SUSTAINABLE LEARNING ENVIRONMENTS IN SMALL ISLAND DEVELOPING

STATES: A STUDY OF CLIMATE CONTROL IN CLASSROOMS IN THE

CARIBBEAN NETHERLANDS

2nd International Conference on governance for Sustainable Development of

Caribbean Small Island Developing States March 7 till 9, 2012 in Curacao

FOCUS TOPICS:

Environment and Education

PAPER TITLE:

Sustainable learning environments in Small Island Developing States: A study of

climate control in classrooms in the Dutch Caribbean

AUTHORS:

Dr. Renske R. Pin

Associate Professor Social and Behavioral Sciences

University of the Netherlands Antilles

Jan Noorduynweg 111. P.O.Box 3059 Curaçao.

Telephone: 005999 8442157. Cell: 005999 6615315

E-mail: renskepin@gmail.com. Website: www.una.an

Ir. Cees M.J.M. van de Sande

Associate Professor Architecture and Civil Engineering

University of the Netherlands Antilles

Jan Noorduynweg 111 P.O.Box 3059 Curaçao.

Telephone: 005999 8442114. Cell: 005999 6987397

E-mail: ceesvandesande@gmail.com. Website: www.una.an

Abstract: Sustainable learning environments in

Small Island Developing States: A study of climate

control in classrooms in the Dutch Caribbean

To meet new legislation and regulatory

requirements associated with the new constitutional

structure where Bonaire, St Eustatius and Saba

became public entities of the country The

Netherlands, the BES islands consider extensive

changes to schools. To choose well-founded

between natural ventilation and air-conditioning in

the classrooms, a study was conducted measuring

actual values of the indoor climate quality while

simultaneously measuring the perception of the

indoor environment by the users, based on the

factors from Fanger's predicted mean vote (PMV)

model of thermal comfort performance (Fanger,

1970).

The objective values of the physical conditions

were measured (air temperature, radiant

temperatures, humidity, air velocity and CO2 -

content). The perception of the classroom,

temperature, air quality and wellbeing of the user,

were assessed with a survey among the users

(teachers and students). Measurements were

performed in six classrooms, one natural ventilated

and one air-conditioned classroom per island, at

three moments of the day in September 2011. These

measurements were compared to optimal values for

comfort (Fanger, 1970) and learning performance.

Furthermore, the teachers were asked about their

long-term experiences with concentration levels en

learning performances of the children in different

climate control settings.

The results show that classrooms without air-

conditioning system are the least valued by students

and teachers. These naturally ventilated classrooms

are characterized by the good (outside) air quality,

but also by many distractions due to noise from

outside the classroom. Most of the time these

classrooms are not meeting the optimal values for a

good learning environment.

The classrooms cooled with air conditioning, are

highly valued by the students and teachers.

Temperature was an important parameter for both

comfort and learning performance. Compared to the

natural ventilated classrooms, the teachers

especially appreciate the peace because there are

less disturbing noises. Also they point out the

higher concentration of students, which is

supported by the literature in terms of learning

performance. With the exception of air quality and

air velocity, the air-conditioned classrooms met

requirements for a good indoor climate in a

classroom. This lower quality of air and air velocity

is due to the so-called split-units, which are the

most commonly used air-conditioners.

Recommendations are made on how the indoor

environment can be brought not only at a

comfortable level, but also at a level that meets the

requirements for a healthy learning environment,

taking into account environmental, energy and

sustainability aspects.

Keywords

Climate control, thermal comfort, perception,

sustainability, learning environment.

Introduction

On the 10th

of October 2010, the Netherlands

Antilles was dismantled as a country within the

Kingdom of the Netherlands. In the new

constitutional structure, Bonaire, St Eustatius and

Saba became public entities as part of the country

The Netherlands. Formerly addressed as the BES

islands, these islands are now called The Dutch

Caribbean.

The Dutch Ministry of Education, Culture and

Science and the local administrations of the three

islands are planning extensive renovations and

building of new schools, mainly to meet the

requirements for the educational systems and the

need for an overall upgrading of the buildings.

