upgrading and wrote the paper.

Declaration of conflicting interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The authors gratefully acknowledge the financial support of the High Impact Research (HIR) grant, no. UM.C/625/1/HIR/ASH/013, obtained from the University of Malaya.

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