Classroom Ventilation Design Strategy to Achieve Thermal Comfort

A Study on Student Access Center Building

Qurrotul A’yun

, Mega Ayundya Widiastuti

, Oktavi Elok Hapsari

Department of Architecture, State Islamic University of Sunan Ampel, Surabaya, Indonesia

Keywords: Classroom, Cross Ventilation, Ecotect Program, Thermal Comfort, Ventilation Design

Abstract: Self Access Center (SAC) is one of the buildings that has several classrooms in State Islamic University of

Sunan Ampel. Learning process needs comfortable classroom. Providing comfort indoor environment is one

of the steps to reach it. From the existing classroom temperature (28.6°C-31°C), it cannot be classified as a

comfortable indoor temperature. Therefore, to overcome this, providing a classroom ventilation design

strategy is the solution. The strategy can be in the form of: 1) increasing the number of active ventilation; 2)

providing inlets and outlets in each room; 3) reducing the effect of solar heat by giving secondary skin and

shading device. By applying these three steps and analyzing through Ecotect program, the room temperature

can be lowered by 2°C.

1 INTRODUCTION

Designing a building should be responsive to the

climate because it will reduce adverse effects on the

environment and increase user comfort. Nugroho

(2007) has said that to create comfortable indoor

environment, one must pay attention to the user

needs. One of them is through the speed of natural

air flow in the building that meets the required

standards of thermal comfort. That is also what is

needed in the classroom.

Kindangen (2005) also wrote that window with

ventilation is only one part of an air control system

that is used to flow to and cool the room; especially

to achieve thermal comfort. To make natural air flow

inside a room, it is needed to have inlet and outlet.

Different dimensions of inlet and outlet will increase

the air flow. According to Dora (2011), increasing

the opening dimension will automatically enlarge

the entry area of light and natural air exchange. The

ventilation opening dimension ideally reaches 40-

80% of the total wall area or 10-20% of the whole

floor area.

Window type and position must be in

consideration. According to Becket (1974), there are

several ventilation window types that influence the

natural air flow to the room. (Figure 1).

Figure 1: Ventilation type

Making a room modelling design with several

window opening types needs to be done to optimize

the thermal specific conditions of the environment,

and to achieve thermal comfort.

2 METHOD

This research uses 2 (two) methods that are

qualitative descriptive and simulation method.

Qualitative descriptive method is used to find the

right design recommendations, based on the

description and theoretical studies that have been

done previously. This method aims to find the best

ventilation design strategy, based on existing

conditions. Meanwhile, the simulation method

serves to test the effectiveness and efficiency of the

design results in the existing conditions. Simulation

will be carried out with Ecotect program.

A’yun, Q., Widiastuti, M. and Hapsari, O.

Classroom Ventilation Design Strategy to Achieve Thermal Comfort.

DOI: 10.5220/0008907500002481

In Proceedings of the Built Environment, Science and Technology International Conference (BEST ICON 2018), pages 62-67

ISBN: 978-989-758-414-5

3 DISCUSSION

3.1 General Description of Self Access

Center (SAC)

Self Access Center (SAC) is one of the campus

facilities in State Islamic University of Sunan Ampel

Surabaya which serves the academic community in

the field of language and culture. This SAC building

is on the north side of the collage site and faces the

south. This is shown in Figure 2 below. This

building consists of 3 (three) floors. The first floor

functions as a management office, while the second

floor functions as classrooms, and the third floor

functions as a multipurpose room.

The windows in the SAC’s classrooms extend

along the height of the floor, so the classrooms on

the 2nd floor will tend to be hot. Moreover, there is

not enough shade around it, especially in the south

and west area. It is contrast with the east area, which

is quite sheltered by the building next to it.

Figure 2: The position of SAC Building

SAC has 5 (five) classrooms namely SAC 201, 202,

203, 204 and 205. The illustration is in Figure 3.

Figure 3: Five classroom in SAC Building

3.2 Existing Condition of Classroom at

Self Access Center (SAC)

The five classes in SAC then were grouped into 2

(two) kinds of classes based on the size and position

of the room. The groups were: 1) Group Class 1:

SAC 201 and 202; and 2) Group Class 2: SAC 203,

204 and 205. However, the capacity is also the same,

for 20 students.