Regarding indoor climate, new legislation and

regulatory requirements were not yet in place and

existing Dutch regulations were not suitable for the

tropical circumstances. One of the choices to make

was whether to implement (expensive) air-

conditioning or not. Therefore the Ministry of

Education, Culture and Science asked the

University of the Netherlands Antilles to advise

them on this matter. This paper is based on the

results of this study, which is called ‘BESte

Scholen’ (BESt Schools) (Sande, van de C., Pin,

R.R., & Meijsing, R., 2012).

Background

Many schools on these islands were (also recently)

originally built without air-conditioning systems

and until recently there was no use of insulation.

‘Cooling’ consists of the wind blowing through the

classrooms and the use of fans. This implicates that

windows can be opened, mostly in the form of

shutters, and there are often big windows in two

opposite walls to let the wind through.

More and more school boards decided to put in air-

conditioning, which resulted in cooler and drier

circumstances in the classrooms. But this also

means higher costs. Not only for buying the

systems, but particularly operating costs. These

costs are very high, due to the absence of

(sufficient) insulation and (a lot of) infiltration.

Shutters are very convenient to regulate the wind,

but they don’t close very well, so lots of warm air is

coming in. And there are some complaints about

too cold classrooms, or headaches and irritated eyes

that could be related to the air-conditioning.

Air-conditioning is expensive, even when the

building is well insulated. So there is some pressure

to design in such way that natural ventilation,

supported by fans, gives a comfortable

environment.

Two of the schools that were surveyed were

specially designed to have optimal natural

ventilation. Still, the users, teachers and pupils

alike, complain about too high temperatures, even

during the cooler season, fatigue and a lack of

concentration. The perception of the users is

ultimately what this is all about. Are there sufficient

arguments to convince the users that natural

ventilation is better, or that air-conditioning is

better?

Research goal and Research Questions

The aim of the study was to investigate the thermal

environmental quality in classrooms at the BES

islands by means of both an objective and

subjective approach to choose well-founded

between natural ventilation and air-conditioning to

achieve an indoor climate that meets the

requirements for a comfortable, healthy and optimal

learning environment in classrooms in the Dutch

Caribbean.

What arguments can be found or formulated to

make a well-founded choice for natural ventilation

or air-conditioning? This leads to three research

questions:

Are there objective values for a

comfortable, healthy and optimal learning

environment?

What are the objective circumstances and

resulting perception in a natural ventilated

classroom, compared to the optimal

values?

What are the objective circumstances and

resulting perception in an air-conditioned

classroom, compared to the optimal

values?

Theoretical Framework

In 1970, Fanger published the results of his

extensive survey on comfort levels, related to

thermal comfort.

Others have been studying the influence of (indoor-

) climate on learning abilities and health. Together,

this gives us a trustworthy set of values that can be

used as the optimal values for a comfortable,

healthy and good learning environment.

Looking at actual climate values and perceptions of

the user in both settings (air-conditioning and

natural ventilation) in the classrooms of the Dutch

Caribbean, and comparing these with the optimal

values, gives an insight in the level of quality of the

indoor climate in these classrooms.

The results of Fanger’s survey show that comfort is

dependent on ambient (air-) temperature, radiant

temperature (of surrounding objects as walls, floor,

and ceiling), humidity, air velocity, and air quality

(mainly CO2 content). And there is the perception

of the human being, which is related to his activity

level and the way he is dressed.

Through the system of PMV (Predicted Mean Vote)

on an 11 point scale from unacceptable cold (-5) to

neutral (0) to unacceptable hot (+5), Fanger found

optimal levels (neutral), related to activity and

clothing. These optimal levels are universal, so not

related to race, age, gender or the location on earth

where one lives. There are some differences related

to one’s personal metabolism. The PMV means that

95% of the people agree on the comfort level.

