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Assessment of the Indoor Environment for Education
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Central Europe towards Sustainable Building 2019 (CESB19)
IOP Conf. Series: Earth and Environmental Science 290 (2019) 012144
IOP Publishing
doi:10.1088/1755-1315/290/1/012144
1
Assessment of the Indoor Environment for Education
M Kraus 1
and P Nováková 1
1
Institute of Technology and Business in České Budějovice, Department of Civil
Engineering, Okružní 517/10, 370 01 České Budějovice, Czech Republic
info@krausmichal.cz
Abstract. Indoor environment quality (IEQ) and its effect on well-being, productivity and
performance are phenomena. Achieving suitable and comfortable indoor environment is a key
factor in the creation and operation of the buildings in terms of basic principles of the sustainable
development. The poor indoor environment is associated with the Sick Building Syndrome
(SBS). The occurrence of pollutants in the indoor environment brings health problems to
occupants as well as affects their productivity and performance. The main aim of the contribution
is the study of indoor environment for educational purposes. The ordinary university
classrooms located on the outskirts of the city České Budějovice (Czechia) are analysed. The
classrooms are places, where the students reading, calculating, writing, and solving the
assigned tasks. Achieving and satisfying the comfort in the indoor environment for education
purposes is necessary for these student’s activities. For example, insufficient air exchange and
the CO2 concentration above of 1000 ppm, cause fatigue and decreased concentration. The
assessment of physical-chemical parameters includes analysis of indoor air temperature [°C],
relative humidity [%], Carbon Dioxide (CO2) concentration [ppm], and illumination intensity
[lx] in the university classrooms. The high-quality sensor for measuring air flow, temperature,
humidity, pressure, heat radiation, CO2 concentration and illumination intensity Testo 480 with
globe probe, IAQ probe, light probe and comfort level probe is used for measurement. The
work is supported by the grant Specific University Research SVV 201802 Address
identification and analysis of the determinants of the Indoor Environment Quality (IEQ).
1. Introduction
In addition to achieving the goal of energy saving and the reduction of greenhouse gas emissions,
currently, attention is increasingly also focused on the quality of the indoor environment. People spend
up to 90% of their time indoors. Indoor environment quality (IEQ) is an extremely important factor in
the context of the health, comfort and performance of building users. Indoor environment quality has
a significant impact on modern life around the globe. The quality of the indoor environment is the result
of interaction between physical, chemical and biological parameters: temperature-humidity parameters,
noise and vibrations, chemicals and odors, dust, light, electro-ion microclimate, non-ionizing radiation,
and microbial contamination. Pollutants have a negative effect on the health, performance and comfort
of building users at given concentrations and exposure times. The long-term unsatisfactory indoor
environment is associated with the Sick Building Syndrome (SBS). Sick Building Syndrome is defined
as a group of symptoms that have no clear etiology and are attributable to exposure to building
variables. These symptoms include eye, nose, and throat irritation, the sensation of dry mucous
membranes, dry, itching, and red skin, headaches and mental fatigue, nausea and dizziness [1]. There
are a number of studies dealing with the performance and productivity in the context of the quality of
Central Europe towards Sustainable Building 2019 (CESB19)
IOP Conf. Series: Earth and Environmental Science 290 (2019) 012144
IOP Publishing
doi:10.1088/1755-1315/290/1/012144
2
the indoor environment [2-5]. According to the review of the literature [6], there are eight physical
factors affecting satisfaction and productivity indoors: indoor air quality and ventilation, thermal
comfort, lighting and daylighting, noise and acoustics, space layout, biophilia and view, look and feel,
location and amenities. None of these factors acts independently, but they are constantly interacting.
