Evaluation of Occupant Perception and Satisfaction in Two New Office ...

Evaluation of Occupant Perception and Satisfaction in Two New Office Buildings 1

Lu Aye1, W. W. S. Charters2, M. Chiazor3,1 and J. R. W. Robinson3

International Technologies Centre (IDTC), Dept. of Civil and Environmental Engineering 2 Department of Mechanical and Manufacturing Engineering 3 Department of Architecture, Building and Planning The University of Melbourne, Victoria 3010, AUSTRALIA E-mail: [email protected]

Abstract A pilot study is undertaken comprising the recording of indoor air quality data and evaluation of occupant perception and satisfaction survey of 22 office workers in two buildings that contain different energy efficiency features. The study was conducted in two consecutive weeks in February 2005, Melbourne. The objective was to test the method developed to quantify and compare the effects of indoor environmental quality such as indoor air quality, and views on specific appraisals of human perception and responses. Physical and subjective measurements were made at five selected offices in each building, while they were occupied. Analysis and discussion of the preliminary findings of the investigation are directed primarily at the method used and at a comparison of occupants’ perception and satisfaction. In addition, the implications of study methods for evaluation of occupant perception of buildings and for further implementation are discussed.

1. INTRODUCTION Building performance evaluation has a long and somewhat notable history of probing outcomes and making recommendations for improvement (Lackney, 2001; Zimring, 2002; Lu Aye et al., 2004). The evaluation of occupant perception of building systems attracts significant interest and brings a number of potential benefits to architecture and building ecology in two main ways. First, the emphasis on measurement of occupant perception has changed the focus of indoor air quality symptom diagnosis to a more holistic view of perception and overall satisfaction of the occupant and building performance. Second, the expediency of environmental perception in the built environment is increasingly of primary consideration in generating value (economic value, social value and ecological value), better knowhow of occupant attitude and comfort (Moore et al., 2002) and the promotion of corporate recognition and sustainable development (Heerwagen, 2001). Indoor environmental quality (IEQ) is a growing social, economic and environmental concern and there is evidence that poor IEQ is an impediment to occupant perception and overall satisfaction with office buildings. Generally, physical and environmental factors, such as temperature, humidity, sound, lighting, contaminants and particulate matters may interact to influence the problems of IEQ. They also affect occupants' perception and satisfaction of built environments. In addition to the factors that directly influence the levels of pollutants to which people are exposed, personal factors can affect how people perceive indoor environmental quality. Factors that are characterised by such an ability to show acceptable values are: • those directly affecting IAQ such as indoor temperature, relative humidity, air velocity and • those affecting perception and satisfaction with the overall indoor environment, such as lighting (brightness and glare), noise, furniture and equipment, overcrowding and psychological discomfort. There is, consequently, a need to evaluate occupants’ perception to begin to understand the impact of different types of indoor environments and IAQ on the occupants in the widest sense. The evaluation of occupant perception and satisfaction forms a significant aspect of probing the indoor environmental quality within the workplace. In building research, perception evaluation is a means to understanding the forces that drive occupants' needs—and enables facilities managers also make decisions and improvements to meet those needs. As (Berger, 1997) argued, perception can be defined as the

Evaluation of Occupant Perception and Satisfaction

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psychological ability to receive, organise, process and interpret sensory information. In the field of psychology, the cognitive sciences, and interdisciplinary sciences literature, perception is defined as the function of smelling, tasting, feeling, via sensory organs (Wikimedia, 2005). As (Bourdieu, 1977) noted, perception also involves behavioural actions or reactions of an organism, consciously or unconsciously, usually in relation to objects, people and the environment. Just like perception, satisfaction is highly subjective and it is difficult to develop appropriate measures and compare results across disciplines (Giese and Cote, 2002). According to the Readership Institute (2005), occupant satisfaction is a weighted ranking that takes into account both the satisfaction with a building and how important that parameter is to the occupant. It provides a reaction on how well the building is performing from the perceptions of a variety of stakeholders, particularly occupants and facilities managers. As (Andrews and Withey, 1976), noted, perception and satisfaction are psychological concepts that involve a feeling of comfort and contentment that result from obtaining what is desired in a product or service. In building science, it is a way to examine, compare and communicate past actions with present performances. Although people evaluate a significant number of performance indicators across the workplace, the ones that explain whether the occupant is feeling the improvement delivered, are those that measure occupant satisfaction and perception. This article concerns the methods of evaluation of IEQ perception and overall satisfaction of two new office buildings in Melbourne, the capital city of Victoria, Australia. Two newly constructed large commercial office buildings are being monitored and evaluated in this study to compare occupant perception of indoor environmental quality impact of the buildings (one of which has energy efficiency features). The aim of this paper is to describe and discuss the method used in the evaluation of occupant perception of and satisfaction with indoor environmental quality (IEQ) of different office areas. Physical and occupant data are being collected in across four seasons of the year.

