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Citation: Lee, G.-B.; Lee, S.-M.; Lee,
S.-E.; Jeong, J.-W.; Lee, J.-W. A
Comparative Field Study of Indoor
Environment Quality and Work
Productivity between Job Types in a
Research Institute in Korea. Int. J.
Environ. Res. Public Health 2022,19,
14332. https://doi.org/10.3390/
ijerph192114332
Academic Editor: Derek
Clements-Croome
Received: 9 October 2022
Accepted: 30 October 2022
Published: 2 November 2022
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International Journal of
Environmental Research
and Public Health
Article
A Comparative Field Study of Indoor Environment Quality and
Work Productivity between Job Types in a Research Institute
in Korea
Gyu-Bae Lee 1, Seung-Min Lee 2, Seung-Eon Lee 2, Jae-Weon Jeong 1and Jong-Won Lee 1,2,*
1Department of Architectural Engineering, College of Engineering, Hanyang University, Seoul 04763, Korea
2
Korea Institute of Civil Engineering and Building Technology, 283 Goyang-daero, Daehwa-dong, Ilsanseo-gu,
Goyang-si 10223, Korea
*Correspondence: jongwonlee@kict.re.kr; Tel.: +82-31-910-0723
Abstract:
Indoor environment quality (IEQ) evaluation can help improve building satisfaction
and productivity of residents. However, for more efficient analysis, it is necessary to gain a large
amount of data on the differences between specific groups, such as building and resident work
types. In this study, we conducted an IEQ evaluation for administrators and researchers, which
are occupational groups of a research institute. The evaluation was conducted using quantitative
and qualitative methods to find the relationships between IEQ satisfaction and work productivity
for each job type. Our results showed that light environment and office layout were correlated
with the work productivity of administrators, and light environment, office layout, thermal comfort,
and sound environment were correlated with the work productivity of researchers. In addition,
there was a significant difference in layout and thermal comfort items between administrators and
researchers. Therefore, this study revealed significant differences in the effect of IEQ evaluation on
work productivity between different occupations in a research institute.
Keywords:
indoor environmental quality (IEQ); occupant satisfaction survey; work productivity;
research institute; job types
1. Introduction
Human efforts to build safe and comfortable residential areas have led to the creation
of different types of complex buildings and housing styles in modern times. Although
the forms of buildings have diversified, people in modern society spend most of their
time inside buildings [
1
]. Thus, indoor environment quality (IEQ) is an important factor
in determining and improving the health and satisfaction of the occupants [
2
–
5
]. More-
over, there is a close relationship between IEQ and the productivity of occupants [
6
–
9
].
Previous studies reported that labor cost accounts for 80% of the total operation cost of
an organization; therefore, the improvement of IEQ and worker productivity is an impor-
tant operational issue [
10
–
12
]. Other studies have mentioned that offices with improved
indoor environment can increase the productivity of occupants by more than 20%, which
corresponds to more than GBP 130 billion per year [
13
,
14
]. In addition, many studies
have argued that improved indoor environment can reduce turnover rate and absenteeism
by improving occupants’ health and quality of life, thereby enhancing productivity and
satisfaction [
3
,
15
–
18
]. All these cases indicate that IEQ has a significant impact on the
building satisfaction, productivity, and health of occupants.
The correlation between IEQ and the satisfaction and productivity of occupants may
vary depending on various factors, such as building use, office type, population density, and
occupational characteristics. Therefore, in previous studies, building elements, including
occupants, were grouped for correlation analysis to elucidate the relationship between
occupants and indoor environment. For example, a previous study has shown that women
Int. J. Environ. Res. Public Health 2022,19, 14332. https://doi.org/10.3390/ijerph192114332 https://www.mdpi.com/journal/ijerph
Int. J. Environ. Res. Public Health 2022,19, 14332 2 of 17
were more likely to be dissatisfied with IEQ items than men [
19
]. In summers, occupants
aged 40 years and older are more satisfied with thermal comfort than those aged less than
40 years [
20
]. Among the IEQ items, acoustic environment may have a greater impact on
occupants with low productivity than on those with high productivity [
21
]. Occupants
whose personal workspaces were far from windows showed generally high satisfaction
with most of the IEQ items [
22
]. It was confirmed that occupants who use a desktop in
their workspace tend to prefer lighting compared to those who do not use a desktop [
23
].
A study conducted in Romania showed that occupants in rural and urban schools may
have relatively different perceptions of IEQ owing to such reasons as habits, outdoor
environment, and class [
24
]. Additionally, it was revealed that the correlation between
occupants’ satisfaction with buildings and IEQ is related to the size, appearance, and
workspace of the building [
5
]. Furthermore, the correlation between residents and IEQ
items was also analyzed for various building types such as airport terminals, libraries,
hospitals, and offices [25–29].
The correlation analysis between IEQ satisfaction and occupant productivity has also
been studied according to buildings and job type. For example, in higher education insti-
tutions, IEQ evaluation was performed mainly for students, and in offices in commercial
buildings, IEQ was evaluated by classifying the work types of occupants into “Admin-
istrative”, “Technical”, “Professional”, and “Managerial” [
30
–
34
]. There are also studies
that specifically divided the occupations of inhabitants and analyzed the correlation be-
tween their IEQ satisfaction and productivity. Sadick et al. [35] conducted research on the
IEQ satisfaction and productivity of students and professors in a university building in
a tropical African climate. They found that IEQ had a positive impact on productivity
in both groups. Kim et al. [
19
] found that technical and managerial groups were more
dissatisfied with air quality and the amount of lighting than other occupational groups
among women working in office buildings. Zuo and MaloneBeach [
36
] investigated IEQ
related to the satisfaction and productivity of workers in assisted living facilities. They
found that the non-medical group, composed of managers and administrative staff, was
more satisfied with the air quality than the medical group composed of nurses and care-
givers. Kamaruzzaman [
37
] analyzed the correlation between IEQ and the satisfaction of
occupants of office buildings and found that the “managerial staff” had the highest average
IEQ score among all occupational groups, which included the “clerical and secretarial”,
“professional”, “managerial”, and “other” staff. Albuainain [
38
] investigated the level of
IEQ satisfaction for government buildings in Bahrain and analyzed its correlations with
non-IEQ factors, such as occupational groups. They found that the IEQ satisfaction level
was different depending on the occupational group, and that the technical group had the
highest IEQ satisfaction among the five occupational groups.
