Indoor environmental quality and pupil perception in Italian primary schools

Building and Environment 56 (2012) 335e345

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Indoor environmental quality and pupil perception in Italian primary schools Valeria De Giuli a, *, Osvaldo Da Pos b, Michele De Carli a a b

Department of Industrial Engineering, Università degli Studi di Padova, via Venezia 1, Padova 31131, Italy Department of Applied Psychology (DPA), Università degli Studi di Padova, via Venezia 8, Padova 35131, Italy

a r t i c l e i n f o

a b s t r a c t

Article history: Received 7 December 2011 Received in revised form 30 March 2012 Accepted 31 March 2012

Working or studying in a comfortable environment enhances not only well being, but also satisfaction and therefore productivity and learning. This research collects some pictures of indoor environmental conditions taken in seven primary schools near Venice (Italy, North-East). Spot measurements were recorded in 28 non air-conditioned classrooms, in springtime, while 614 children (age 9e11) completed a questionnaire about the evaluation of indoor environmental conditions and the related psychological impact, their behaviour towards discomfort and if their level of interaction with the environment (opening a window, switching off a light etc.). Nonparametric statistical tests were carried out to find significant differences between schools and between girls and boys in the same school and to see if gender might influence perception. Moreover, physical measurements were compared to the answers given to the questionnaire to find a relationship between them. Finally, children’s reactions towards discomfort were evaluated to understand if pupils behave like “passive users” as frequently occurs with adults. Monitoring revealed very high CO2 concentration levels, which confirm insufficient air exchange by means of open windows, occasional insufficient lighting levels over the desks and, in general, nonuniform illuminance-distribution, probably due to improper solar shading use or even inappropriate shades. Pupils complained mostly about thermal conditions in warm seasons, poor indoor air quality and noise. Classroom conditions depended strongly on teachers’ preferences; therefore a building management system would be advisable to provide good indoor environmental quality, which cannot be otherwise guaranteed. Ó 2012 Elsevier Ltd. All rights reserved.

Keywords: Indoor environmental quality Comfort Pupil perception Primary schools Nonparametric statistical test

1. Introduction Many studies have demonstrated that if people work in good environmental conditions their productivity and well-being improve. The need to achieve a good comfort level in commercial and educational buildings is due to the fact that people spend more than 90% of their time indoors, and pupils around 30% of their life in schools. Many studies have aimed to evaluate which conditions are considered to be comfortable, and recently standards have been improved to set Indoor Environmental Quality (IEQ), defining acceptable ranges for different parameters. However, although indoor parameters fall into these ranges, not all building users are satisfied with their environment: the reason, beyond the fact that each person differs from the next, could be that there are nonenvironmental factors which, in addition to physical conditions, influence human perception. An interesting literature review investigates what constitutes “comfort” for building occupants,

* Corresponding author. E-mail address: [email protected] (V. De Giuli). 0360-1323/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.buildenv.2012.03.024

analysing whether all environmental conditions have an equal impact on human comfort and which non-environmental conditions affect indoor quality [1]. The review analyses the impact of individual characteristics of building occupants (gender, age, country of origin), building-related factors (room interior, type of building, possibility of user control), outdoor climate and season on satisfaction with IEQ. Some studies have already delved into indoor environmental conditions in educational buildings: indoor air quality, thermal comfort and acoustic performance of recently built secondary schools in England [2] were evaluated by means of field measurements which showed that, in mechanically ventilated schools, internal ambient noise levels and cold draughts were present. Thermal comfort was acceptable, but temperatures tended to be much higher in practice, compared to those desired. Another study [3] focused on the actual thermal sensitivity and clothing insulation of children in non air-conditioned classrooms in the Netherlands, by means of both physical measurements and questionnaires. The study shows that children prefer lower temperatures than the ones predicted by a PMV model, confirming the theory of adaptive comfort in non-conditioned spaces [4]. One