2. METHOD This study uses a facilities performance-based method to investigate two newly completed office buildings in Melbourne after occupation for a period of time. One building has a range of energy efficient features and the other is a conventional building (Lu Aye et al., 2004). Two research methods were employed: First a quantitative survey method was employed through which data-loggers/sensors were set-up in working offices to record the indoor air quality on a daily basis. Recorded data of physical environment parameters such as temperature, relative humidity, air ventilation rates are down-loaded to a computer after 24 hours. From the office population lists, (see Table1) the required sample sizes of offices were determined using a statistical method. The formula used for determining the sample size is:

n=

σ2 ⋅ Z 2 E2

(1)

Where: n = sample size σ = estimate of sample standard deviation Z = a value which depends on confidence level (1.96 for 95% confidence level) E = sampling error to be tolerated The relationships among the variables will next be examined by correlation analyses (Pearson product moment correlations, two-tailed tests). In addition, ANOVA will be used. To compare the two buildings, measures of number of offices, occupant perception and satisfaction by cross-tabulation were conducted on the groups of related variables. The proposed allowable error tolerance is +/- five percent at a 95 percent confidence interval. The second research method – the occupant survey, was a qualitative survey through which working offices and occupants representative of the overall number of offices and users in the both buildings were counted and contacted by email. The questionnaire surveys cover issues including perception of indoor environmental quality at workplace, the total work environment and climate in the work area, exposure to noise by people and equipment, job satisfaction, psychological well-being, sick building Renewable Energy for a Sustainable Future – A challenge for a Post Carbon World ANZSES 2005 Reviewed as fullpaper

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syndrome, as well as absenteeism. Table 1. Research sample size Alan Gilbert building ICT building Level 1 2 3 4 5 6 7 Total

Offices nil 44 34 52 75 37

No of Staff Nil 58 95 61 75

Level GF 1 2 3 4 5

Offices 18 2 6 47 46 45

22 264

57

6 Total

29 193

346

No of Staff

137

Furthermore, interviews which randomly select occupants in the offices environment, such as managers, were undertaken to provide in-depth opinion on the office environment. Questions are semi-structured and with open-ended answers. Occupant interview - textual data will be analysed with Analysis Software for Word-based Records (AnSWR), (CDC 2005.). AnSWR was chosen because it is suited to content analysis and identification of recurrent patterns within text based data. It is Ideal in mixed method research because it is able to coordinate and analyse data that integrate qualitative and quantitative techniques. It performs automatic source coding utilising a user selected default source, manual and direct text entry, instant processing of coded segments, code graphics, file level coding, coding of HTML documents located anywhere on the World Wide Web, ACSII text (.txt) files, Rich Text (.rtf) files, Microsoft Word and Excel documents. In addition, it computes frequencies, classifies texts passages and attaches comment to codes. To analyse text-based data, textual data will be entered manually or imported into computer, they will be coded to form a dictionary or categorization of texts, testing hypothesis concerning the text material analysed, exporting the text to other software, generating reports on the coding performed. Perceptions of current and acceptable IEQ were assessed with a 5-point rating scale. Frequencies, means and standard deviations were used to describe and compare the prevalence and forms of indoor air quality symptom, and reported sick building syndrome symptoms among respondents in the study. Measurement and evaluation of IEQ is compared with ASHRAE, EPA Victoria, USEPA and WHO threshold limit values (TLVs) of the reference buildings (See Table 2). Table 2. Indoor environmental quality objectives for office buildings ASHRAE EPA VICTORIA Substance/Parameters Concentration Averaging Concentration Averaging period period Carbon dioxide 500 -1000 ppm Carbon monoxide 29 ppm 1 hour Particulates (PM10) 0.080 ug/m3; 1 hour Particulates (PM2.5) 0.050 ug/m3 1 hour Ventilation rate 10 L/s Total Volatile Organic 0.5 mg/m3 Compounds Temperature 20 - 23.5 oC (Winter) o 23 - 26 C (Summer) Relative humidity 30 - 60% Nitrogen oxide 0.19 ppm 1 hour 0.03 ppm 1 year Light 500 lux Sound 45 (dBA) Source: ASHRAE 1992; Victoria Government Gazette 1999

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2.1.

Lu Aye et al.