The results of previous studies can be summarized as follows. IEQ items are important
for the work productivity and satisfaction of occupants. In addition, occupants’ evaluation
and preference rankings for IEQ items may vary depending on individual factors (e.g., sex
and age) or building type and characteristics. In particular, the correlation between job types
and IEQ is expected to be diverse, but different research results can be obtained depending
on the building and region because related studies are insufficient. Therefore, research on
IEQ must continue for various targets and factors, and more correlation data need to be
analyzed by constantly studying related scenarios. However, occupants’ evaluation and
preference rankings for IEQ items may vary depending on individual factors (e.g., sex and
age) or building type and characteristics. Therefore, an increasing number of previous
studies are analyzing the IEQ evaluation of residents through correlation with various
factors. In previous studies, it was confirmed that the job type was also correlated with
the IEQ evaluation of the occupant [
30
–
38
]. However, because IEQ can obtain different
research results depending on buildings and regions, research on various targets and
factors should continue, and it is necessary to obtain additional relevant scenarios to
analyze correlation data.
Int. J. Environ. Res. Public Health 2022,19, 14332 3 of 17
As one of the building types, research buildings are also significantly influenced by
IEQ in the research efficiency and work productivity of offices [
21
]. In general, previous
studies selected research offices of universities and research offices of commercial com-
panies as targets for the IEQ evaluation of research buildings [
21
,
29
]. In addition, the
majority of papers analyzing research buildings such as university laboratories focused on
analyzing the evaluation of student groups, and did not evaluate employees working in
the building [
30
,
31
,
39
,
40
]. Therefore, it is necessary to analyze IEQ data for non-universal
research building and worker types to expand the IEQ evaluation scenario. In this study,
the correlation between IEQ items of the public research building in Korea was analyzed. It
is meaningful in analyzing occupant’s satisfaction and productivity by job group in a public
research building that has been rarely conducted in previous studies. The correlation by the
job group studied is expected to contribute to shaping the direction of IEQ improvement in
research institution buildings in the future.
The specific objectives of this study were as follows. The first objective was to identify
IEQ items that affect building satisfaction and work productivity for each occupational
group in the research institute. To this end, quantitative measurements, based on sensors
and qualitative assessments based on a survey, were performed. The second objective
was to analyze differences in the perception of IEQ between occupational groups in the
research institute by comparing the results of quantitative and qualitative evaluations. The
statistical significance of each result was analyzed. To this end, an additional literature
review was performed.
2. Methodology
The present study focused on measuring IEQ items related to the satisfaction and work
productivity of occupants. For evaluating and comparing IEQ items between researchers
and administrators, a matching analysis framework was constructed. Figure 1illustrates
the analysis and comparison of quantitative and qualitative data of these two job types
in relation to five IEQ items. Each item was based on the IEQ items of the Center for the
Built Environment (CBE), in accordance with previous studies [
19
,
21
,
29
,
41
]. Based on this,
the IEQ items measured in this study were classified into five categories: layout, thermal
comfort, air quality, lighting environment, and acoustic environment. For the layout item,
qualitative data for “amount of space”, “visual privacy”, and “ease of interaction” and
quantitative data for “area per person” and “storage volume per person” were compared
and analyzed. For the thermal comfort item, qualitative data for “thermal comfort level”
and quantitative data for “air temperature” and “relative humidity” were compared and
analyzed. For the air quality item, qualitative data for “air quality level” and quantitative
data for “CO
2
concentration” were compared and analyzed. For the lighting environment
item, qualitative data for “lighting level” and “visual comfort” and quantitative data for
“horizontal illuminance” were compared and analyzed. For the acoustic environment,
qualitative data for “noise level” and “sound privacy” were measured and analyzed. The
“noise” item, which is a quantitative measure, was not measured in this study.
2.1. Occupant Database
Table 1describes the basic information of a total of 98 occupants of the research
building K who participated in this study. The data were collected to identify the employees
in the institute, and only job type and floor data were used in this study. The data in Table 1
were divided into administrators and researchers, which are the job types within the
research building K used in this study. As shown in the table, the administrative group
was located on the first (18), second (14), and third (13) floors, whereas the research group
was located on the fourth (21) and fifth (32) floors. The numbers in parentheses indicate
the number of workers. In both the administrative group and the research group, the
proportion of men was higher than that of women, but there was no significant difference.
The proportion of people aged 31 to 50 in the administrative group (82.2%) was higher than
the research group (67.9%), and the proportion of people aged over 50 in the administrative
Int. J. Environ. Res. Public Health 2022,19, 14332 4 of 17
group (15.6%) was lower than the research group (28.3%). The proportion of workers who
worked for three months to one year in the administrative group (46.7%) was higher than
that of the research group (35.8%), and the proportion of workers who worked for more
than one year (48.9%) was lower than that of the research group (58.5%). In addition, about
90% of the workers in both groups worked more than 30 h per week. Figure 2shows the
panoramic view of the K research building where the research was conducted. The space
of the research group was 1.5 times larger than that of the administrative group, resulting
in higher density for the administrative group. In addition, 1.2 m cubicles were applied
to the administrative group and 1.5 m or larger cubicles for the research group owing to
the layout difference. A survey was conducted for approximately 14 days from December
14 to 28, 2021. The offices were equipped with basic facilities with no special facility (one
computer per person and a partition height of 1.2–1.5 m).
Int. J. Environ. Res. Public Health 2022, 19, x FOR PEER REVIEW 4 of 18
Figure 1. Framework used for analysis in the present study.