3.2.1 Group Class 1 : SAC 201 and 202

This group of classrooms has 42m² area (6mx7m).

These rooms are on the west side of the building.

Figure 4 describes the SAC 201 classroom existing

condition.

Figure 4: SAC 201 Classroom

The SAC 201 class only has 1 (one) compact

ventilation on the west side, with 2 (two) types of

ventilation at once, that are the fixed type (Figure

5a) and top hung casement type (Figure 5b). Beckett

(1974) has said that fixed type ventilation cannot

flow air while top hung casement type is active

ventilation that can create air flow until 75%.

(a) (b)

Figure 5: (a) Fixed type and (b) Top hung casement

type

SAC 201

SAC 203

SAC 204

SAC 205

SAC 202

Classroom Ventilation Design Strategy to Achieve Thermal Comfort

The SAC 201 ventilation is shown in Figure 6

below. It can be seen that active ventilation in top

hung casement type is very small because it is only

1.7m² (19%) of total ventilation of 8.925m².

Figure 6: SAC 201 Ventilation

: Ventilation with top hung casement type

Whereas, according to Lechner (2014), ideally a

room at least has 10% of the floor area.

Ideal Ventilation Size = 10% x 42 = 4.2m².

Ideal Number of Ventilation = 4,2 / (0.85x1) = 5

So, ideally SAC 201 classroom should have at

least 5 (five) active ventilations with top hung

casement type. Meanwhile, now there are only 2

ventilations of that kind. Now, the SAC 202

classroom existing condition is the described in

Figure 7.

Figure 7: SAC 202 Classroom

Unlike SAC 201, SAC 202 classroom has 2

(two) separate ventilations on the west side. The

shape and size detail of ventilation in the SAC 202

classroom are in Figure 8.

Figure 8: SAC 202 Ventilation

: Ventilation with top hung casement type

The size and type of ventilation in the SAC 202

classroom are on the right side, the same as the one

in the SAC 201 classromm. Meanwhile, the size and

type of ventilation on the left side are 1/3 the size

modulation of the large model ventilation, like in

Figure 6.

So, if the number of ventilations in SAC 202

classroom is calculated according to the Lechner

formula, while the size of SAC 201 classroom and

SAC 202 classroom is the same, then ideally the

SAC 202 classroom should have 5 (five) active

ventilations too, with the same size as the existing

active ventilation.

3.2.2 Group Class 2 : SAC 203, 204 and 205

SAC 203, 204 and 205 classrooms have a typical

form, both in the room size, and the ventilation

position and size. So, the explanation of this group

class 2 will be represented by only one room, that is

SAC 203 classroom.

This type of classrooms has 36m² area (6mx6m).

These rooms are on the west side of the building,

and there are 1 (one) compact ventilation on the west

side, with 2 (two) types of ventilation at once, that

are fixed type and top hung casement type, like

shown in Figure 6. Figure 9 describes SAC 203

classroom existing condition.

(Left)

(Right)

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Figure 9: SAC 203 Classroom

3.2.3 Existing Classroom Temperature

Temperature of the five classrooms was measured

regularly, as listed in Table 1 below:

Table 1: Temperature of Existing Classroom in SAC

Measurement

time

Class

Temperature (°C)

April 13

2018

201

28,5

29,4

28,4

28,7

202

28,5

29,4

28,7

203

28,4

30,5

34,2

31,0

204

28,4

30,5

34,2

31,0

205

28,4

30,5

34,2

31,0

April 27

2018

201

28,2

29,7

27,8

28,6

202

28,2

29,7

27,8

28,6

203

27,6

29,8

30,5

29,0

204

27,6

29,8

30,5

29,0

205

27,6

29,8

30,5

29,0

remarks:

M : Morning Temperature

N : Noon Temperature

AN : Afternoon Temperature

A : Average Temperature

From the table 1, it can be concluded that group

class 1 has cooler temperature with 28.6°C-28.7°C

than group class 2 with 29°C-31°C. This can happen

because the group class 2 is on the east side of the

building. Moreover, there is no building or

vegetation that becomes shelter from the sun heat, so

sunlight with high heat intensity directly penetrates

classrooms. Based on SNI 03-6572-2001, the

existing classroom temperature is not classified as

comfortable indoor temperature, because maximum

temperature for comfortable indoor is 27.1°C.