Tools

There are several indoor air quality measurement devices suited to building evaluation. We have chosen the following tools because they are optimized for easy operation yet still provide a full range of high -level capabilities, such as data logging and statistical analysis. In addition, they met our research objectives regarding method detection limit and representativeness, and they have been tested for precision and accuracy. They also meet international standards for measuring indoor air quality in new, single and mixed mode buildings. All equipment used meets ASHRAE, USEPA and WHO specifications. The measuring instruments include: • Q-trak Plus IAQ models 8554 (TSI Inc., St Paul, MN, USA) was used for measuring carbon dioxide (ppm), temperature (OC) and relative humidity (%) and carbon monoxide (CO); it has multiple-line display that shows air quality parameters simultaneously. • Dust-trak Aerosol Monitor (TSI Inc., St Paul, MN, USA) was used for measuring particulates including PM10 & PM2.5 (mg/m3) and Aerosols. • SVAN 949 sound analyzer (SVANTEK Ltd, Warsaw, Poland) was used for measuring noise level (decibel) (dB)A, • Testo 545 lux meter (Testo, GmbH& co. Germany) was used for measuring light intensity (lux).

2.2.

Analyses

Data analyses will be performed using a multi-level approach. The HLM procedure was employed because it is able to deal with the non-independence of observations that is typically associated with grouped data. HLM also is able to deal with the possibility that relationships among variables may vary in strength (and direction), from one group to another. It will include statistical evaluation and measurements of IEQ parameters against the IEQ metrics in order to identify the effects of IEQ. Frequencies, means and standard deviations will be used to describe and compare the prevalence and forms of indoor air quality symptom among respondents in the study. Thermal comfort data will be analysed to identify the extent to which the IEQ is able to provide a thermally acceptable environment.

3 THE PILOT STUDY The study commenced in February 2005-summer season. Physical data of indoor air quality (IAQ) parameters was monitored and recorded continuously on a 24-hour basis in each office space. The IAQ parameters that were measured included air temperature, relative humidity, carbon dioxide, carbon monoxide, particulate matters (PM10), light intensity and sound level. All of the data-loggers were set up about 1.0m above floor level; all measurements were recorded on three floors (levels 1, 5 & 6) of the ICT building and three floors (levels 5, 6 & 7) of the Alan Gilbert building. Twenty two participants (office workers only) were recruited, 11 from each of the two buildings for the pilot study. Participants were between 20 and 60 years of age. Two types of surveys: a questionnaire and a semi-structured interview were used to collect information on participants’ perceptions and satisfaction with the work environments and their psychosocial evaluation of those environments. Comprehensive questionnaires were administered to the participants concurrently with each environmental sampling event to gather information on participants’ perceptions of the comfort conditions in the office environments. It is a 25-item self-report questionnaire that provides sociodemographic information about the participants, details of their workplace, physical and psychological well-being. The questionnaire was designed in plain language and a 5-point scale was employed for the analysis. Other parts of the questionnaire collected information regarding occupant behaviour in and opinions on individual work areas, noise intensity, dust pollution levels, gender, age, interaction, view and activity of interviewees, most of which are not discussed in this report. The questionnaires were distributed to the participants once during the study. The interview was a longer form of the questionnaire; it was intended to explore more detailed information from participants about IEQ perception and satisfaction. The questionnaire protocols were approved by the institutional human research and ethics committee, and informed written consent obtained from each respondent. Information was collected on respondent’s socio-demographic Renewable Energy for a Sustainable Future – A challenge for a Post Carbon World ANZSES 2005 Reviewed as fullpaper

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characteristics, e.g. age, sex, job and categories their perception of indoor environmental quality. Each respondent was interviewed for approximately 20 minutes in their office work areas. The analyses were performed using SPSS version 12.0.2 for Windows. Descriptive statistics and ANOVA will be used to examine the relationships between perceptions of IEQ and overall satisfaction with work areas in buildings. In addition, cross-tab procedure will be used because descriptive statistics are reported here in their raw form.

4 RESULTS Table 2 shows the statistical summary of indoor air quality features measured for buildings one and two. The statistical mean for temperature and relative humidity, CO2 and CO values in the two buildings meet the ASHRAE Standards 55-1992R for thermal environmental conditions for acceptable human occupancy (American Society of Heating, 1992). Table 2. Statistical summary of recorded IAQ parameters in buildings Building One (ICT building) (Building with conventional features) Values Minimum Maximum Mean Std. Error Std. Deviation

Temp (oC) 22.90 23.71 23.48 0.15 0.33

CO2 (ppm) 389.19 428.32 400.07 7.44 16.63

Rh (%) 35.45 40.27 38.18 0.87 1.95

CO (ppm) .00 .11 4.184E-02 2.142E-02 4.789E-02

PM10 .009 .009 .009 -. -.

Light (lux) 132.56 657.46 295.19 98.92 221.19

PM10 .006 .006 .006 -. -.