2.1. Occupant Database
Table 1 describes the basic information of a total of 98 occupants of the research build-
ing K who participated in this study. The data were collected to identify the employees in
the institute, and only job type and floor data were used in this study. The data in Table 1
were divided into administrators and researchers, which are the job types within the re-
search building K used in this study. As shown in the table, the administrative group was
located on the first (18), second (14), and third (13) floors, whereas the research group was
located on the fourth (21) and fifth (32) floors. The numbers in parentheses indicate the
number of workers. In both the administrative group and the research group, the propor-
tion of men was higher than that of women, but there was no significant difference. The
proportion of people aged 31 to 50 in the administrative group (82.2%) was higher than
the research group (67.9%), and the proportion of people aged over 50 in the administra-
tive group (15.6%) was lower than the research group (28.3%). The proportion of workers
who worked for three months to one year in the administrative group (46.7%) was higher
than that of the research group (35.8%), and the proportion of workers who worked for
more than one year (48.9%) was lower than that of the research group (58.5%). In addition,
about 90% of the workers in both groups worked more than 30 h per week. Figure 2 shows
the panoramic view of the K research building where the research was conducted. The
space of the research group was 1.5 times larger than that of the administrative group,
resulting in higher density for the administrative group. In addition, 1.2 m cubicles were
applied to the administrative group and 1.5 m or larger cubicles for the research group
owing to the layout difference. A survey was conducted for approximately 14 days from
December 14 to 28, 2021. The offices were equipped with basic facilities with no special
facility (one computer per person and a partition height of 1.2–1.5 m).
Table 1. Basic information on the administrator and researcher floors.
Type
Administrator
Researcher
Floor
1F
2F
3F
Total
(N)
Total (%)
4F
5F
Total (N)
Total
(%)
Number of occupants who responded
to survey
18
14
13
45
100.0
21
32
53
100.0
Sex
Male
8
6
9
23
51.1
16
13
29
54.7
Female
10
8
4
22
48.9
5
19
24
45.3
Figure 1. Framework used for analysis in the present study.
Table 1. Basic information on the administrator and researcher floors.
Type Administrator Researcher
Floor 1F 2F 3F Total
(N)
Total
(%) 4F 5F Total
(N)
Total
(%)
Number of occupants who responded
to survey 18 14 13 45 100.0 21 32 53 100.0
Sex Male 8 6 9 23 51.1 16 13 29 54.7
Female 10 8 4 22 48.9 5 19 24 45.3
Age
Under 30 0 1 0 1 2.2 2 0 2 3.8
31 to under 50 15 11 11 37 82.2 13 23 36 67.9
Over 50 3 2 2 7 15.6 6 9 15 28.3
Working
experience
Under 3 months 1 0 1 2 4.4 1 2 3 5.7
More than 3 months
and less than 1 year 10 6 5 21 46.7 13 6 19 35.8
Over 1 year 7 8 7 22 48.9 7 24 31 58.5
Weekly
working
hours
Under 10 h 2 0 0 2 4.4 1 4 5 9.4
11 h to under 30 h 0 1 1 2 4.4 1 0 1 1.9
Over 30 h 16 13 12 41 91.1 19 28 47 88.7
Int. J. Environ. Res. Public Health 2022,19, 14332 5 of 17
Int. J. Environ. Res. Public Health 2022, 19, x FOR PEER REVIEW 5 of 18
Age
Under 30
0
1
0
1
2.2
2
0
2
3.8
31 to under 50
15
11
11
37
82.2
13
23
36
67.9
Over 50
3
2
2
7
15.6
6
9
15
28.3
Working expe-
rience
Under 3 months
1
0
1
2
4.4
1
2
3
5.7
More than 3 months
and less than 1 year
10
6
5
21
46.7
13
6
19
35.8
Over 1 year
7
8
7
22
48.9
7
24
31
58.5
Weekly work-
ing hours
Under 10 h
2
0
0
2
4.4
1
4
5
9.4
11 h to under 30 h
0
1
1
2
4.4
1
0
1
1.9
Over 30 h
16
13
12
41
91.1
19
28
47
88.7
(a)
(b)
Figure 2. A panoramic view according to the type of office ((a) = administrator, (b) = researcher).
2.2. Physical Measurements
In the case of quantitative measurements, the main IEQ parameters identified in re-
lated studies were selected. For thermal comfort, air temperature and relative humidity
were measured with consideration for window and interior positions [42,43]. In previous
studies, quantitative evaluation of air quality was generally performed through CO2 con-
centration measurement [28,44–46]. Therefore, in this study, the air quality item measured
the indoor ventilation level and the freshness of air by deriving the CO2 concentration
from the representative value of each floor. For assessing the lighting environment, a sen-
sor that could measure the brightness of natural light and lighting was installed and op-
erated [47–49]. In this study, however, decibel measurement was not performed using a
sound level meter. Table 2 and Figure 3 show the accuracy information on the sensors.
Each sensor was pre-measured at the same location for 24 h prior to quantitative meas-
urement to ensure that the error range was within the accuracy of each instrument. As a
result of the pre-measurement, it was confirmed that each sensor was operating within
the error range, so the measured values of each sensor were analyzed for common use.
Figure 2. A panoramic view according to the type of office ((a) = administrator, (b) = researcher).
2.2. Physical Measurements
In the case of quantitative measurements, the main IEQ parameters identified in re-
lated studies were selected. For thermal comfort, air temperature and relative humidity
were measured with consideration for window and interior positions [
42
,
43
]. In previous
studies, quantitative evaluation of air quality was generally performed through CO
2
con-
centration measurement [
28
,
44
–
46
]. Therefore, in this study, the air quality item measured
the indoor ventilation level and the freshness of air by deriving the CO
2
concentration
from the representative value of each floor. For assessing the lighting environment, a
sensor that could measure the brightness of natural light and lighting was installed and
operated
[47–49]
. In this study, however, decibel measurement was not performed using a
sound level meter. Table 2and Figure 3show the accuracy information on the sensors. Each
sensor was pre-measured at the same location for 24 h prior to quantitative measurement
to ensure that the error range was within the accuracy of each instrument. As a result of
the pre-measurement, it was confirmed that each sensor was operating within the error
range, so the measured values of each sensor were analyzed for common use.
Table 2. Information on measurement equipment.