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other study [5] found significant gender differences in thermal comfort, temperature preferences and use of thermostats. In general, the study showed that females were less satisfied by indoor temperature than males. With regards indoor air quality, the European Standard EN15251 [6] and Rheva Guidebook [7] suggest limiting carbon dioxide concentration to 1500 ppm over a full day, from 9:00 to 15:30, but CO2 levels above these ranges are usually registered in classrooms [8], and also in the schools there presented. Good indoor air quality in educational buildings is necessary, since children are more vulnerable than adults to environmental pollutants [9,10]; nevertheless ventilation rates are often inadequate in classrooms [11,12]. Further research has widely investigated how low ventilation rates in classrooms can reduce pupils’ attention and vigilance, lowering memory and concentration [13e16]. Among the different parameters affecting the indoor conditions, light may also have a relevant role in the perception of the environment, since light has a deep psychological and physiological impact on humans [17,18]. The amount of light entering the eyes has been considered to be responsible for the regulation of some hormone secretions, such as melatonin and cortisol [19]. Often the influence of lighting conditions has been analysed in short-term conditions, while the long term would be more advisable, especially with regard to seasonal variations. A long-term study (one school year) has been performed in a Swedish school. The impact of natural daylight was compared to two types of fluorescent lights, considering the production of stress hormones (cortisol), based on samples of urine, classroom performance (analysing children’s behaviour in terms of ability to concentrate and to socialize), body growth and sick leave [20]. This study confirmed once again that a windowless environment and a lack of illumination may disturb the chronobiological system which regulates the production of hormones. Moreover it was found that seasonal factors influence behaviour, body growth and sick leave. The present work concerns both physical measurements and questionnaires: this kind of approach in environmental evaluation has already been tested to analyse thermal comfort in some Italian classrooms in heated conditions [21] and in free running conditions [22]. Spot measurements of indoor environmental conditions were carried out in 28 classrooms at 7 different primary schools, located in 4 different villages near Venice, in the North-East of Italy. From recorded values of indoor and outdoor air temperatures and indoor mean radiant temperatures, the adaptive thermal approach [4], also acknowledged in standard EN15251 [6], was applied for the evaluation of thermal comfort. Further research work [4,23,24] shows that the range in which microclimatic values guarantee good thermal comfort is larger in naturally ventilated indoor environments than in fully conditioned ones. Comprehensive thermal comfort criteria and predictions based on the Predictive Mean Vote (PMV) were introduced by Fanger [25] and included in ISO 7730 [26]. In Ref. [4] it has been shown that a PMV model can accurately predict comfortable temperatures for HVAC buildings, but for free running buildings (as the condition in which the present buildings were evaluated in this study) the thermal sensation is underestimated in winter and overestimated in summer. Moreover, children were not included in the Fanger climate chamber tests and Humphreys [27] found that children have a lower sensibility to temperature change than adults, their thermal responses are widely different and they do not usually change clothing during the day. Standards 55-2004 [28] and EN15251 are the most widely used adaptive assessment thermal charts, to be used as an alternative to the PMV method. The adaptive thermal comfort diagram for the design of naturally ventilated environments, adopted into Standard EN15251 [6] was chosen as most closely corresponding to the examined environments and it was applied in the field study.

Finally, CO2 concentration was used for indoor air quality analysis and visual comfort has been investigated by measuring illuminance on the desks. A questionnaire, developed in cooperation with psychologists, statisticians and teachers, was submitted to both pupils (age 9e11) and teachers. At the same time, the microclimatic parameters were recorded, during regular lesson times. The aim of this work is not merely to look for a correlation between measured physical parameters and human perception, but most importantly to study children’s personal impressions about the building in which they study. Occupants’ satisfaction and well-being are probably the main objective that designers have to reach, and the primary way to investigate them is by having users complete a questionnaire. The statistical analysis of the answers given to the survey was performed by using multivariate permutation methods which represent a new robust approach for analysing data from sample surveys with many variables and the possible presence of missing values [29]. In Refs. [30,31], indoor environmental quality was analysed in terms of student learning performance, whereas in Ref. [32], in terms of pupils’ absenteeism, many studies focus on the effects of a single environmental condition on children (e.g. thermal comfort [3,21e24], air quality [13], acoustic quality [33] and visual comfort [34]), while other works analyse two or more aspects involved in IEQ together [2,30,35e37] and often both the objective and the subjective approach is considered, as in the present study. Nevertheless, the present analysis involves not only pupil evaluation of indoor environments, but also the psychological impact of indoor conditions, pupils’ behaviour towards discomfort and the interaction between children and their environment (opening a window, switching off a light, operating shades). The differences between schools have been investigated and pupils’ gender has also been considered. Usually, in the literature, for analysing such kinds of data, standard parametric techniques are used (such as t-tests, ANOVA or regression analysis). It is accepted in the statistical field that parametric methods are weak when analysing multivariate data [38,39]. On the contrary, permutation methods are distribution free and stand up well to departures from normality which is the basis for standard parametric techniques. 2. Case study This work presents the analysis of indoor environmental conditions, based on both objective and subjective approaches, of seven primary schools, located in four different villages near Venice. Venice is in the North-East of Italy and it is characterized by a rather continental climate, with cold and sometimes even humid winters and hot-humid summers. Schools X and Y (Table 1) were firstly selected, in 2009, since they differ in terms of space arrangement and in architectural and technological choices, therefore a difference in both physical conditions and pupils’ perception could be expected. “School X” (Fig. 1) is located in a quiet and recently built residential area of Ceggia, a little village near Venice, where the traffic is so rare that it cannot be considered

Table 1 Main features of the schools in question. School

Location

NC

NP

Period

X Y A B C D E

Ceggia Noventa di Piave Maerne Spinea Spinea Spinea Spinea

4 6 7 4 2 2 2

110 140 151 72 48 45 48

Apr, 29th, 2009 May, 4th, 2009 May, 20th, 2010 May, 19th, 2010 May, 19th, 2010 May, 19th, 2010 May, 20th, 2010

NC: number of classrooms analyzed; NP: number of pupils.

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Fig. 1. School X: central hall (a) and classroom (b).

a source of noise. Its main characteristic is its circular shape which creates a sort of central atrium, two levels high, around which all the classrooms are positioned. In the classrooms, the blackboard is positioned in front of the windows which are shaded by an external manually operated brise-soleil. The school is equipped with a builtin water based floor heating system and a mechanical ventilation system which operates during occupancy time. PV solar collectors have also been mounted on the roof. Finally, the lighting system consists of fluorescent lamps which can be dimmed according to levels of natural light. “School Y” (Fig. 2) is located in Noventa di Piave, a small city near Venice, along a street that is close to a main road. It is a traditional educational building, with most of the 22 classrooms South-East facing and, on the other side, the main corridor. The building has no particular features which can be considered innovative in the architecture of primary schools. The available shading devices are fabric blinds and rolling shutters. The building is made of brick and concrete, with radiators as a heating system but no mechanical ventilation system is installed. The second IEQ analysis also took place in May 2010, in five other primary schools near Venice (Table 1). The buildings are of a traditional type, all being located in residential areas. School A (Fig. 3) and school E (Fig. 7) have internal venetian blinds, while school D (Fig. 6) and school C (Fig. 5) have internal fabric blinds. Each classroom of school B (Fig. 4) faces a terrace and it is equipped with internal roller blinds. In all of the five schools there are fluorescent lamps and the blackboard is positioned traditionally, but the desks arrangements differ according to school activities. All the classrooms are ventilated by air infiltration or by opening windows and they are equipped with radiators as terminal heating units.

