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Philomena M. Bluyssen
Prof.dr., Chair Indoor environment, Faculty of Architecture and the Built Environment, Delft University of Technology, Delft, The Netherlands
It is well-known that the environmental conditions in a classroom can affect health, comfort and performance of children . Problems occur even though the guidelines are met, most likely due to the fact that these guidelines are based on criteria that are originally set up for adults, on top of the focus on single factors, which do not consider interactions between them. To gain more insights into the current and potential role of indoor environmental factors on health, comfort and performance of children, an investigation was performed based on a recent introduced research model (Figure 1) , comprising of a field study and a series of laboratory studies. Part 1 reported here, describes the field studies performed in 54 classrooms of 21 primary schools in the Netherlands, to collect information on ‘Stressors and effects’, ‘Preferences and needs’ and ‘Interactions at environment level’, for different situations, by asking children themselves what they experience and need in classrooms to feel and perform well . The SenseLab studies are reported in Part 2 .
Figure 1. Model for the integrated analysis approach .
In the spring of 2017, a survey on the health and comfort of school children of group 6 and 7 in 54 classrooms of 21 schools in the Netherlands was performed . From the 54 classrooms studied, 45 classrooms studied had a traditional educational system, and 9 classrooms had a non-traditional educational system (following the educational theory of Jena, Montessori or Dalton).
The survey of the schools comprised of a questionnaire for the children about their health and comfort, preferences and needs; a questionnaire for the teacher about activities they perform to improve IEQ; an inspection of the school and its installations, and the classrooms surveyed using checklists. 1,145 completed questionnaires were collected. It took the children about 30 minutes to complete the questionnaire.
In general, boys and girls were equally distributed. The average age of the children studied was 10 years and about one fifth wore glasses or lenses, about one third of the children had someone who smokes at home, and around 52% had a dog, a cat, or a rodent as pet.
At the moment of filling in the questionnaire, 87% claimed to feel good. Most reported diseases (in the last 12 months) were allergy (26%), rhinitis (17%), hay fever (16%) and eczema (16%). The most prevalent school-related health symptoms were headache (17%), sneezing (15%) and itchy eyes (14%) (Table 1). Boys reported these symptoms slightly more than girls.
Table 1. Symptoms at least once every 2-3 weeks (related to indoor environment).
Itching or watery eyes
Dry, itchy skin
87% of the children was bothered by noise (mainly caused by children themselves), 63% was bothered by smells (mainly caused by children themselves), 42% by sunlight when shining, 37% by garbage on the floor, 35% (did not like the temperature in the classroom (too cold or too warm) and 34% (experienced temperature changes (Table 2). Girls were in general more bothered than boys.
Table 2. Complaints about the indoor environment.
I do not like the classroom
Thermal discomfort at this moment (too warm/cold)
Bothered by temperature changes
Bothered by wind/draught
Bothered by smells
Bothered by noise
Bothered by sunlight when shining
Bothered by artificial light when on
Classroom-related comfort complaints and Classroom-related health symptoms were evaluated for both the traditional and the non-traditional school children by respectively the Personal Comfort Index (PCI) based on 7 complaints: thermal discomfort, temperature changes, wind/ draught, smells, noise, sunlight and artificial light; and the Personal Symptom Index (PSI) based on nine symptoms: dry eyes, itching or watery eyes, blocked or stuffy nose, running nose, sneezing, dry throat, difficulty breathing, dry, irritated or itching skin, and headache. So, for each child it was calculated for how many of the complaints and symptoms they were bothered with. The average PCI-7 for all school children, for school children from traditional schools and for school children of non-traditional schools, was respectively 2.76, 2.87 and 2.24 (Figure 2a). The average PSI-9 for all school children was 3.97, for the children going to non-traditional schools 3.69 and for school children of the traditional schools 4.02 (Figure 2b). The differences between the traditional and non-traditional schools were statistical relevant, indicating that children of non-traditional schools had on average less symptoms and less complaints than children from traditional schools.
Figure 2. Percentage of children a) with complaints about classroom conditions and b) with symptoms every day or sometimes at school, that went away when not at school.
Multivariate analysis was performed for the 949 children of the 17 traditional schools, to find patterns of stressors: associations of building-related indicators with occupant-related indicators . The analysis showed that a child at a school in the suburbs had fewer symptoms than a child at a school in a village (in a rural area). A child in a classroom with radiators below windows had more symptoms than in a classroom with floor heating, or in a classroom with air heating as an important way of heating the classroom. Both findings can indicate the presence of air pollution, either caused by inefficient cleaning or inefficient maintenance of the components of the building services. The presence of a solar shading device that hampers ventilation/opening window also increased the number of symptoms, which might indicate inefficient ventilation when required. Furthermore, it was seen that a child in a classroom with mechanical assisted ventilation (no mechanical supply) had more comfort complaints than in a classroom with natural ventilation. A classroom with a dark coloured window frame caused more complaints than a light coloured one, as did laminated flooring vs. synthetic smooth flooring material. Also, vacuuming the classroom floor less than once a week vs. more than once a week increased the PCI.