Equipment Measurement
Parameter Accuracy Measurement Time
Data Logger
(UX100-011A)
Air temperature ±0.21 ◦C from 0 to 50 ◦C
10 min
(at each point)
Relative humidity ±2.5% from 10% to 90%
Data Logger
(MX1102A)
Air temperature ±0.21 ◦C from 0 to 50 ◦C
Relative humidity ±2% from 20% to 80%
CO2concentration ±
50 ppm
±
5% reading at 25
◦
C, less than
90% RH
USB Connectable
Loggers
(TR-74Ui-S)
Air temperature ±0.3 ◦C at 10 to 40 ◦C
Relative humidity ±2.5% at 15 to 35 ◦C, 30% to 80%
Illuminance ±5% at 25 ◦C, 50% RH
Int. J. Environ. Res. Public Health 2022,19, 14332 6 of 17
Int. J. Environ. Res. Public Health 2022, 19, x FOR PEER REVIEW 6 of 18
Table 2. Information on measurement equipment.
Equipment
Measurement
Parameter
Accuracy
Measurement
Time
Data Logger
(UX100-011A)
Air temperature
±0.21 °C from 0 to 50 °C
10 min
(at each point)
Relative humidity
±2.5% from 10% to 90%
Data Logger
(MX1102A)
Air temperature
±0.21 °C from 0 to 50 °C
Relative humidity
±2% from 20% to 80%
CO₂ concentration
±50 ppm ±5% reading at 25 °C,
less than 90% RH
USB Connectable
Loggers
(TR-74Ui-S)
Air temperature
±0.3 °C at 10 to 40 °C
Relative humidity
±2.5% at 15 to 35 °C, 30% to 80%
Illuminance
±5% at 25 °C, 50% RH
(a)
(b)
(c)
Figure 3. Sensors used in the study ((a) = UX100-011A, (b) = MX1102A, (c) = TR-74Ui-S).
Figure 4 shows the sensor installation positions. The sensors were positioned so that
the representative values of the perimeter zone and the interior zone could be identified
in consideration of the number of equipment possessed. The sensors were installed at a
height of approximately 1.2 m from the floor to perform continuous measurements, and
the data obtained during flexible work hours (07:00–19:00) were analyzed. Most measure-
ments were performed during work hours. The window shades could be adjusted indi-
vidually, and personal computers and the heating system were in normal operation. All
the sensors performed measurements at the same time during the aforementioned period,
and the measurements were recorded every 10 min.
Figure 3. Sensors used in the study ((a) = UX100-011A, (b) = MX1102A, (c) = TR-74Ui-S).
Figure 4shows the sensor installation positions. The sensors were positioned so that
the representative values of the perimeter zone and the interior zone could be identified
in consideration of the number of equipment possessed. The sensors were installed at a
height of approximately 1.2 m from the floor to perform continuous measurements, and the
data obtained during flexible work hours (07:00–19:00) were analyzed. Most measurements
were performed during work hours. The window shades could be adjusted individually,
and personal computers and the heating system were in normal operation. All the sensors
performed measurements at the same time during the aforementioned period, and the
measurements were recorded every 10 min.
2.3. Qualitative Evaluation
In the case of qualitative measurement, based on CBE’s survey data, it was performed
through a questionnaire partially revised to suit the purpose of the study and the climate
of Korea. In addition, exploratory factor analysis was conducted to examine whether the
questionnaire used in the study could reliably identify the factors determining occupant
satisfaction in each group. As a result of exploratory factor analysis, the Kaiser–Meyer–
Olkin (KMO) measure was 0.641, and the significance probability was less than 0.05 in the
Bartlett’s sphericity test results, thereby confirming that the questionnaire was suitable.
Moreover, reliability analysis was conducted to examine the internal consistency of each
factor. Cronbach’s alpha was used to determine the internal consistency, and the Cronbach
α
value for each variable ranged from 0.767 to 0.941. This result was satisfactory, as a value
of 0.6 or higher was recommended in previous studies to determine whether the question-
naire was appropriate [
21
,
29
,
50
]. After exploratory factor analysis, the questionnaire was
distributed and collected during the same period as the quantitative measurement period.
A total of 150 questionnaires were returned, out of which 98 were valid (a valid response
rate of 65.3%). In these valid responses, 36 questionnaires (14 males and 22 females) were
from administrators and 62 questionnaires (45 males and 17 females) from researchers.
Therefore, in this study, data for 98 people were qualitatively analyzed. Quantitative
evaluation was performed by partially reconstructing according to the climate of Korea
by referring to the IEQ evaluation items of CBE [
41
]. For the evaluation of IEQ in the
target building, five items (layout, thermal comfort, air quality, lighting environment, and
acoustic environment) were analyzed. In addition, total productivity items were analyzed
to evaluate overall work productivity for the overall environmental conditions and to find
out how the evaluated work productivity and overall work productivity evaluation in
each IEQ item correlated. The survey began with the collection of individual information,
such as sex, age, and number of years in the office, from the respondents. The degree of
comfort felt by each respondent was then measured for assessing the productivity, five IEQ
items, and other factors. Satisfaction evaluation for each item was conducted with a survey
reflecting the 7-point Likert scale from 1 (very dissatisfied) to 7 (very satisfied), as studied
in CBE and ASHRAE 55 [
41
,
42
]. In addition, total productivity and work productivity were
evaluated through a survey on the same 7-point Likert scale from 1 (very low) to 7 (very
high). In addition to evaluating satisfaction and productivity for each IEQ item, additional
options (e.g., causes of dissatisfaction and time zones of dissatisfaction) that may be used
in future studies were also collected. Table 3shows the details of the survey.
Int. J. Environ. Res. Public Health 2022,19, 14332 7 of 17
Int. J. Environ. Res. Public Health 2022, 19, x FOR PEER REVIEW 7 of 18
Figure 4. Sectional layout of each floor of the research institute. For security reasons, the floor plan
is presented in limited details. The symbol P stands for the period zone, and the symbol I stands for
the interior zone. Sensors A, B, and C are the same as those shown in Figure 3.
2.3. Qualitative Evaluation
In the case of qualitative measurement, based on CBE’s survey data, it was performed
through a questionnaire partially revised to suit the purpose of the study and the climate
of Korea. In addition, exploratory factor analysis was conducted to examine whether the
questionnaire used in the study could reliably identify the factors determining occupant
satisfaction in each group. As a result of exploratory factor analysis, the Kaiser–Meyer–
Olkin (KMO) measure was 0.641, and the significance probability was less than 0.05 in the
Bartlett’s sphericity test results, thereby confirming that the questionnaire was suitable.