Fig. 2. School Y.

3. Methods 3.1. Objective approach The indoor environmental conditions in the seven primary schools were analysed only once: in schools X and Y in springtime 2009, while in the other five in springtime 2010 (Table 1). The measured indoor parameters were: air temperature, mean radiant temperature, mean air velocity and turbulence, relative air humidity, CO2 concentration and illuminance levels over the desks. The measurements of thermal comfort parameters were performed with the Indoor Climatic Analyser Brüel&Kjær positioned in the centre of each classroom. The parameters were measured at a height of 0.6 m above the floor, according to the Standard ISO 7726 [40] for seated persons, for the whole classroom. The prediction of the thermal comfort was carried out by means of the adaptive approach, based on the method given in standard EN15251 [6], for naturally ventilated environments, since this method most closely corresponded to the examined environments in the analysed classrooms. The three acceptable ranges for the indoor operative temperature, corresponding to the different expected percentages of satisfied people (90%, 80% and 65% for categories I, II and III, respectively) were calculated based on a weighted value of the outdoor running mean temperature. These values derive from the outdoor daily mean temperatures of the days preceding the day of the measurements being taken. These were obtained from hourly data, recorded by the ARPAV meteorological station [41]. The operative temperature was calculated, in order to evaluate if the indoor temperature was acceptable, according to Standard EN15251, Annex A (building without mechanical cooling systems). The operative temperature,

Fig. 3. School A.

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Fig. 4. School B.

Fig. 6. School D.

calculated for each classroom from the recorded measurements, was compared to the limit values, in order to determine which range they belong to. The operative temperature range of category I, calculated from the adaptive thermal diagram reported in the standard EN15251 [6], corresponds to the following values:

The subjective approach of this study consisted of pupils completing a questionnaire during the regular lesson period, while

the physical measurements were being carried out. Only the questions concerning pupils’ thermal sensitivity and their state of health refer to the instantaneous assessment of microclimatic conditions, while all the other questions investigate the children’s perception of indoor environment over an extended time (a school year). The choice of questions and the way in which they were structured resulted from careful considerations made in cooperation with professors of Psychology, Statistics and Science of Education. The survey was modified, from the first edition to the second one, according to children’s understanding and feedback. A third edition will be arranged, since some other corrections are considered advisable, especially in the way a question is asked and in the choice of answers given to the questions concerning possible pupil reactions to discomfort. The goal of the presented survey is to understand whether different types of building affect the well-being, satisfaction and the perceived IEQ of the students in different ways. The survey was devised and written for Italian pupils, therefore it would be necessary to test the English translation suggested in this paper in the event of it being submitted to English pupils. Considering whom the study is addressed to, technical terms such as air quality, acoustic quality or illuminance are avoided to make it easy-to-understand and cartoon pictures were added to make the survey look more attractive to children. A scale of four points was chosen; therefore pupils are forced to give an answer that is clearly positive or negative, removing the possibility to choose a neutral option that would result in a loss of information. This might be criticized, since a middle answer is not allowed and the whole question might remain unanswered. On the contrary, few blank answers occurred in this work.

Fig. 5. School C.

Fig. 7. School E.

1. 21e25
C for school X (outdoor running temperature ¼ 12.8
C) 2. 21.8e25.8
C for school Y (outdoor running temperature ¼ 15.3
C) 3. 22.3e26.4
C for schools B, C and D (outdoor running temperature ¼ 16.9
C) 4. 22.4e26.4
C for schools A and E (outdoor running temperature ¼ 17
C)

mean mean mean mean

Even though the outdoor running mean temperatures for schools A to E were similar, classroom conditions during the monitoring, in terms of both shading and open windows, varied: this goes a way to confirming how much user behaviour depends on human perception, which in turn differs from one person to another. The CO2 concentration was measured with the IAQ monitor AirBoxx, while the illuminance was recorded by the Minolta CL200 lux-meter. The microclimatic parameters were recorded during survey administration. 3.2. Pupils’ perception of the indoor environment

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The survey is divided into questions which do not only investigate indoor environmental conditions, but also child satisfaction about school, furniture, their behaviour when discomfort occurs and on classroom habits in terms of opening windows and the position of blinds. It involves many different aspects that can be grouped as follows:  general information (age, gender, etc.);  children satisfaction towards building-related factors (school, school mates, furniture, etc.);  evaluation of indoor environmental conditions (thermal, acoustic, visual, indoor air conditions and interaction with the indoor environment);  psychological impact of indoor environmental conditions  children behaviour in event of discomfort; A more detailed description of preliminary analysis which utilised the first edition of the survey can be found in [42], which constitutes the beginning of a research project focused on the evaluation of environmental conditions in primary schools in the North-East of Italy. The first version contained 38 questions (schools X and Y), while the second had 51 (schools from A to E). The five open questions were reduced to two, while all the others were based on a rating scale, agreement scale or multiple choices. The differences between the old version and the new one concern the judgement order, the scale, the investigated topics and the layout. The answers on the old version started from the positive answer, while the new one started from the negative one. Moreover, the first edition had a three-point scale for the questions concerning the evaluation of indoor environment and a four points scale for the questions concerning the psychological impact of indoor conditions, while the second edition has a four points scale for both kinds of question. Considering the investigated topics, some other questions concerning the switching on and off of lights and the thermal sensitivity were added to the survey. Finally, the layout of the new survey was organised in order to allow optical reading.