The frequency of teachers’ actions to improve IEQ in classrooms (such as turning on/off lights; lift/lower shades; close/open windows; etc.) was studied to get more insight into the impact of teachers’ actions . The percentage of teachers who performed the actions to improve the IEQ in classrooms at least once per day (Figure 3) was related to primary school children’s comfort perceptions in classrooms. From the comparison was concluded that those actions hardly had an effect on how the children felt. The teachers could not fulfil every child’s needs, even though teachers’ actions did relate to the child’s requests. Two reasons can be put forward: 1. Not all children have the same needs; which makes it is impossible for a teacher to satisfy each child. 2. A certain action can improve the conditions for one child, while for the other child the same action can cause a problem.
Figure 3. Percentage of teachers who performed the actions asked by children to improve the IEQ in classrooms at least once per day. The reasons for the actions are given in the parenthesis (Adapted from ).
Using two-step cluster analysis, six clusters (profiles) of children based on their comfort perceptions and the importance of environmental factors were identified  (Table 3).The children were asked to rate the importance of 10 indoor environmental factors to their school performance (including feet temperature, air temperature, chair temperature, scent, fresh air, light on desk, light on board, hearing teacher, outdoor sound, indoor sound) on a scale from 0 to 10 (10: very important; 0: not important at all) (Figure 4a). Children thought that ‘Hearing teacher’ had the most important impact on their school performance (8.6). The second and third most important factors were ‘Fresh air’ (8.0) and ‘Air temperature’ (7.4).
Table 3. Six profiles of children (adapted from ).
Most bothered by
Noise indoors and outdoors
Smell and sound
Noise and smell
Understand teacher and fresh air
Thermal and draught
Draught and temperature
Draught and temperature
Artificial and sunlight
Light at desk and (smart)board
The children were also asked to give their preference for an ICD (individual control device), including a heated chair, a heated desk, a heated back, a desk lamp, a personal ventilator and a headphone (Figure 4b). The most preferred device, according to the children’ answers, was ‘headphone’. Almost 60% of the children in a classroom indicated that they wanted to have a headphone, followed by the ‘ventilator at desk’ indicated by 53% of the children . The ‘headphone’ complied with the ‘hearing teacher’ importance index, while the ‘ventilator at desk’ corresponded to the second and the third highest importance index of ‘Fresh air’ and ‘Air temperature’.
Figure 4. a) Importance index of indoor environmental factors; and b) Preference for six ICDs (%) of children from traditional schools (adapted from ).
The field study of the 21 primary schools, resulted in the following main findings:
<![if !supportLists]>· <![endif]>Boys in general reported more symptoms, while girls reported more complaints.
<![if !supportLists]>· <![endif]>Main complaints were related to noise and smell (produced by children themselves).
<![if !supportLists]>· <![endif]>Different situations (traditional vs. non-traditional schools) resulted in statistically different health and comfort effects: children from traditional schools had more complaints/symptoms than children from non-traditional schools.
<![if !supportLists]>· <![endif]>Patterns of stressors (ventilation type, solar devices hampering opening windows, heating system, window frame colour, floor material and vacuum cleaning frequency) were associated with health and/or comfort by applying multivariate analysis.
<![if !supportLists]>· <![endif]>Children differed in needs and preferences and were clustered in clusters with different profiles using 2-step cluster analysis.
<![if !supportLists]>· <![endif]>Teachers could not fulfil each child’s needs in a classroom with the possibilities that were available to change/adapt the indoor environmental conditions.
The outcome of the field study confirmed the need for the newly introduced model  (Figure 1) and the need for more studies with primary school children on their preferences, needs and responses to single components (sound, thermal, light and air) and interactions of different environmental configurations as reported in Part 2 .
This study was sponsored by the fellowship of Philomena Bluyssen provided by the Delft University of Technology under the chair of Indoor Environment. Dadi Zhang, Marco Ortiz, Stanley Kurvers and MarjoleinOvertoom arethanked for their contribution to the field studies.
1. Bluyssen PM (2017) Health, comfort and performance of children in classrooms – new directions for research.Indoor Built Environ.26(8) 1040-50.
2. Bluyssen PM (2019) Towards an integrated analysis of the indoor environmental factors and its effects on occupants Intell. Build. Int. doi.org/1080/17508975.2019.1599318.
3. Bluyssen PM, Zhang D, Kurvers S, Overtoom M, Ortiz M (2018) Self-reported health and comfort of school children in 54 classrooms of 21 Dutch school buildingsBuild. Environ.138 106-23.
4. Bluyssen PM (2020) Understanding the indoor environment and its effects, Part 2: SenseLab studies with 335 primary school children, REVHA Journal issue 2020-03.
5. Zhang D and Bluyssen PM (2019) Actions of primary school teachers to improve the indoor environmental quality of classrooms in the Netherlands, Intelligent Buildings International, DOI: 10.1080/17508975.2019.1617100.
6. Zhang D, Ortiz M, Bluyssen PM (2019) Clustering of Dutch school children based on their preferences and needs of the IEQ in classrooms Build. Environ.147 258-66.
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