University classrooms are spaces where calculating, reading, writing, working of the laptop or
focusing attention on monitors takes a lot of time [7]. Moreover, the high level of Carbon Dioxide
(CO2) concentration level in the classroom has a significant effect on performance, such as lower
attention and vigilance [8,9]. Indoor environment quality in the places used for education affect
learning processes, concentration, and productivity of students. It also could affect the health of
students and academic staff in long-term. Students are at greater risk from the reason that they spend
hours of time in the educational facilities. Generally, the indoors for educational purposes are strongly
affected by the synergic action of volatile organic compounds (VOCs), dust particles and
microorganisms [10]. High indoor air quality (IAQ), suitable lighting and daylighting, appropriate
acoustic solutions, suitable thermal-humidity conditions are crucial to the health of students and
academic staff [11]. Students are more sensitive to environmental conditions than adults, especially to
environmental pollutants and acoustics [12]. Users' perceptions of the indoor environment are the key
parameter of sustainable buildings [13]. Sustainability in buildings could be mainly achieved by the
incorporation of users' perceptions of indoor environment already in building design.
2. Method
Measurements and sensory assessments were carried out at the Institute of Technology and Business
situated in the city of České Budějovice, South Bohemia, Czechia. Ten different university classrooms
are selected for indoor quality research. Two of the observed university classrooms are the computer
classrooms. Two classrooms serve as lecture halls for more than 200 listeners. One of them is
equipped with a forced ventilation system. One classroom serves as a laboratory. The walls and
ceilings are fitted with a classic internal plaster with white paint. Flooring is synthetic smooth flooring
– linoleum. The windows are new, plastic with a shading system of internal blinds. The classroom
equipment is classical and includes tables, chairs, whiteboard, computer and projector.
Measurements took place in October under favorable climatic conditions. During the
measurements, the mean outdoor air temperature is 15,86°C the mean outdoor relative humidity is
63,74%. The mean concentration of Carbon dioxide is 645 ppm.
Before the assessment, the students were instructed on to using the scales. There is no restriction on
the distribution of gender or smoking habits. The age ranged from 20 to 25 years. All panellists are
university students. Overall, 289 students were interviewed. The panellists stay outdoor odors before
the assessments. Before the lesson, the panellists indicated their immediate evaluation on eight
continuous scales regarding air acceptability, odor intensity, thermal comfort, humidity comfort, visual
comfort, color comfort, noise load and total satisfaction. Then the percentage of dissatisfied (PN) was
estimated. The scale of air acceptability is divided into 2 separates scales with end-point clearly
acceptable (+1) / just acceptable (0) and just unacceptable (0) /clearly unacceptable (−1). The scale of
odor intensity has five levels of intensity odor: 0 no odor, 1 slight odor, 2 moderate odor, 3 strong
odor, 4 very strong odor and 5 overwhelming odor. According to ASHRAE the scale of thermal
comfort has 7 levels: +3 hot, +2 warm, +1 slightly warm, 0 neutral, −1 slightly cool, −2 cool, −3 cold.
The humidity scale has 5 levels: 2+ too humid, +1 slightly humid, 0 just right, −1 slightly dry and
−2 too dry. The range of perceived visual levels has 5 level: +2 too bright, +1 slightly bright, 0 just
right, −1 slightly dark and −2 too dark. The noise load scale is divided into 5 levels: 1 no noise,
2 slight noise, 3 acceptable noise, 4 strong noise and 5 intolerable noise. The scale of perceived colors
applied in the interior has 5 level: +2 too high, +1 high, 0 just right, −1 low, −2 too low. The scale of
overall satisfaction includes 5 levels: +2 too high, +1 high, 0 just right, −1 low, −2 too low. The limit
answers (maximum values of each scale) are regarded as discomforts in this study.
Students' self-evaluation results are compared with the measured indoor environment parameters.