Figure 4.
Sectional layout of each floor of the research institute. For security reasons, the floor plan is
presented in limited details. The symbol P stands for the period zone, and the symbol I stands for the
interior zone. Sensors A, B, and C are the same as those shown in Figure 3.
Int. J. Environ. Res. Public Health 2022,19, 14332 8 of 17
Table 3. Information of IEQ survey items.
Items Questionnaire
Items Survey Questions
Layout
Amount of space How satisfied are you with the amount of space in your workspace?
How improved is your productivity with the amount of space in your workspace?
Visual privacy How satisfied are you with the visual privacy in your workspace?
How improved is your productivity with visual privacy in your workspace?
Ease of
interaction
How satisfied are you with the ease of interaction in your workspace?
How improved is your productivity with the ease of interaction in your workspace?
Thermal
productivity
Thermal
comfort level
How satisfied are you with the thermal comfort level in your workspace?
How improved is your productivity with the thermal comfort level in your workspace?
Air quality Air quality
level
How satisfied are you with the air quality level in your workspace?
How improved is your productivity with the air quality level in your workspace?
Lighting
environment
Lighting level How satisfied are you with the lighting level in your workspace?
How improved is your productivity with the lighting level in your workspace?
Visual
comfort
How satisfied are you with the visual comfort in your workspace?
How improved is your productivity with the visual comfort in your workspace?
Acoustic
environment
Noise level
How satisfied are you with the noise level in your workspace?
How improved is your productivity with the noise level in your workspace?
Sound
privacy
How satisfied are you with the sound privacy in your workspace?
How improved is your productivity with the sound privacy in your workspace?
Total
productivity
Perceived work
productivity level
How much has overall work productivity improved through the overall environmental
conditions of the workspace?
3. Results and Analysis
3.1. Results of Quantitative Measurements
Table 4shows the comparison of air temperature, relative humidity, horizontal illu-
minance, CO
2
concentration, area per person, and storage volume per person between
administrators and researchers, as analyzed using the Mann–Whitney U-test. The results
can be summarized for each IEQ item as follows:
(1)
For the office layout, there was a significant difference between the research and
administrative groups. Each item is a parameter closely related to the personal
space of occupants in the office. Area per person was calculated using the formula
“room area/seat number”, whereas storage volume per person was determined using
the formula “total volume of cabinets/seat number” [
29
]. For the office layout, the
difference in area per person was not significant, but storage volume per person
exhibited a significant difference (p< 0.001). In the target building, the average area
per person and storage volume per person of the research group were 16.9 m
2
and
1.4 m
3
, respectively, which were relatively higher than those of the administrative
group (14.8 m
2
and 0.8 m
3
, respectively). This finding indicates that the average
personal space of occupants in the research group was considerably larger than that
in the administrative group.
(2)
For the thermal environment, there was no significant difference in indoor humidity
between administrators and researchers. However, indoor temperature was signif-
icantly different between administrators and researchers (p< 0.01). According to
EN 16798-1:2019 [
51
], the recommended temperature range is 19–25
◦
C, and the rec-
ommended humidity range is 25–60% for office buildings. This confirmed that the
relative humidity of the target building was lower than the recommended range. For
Int. J. Environ. Res. Public Health 2022,19, 14332 9 of 17
temperature, the recommended range was satisfied in most of the rooms but was
not met on the fourth floor, which belonged to the research group. In addition, the
average temperature of the research group (25.0
◦
C) was 1.1
◦
C higher than that of the
administrative group (23.9
◦
C). Therefore, on average, the physical environment of
the administrative group was better than that of the research group.
(3)
For the air quality item, there was no significant difference in CO
2
concentration
between the research and administrative groups. According to the recommenda-
tion by BS EN standard 15251:2007, CO
2
concentration in offices must be less than
800 ppm [
48
]. According to the data, CO
2
concentration in several sections where
the administrative group worked exceeded the recommended range. In addition, the
average CO
2
concentrations of the research and administrative groups were 586.0
and 676.5 ppm, respectively. This indicates that the research group had a better
environment than the administrative group in terms of air quality.
(4)
For the lighting environment item, there was no significant difference between the
administrative and research groups. The average illuminance of the administrative
group (1048.0 lx) was higher than that of the research group (927.8 lx). According
to BS EN standard 12464-1:2011, the recommended illuminance for offices is 500 lx
or higher [
42
]. Therefore, the recommended illuminance in the target building was
satisfied for both the administrative and research groups. However, the lighting
intensity of the administrative group was higher than that of the research group.
(5)
Acoustic environment was not included in this study.
Table 4.
Comparison of quantitative measurements between the administrative and research groups,
analyzed using the Mann–Whitney U test.
Classification
Administrator Researcher
Zbp-Value cRd-Value
1F a2F 3F Mean 4F 5F Mean
Temperature (◦C) 23.7 23.3 24.8 23.9 25.7 24.2 25.0 −2.681 0.007 * 19–25 [51]
Humidity (%) 18.4 19.5 18.5 18.8 17.0 18.2 17.6 −1.566 0.117 25–60 [51]
Ev (lx) 927.0
1035.0
1182.0 1048.0 806.5 1049.0 927.8 −0.655 0.513 ≥500 [47]
CO2(ppm) 645.0 750.0 634.5 676.5 594.0 578.0 586.0 −1.549 0.121 ≤800 [48]
APP (m2)12.8 14.0 17.6 14.8 18.3 15.5 16.9 −0.577 0.564 -
SVPP (m3)0.8 1.4 −6.403 0.000 ** -
a
Floor;
b
Z distribution;
c
analyzed using the Mann–Whitney U test (* p-value <0.01, ** p-value < 0.001);
drecommended; Ev, horizontal illuminance; APP, area per person; SVPP, storage volume per person.