339

The answers given to the survey were analysed with a multivariate system called nonparametric combination (NPC) methodology [29,43]. This inferential technique is based on both permutation tests and nonparametric combination methodology that allow relaxation from stringent assumptions of parametric methods (such as T and F tests). NPC permits a more flexible analysis in terms of both the specification of the multivariate hypotheses and the nature of the variables involved. The application of nonparametric statistics, such as the permutation test, showed better performance in the case of asymmetric and non-normal distribution of variables (as happens when analysing the answers given to a survey) in comparison with other parametric approaches [29]. Moreover, the NPC methodology does not need a model for dependence among variables and is not affected by the problem of a loss of degrees of freedom when the number of variables is large with respect to the sample size [29]. The analysis of the main differences between the educational buildings, considering also the gender, was carried out with the freeware software NPC R10 [44]. The possible difference between the answers was evaluated in terms of p-value (p-value below 0.05 identifies a significant difference). 4. Results and discussion 4.1. Physical measurements Indoor environmental parameters, recorded in the seven educational buildings, are reported in Table 2. It can be noticed that, on occasion, CO2 values are extremely high and this confirms the fact that windows are not sufficiently open so as to provide correct ventilation. School X is the only school in which a mechanical ventilation system is provided, but the system was not running due to previous complaints about draughts made by the teachers and the windows were often closed. Concentrations of CO2 in school X are the highest, a fact most likely due to the lowest outdoor temperatures. In school Y the windows were open, except in classrooms 5B and 5C. In school A, windows were closed only in

Table 2 Indoor environmental parameters in the seven schools in question. School classroom

X

X

X

X

X

Y

Y

Y

Y

Y

Y

A

A

A

4A

4B

4C

5A

5B

4A

4B

4C

5A

5B

5C

4A

4B

4C

Tair (
C) RH (%) Top(
C) Qrm (
C) CO2 (ppm)a Emin (lux) Emax (lux) Mean (lux) St. dev. (lux) Lights Shadings

20.5 58 21.2 12.8 3635 805 2419 1403 485 Off Up

21.2 56 21.2 12.8 2553 778 1650 1210 289 Off Up

21.2 61 21.7 12.8 940 915 1800 1403 286 Off Up

20.6 58 21.3 12.8 910 840 1800 1299 325 Off Up

20.3 65 20.8 12.8 641 668 2141 1389 439 Off Up

22.7 38 23 15.3 845 210 1320 499 240 On h-d

23.2 42 23.2 15.3 145 140 1700 474 535 On Up

23.2 52 23.2 15.3 743 200 1500 550 372 Off h-d

22 40 22.4 15.3 45 130 530 259 119 Off Up

22.8 40 23.1 15.3 2491 170 1800 515 422 Off Up

22.2 53 22.2 15.3 1687 240 850 489 164 On Up

24.3 40 25 17.0 568 230 1210 429 261 On Up

25.1 36 25.4 17.0 579 440 820 637 126 h-o Down

23.7 47 23.8 17.0 785 140 4300 1394 1468 Off Up

School classroom

A

A

A

A

B

B

B

B

C

C

D

D

E

E

4D

5B

5C

5D

4A

4B

5A

5B

4A

5A

4B

5A

4A

5A

23.8 47 24.1 17.0 1077 366 3850 1384 1216 h-o Up

24.8 38 25.4 17.0 462 610 2600 1127 574 h-o Up

24.5 42 24.4 17.0 1068 47 900 299 277 Off Up

25 50 24.9 17.0 777 190 900 425 196 On Up

25.9 43 26.2 16.9 1699 380 740 473 100 On h-d

25.4 36 25.5 16.9 488 150 390 320 72 h-o h-d

25.9 33 26.4 16.9 611 180 850 433 234 Off Up

25.8 31 25.9 16.9 784 318 590 425 86 On h-d

25.7 51 25.7 16.9 1980 81 420 152 80 Off h-d

24 41 24.2 16.9 1059 90 560 208 130 Off Up

23.1 53 23.2 16.9 2129 140 460 303 79 On Down

24.4 49 24.5 16.9 1250 202 3890 1123 1029 Off Up

25.4 48 25.5 17.0 613 220 1200 512 295 On h-d

23.9 45 24.4 17.0 1605 190 2170 583 495 On h-d

Tair (
C) RH (%) Top(
C) Qrm (
C) CO2 (ppm)a Emin (lux) Emax (lux) Mean (lux) St. dev. (lux) Lightsb Shadings

Tair ¼ air temperature; RH ¼ relative humidity; Top ¼ operative temperature; Qrm ¼ running mean temperature; Emin ¼ minimum illuminance; Emax ¼ maximum illuminance. a CO2 concentration above outdoor concentration. b h-d: half shades kept down, h-o: half lights switched on.

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separately comparing the other 5 schools, since survey structures and scales are different, as explained in the previous section. Only pupil behaviour in the case of discomfort is compared across the seven schools, because these questions are the same in both versions of the survey.