There are however differences with a growing

significance as the perception is further from

‘neutral’, mainly due to being accustomed to high

or low temperatures when living in a certain

climate zone. Later studies (Charles, K.A., 2003)

found that higher or lower temperatures are fully

accepted as long as the period of this situation is

not too long and incalculable. Furthermore lower

temperatures are less accepted than higher

temperatures.

Figure 1. Neutral (PVM) temperature in different circumstances (winter and summer seasons and 5

activity levels)

The above table gives the neutral (PMV)

temperature in different circumstances. We look at

activity level III and IV and the temperature Ts =

Tl. This means that there are no radiant

temperatures that differ more than 2 °C from the air

temperature. For clothing in the tropics the cloth

factor (Lclo) is 0.5. For 0.2 differences in Lclo,

there is a difference of 1 °C.

So for activity level III the optimal temperature is

23 °C and for activity level IV it is 25 °C.

Acceptable levels are + or – 2 °C. However, these

are not advised for longer periods (several hours).

Especially not the lower levels, as lower

temperatures are less accepted than higher

temperatures.

Air velocity should be less than 0.5 m/s for

comfort, with an optimum at 0.2 m/s at 25 °C. A

constantly changing velocity is certainly to be

avoided.

Fanger concentrates on comfort. Other studies

surveyed the influence of all Fanger’s climate

factors on learning abilities and health. The

‘Gezondheidsraad’ (Council for Health,

Netherlands) published a survey in 2010, regarding

air-quality in classrooms, focused on CO2 content.

A similar survey was done in Belgium (BIBA, M.

Stranger, e. a., Belgium 2010) with the same results

regarding CO2 content. CO2 content is preferable

between the content of outside air (350 to 400 ppm)

and 800 ppm, but not more than 1200 ppm. Above

1200 ppm there is influence on concentration level

and learning ability. CO2 content is a good

indicator for the level of fresh air ventilation, and is

also used as indicator for air-quality, which is

acceptable if the outside air is not polluted (fine

dust, chemicals, bacteria or viruses) because of

industry or other circumstances. Regarding the

islands of the Dutch Caribbean there is no

indication that the outside air is polluted. This was

also one of the reasons why only CO2 content was

measured.

There are several surveys to establish optimal

learning circumstances (e.g. Mayer, 1990, 1994).

They found that learning abilities as math, reading

and memory ability are negatively influenced if

certain levels like temperature are being trespassed.

Optimal learning abilities were found between 20

and 25 °C and between 40 and 60% humidity.

Several surveys were found regarding the

perception of the users (e.g. Wong & Khoo, 2003;

Corgnati, Filippi &Viazzo, 2007; Corgnati, Ansaldi

&Filippi, 2009, Youa et al, 2007). Several studies

focus on the perception of 'thermal comfort'. Some

studies have been done in working environment,

living environment and in learning environments.

Some studies deal specifically with the tropical

setting. A number of studies compare the

perception of comfort in the classroom with the

physical values and show the growing interest in

the last years about qualifying the thermal

environment both objectively (by measurements)

and subjectively (by occupants judgements)

(Corgnati, Filippi &Viazzo, 2007).

All these surveys lead to the following objective

values for optimal indoor climate for classrooms:

Temperature: 23 – 25 Celsius (in

tropical areas as in the Dutch

Caribbean, due to the clothing factor)

Humidity: 40 – 60 % (optimum 55 %)

Air quality/CO2 content: 400 – 800

ppm, max 1200 ppm (maximum is

recorded in Dutch regulations for any

building)

Air velocity: 0.2 – 0.5 m/s

Method

In the study on the classrooms in the Dutch

Caribbean, the objective values of the physical

conditions were measured (air temperature, radiant

temperatures, humidity, air movement and CO2 -

content) and the perception of the classroom,

temperature, air quality and wellbeing of the user

were assessed with a survey among the users

(teachers and students). Measurements were

performed in six classrooms, one natural ventilated

and one air-conditioned classroom per island, at

three moments of the day in September 2011.