3.3 Classroom Ventilation Design

Strategy

Because the ventilation in every SAC classroom has

the same shape and size, as it is shown by Figure 6,

so discussion about ventilation design strategies will

be based on that one prototype only. Based on

Lechner theory (2014) about the calculation of the

ideal number of ventilation in one room, it is clear

that the number of active ventilation that is available

in SAC classrooms is less and needs to be added

without changing the existing structure. Therefore,

the number of active ventilation that is only two

from the existing ventilations (Figure 5) will be

added by four more sections with top hung casement

type, as illustrated in Figure 10.

Figure 10: Addition of active ventilation

in existing window

: Existing Ventilation

: Planned Ventilation

According to Mediastika (2004), creating

natural air conditioning systems in tropical buildings

is very dependent on ventilation as the air flow

medium. Ventilation needs inlet and outlet to make

air flow process. Whereas in the SAC classroom

existing condition, there is only one ventilation hole

at one side, so the concept of cross ventilation

cannot run yet. Therefore, the second strategy that

can be done to maximize air flow is by adding

ventilation holes on the other side, in which one

becomes inlet and the other becomes outlet. The

illustration is in Figure 11 and 12.

Classroom Ventilation Design Strategy to Achieve Thermal Comfort

Figure 11: Adding ventilation on other side

Figure 12: Natural air flow illustration in SAC classroom,

after using cross ventilation

Seputra (2017) has said that to maximize cross

ventilation, the placement of ventilation must be in

consideration. Inlet must be placed at human height

in sitting or standing positions which is 60cm-

150cm, so the natural air flow can be felt. Besides

that, outlet is placed in higher position, so hot air can

be easily removed. Mediastika (2004) also said that

the different dimension of inlet and outlet will

increase the air speed. Based on this theory, the

inlet and outlet should be placed like in Figure 12.

The third way of classroom ventilation design

strategy to maximize natural air flow can be done by

giving jettying and secondary skin around the inlet

to avoid direct sun heat and to become a wind

direction tool to the room. Vegetation is also added

to make the room cooler. It is very suggested for

group class 1 (SAC 201 and 202) to use shading

device and secondary skin. The illustration is in

Figure 13.

Figure 13: Shadding device and secondary skin in front of

the inlet ventilation

According to Mediastika (2004), secondary skin

with jalousie model can increase natural air flow by 75%.

3.4 Ecotect Simulation Analysis

The effect of ventilation design to temperature is very

difficult to determine with a simple analysis approach. It is

then necessary to conduct an investigation using computer

simulations, by entering climate data and building

elements into the program. Ecotect is a tool used to model

the temperature of the room and the surrounding

environment. The Ecotect validity is obtained from the

comparison between the results of the field study and the

results of the Ecotect simulation itself.

After cross ventilation system created by adding

several active ventilations in inlet and outlet, and by

adding secondary skin too, there are significant effect on

the classroom temperature. The temperature decreased

2°C. The visualization is shown in Figure 14 and 15. A lot

of blue colour interpreted that the room is in cool

INLET

(existing)

OUTLET

(plan)

SHADDING

DEVICE &

SECONDARY

SKIN

INLET

(existing)

OUTLET

(plan)

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temperature. Otherwise, yellow colour means the hottest

temperature.

Figure 14: Simulation in group class 1

Figure 15: Simulation in group class 2

4 CONCLUSIONS

Comfortable indoor environment is one thing that

supports human activity, which can be pursued

through ventilation design. To make a good natural

airflow in the room, cross ventilation is a must. It

needs inlet and outlet. The choice of ventilation type

will also determine the speed of airflow in the room.

Ecotect program will help us to check the indoor

temperature distribution, which is influenced by

ventilation design and wind flow strength.

ACKNOWLEDGEMENTS

We thank the entire academic community of the

State Islamic University of Sunan Ampel in

Architecture Department for all their support, so that

this paper can be completed. Especially we would

like to thank fellow students, Asmaul Karimah,

Moch. Yazid Rohman, and Nuri Choiriyyah, for

their assistance in collecting research data.

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Classroom Ventilation Design Strategy to Achieve Thermal Comfort