Fig. 8. Desk and blackboard visibility in schools X and Y.

classroom 5C. In school B, the windows were closed in all the classrooms, except in 4B, and the door was open only in 4B and 5A. In school C, windows were open only in 5A, while, in school D, they were closed everywhere. Finally, in school E, there were some windows open in classroom 4A only. The lowest CO2 value in school B occurred in the classroom where the windows were open. According to Ref. [6] of standard EN15251 about ventilation rates calculated from CO2 concentrations above outdoor, 15 classrooms were in category IV (CO2 > 800 ppm), 9 in category III (CO2 < 800 ppm), 2 in category II (CO2 < 500 ppm) and 2 in category I (CO2 < 350 ppm). In classrooms where CO2 concentration was within category III, the windows were open. According to standard EN15251 [6], from the operative temperature and the external running weighted mean temperature, all the classrooms were comfortable and fell into Category I. Minimum and maximum illuminance values, recorded over the desks during survey administration, are reported in Table 2. The weather was sunny on all the days measured. In school X, illuminance values were always above the required value of 300 lux [45], while in all the classrooms in school Y, there were desks in which the minimum illuminance level was not reached. In schools C, D and E, illuminance values over the desks were under 300 lux, while in the two other schools this happens only in some classrooms. Of most concern are classrooms 4A and 5D of school A where the required illuminance level is not reached even with the light switched on and the shades up (,) meaning that both window size and lighting system may be not properly designed. 4.2. Questionnaire Children satisfaction towards indoor conditions and the psychological impact that these conditions have on them are reported, first by comparing school X to school Y and, then, by

a

4.2.1. Comparison between school X and school Y The differences between the schools did not lead to significant differences in results, except for on two questions: blackboard and desk visibility (Fig. 8), which were better in school X. It is interesting to notice that if desk visibility is good, blackboard visibility is also acceptable. Pupils’ answers about IEQ were not significantly different even with a multivariate analysis (i.e. taking into account these items all together): from a descriptive point of view, considering indoor air quality, the fact that in school X there is a greater percentage of pupils saying that the classroom rarely smells bad (Fig. 9, question “1”) can be a consequence of the presence of mechanical ventilation (even though the system does not work in non-heated periods), or simply by the fact that the school is surrounded only by houses and public parks (no traffic). The visual quality in the two schools, in terms of glare occurrence, is good, in fact more than 60% of the pupils are not annoyed by blinding lights, even though in school X there is a greater percentage of children who state that glare does not frequently occur. This can be explained by the installed shading systems (manually operated brise-soleil instead of traditional rolling shutters): in school Y the available fabric blinds are too thin and therefore insufficient to reduce solar radiation and the rolling shutters are not frequently closed (44% of children answered “sometimes”) probably because otherwise no view out is available. On the contrary, the external venetian blind in school X can, on the one hand, control daylight and, on the other, allow a view out. Regarding acoustics, one can notice, from Fig. 9, question “4”, that school Y is considered more noisy than school X (30% in school Y instead of 17% in school X answered that there is often noise). This can be explained by the traffic noise caused by the main road on which school Y is located: in fact, only 8% of pupils in school X said that noise comes from outside, compared to 26% of school Y. No significant problems of speech intelligibility are present in either school. The answers given to the question concerning how pupils feel in terms of perceived temperature (6% and 19% of pupils felt very hot in schools X and Y respectively) is in agreement with the recorded operative temperature in the classrooms (in school Y, the temperature was around 22e23
C, while, in school X, 20e21
C.) This may be due to weather conditions, since outdoor temperature was higher during measurements in school Y. The interaction with the environment, in terms of air change and blind operation, is reported in Fig. 10: no significant differences were found when comparing the two schools, even by

b

1 (black): How often do you notice bad smells in your classroom?; 2 (white): Do you feel air draughts in your classroom?; 3 (dark grey): Are there blinding lights that annoy you in your classroom?; 4 (light grey): How often do you hear noise in you classroom? Fig. 9. Frequency of discomfort in schools X (a) and Y (b).

V. De Giuli et al. / Building and Environment 56 (2012) 335e345

a

341

b

5 (black): Does the teacher open the windows during the break? ; 6 (white): Does the teacher open the windows during the lesson?; 7 (dark grey): Does the teacher move the blinds during lessons? Fig. 10. Frequency of air exchange and solar control by means of blinds in school X (a) and Y (b).

a multivariate analysis. From a descriptive point of view, it can be noticed that air is changed mainly during break, while, during lesson time, windows are usually closed (70% and 40% for schools X and Y, respectively) and solar radiation is rarely controlled (question “7”). Although children have experienced only one school, the two schools belong to the same geographical and social area, therefore it makes sense to compare the schools by keeping girls and boys separate. The answers given by boys of the two schools were therefore compared, and the same was done for the answer given by girls, to see whether gender may influence children’s perception in the studied conditions. No significant differences were found for questions concerning indoor environmental conditions. The multivariate analysis, carried out considering questions from “1” to “4” of Fig. 9, showed a significant difference only for boys (p-value < 0.05). Further statistical tests were then performed, selecting not only the gender as a stratification variable, but also the age. The schools were then compared from a ‘younger (classrooms named 4) and older’ (classrooms named 5) and a girls’ and boys’ point of view individually. In classrooms 5 (age 10e11), the boys differ in three aspects, while the girls only in two. In Fig. 11, the percentage of boys who answered “yes” or “enough” have been summed, to compare the two schools, highlighting the positive answer from the negative one (“Top 2 Box” metric [46],). The main difference is in the question concerning school satisfaction: in school Y, only 3% of boys did not feel comfortable, compared to 29% in school X. Moreover, 88% of boys in school Y answered “yes” to question “10”, in contrast to 62% at school X, therefore, from the boys’ point of view, school Y has a greater speech intelligibility. Finally, 40% of boys in school Y like the desk arrangement, while 40% of those in school X do not. From the girls’ point of view, school X has good air quality (even though the recorded CO2 level on the day of measurement was higher in that school than in school Y): 36% of them did not complain about that, whereas only 15% of school Y did not. Considering the appearance of glare, 90% of girls of school X did not