The high-quality sensor for measuring air flow, temperature, humidity, pressure, heat radiation, CO2
Central Europe towards Sustainable Building 2019 (CESB19)
IOP Conf. Series: Earth and Environmental Science 290 (2019) 012144
IOP Publishing
doi:10.1088/1755-1315/290/1/012144
3
concentration and illumination intensity Testo 480 with globe probe, IAQ probe, light probe and
comfort level probe is used for measurement. Measurements and questionnaires are conducted in the
first 15 minutes after the beginning of the lesson to eliminate the impact of the adaptation. Descriptive
statistics such as percentages, range (minimum-maximum), or arithmetic mean are used to summarize
the characteristics of the university student and their classrooms.
3. Results and discussion
Table 1 summarizes the measured values of the parameters of the indoor environment in observed
classrooms. In the case of measuring the intensity of illumination is also the simultaneously measured
value of the intensity of illumination outdoors. Subsequently, the daylighting factor DF [%] is
expressed from both values. Occupancy [%] expresses an immediate capacity used classrooms for
a total capacity of classrooms. Classroom occupancy ranges from 25 to 90%.
Table 1. Indoor Environment Quality (IEQ) in observed classrooms
Classrooms
Occupancy
[%]
Indoor air temperature
[°C]
Relative humidity
[%]
CO2 concentration
[ppm]
DF
[%]
1 25% 22.2 46.8 898 11.54
2 50% 23.1 50.1 1550 7.08
3*
48% 20.6 51.4 941 0.33
4*
60% 22.6 45.3 1039 5.43
5 57% 22.1 52.1 1422 0.76
6**
29% 24.2 44.7 611 2.05
7 25% 19.8 62.8 968 0.08
8 33% 24.1 49.8 1369 1.22
9 43% 22.7 56.7 854 1.98
10 84% 22.5 40.7 708 0.93
* computer classroom ** lecture hall with a forced ventilation system
According to the valid Czech regulations defining the requirements for classrooms, the following
parameters must be met: minimal indoor air temperature 20°C, optimum indoor air temperature
22±2°C, maximum indoor air temperature 28°C, air flow rate from 0.1 to 0.2 m/s, relative humidity
ranges between 30 and 65%, and air change rate ranges from 20 to 30 m3
per student. According to
Table 1, the indoor air temperature in monitored classrooms ranges from 19.8 to 24.2°C. The mean
value of indoor. air temperature is 22.39°C, which meets the optimal requirements. The values of
relative humidity of observed classrooms range from 44.7% to 62.8%. The mean value of RH is
50.04%. In terms of relative humidity, the conditions of the classroom's indoor environment are
acceptable.
The mean outdoor CO2 concentration is approximately 650 ppm during in České Budějovice during
measures. The general requirement for indoor air quality is the concentration of carbon dioxide less
than 1000 ppm. The indoor air may appear heavy and breathless at concentrations of carbon dioxide
above 1000 ppm. The maximum permissible concentration is 1500 ppm. The classrooms were
ventilated doors during the break, as is usual with the conventional operation. In 4 out of 10 classrooms,
the 1000 ppm concentration is exceeded at the beginning of the lesson. In one case, the concentration
exceeds even 1500 ppm. It is obvious that conventional ventilation by the open door during a break is
insufficient in terms of indoor air quality. The main influence on increasing CO2 concentration has the
number of people, the frequency of ventilation and the size of the space. The lowest concentration of
Carbon Dioxide (611 ppm) is achieved in a lecture room with a forced ventilation system.
The daylight factor (DF) is a very common and easy to use measure for the subjective daylight
quality in an indoor space. It describes the ratio of outside illuminance over inside illuminance,
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IOP Conf. Series: Earth and Environmental Science 290 (2019) 012144
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doi:10.1088/1755-1315/290/1/012144
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expressed in per cent. According to valid standards (for example CSN 83 0580-1 Daylighting in
buildings – Part 1: Basic Requirements), school classrooms must always have adequate daytime lighting
in addition to special audiences. The daylight factor (DF) ranges between 0.33 and 11.54 %. It is also
advisable to avoid glossy surfaces such as sheets, workspaces, floors that can cause reflection glare.