3.2. Results of Qualitative Evaluation
3.2.1. Evaluation of IEQ Aspects and their Impacts on Work Productivity
Table 5shows the results of the qualitative assessment. The average satisfaction of
the occupants with IEQ is presented in the table. For the administrative group, lighting
environment (5.10) showed the highest satisfaction, followed by thermal comfort (4.71),
layout (4.52), air quality (4.02), and acoustic environment (3.60). For the research group,
layout (5.15) exhibited the highest satisfaction, followed by lighting environment (5.11),
air quality (3.97), thermal comfort (3.77), and acoustic environment (3.58). Both groups
showed high satisfaction with lighting environment, and there was a difference in the
average satisfaction with layout and thermal comfort. In addition, significant differences
in layout, thermal comfort, air quality, lighting environment, and acoustic environment
between the administrative and researcher groups were examined. As the data did not
pass the normality test, the Mann–Whitney test was applied for data analysis. Table 6
shows the comparison of the average satisfaction with the target building, as analyzed
using the Mann–Whitney test. The satisfaction data for each item in Table 5was used for
the analysis, and the symbol M in Table 6means the average ranking value of IEQ items
by job type. In Table 6, when the p-value of the corresponding IEQ item is significant, the
higher the average ranking value, the higher the average satisfaction with the item. As a
Int. J. Environ. Res. Public Health 2022,19, 14332 10 of 17
result of the Mann–Whitney test, there were significant differences in layout (Z =
−
2.757,
p< 0.01) and thermal comfort (Z =
−
2.808, p< 0.01) between the occupational groups. In
the target building, the average ranking of researchers (M = 55.48) was higher than that of
administrators (M = 39.21) for layout, and the average ranking of administrators (
M = 59.90
)
was higher than that of researchers (M = 43.46) for thermal comfort. In contrast, there was
no significant difference in air quality, lighting environment, and acoustic environment
(p> 0.05).
Table 5.
Respondents’ perception of satisfaction with indoor environment quality (IEQ) items (Likert
7-point scale).
Administrator Researcher
Layout 4.52 5.15
Thermal comfort 4.71 3.77
Air quality 4.02 3.97
Lighting environment 5.10 5.11
Acoustic environment 3.60 3.58
Table 6.
Qualitative assessment of satisfaction in administrators and researchers, analyzed using the
Mann–Whitney U test.
Ma(Administrator) M
(Researcher) UbZp-Value c
Layout 39.21 55.48 745.500 −2.757 0.006 *
Thermal
comfort 59.90 43.46 741.500 −2.808 0.005 *
Air quality 43.11 53.21 886.000 −1.736 0.083
Lighting
environment 45.50 51.82 972.000 −1.091 0.275
Acoustic
environment 48.08 50.32 1065.000 −0.379 0.705
aM average ranking value; bMann–Whitney U; c*p-value < 0.01.
Table 7shows the work productivity evaluation of the occupants by IEQ item, and
shows the total productivity evaluation for the entire work environment. Significant differ-
ences in total productivity, layout productivity, thermal comfort productivity, air quality
productivity, lighting environment productivity, and acoustic environment productivity
were determined between the administrative and research groups. As the data did not pass
the normality test, the Mann–Whitney test was applied. As shown in Table 8, there were
significant differences in layout productivity (Z =
−
2.136, p< 0.05, Mann–Whitney test)
and thermal comfort productivity (Z =
−
2.252, p< 0.05, Mann–Whitney test) between the
occupational groups. In the target building, the average ranking of researchers (
M = 54.01
)
was higher than that of administrators (M = 41.74) for layout productivity, and the average
ranking of administrators (M = 57.83) was higher than that of researchers (M = 44.66)
for thermal comfort productivity. On the contrary, there was no significant difference in
total productivity, air quality productivity, lighting environment productivity, and acoustic
environment productivity (p> 0.05).
Int. J. Environ. Res. Public Health 2022,19, 14332 11 of 17
Table 7. Respondents’ perception of productivity in relation to IEQ aspects (Likert 7-point scale).
Administrator Researcher
Total productivity 4.79 5.08
Layout 3.99 4.62
Thermal comfort 4.58 3.89
Air quality 4.14 3.91
Lighting environment 4.87 4.71
Acoustic environment 3.71 3.73
Table 8.
Qualitative assessment of productivity in administrators and researchers, analyzed using
the Mann–Whitney U test.
M (Administrator) M
(Researcher) U Z p-Value a
Total
productivity 45.29 51.94 964.500 −1.147 0.251
Layout 41.74 54.01 836.500 −2.136 0.033 *
Thermal
comfort 57.83 44.66 816.000 −2.252 0.024 *
Air quality 46.67 51.15 1014.000 −0.770 0.441
Lighting
environment 45.19 52.00 961.000 −1.193 0.233
Acoustic
environment 51.81 48.16 1033.000 −0.623 0.533
a*p-value < 0.05.
Spearman correlation analysis was conducted to examine the correlation of total
productivity with layout, thermal environment, air quality, lighting environment, and
acoustic environment, and the results are presented in Table 9. For administrators, lighting
environment (0.444) showed the largest absolute coefficient value, followed by layout
(0.370), air quality (0.326), acoustic environment (0.319), and thermal comfort (0.251).
For researchers, layout (0.507) exhibited the largest absolute value, followed by lighting
environment (0.387), thermal comfort (0.325), acoustic environment (0.319), and air quality
(0.160). In addition, the work productivity of administrators showed a significant positive
correlation with layout (r = 0.370, p< 0.05) and lighting environment (r = 0.444, p< 0.01),
whereas the work productivity of researchers exhibited a significant positive correlation
with layout (r = 0.507, p< 0.001), thermal environment (r = 0.325, p< 0.05), lighting
environment (r = 0.387, p< 0.01), and acoustic environment (r = 0.319, p< 0.05).
Table 9. Spearman rank correlation coefficients of work productivity and IEQ aspects.
Layout Thermal
Comfort Air Quality Lighting
Environment
Acoustic
Environment
Productivity
(Administrator) 0.370 * 0.251 0.326 0.444 ** 0.319
Productivity
(Researcher) 0.507 *** 0.325 * 0.160 0.387 ** 0.319 *
*p-value < 0.05. ** p-value < 0.01, *** p-value < 0.001.