a

perceive visual problems inside the classroom, whereas 40% in school Y did notice this discomfort. In conclusion, in terms of both visual and indoor air quality, it seems that, for girls, school X is better than school Y. When considering classrooms 4 (age 9e10), school satisfaction and blackboard visibility were judged dissimilarly by boys and girls. In school X, more than 90% of girls and 80% of boys are satisfied with the school, while only 60% of both boys and girls are satisfied in school Y. With regards blackboard visibility, both boys and girls of school X did not have a problem, while both boys and girls of the other school sometimes noticed a problem. Younger girls, of one school with respect to the other, express differing judgment in three additional aspects (Fig. 11): Satisfaction about desk arrangement: 70% of school X approve, while 20% of school Y is not satisfied. Desk visibility: all the girls of school X agree that they can see well at their desk, while in school Y this percentage is 80%. Perceived temperature (p-value < 0.001): at the moment of survey administration, over 90% of school X felt good, while, in school Y, 30% felt warm and 20% very warm. As already mentioned, the two schools were monitored on two days which had different external air temperatures, therefore this difference could have depended on weather conditions.

4.2.2. Comparison between schools A, B, C, D and E On the day the survey was performed, more than the 80% (88% in schools B and C) of pupils felt fine in all the schools. Considering thermal sensitivity, 54% of the pupils of school B and 61% in all the others answered that they felt fine, while the remainder felt warm (around 25%.) or very warm (around 15%). The highest percentage of school satisfaction was recorded in school C (83%), while the lowest was in school E (57%). The classroom was most appreciated

b

8: Do you feel comfortable at school?; 9: Do you like the desk arrangement in your classroom? ; 10: Can you hear your teacher well?; 11: Can you see the blackboard well?; 12: Can you see well at your desk? Fig. 11. Schools X (a) and Y (b): significant differences between boys of classroom 5 and girls of classroom 4.

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V. De Giuli et al. / Building and Environment 56 (2012) 335e345

a

b

1: In wintertime, do you feel cold in your classroom?; 2: In summertime, do you feel warm in your classroom?; 3: How often do you notice bad smells in your classroom?; 4: Do you feel air draughts in your classroom?; 5: Are there blinding lights that annoy you in your classroom?; 6: How often do you hear noise in you classroom? Fig. 12. Psychological impact of environmental conditions on pupils in schools A, B, C, D and E, considering all the pupils (a) and taking into account the gender (b).

in school D (69%), while the least appreciated classrooms were in school A (39%). Finally, the pupils were generally satisfied with their classmates (88% in school B and 57% in school E). The psychological impact of environmental conditions on pupils is reported in Fig. 12. The percentage calculated indicates the sum of the answers given to “many times” and “sometimes” in order to assign each school with one value, and so to range the schools (“Top 2 Box” metric [46],). As mentioned, it was not possible to compare all the seven schools together mainly because the multiple choices options used in the old version of the survey were limited to three rather than four. In all five schools, more than the 60% of pupils complained about indoor temperature in warm seasons, while, in wintertime, they do not usually feel cold. The warmest school in summertime is school E, where 95% of pupils feel warm most of the time. Moreover, in schools D and E there is a large percentage of thermal dissatisfaction in winter conditions. Noise is frequent in schools C and E, while school B is not considered noisy by 80% of students. Problems connected to air draughts or to blinding lights are not present in any school. With the multivariate analysis, taking into account the answers given to questions 1 to 6 (Fig. 12), the difference between the five schools is very significant (p-value < 0.0001). Considering all the environmental parameters, school E has the most negative results, especially considering thermal comfort; the classrooms have been enlarged because of the large number of students, and probably the new exterior is not properly insulated. Moreover, the entire school is lacking in space; not all the pupils can have breaks outside their classrooms because only one hall is available and furthermore, the toilet facilities are insufficient. Girls have different perceptions to that of boys [5], therefore the survey has also been analysed taking gender into consideration. The main difference is in thermal sensitivity: in summertime, for school B, 100% of boys says that they feel warm, compared to 75% of girls (p-value < 0.01), while, in wintertime, in school D, 20% of girls, but 40% of boys feel cold. In general, in both wintertime and summertime, the thermal sensitivity of girls differs from that of boys in the same school, with the exception of school A. Moreover, the thermal sensitivity reported by girls is the same only in schools A and B and that reported by boys is the same only in schools A and C, while in all the other schools the respective judgement always changes. However, the thermal sensitivity and all the questions concerning the frequency of discomfort do not show significant differences when testing the schools from the point of view of girls and boys belonging to the same school. This happens even if a multivariate analysis, carried out considering all variables, from items “1” to “6”, in the same statistical test, (Fig. 12) is performed. The five schools are part of the same geographical and social area, therefore it is justifiable to compare the answers given by the