3.1. Thermal comfort
Thermal comfort reflects whether the user is in the room feels warm or cold depending on the actual
conditions of the internal environment. The goal is to reach the maximum number of satisfied people
in the room. The indoor air temperature measurements show a large range (19.8–26.2 °C). The graph
(Figure 1) shows the sensory perceived component of temperature comfort, depending on the
measured temperatures in the observed classrooms. The percentage of dissatisfied is 4.2%. These
panellists feel cold (−3) or hot (+3). Perceived thermal comfort is rated as neutral by approximately
28.4% of panellists. Almost 60% of panellists evaluate the classroom's indoor environment on the
warmer (positive) side of the scale. The mean value of perceived thermal comfort equals 0.75,
reflecting thermal comfort between neutral and slightly warm.
Figure 1. The relationship between perceived thermal comfort and indoor air temperature in observed
classrooms of the university.
Figure 2. The relationship between perceived humidity comfort and relative humidity in observed
classrooms of the university.
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Central Europe towards Sustainable Building 2019 (CESB19)
IOP Conf. Series: Earth and Environmental Science 290 (2019) 012144
IOP Publishing
doi:10.1088/1755-1315/290/1/012144
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Figure 2 shows relationships between perceived humidity comfort and measures values of RH in
observed classrooms. The percentage of dissatisfied is 0%. The mean value of perceived humidity
comfort equals −0.05. This can be expressed as neutral. The results reflect the fact that measured
values of relative humidity in the monitored classrooms are within optimal limits.
3.2. Indoor air quality and odor intensity
The relationship between air quality responses (bothered by smell) and CO2 concentration and
intensity of ventilation is generally assumed. The results of the physical-chemical analysis of the
environment show that the recommended concentrations of CO2 are already exceeded at the very
beginning of the lesson. Figure 3 shows the results of air acceptability related to the concentration of
CO2 in the monitored classrooms. Even before the exceeded values of the recommended carbon
dioxide concentration, the percentage dissatisfied with the air acceptability is only 1.4% (clearly
unacceptable). By contrast, more than 15% of questioned students assess air acceptability as clearly
acceptable. The mean value of air acceptability is 0.2362, reflecting a slight positive air acceptability.
The human sense of smell is a primary factor in the sensation of comfort. Odor intensity is the
perceived strength of odor sensation. None of the observed university classrooms has undergone
recent refurbishment. It can be assumed that no new furniture materials were introduced into the
classroom as a source of volatile organic compounds (VOCs). Besides outdoor air and classroom´s
occupants, the indoor sources of odor are furniture and computers. The mean value of odor intensity
for all university classes is 1.15 at the beginning of the lesson. It means a slight odor which can have
represented the rising concentration of Carbon Dioxide.
Figure 3. The relationship between perceived air acceptability and CO2 concentration in observed
classrooms of the university.
3.3. Acoustics and noise load
According to [14], one of the main effects of noise in the classroom is the reduction of speech
intelligibility. An intolerable noise load of the internal environment is estimated by 0.2% of panellists.
Figure 4 illustrates the perceived level of noise load in the observed university classrooms. From the
point of view of noise load, the lecture hall with a forced ventilation system is the worst (classroom
n. 6). The mean value of the noise load is 1.31. It corresponds to the acceptable slight noise level.
y = 6E-05x + 0.2315
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Central Europe towards Sustainable Building 2019 (CESB19)
IOP Conf. Series: Earth and Environmental Science 290 (2019) 012144
IOP Publishing
doi:10.1088/1755-1315/290/1/012144
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Figure 4. Perceived noise load in the observed university classrooms.
3.4. Visual comfort and applied colors in interior
Different activities require different levels of daylighting [6]. The relationship between perceived
visual comfort and daylighting factor in observed classrooms of the university is shown in Figure 5.
The percentage of dissatisfied is 0%. The mean value of visual comfort for all university classrooms is
0.02. The mean value is acceptable and represents the just right environment.
The questionnaire also includes questions about the perception of colors applied in classrooms.