3.2.2. Evaluation of Sub-Factors of IEQ Aspects
The Mann–Whitney test was conducted to determine differences in the sub-factors of
layout, thermal comfort, air quality, lighting environment, and acoustic environment be-
tween the administrative and research groups. For administrators, thermal comfort (59.90)
showed the highest average ranking value, followed by sound privacy (50.24), lighting
Int. J. Environ. Res. Public Health 2022,19, 14332 12 of 17
(47.42), ease of interaction (47.25), noise level (45.97), visual comfort (44.15), air quality
(43.11), visual privacy (40.46), and the amount of space (39.79), as shown in Table 10. For
researchers, the amount of space (55.14) exhibited the highest average ranking value, fol-
lowed by visual privacy (54.75), air quality (53.21), visual comfort (52.60), noise level (51.55),
ease of interaction (50.81), lighting (50.71), sound privacy (49.07), and thermal comfort
(43.46). In addition, there were significant differences in the amount of space (
Z = −2.658
,
p< 0.01
), visual privacy (Z =
−
2.443, p< 0.05), and thermal comfort (
Z = −2.808
,p< 0.01),
which are the sub-factors of layout, between the occupational groups. The average rank-
ing of researchers (M = 55.14) was higher than that of administrators (M = 39.79) for the
amount of space. The average ranking of researchers (M = 54.75) was higher than that of
administrators (M = 40.46) for visual privacy, and the average ranking of administrators
(M = 59.90) was higher than that of researchers (M = 43.46) for thermal comfort. On the
contrary, there was no significant difference in ease of interaction, which is the sub-factor
of layout, as well as air quality, lighting environment, and acoustic environment (p> 0.05).
Table 10. Comparison of average satisfaction with sub-factors.
Items M (Administrator) M (Researcher) U Z p-Value a
Layout
Amount of space 39.79 55.14 766.500 −2.658 0.008 **
Visual privacy 40.46 54.75 790.500 −2.443 0.015 *
Ease of interaction 47.25 50.81 1035.000 −0.625 0.532
Thermal
comfort Thermal comfort 59.90 43.46 741.500 −2.808 0.005 **
Air quality Air quality 43.11 53.21 886.000 −1.736 0.083
Lighting
environment
Lighting 47.42 50.71 1041.000 −0.581 0.561
Visual comfort 44.15 52.60 923.500 −1.482 0.138
Acoustic
environment
Noise level 45.97 51.55 989.000 −0.952 0.341
Sound privacy 50.24 49.07 1089.500 −0.199 0.842
a*p-value < 0.05. ** p-value < 0.01.
4. Discussion
Table 11 summarizes the differences in the quantitative and qualitative evaluation
results for key IEQ aspects between the administrative and research groups.
Table 11.
Differences in quantitative and qualitative assessment results between the administrative
and research groups.
Key IEQ Aspects
Evaluation Results
Based on Quantitative
Measurements
Evaluation Results
Based on Qualitative
Evaluation
Evaluation Results
Based on Qualitative
Assessment of
Productivity
Is Qualitative Evaluation
Consistent with
Quantitative Results?
Layout Researchers better than
Administrators
Researchers better than
Administrators
Researchers better than
Administrators YES
Thermal comfort
Administrators better
than Researchers
(Temperature)
Administrators better
than Researchers
Administrators better
than Researchers YES
Note: Only items with significant differences between the administrative and research groups are included in this
table. The humidity parameter does not meet this requirement.
In the case of layout, as a result of the quantitative measurement shown in Table 4, the
difference in area per capita between the group of researchers and the group of administra-
tors was not statistically significant, but the difference in storage per capita was significant
(p< 0.001). In addition, in the qualitative evaluation in Table 6, the administrative group
Int. J. Environ. Res. Public Health 2022,19, 14332 13 of 17
(39.21) had lower average satisfaction with the placement than the research group (55.48),
and this difference was statistically significant (p< 0.01, Mann–Whitney test). Moreover,
in Table 8, the manager group (41.74) had a statistically significantly lower productivity
evaluation for batches than the research group (54.01) (p< 0.05, Mann–Whitney test). These
results are basically inferred because the research group received more office supplies
due to the larger office space and higher partitions than the manager group. Similarly,
previous studies have pointed out that problems can occur when offices are dense or
have small storage space [
21
,
52
]. Therefore, through this study, it was confirmed that
layout can have a great influence on the satisfaction and work productivity of residents in
laboratory buildings.
In the case of thermal comfort, the temperature and humidity of the work space were
quantitatively measured. According to EN 16798-1:2019 [
51
], it is recommended that the
average temperature in winter workspaces be maintained in the range of 19 to 25
◦
C and
humidity in the range of 25 to 60%. In Table 4, in the case of humidity, neither group be-
longed to the recommended range, but it was not a statistically significant result. However,
in the case of temperature, the average temperature of the research group (25.0
◦
C) was
found to be higher than the average temperature of the administrative group (23.9
◦
C), and
it was found to be statistically significant (Table 4). In the qualitative evaluation of Table 6,
the administrative group (59.90) had a higher average ranking value in terms of satisfaction
than the research group (43.46), and this difference was significant (p< 0.01, Mann–Whitney
test). Similarly, in Table 8, which evaluated work productivity, the administrative group
(57.83) had significantly higher productivity evaluation for thermal comfort than the re-
search group (44.66) (p< 0.05, Mann–Whitney test). As shown in Table 11, in quantitative
and qualitative evaluations, the research group with high average temperature had the
same lower satisfaction and productivity than the manager group, and it was statistically
significant. This is consistent with previous studies showing that building temperatures
affect building satisfaction and work productivity of residents [
53
–
56
]. Therefore, even in
laboratory buildings, thermal comfort was found to have a significant association between
employee satisfaction and work productivity. In the case of air quality, both the quanti-
tative and qualitative results showed no significant difference between the research and
administrative groups. In the quantitative measurement results, CO2 concentration met
the recommended range (less than 800 ppm) presented by BS EN standard 15251:2007 [
48
]
for both researchers and administrators. As a result of the qualitative evaluation, it was
confirmed that there was no statistically significant difference in both satisfaction and work
productivity in the two groups (Tables 6and 8). In addition, there was no statistically
significant correlation between the total productivity and work productivity of IEQ items
(Table 9). Therefore, in this study, it can be concluded that air quality is not a factor that
greatly affects satisfaction and productivity for both administrators and researchers of the
K research building. However, this is a result limited to the K research building where
the study was conducted, and the data are insufficient to generalize. Therefore, it is be-
lieved that research on the IEQ evaluation of the research building should be continuously
conducted. For the lighting environment, the quantitative measurement results exceeded
500 lx, conforming to BSEN standard 12464-1:2011 [
47
], and the average illuminance of
the manager group (1149.1 lx) was higher than that of the research group (932.8 lx). As
a result of qualitative evaluation, there was no statistically significant difference in the
lighting environment between the two groups in terms of satisfaction and work productiv-
ity. In previous studies, it was mentioned that the lighting environment had a significant
association with the IEQ of occupants of the laboratory building [
21
,
29
]. Other previous
studies have noted that satisfaction with the lighting environment is associated with the
health and productivity of the occupants [
57
,
58
]. Furthermore, in the Spearman test in
Table 9, the lighting environment was found to be statistically significant in the association
between total and work productivity in both groups. Therefore, the association analysis of
IEQ with the lighting environment of the research building conducted in this study should
Int. J. Environ. Res. Public Health 2022,19, 14332 14 of 17
supplement the data with additional survey data, and further research on the association
with non-occupational factors or environmental factors is needed.