Furthermore, the teachers were asked about their

long-term experiences with concentration levels en

learning performances of the children in different

climate control settings.

Research Design

First step in this research was to establish objective

values for a comfortable, healthy and optimal

learning environment. This research was done

through literature review.

Second step was simultaneously measurement of:

Study 1: The objective values of the

physical conditions (air temperature,

radiant temperatures, humidity, air

movement and CO2 - content)

Study 2: Perception of the classroom,

temperature, air quality and wellbeing

of the user; a survey among the users

(teachers and students).

Furthermore, the teachers were asked about their

long-term experiences with concentration levels en

learning performances of the children in different

climate control settings.

Measurements were performed in six classrooms, at

three moments of a school day in September 2011.

Table 1. Research design

The third step was to analyse the outcome of the

measurements and draw conclusions on the topic of

choosing between air-conditioning and natural

ventilation.

The last step was to formulate some

recommendations how to deal with the outcome for

the different situations and circumstances of the

classrooms on the three islands.

Method Study 1: Measurement objective values

physical conditions

Measurements of ambient temperature and

humidity were done in the classrooms with loggers

that automatically measure every 15 minutes during

24 hours. One logger per classroom was used on a

similar spot, as on top of a bookcase.

Ambient temperature was measured again, indoors

and outdoors, three times as mentioned. The values

found were sometimes slightly different from the

loggers, due to when or where exactly the

measurement was performed.

Radiant temperatures were measured with special

equipment to find the temperature of the surface of

walls, ceiling and floor. Some classrooms have

large windows and therefore the temperature on the

surface of the window was measured as well.

Surface temperature was also measured on the

outside of the walls. This gives some indication of

the insulating value of the walls.

Measurements were done for CO2 content as well

as for air velocity, indoors and outdoors.

All measurements were systematically written

down as shown in the example. In the first and

second block of rows you find the radiant

temperatures of walls, floor and ceiling. In the third

block of rows you find the values of inside and

outside temperatures, humidity, velocity and CO2

content. The three large blocks of columns

represent the three measurements during the school

day, which is typically for the tropics, between 7.30

am and 1.30 pm. The air quality was only measured

for values of CO2 content. Other values as fine

dust, chemical or biological hazards were not

looked for, mostly due to the limited goal of this

study. The geographical situation of the islands is

such that there are no known reasons to suspect any

other (significant) pollution of the air.

Classrooms Natural ventilated Air-conditioned

Bonaire Classroom 1:

Beginning of the day

Middle of the day

End of the day

Classroom 2:

Beginning of the day

Middle of the day

End of the day

St. Eustatius Classroom 3:

Beginning of the day

Middle of the day

End of the day

Classroom 4:

Beginning of the day

Middle of the day

End of the day

Saba Classroom 5:

Beginning of the day

Middle of the day

End of the day

Classroom 6:

Beginning of the day

Middle of the day

End of the day

Meetpunten opmerkingen

locatie 1n* locatie 1o* locatie 1z* locatie 1w* locatie 2n locatie 2o locatie 2z locatie 2w locatie 3n locatie 3o locatie 3z locatie 3w

wand noord bi 26.1 26.2 25.6 25.4 25.4 (25.4*) 24.9 * gemeten op glas

wand noord bu x x x x x x aangrenzend lokaal

wand oost bi 26.2 26.2 27.1* 25.9 25.5 (25.5*) 26.1 * gemeten op glas

wand oost bu 30 30 29.3 29.3 27.3 27.8

wand zuid bi 26.8 26.4 25.9 (26.5*) 25.5 26.0 (28.9*) 25.9 * gemeten op glas

wand zuid bu 29.7 29.7 29.9 29.9 34.5 34.2

wand west bi 26.1 26.2 24.5 24.5 24.6 24.5

wand west bu 27.5 27.5 28.5 28.4 29.2 29.2 binnenwand

locatie 1A locatie 1B locatie 1C locatie 1D locatie 2A locatie 2B locatie 2C locatie 2D locatie 3A locatie 3B locatie 3C locatie 3D