girls (and the boys) of one school to the answers collected from others: when these schools are tested selecting gender and age as stratification variables, many differences were found (Table 3), while, with a multivariate analysis, only older boys (classroom 5) resulted to be significantly different (p-value < 0.05). This confirms the fact that uniform indoor conditions may lead to different subjective responses because people differ, and are not all comfortable in the same conditions. The interaction between pupils and school environment is reported in Fig. 13, where the use of lighting, blinds and windows has been investigated. Schools gave significantly different results, except for the use of blinds, since the multivariate analysis lead to a p-value under 0.0001, which means that the interaction between users and schools is, in general, extremely different. This can be explained by differing indoor environmental conditions, but also by the fact that pupils cannot interact with the environment and passively accept indoor conditions: the teacher decides how to set lighting, windows and shades and, on the days of measurement, the teacher’s preferences and habits were understandable. Classroom conditions depend mainly on teacher preferences, therefore a building management system would be advisable to provide a good quality indoor environmental which cannot be otherwise guaranteed. With regards lighting the environment, the primary source of glare in schools B and C is natural light, while in school D it is electrical light. In schools A and E glare occurrence is equally due to daylight and electrical light. In school C, pupils study in only daylight for 50% of the school year, while in all the other schools this occurs for only 20% of the year. Lights are often switched on in the morning, without taking into account climatic conditions and daylight availability. In all but school E, noise is due mostly to internal sources. The windows are kept open most of the time to allow air flow, but in school B the pupils answered that they are open because of high temperatures in the classroom. The shades are closed to control Table 3 Significant differences, in terms of p-value, between schools A, B, C, D and E, considering both gender and age. Classroom

4

4

5

5

Gender

Boys

Girls

Boys

Girls

n.s. <0.05 <0.05 n.s. n.s. n.s.

n.s. <0.05 <0.01 <0.05 n.s. n.s.

n.s. <0.05 <0.01 n.s. n.s. <0.0001

<0.01 n.s. n.s. n.s. <0.01 <0.01

Question Question Question Question Question Question

aa ba ca da ea fa

n.s.: not significant. a see Fig. 12 for questions “a” to “f”.

V. De Giuli et al. / Building and Environment 56 (2012) 335e345

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4.2.3. Child behaviour towards environmental conditions in all seven schools in question Children’s reactions when discomfort occurs are reported in Table 4. The following should be noted:  the question concerning reactions to air draughts is only included on the new version of the survey;  the question about blackboard visibility cannot be taken into consideration, because, due to printing problems in the new version of the questionnaire, the box for the answer “nothing” was too small to be read; nevertheless this matter is presented;  the sum of partial percentages is sometimes lower than 100% due to the fact that children gave two or more answers to the same question, therefore these answers were not taken into account.

7: How often is the light switched on during the school year?; 8: Does the teacher switch off the light when nobody is in the class?; 9: Does the teacher open the windows during the break?; 10: Does the teacher open the windows during the lesson?; 11: Does the teacher close the blinds during lessons? ; 12: Are the blinds reopened after being closed? Fig. 13. Pupils answers in schools A, B, C, D and E on the interaction between occupants and the school building.

lighting conditions except for in school B, where they are also operated when it is too warm inside, despite the fact that internal blinds do not influence the temperature of the environment. Blinds are opened again when it is too dark, but in school B, 20% of the pupils said that they remain closed until the school caretaker raises them. The fact that in school A 24% of the pupils answered that the teacher often opens the windows during break explains the fact that CO2 concentrations are lower in that school compared to the other schools. The schools in question are not equipped with a mechanical ventilation system, therefore the only way in which air can be changed is by opening windows. From the survey, it was found that windows are open during breaks but rarely during lessons in all the seven schools, not taking into consideration that more frequent change of air is necessary because of the high CO2 concentrations measured.

Table 4 Child behaviour with respect to discomfort occurrence in schools X, Y, A, B, C, D and E. School

X

Y

A

B

C

D

E

(%)

(%)

(%)

(%)

(%)

(%)

(%)

6 15 57 22

9 12 59 20

10 24 56 10

22 20 38 20

14 27 41 16

8 18 33 41

6 29 23 42

8 31 24 37

9 11 27 52

7 16 35 42

29 28 14 29

23 5 25 47

35 21 9 35

35 2 10 53

29 41 5 24

31

18

17

23

17

14 29 26

26 38 17

23 40 20

24 24 29

19 47 17

What do you do if your classroom smells bad? I tell the teacher. 19 18 I hold my nose. 12 17 I ask the teacher to open the windows. 44 46 Nothing. 25 19 What do you do if you feel air draughts? I tell the teacher. e e I ask the teacher to close the door. e e I ask the teacher to close the windows. e e Nothing. e e What do you do if you cannot see well at your desk? I ask the teacher to switch on the light. 41 33 I ask the teacher to open the blinds. 14 12 I move my desk. 27 26 Nothing. 18 26 What do you do if you cannot hear your teacher well? I ask the teacher to close the door, 44 23 if it is open. I ask the teacher to raise their voice. 19 25 I tell my school mate to be quiet. 18 21 Nothing. 12 20