Building Two (Alan Gilbert building) (Building with energy efficiency) Values Minimum Maximum Mean Std. Error Std. Deviation

4.1

Temp (oC) 20.30 21.93 21.08 0.29 0.64

CO2 (ppm) 374.72 389.77 381.16 2.95 6.60

Rh (%) 46.03 48.16 47.19 0.42 0.94

CO (ppm) .03 1.26 0.36 0.23 0.51

PM10 .021 .021 .021 -. -.

Light (lux) 36.45 1067.24 365.86 183.99 411.42

PM10 .028 .028 .028 -. -.

Occupant survey findings

Comparisons of occupant perception and satisfaction on IEQ across behavioural modalities provided clear evidence that the IEQ problems had a major influence on the occupants of both buildings. In these buildings, occupants complained about physiological symptoms such as headaches, itchy eyes and throat and mostly indicated “frequently” occurrence for these symptoms. However, more of these complaints came from building one and could be correlated to occupants’ physical awareness, such as from lack of steady air flow, equipment malfunctions and operation (see Table 3). Table 3. Complaint about IAQ by Building Features Building one Building two Total

Frequently 8 6 14

Complaints about IAQ Occasionally 3 3 6

Rarely 0 2 2

Total 11 11 22

Building one (ICT Building) appeared to have more IAQ-related complaints from the occupant perception than in building two as shown in Table3. However, temperature/RH-related concern is higher in building two as indicated in Table 4. In addition, complaint of discomfort to occupants (related to temperature) was higher among female respondents than male and more frequently in building two than one (see Figure 1).

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Table 4. Perception of indoor temperature/Relative humidity by Building Not acceptable Acceptable Features Count % of Total Count % of Total Building one 6 27.3% 5 22.7% Building two 8 36.4% 3 13.6% Total 14 63.6% 8 36.4%

10

Building oneConventional Building two-Energy efficient

Count

8

6

4

2

0

Related to temp

Not related to temp

No Discomfort

Figure 1. Discomfort to Occupants by Building Table 5. Perception of work area by building Others Very satisfied

Features

Count 7 7 14

Building one Building two Total

% of Total 31.8% 31.8% 63.6%

Count 4 4 8

% of Total 18.2% 18.2% 36.4%

In the case of workers’ perception of office environment, female respondents were “very satisfied” compared with the males as shown in figure 2; yet, both male and female respondents show equal satisfaction by building type as indicated in table 5. Others in table 5 indicate respondent who are barely satisfied and not satisfied about perception of their work area. Table 6. Perception of work area by Gender Building type

Respondents

1

2

Building one

4

0

2

2

8

4

1

4

2

11

Male

3

1

4

8

Female

1

1

1

3

4

2

5

11

Total Gender

Building two

Female

Total

Satisfied

Total Not satisfied 0

Male Gender

Perception of workarea Very satisfied 0

Neural

3

The overall occupant perception and satisfaction rating of work space shows equal satisfaction by gender and by building type as shown in figure 2. The perception measures varied considerably in the way the indoor environment survey was evaluated. In some situations, occupants rated how satisfied they were with a range of IEQ parameters such as temperature, sound, lighting, air quality view, and pollutant and these ratings were combined to generate an overall score of IEQ perception and Renewable Energy for a Sustainable Future – A challenge for a Post Carbon World ANZSES 2005 Reviewed as fullpaper

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satisfaction. The rating of work area by gender shows variation in perception and satisfaction.

6

Gender Male Female

5

Count

4

3

2

1

0

Very satisfied

Satisfied

Neural

Not satisfied

Perception of workarea

Figure 2. Overall satisfaction with IEQ by Building

5. DISCUSSION The European project (Bluyssen et al., 1996) and the American Society of Interior Designers (ASID., 1997) have recognized workplace perception as a serious issue in workplaces, and have expressed their concern about the effects of IAQ perception on the well-being and productivity of workers. Research into IEQ symptoms has been and is going on in many developed countries. The recorded data for temperature, relative humidity, carbon monoxide measurements are within acceptable limit, yet temperature and relative humidity are not consistent with Ashrae standards and of cities with similar characteristics for summer seasons. Light level data on the other hand showed remarkable variation,- high glare level was noticeable in building Two. This is significantly accounted for by the direction of specific offices in the study that had North-facing orientation. Also, carbon dioxide and PM10 was below acceptable threshold limit values. The low level of particulate matter (PM) can be attributed to, the wet period experienced during data collection period in February 2005. This study provides new insights and perspectives into the influence of indoor environmental quality, particularly, with respect to different office settings, gender differences, and the health impact of prolonged IAQ symptoms, as well as into the role of indoor environment parameters in predicting its onset. Regarding the connections between IAQ and the work environment, the findings are in agreement with other studies (Wargocki et al., 1999); (Wang et al., 2005). In particular, a poor indoor air quality seemed to be a risk for perceived dissatisfaction and satisfaction. On the basis of this study, the thermal conditions of both buildings included acceptable temperatures (