plafond 26.3 26.1 26.7 26.8 25.3 26.1 26.3 25.7 25.5 25.5 26.4 26

vloer 26.9 26.7 27.2 27 25.5 26 26 25.8 25.1 24.9 25.8 25.4

luchttemperatuur 24.7 23.5 24

luchttemp logger 25.7 24 23.6

luchtvochtigheid bi 55.7 51.6 47.1

luchtvochtigheid bu 72 72 72 gemiddeld, +/- 2

luchtsnelheid bi 0 - 0.5 (1 - 1.5)* 1 - 0.5 (1 - 1.5*) 1 - 0.5 (1 - 1.5*) * luchtstroom airco

CO2 bi [ppm] 1020 2175 1680 - 1700

CO2 bu [ppm] 350 425 425

buitentemperatuur 26.7 28.3 30

weersgesteldheid zonnig zonnig zonnig

windsnelheid 0.5 - 1.5 1 a 2 1 a 2

windrichting N-O N-O N-O

luchttemperatuur in lokaal gemeten met handmeter en logger. Luchtvochtigheid gemeten met logger. Zie bijlage voor loggergegevens.

* aanduidingen: noordzijde, oostzijde, zuidzijde en westzijde

meting 1 07.45 - 08.15 u meting 2 10.45 - 11.15 u meting 3 13.30 - 14.00 u

Saba Comprehensive School 3 oktober 2011 lokaal met airco (2 plafondfans, zeer langzaam) orkaanshutters geplaatst.

Figure 2. Example of systematically tracking of all measurements

These objective values were analysed. This was

done by comparing them to the earlier mentioned

values and establishing the differences.

Furthermore there were made comments regarding

the probable reasons for found differences, as lack

of or insufficient insulation, the use of split units as

air-conditioning system, absence of efficient

shading of windows and/or walls, maintenance of

the system.

Method Study 2: Measurement perception by

users

Respondents

The users of the classrooms that participated in the

study were:

• The students (with the minimum age of 9 years)

• The teachers

In total, 221 users of the classrooms filled in the

questionnaires, including 78 on Bonaire, 60 on St

Eustatius, and 83 on Saba. During the day the

classrooms were used by different groups of

students. The measurements at the three moments

on the day were filled by a new group of students

entering the classroom; therefore creating a

learning effect was no threat to the reliability of the

results.

Questionnaires

To assess the perception of the thermal comfort in

the classrooms a mixed method with a competitor

explanatory design was used.

Two questionnaires were used to investigate the

thermal perception:

Quantitative: multiple choice

questions, filled in by all users of the

classroom (students and teacher ) 3

times (duration 5 min) (n=221)

Qualitative: open questions, filled in

by the teacher at the end of the day

(duration 10 min) (n=6)

Both questionnaires were available in three

languages (English, Dutch, Papiamentu), freely

chosen by the respondents. The quantitative

questionnaires were delivered and filled by the

students while the measurements (see section 2.2)

were going in the 6 classrooms (one naturally

ventilated room and one room with air conditioning

per island). The answers to the questions concern

the instantaneous assessment of the conditions in

the classrooms. Students were uniformly distributed

in their own classroom during their regular lecture

hours. Everything possible was done to maximise

the “naturalness” of the situation. The questionnaire

was developed to measure perception of

environmental quality in classrooms and was

divided in 5 sections concerning:

1. Background information of the user

2. Perception of the temperature

(temperature, acceptance)

3. Perception of the air (humidity, smell, air

velocity)

4. Perception of the classroom (sound, feel)

5. State of the user (concentration, fitness)

The variables were measured on a 5 pt likert scale.

Statistical analysis was performed with SPSS 17.0

software.

The qualitative questionnaire assessed the

perceptions of the teachers at the classrooms, and

elaborated on all 5 sections of the quantitative

questionnaire. Furthermore teachers were asked

about their experiences with teaching in both air-

conditioned and naturally ventilated classrooms,

especially concerning the students’ performance, in

terms of attention, comprehension and learning

levels.