Visual comfort is largely influenced by the color of the interior. Previous studies have shown that
combinations of applied colors, surface materials and lighting of indoor affect the receptivity of
students and their behavior and mood [15, 16]. The percentage of dissatisfied is also 0%. The mean
value of perception of color is 0.02. This mean value represents the just right quality of interior colored.
Figure 5. The relationship between perceived visual comfort and daylighting factor in observed
classrooms of the university
y = 0.1162x - 0.0715
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Central Europe towards Sustainable Building 2019 (CESB19)
IOP Conf. Series: Earth and Environmental Science 290 (2019) 012144
IOP Publishing
doi:10.1088/1755-1315/290/1/012144
7
3.5. Overall satisfaction
Figure 6 shows a histogram of perceived overall satisfaction of the indoor environment quality of
observed university classrooms. The distribution of the values indicates a normal (Gaussian)
distribution of values. More than 60% of panellists refer to overall quality as just right. The percentage
of dissatisfied is 0%.
Figure 6. The distribution of the perceived overall satisfaction of the indoor environment quality of
observed university classrooms.
Table 2 shows the results of perceived indoor environment quality in observed classrooms in the
university. Perceived indoor environment quality is expressed by the mean value. The last column
expresses the mean value for all monitored classrooms.
Table 2. Indoor Environment Quality (IEQ) in observed university classrooms.
1 2 3 4 5 6 7 8 9 10 ∅
Thermal comfort 0.60 0.37 1.10 0.89 0.29 0.80 1.11 0.75 0.74 0.14 0.75
Humidity comfort 0.10 0.11 0.10 -0.06 -0.29 0.02 -0.17 -0.13 -0.05 -0.23 -0.06
Visual comfort 0.60 0.68 -0.20 0.61 -0.18 -0,14 -0.08 -0.13 0.37 -0.14 0.03
Color comfort -0.20 0.05 -0.10 -0.22 -0.53 -0,13 0.09 -0.44 0.00 0.05 -0.10
Odor intensity 1.10 0.84 1.40 1.17 1.24 1.24 1.32 0.81 0.74 1.05 1.15
Noise load 1.10 0.95 1.30 1.50 0.88 1.61 1.38 1.06 0.90 0.86 1.31
Overall satisfaction 0.20 0.21 0.20 0.28 0.29 0.29 0.40 0.25 0.21 0.41 0.30
4. Conclusion
There are many studies focusing on indoor air quality in primary and secondary schools. Nevertheless,
studies in university classrooms are still few. The presented case study is a primary study for assessing
the indoor environment quality (IEQ) of Czech university students. This paper presents the results of
the investigation devoted to the quality of the indoor environment in Czech university classrooms.
Understanding the perception of the quality of the inner environment by students is essential to
increase the performance and productivity of not only students but also the academic staff. The longterm
low indoor environment quality can lead to poor productivity, performance and ability to learn. It
is also necessary to take into account the health of students and also academic staff in the context of
Central Europe towards Sustainable Building 2019 (CESB19)
IOP Conf. Series: Earth and Environmental Science 290 (2019) 012144
IOP Publishing
doi:10.1088/1755-1315/290/1/012144
8
the hygiene of the internal environment. The paper provides a concise starting point for future
researchers in the field of indoor environmental quality in building for education. Although different
students have different problems of IEQ in classrooms, the quality of the university's indoor
environment is assessed as acceptable. Insufficient indoor environment quality in university
classrooms are difficult to generalize due they differ from student to student, so to the possible
measures. This knowledge is necessary and useful to develop appropriate strategies to create and
maintain a sustainable internal environment for education and training. Without a proper functioning
management system of the indoor environment, it is impossible to sustain a comfortable indoor
environment for student occupants.
Acknowledgments
The contribution is supported by the Specific University Research SVV 201802 Address identification
and analysis of the determinants of the Indoor Environment Quality (IEQ).
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