The reason “nothing” is one possible answer is to evaluate whether children interact with the environment, that is look for a solution when in discomfort, or if they can be classified as “passive users”, as often happens with adults. Even the answer “I tell the teacher” sounds like a passive reaction: children realise that there is a problem, but they would prefer someone else (the teacher, in that case) solve it. The answers given about reactions to discomfort, especially those regarding poor air quality, confirm the author’s expectations, as many pupils ask the teacher to open the windows (from 38% in school D to 59% in school B). In the presence of air draughts, which occur rarely in all the schools in question, many pupils do not react in any way (37e52% of pupils answered “nothing”). The ones who answered “close the door” (from 11% in school D to 31% in school C) or “close the windows” (from 23% in school B to 35% in school E) were expected to be in the majority. Only in school X is there a mechanical ventilation system (the system is however often switched off or the air vents are closed), therefore in all the other schools the presence of air draughts can occur only when the windows and the doors are left open or when it is windy (during monitoring, the recorded air velocities were low). Considering that many pupils react to noise by asking their school mates to be quiet, this behaviour agrees with the answers about the noise source (internal). Blackboard visibility is directly connected to desk position with respect to the blackboard (in fact the common reaction is to move or to ask the school mate in front to move), while visibility from the desk primarily depends on lighting conditions (“I ask to switch on the light”) or on the shadings. It has to be remembered that shadings cannot be operated in schools B and D, because they are broken, which explains why in those schools only 5% of pupils answered “I ask the teacher to open the blinds”. No significant differences were found between the reactions of girls and boys belonging to the same school, but, from one school to another, both girls’ reactions (blackboard visibility: p-value < 0.05 for younger girls, p-value < 0.01 for older girls), and boys’ reactions (for older boys: air draughts, p-value < 0.05 and desk visibility, pvalue < 0.001) are significantly different. In general, the school buildings in question are not equipped with systems which can be operated to change environmental conditions (thermostats, shades, adjustable lighting, mechanical ventilation) and in many cases the shades are broken (often in closed position), or only an insufficient curtain is provided. For example, when visual discomfort occurs at the desk, a large percentage of pupils in all the schools (even 53% in school D) do not react, because no possible solution is available. Considering all the reactions towards the analysed microclimatic aspects, school D has a large percentage of “passive users”, while in school X many “active users” are found. School X differs from all the other schools

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studied in terms of both architectural design and technological systems, therefore it could be inferred that a school equipped with such kinds of systems and space arrangements could have an influence on the child’s relationship with the environment. This hypothesis will be verified in further studies. This study presents a method to analyse indoor school environments, by means of both physical measurements and psychological surveys, which investigates the psychological impact of indoor conditions on pupils. After being tested in seven educational buildings, the tools adopted here can be further developed for future research; the need of a long-term study, analysing a full school year, is advisable, both in terms of recorded environmental parameters and in terms of children’s perceptions, to see, for example, how seasonal variation interacts with building characteristics and how it can influence human well-being. Spot measurements need to be associated with continuous ones in order to collect data for an extended period and to understand if they are representative of a longer period (i.e. a season). Noise measurements are necessary mainly because teachers and children often complain about them, especially during breaks, lunch and in the gym. The survey should be administered three or more times in order to measure the influence of seasonal variations and to see if children become more aware of the topic, as long as the research is going on. A new environmental analysis, with a new kind of approach, which considers all these remarks, is ongoing. 5. Conclusions In this study some pictures of indoor environmental conditions of seven Italian schools were taken, measuring the main physical parameters (temperature, humidity, illuminance, CO2 concentration, etc.) and asking the pupils to express their satisfaction about the environment, the school, the interaction with the building (open windows, lights, functional shades, etc.) and their reaction when discomfort occurs, aiming at finding a relationship between human well-being and the building in which pupils stay. The main problem is that of uncomfortable temperatures in the warm season. In all the schools (except schools X and Y, as the old version of the survey did not investigate this) pupils feel warm most of the time. Some buildings have problems with poor air quality (X, Y, C and E); moreover, in these schools pupils complain about noise (around 20% and even 30% in school Y). The genders do not show particular differences in the questions related to IEQ. The influence of the environment on pupils’ behaviour has been taken into account, being aware that the way in which children behave depends on many factors (e.g. social level, life style, etc.), which also influences children’s expectations. It might seem that they are not aware of environmental conditions just because they never paid attention to such kinds of aspects, or that they do not express their own opinion, rather they just report that of their parents. Children passively accept indoor conditions, because classrooms conditions depend mainly on teachers’ preferences, therefore a building management system would be advisable to provide good indoor environmental quality which cannot be otherwise guaranteed. No significant differences were found between schools with regards levels of childeenvironment interaction, except for shading operations. Windows are opened in general during the break and rarely during lectures, even though a more frequent air change would be necessary because of the high CO2 concentrations measured. The answers concerning pupils’ reactions to a discomfort occurrence, especially the one about poor air quality, confirm the expectations. No significant differences

were found between the reactions of girls and boys belonging to the same school, but from one school to another, both girls’ reactions (about blackboard visibility) and boys’ reactions (about air draughts and desk visibility) are significantly different. In general, school D showed the largest percentage of “passive users”, while school X the largest percentage of “active users”. Physical conditions play a role in determining people’s satisfaction inside of buildings, which justifies an analysis from different points of view (e.g. psychological) as this study aims. Moreover, the method here presented also investigated the interaction between pupils and the environment and on pupils’ reaction to a discomfort occurrence and not only on satisfaction about indoor conditions; in this respect, it could be considered an efficient “environmental picture” to evaluate indoor quality of schools. This pilot study has been useful to test this methodology in order to develop and improve it in future research.

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