Results

Results study 1: Measurement objective values

physical conditions

Naturally ventilated Classrooms were characterized

by the good (outside) air quality, although the

standards for a good indoor climate were not met,

except for air quality (CO2).

With the exception of air quality and air velocity,

the air-conditioned classrooms met requirements

for a good indoor climate in a classroom. The

temperature of 26.8 degrees as mentioned in the

table below was found in one of the classrooms

where only one split unit was functioning, where 2

units are necessary.

Too low temperatures were found in the air stream

of the split units. This also leads to extra cooling of

the body, resulting in experiencing an even lower

temperature than the actual ambient temperature.

Lower air velocity can solve this problem.

The radiant temperatures were overall not much

higher (up to 2.3 °C) than the ambient temperature,

despite the lack of sufficient insulation regarding

the tropical climate. Therefor there was no

significant discomfort found due to radiant

temperature. One school had radiant temperatures

on the ceiling and walls that were up to 7° C higher

than the ambient temperature. This resulted in

lower air temperature as the air-conditioner was set

on lower temperature to achieve an overall

comfortable feeling. No need to say this leads to

extra energy consumption, a part of the energy loss

due to insufficient insulation.

The radiant temperature can be seen as an indicator

for the effectiveness of the insulation.

Natural Ventilation Air-conditioning

Temperature 27.5 - 32 too high 22.5 – 26.8 good

Humidity 70 – 85% ‘high’ to ‘much

too high’

50 – 60% good

Air quality

(CO2)

350 – 470 ppm good 700 – 2200 ppm ‘high’ to ‘much too high’ (due

to split units!)

Air velocity 0 – 5 m/s too high 0.5 – 1.5 m/s a little too high

Figure 3. Summary of findings of the objective measurements

Based on the objective measurements, classrooms

with air-conditioning would be preferred. Split

units are not preferred, unless enough fresh air

ventilation is provided. The air-conditioning system

should be quiet and should perform well with low

air velocity.

Results study 2: Measurement perception by

users

Concerning the perception of the temperature

(temperature, acceptance), users experienced the

temperature in a naturally ventilated room as higher

than an air-conditioned classroom. The desire to

adapt (cooler) is larger and the acceptance of the

temperature is less. After 9am it is too hot for

natural ventilation

As to perception of the air (humidity, smell, air

velocity), air-conditioned classrooms were more

negatively evaluated than the air in the naturally

ventilated room. The perceived smell became worse

as the day progressed; the air drier and the air

velocity went down.

The perception of the classroom (sound, feel), was

perceived more positive at start of the day in

naturally ventilated classrooms. Users were more

negative about sound in naturally ventilated

classroom.

Concerning the state of the user (concentration,

fitness), generally the users feel better, fitter and

more concentrated in the classrooms with air

conditioning than in the naturally ventilated

classrooms.

Over all, naturally ventilated Classrooms were least

valued by students and teachers. The biggest

concern was the many distractions due to noise

from outside the classroom. Air-conditioning

cooled classrooms were highly valued by the

students and teachers. Temperature was an

important parameter for both comfort and learning

performance. The teachers especially appreciate the

tranquillity because door and windows were closed

and therefore there was less disturbing noise. This

resulted in higher concentration levels of the

students

Based on the perception research, classrooms with

air-conditioning would be preferred.

Discussion

Conclusions

Based on both studies, classrooms with air-

conditioning would be preferred. With air-

conditioning the indoor environment can be

brought not only at a comfortable level, but also at

a level that meets the requirements for a healthy

and optimal learning environment, taking into

account environmental, energy and sustainability

aspects, by improving behaviour, building

improvements, equipment (including fresh air

ventilation), and regulations

The results show that the classrooms without air-

conditioning system are least valued by students

and teachers. These naturally ventilated classrooms

are characterized by the good (outside) air quality,

but also by many distractions due to noise from

outside the classroom. The standards for a good

indoor climate are met only for air quality.