In the case of the acoustic environment, quantitative evaluation was not performed
due to the security of the government laboratory building, but only qualitative evaluation
was performed. In Tables 5and 7, which are the results of the survey, the satisfaction and
productivity of the sound environment were very low compared to other IEQ items. In
some previous studies, the IEQ evaluation for the acoustic environment was also confirmed
to be the lowest [
19
,
21
]. Previous studies have shown that every day and various noise
sources such as conversations, phone ringtones, and computer typing have a significantly
negative relationship with satisfaction with the acoustic environment in the office [
56
].
In addition, due to the features of the research building, the requirements for the sound
environment may be high because of the complex and concentration-dependent work
being carried out [
29
]. However, in the Mann–Whitney test, which determines whether
the results of the survey conducted in this study are statistically significant, the results in
Tables 6and 8prove that the survey values for the acoustic environment conducted in this
study were not significant. Although Table 9shows that total productivity and researchers’
work productivity are statistically significant, comprehensively considered, it is considered
that additional factors need to be correlated to evaluate the sound environment of residents
in research buildings.
5. Conclusions
In this study, the IEQ satisfaction and productivity of administrators and researchers
in the research building K in Korea were evaluated and compared using quantitative
measurements and a qualitative survey, respectively. The main results can be summarized
as follows:
(1)
The IEQ items with statistically significant differences between the research group
and the administrative group in the research building were the layout and thermal
comfort. The two items showed significant differences in both quantitative and qual-
itative evaluations. In addition, in the total productivity item that evaluated the
relationship between overall work environment and work productivity, the admin-
istrative group was associated with lighting environment and layout items, and the
research group was associated with layout, lighting environment, thermal comfort,
and sound environment.
(2)
Among the surveyed IEQ items, the statistically significant layout and thermal com-
fort were consistent with the results of quantitative and qualitative analysis. In the
quantitative measurement results for the target building, the layout environment was
more positive for researchers than for administrators, and the thermal comfort was
more positive for administrators than for researchers. In addition, the qualitative
data showed that researchers were more satisfied with the layout than administrators,
while administrators were more satisfied with the thermal comfort than researchers.
This echoes the results of previous studies that the more comfortable the space ar-
rangement and thermal comfort are, the better the satisfaction and work productivity
of the residents. Therefore, as a result of this study, if the difference between IEQ
items between groups is statistically significant, it is inferred that there is a possibility
that the quantitative and qualitative evaluation results may be the same.
However, this study has the following limitations. Since this study was conducted on
specific buildings in a specific climate, there is insufficient data to conclude with an IEQ
evaluation representing the research building. In addition, since the IEQ evaluation of this
study is concentrated on the research and administrative groups, a study that considers ad-
ditional indicators or environmental factors should be conducted. Further research should
also be conducted on the acoustic environment because no quantitative measurements have
been made for security reasons in the building. Therefore, it is believed that the results
of this study need to be improved through continuous investigation and data update.
Nevertheless, this study was conducted on research buildings of government agencies
Int. J. Environ. Res. Public Health 2022,19, 14332 15 of 17
that were rarely used in IEQ evaluation of existing research buildings, and significant
comparison results were obtained for the laboratory occupational group. Therefore, the
results of this study are expected to be useful for IEQ evaluation for various occupational
groups of research institutes and similar buildings. In the future, IEQ evaluation will be
conducted with various building groups, individual elements, and environments. Through
this, it is expected that it will be possible to establish a research method that provides
optimal building IEQ to residents and increases work productivity.
Author Contributions:
Conceptualization, J.-W.L.; data curation, S.-M.L.; formal analysis, J.-W.L.;
funding acquisition, S.-E.L.; project administration, S.-E.L. and J.-W.J.; resources, S.-M.L.; supervision,
J.-W.J. and J.-W.L.; visualization, G.-B.L.; writing—original draft, G.-B.L.; writing—review and editing,
S.-M.L. and J.-W.L. All authors have read and agreed to the published version of the manuscript.
Funding:
This research was funded by the Major Project of the Korea Institute of Civil Engineering
and Building Technology (KICT) (grant number 20220260-001).
Institutional Review Board Statement:
Ethical review and approval were waived for this study.
This study was funded by KICT and conducted for employers in KICT with their information and
consent. It was clearly stated that the study should have the guarantee of confidentiality and be only
for research purposes (publication), and not to be used for other purposes according to Article 15,
33 of the Korean National Statistical Act. Additionally, the subjects of the study were not specified
and sensitive information was not collected or recorded in accordance with Article 23 of the Personal
Information Protection Act.
Informed Consent Statement:
Informed consent was obtained from all subjects involved in the study.
Data Availability Statement:
The data presented in this study are available on request from the
corresponding author. The data are not publicly available due to ethical reasons.
Conflicts of Interest: The authors declare no conflict of interest.
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