The classrooms cooled with air-conditioning are

highly valued by the students and teachers.

Temperature was an important parameter for both

comfort and learning performance. Compared to the

natural ventilated classrooms, the teachers

especially appreciate the peace because there is less

disturbing noises. Also they point out the higher

concentration of students, which is supported by the

literature in terms of learning performance. With

the exception of air quality and air velocity, the air-

conditioned classrooms in this survey met

requirements for a good indoor climate in a

classroom.

Air quality and velocity can be controlled very well

with air-conditioning systems. Split units are not

suited for classrooms, unless there is an extra

system for fresh air ventilation and the equipment

works efficiently with low air velocity and low

noise.

Limitations

Despite these findings, this study has some

limitations that must be considered. First, due to

small size and short duration of measurement, this

study is only indicative of the interior of the

premises and the experience of the users. Second,

the measurement in the classroom with air-

conditioning in Bonaire is not representative

because of the lack of a second split unit and

probably not the optimal functioning of the existing

unit. In Bonaire also were much higher outside

temperatures measured on that day. Together with

the insufficient equipment this resulted in

temperatures of more than 26° C and therefor a

lower acceptance than measured in Saba and St.

Eustatius.

The additional literature search for comfort, indoor

air quality and relationships with academic

performance gives a good idea about the optimal

values for a good and optimal learning indoor

climate in classrooms. In some studies, higher

temperatures than can be deduced from the model

of Fanger were characterized as “neutral”. Those

studies were performed in places where most

people were not accustomed to air-conditioned

circumstances. In these studies no link was made

with learning abilities. An examination of Mayer

(1990 --- 1994) has shown that a 1° C lower

temperature is less acceptable for the comfort than

a 1° C higher temperature. The learning outcomes

in the studies are mainly related to temperature and

air quality (CO2 content) and partly to the

humidity. The corresponding values found for best

learning environment are sharper than the limited

comfort levels and are therefore decisive for

classrooms. The sometimes low occupancy of the

premises and the not insulated buildings with (a lot

of) air infiltration is the main reason that in most

cooled classrooms the CO2-level remains within

the standards. At a higher occupancy these

standards will be exceeded unless proper measures

are taken.

Further research is needed to set standards and

guidelines for climate control in the classrooms in

the tropics.

Recommendations

Based on the findings in this study,

recommendations are made on how the indoor

environment can be brought not only at a

comfortable level, but at a level that meets the

requirements for a healthy and optimal learning

environment, taking into account environmental,

energy and sustainability aspects.

The recommendations can be categorised in

behaviour, building improvements, equipment

(including fresh air ventilation), and regulations.

These recommendations are summed up below.

Behaviour:

Limited influence by user on the setting of

the temperature and fan speed of the air

conditioning installation.

Managing and maintaining the equipment

Information to the users about the use of

the equipment and attention to ventilation

Building improvements:

Insulate the building, especially the roof.

Restrict infiltration

Apply ventilation facilities

Shading on outside of building in such

way that walls are shaded, especially the

windows.

Equipment:

No split units, unless extra fresh air

ventilation is provided

If possible, choose integrated

cooling/ventilation

Low noise and low air velocity

Regulations:

Set up new regulations for classrooms in

the Dutch Caribbean, based on further

survey and experience after applying the

recommendations of this study.

Other:

Always choose the best air-conditioning

system available. Experience learns that

choosing the next best solution (mostly the

cheaper solution) will cost more money in

the end, due to complaints, maintenance,

operating costs and the inevitable renewal

of the system before the end of the

technical lifetime.

Literature

Ansaldi, R., Corgnati, S. P., & Filippi, M. (2007).

Comparison between thermal comfort predictive

models and subjective responses in Italian

university classrooms. Proceedings of Clima,

WellBeing Indoors.

Arundel, A. V., Sterling, E. M., Biggin, J. H., &

Sterling, T. D. (1986). Indirect health effects of

relative humidity in indoor environments.

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