SUSTAINABLE ENVIRONMENTAL ARCHITECTURE-2006

THE THERMAL BEHAVIOR AT A HIGH DENSITY ENVIRONMENT

Case Study in Surabaya/ Surakarta, Malang, and Sumenep

B. Heru Santoso,

Architecture Department Sebelas Maret University,Surakarta

Ph.D Student at ITS Surabaya

Email: Hersant05@yahoo.com

Mas Santosa

Achitecture Department  ITS Surabaya

Email: massan@indo.net.id

Abstract

High density is a common characteristic of urban settlement in Indonesia, the higher the population in an urban area, the higher the building density. The phenomenon of such settlement will impact to the quality of living especially in fulfilling the standard of thermal comfort requirement and the quality of air movement. Because of air movement problem both indoor and outdoor in high density settlement, high humidity and the intense solar penetration, the heat gain on building is predicted be able to increase both externally and internally. It influences to the thermal comfort mainly inside the building. The research question is how far the thermal behavior of an urban settlement at high density environment influences to the thermal comfort.

The used research method is by studying the data collected in the field on some different characteristics of climatic condition to generate typology and building variants. Then they are simulated with a computational program as analyzing software. The research takes place in Malang, Sumenep, and Surabaya /Surakarta as case study.

The research result is that commonly the buildings in a high density have a poor thermal behavior. The design of building characterized by spatial arrangement, building material, orientation of opening, and narrow passageway etc, can not provide an adequate thermal comfort. Therefore, based on the field condition  this research recommends that A2 Model( RL-WL-V1-P0is suitable for Surabaya, A6 (RL-WH-V1-C1) is suitable for Malang and A4 Model (RH-WH-V1-P1) is suitable for Sumenep.

Keywords: Thermal Behavior, A High Density Environment    

I. Introduction

I.1. The Building Density Phenomenon

            The fast growing of people in Indonesia particularly in big cities gives an influence to many aspects, in which one of them is growing of building, especially the need of house living. The condition of building growing has become a common phenomenon in every place, mainly in big cities, such like: Jakarta, Surabaya, Medan, Semarang and so on. Even in smaller cities like: Solo, Malang, Yogyakarta as well as the other cities, the need of house living increases rapidly as well. Therefore the phenomenon of high building density as an impact of the growing of people and buildings, and also without supporting of good implementation in building code will be trend issues for every region especialy relating to the thermal behavior of building.

            Based on the study of building characteristics in high density conducted in some region, such as: Surabaya, Malang, Sumenep and Surakarta, it can be seen that commonly there no significant differences among those regions. It means that each region with specific climatic condition do not have specific characteristics as building condition in the past. In the past, every region had a characteristic of building specifically based on its microclimatic condition. This can be seen from the form of roof, material usage, spatial lay-out, open space patterns, vegetations, building height, type and form of opening, uniformly building orientation, etc.

            But now, as the globalization and modernization era, the building caharacteristics particularly in study area representing coastal land, upland and lowland, have a similar characteristic of building. The similarity of building characteristics at 3 different climatic regions include: the phenomenon of building density; the use of building material; the thickness of building material; form and type of building opening; limited opening; ununifomly building orientation; configuration of building; spatial lay-out; very limited open space; etc.

I.2. Building Density Parameter

            Density is an ambiguous terminology or multiperception terminology (Forsyt, 2003) to understand. Rapoport, 1977 said that the characteristics of high density is tight spaces, large building height to space, many signs, many light and high artificial levels, many people visible, most made man, high noise levels, many cars and high traffic density.

            Meanwhile Santosa Mas (2000) defined high building density by illustrating a kampong condition in Indonesia. According Santosa, a kampong is a form of urban settlement with high density population. The traditional social and cultural living style exist in kampong. It revealed from the way the people organize their social environment. Phisically the form of kampong is dominated high density settlement (buildings), narrow pathway patterns and several open spaces which are spread in several places (Mas Santosa, 2000).

            From those statements above, it can be seen that the terminology of building density is rather different. Rapoport referred to density condition on western countries, meanwhile Santosa referred to the density condition on developing countries. The similarity of both statements is that density is characterized by high population, tight spaces and buildings dominating a given area (settlement).

            Sudiarso, 2003 stated that the parameter of density quantitatively refers to the sum of population per acre. It is also considered to the sum of buildings per acre or the coefficient of Building Base (KDB). The building density will be dense if the sum of building reaches 80 – 100 buildings per acre or more than 100 buildings per acre for very dense. In other word, the coefficient of Building base (KDB) reaches 50 – 70 % for dense and more than 70 % for very dense settlement (see table 1). In other part Sudiarso also stated that density problem indicates slum condition of an area.

Table 1 : The category of Slum and very Slum

Source : Sudiarso Budiyono, 2003

I.3. Building Density and Ventilation Condition

            (Urban) building density is one of the principal factors that affects the microclimate of a given area and determines the urban ventilation condition and urban air temperature. The heat island phenomenon is mainly affected by urban density rather than the size of the urban area, the higher the density of building in a given area, the poorer its ventilation. On the other hand, a high density is beneficial for reducing the solar exposure of building during the summer period. The influence of the urban density on the ventilation condition depends on the wind and the spatial arrangement of the building and their height (Santamouris, 1997: 100)

            Related to the climatic condition in hot humid tropical region, high growing of building with no good strictly supervising from city council can be ensured that heating process and ventilation problem in most building will occur very intense. It affects achievement the thermal comfort in building. Therefore the choosing of suitable building material and ventilation system in the region with specific climatic condition is very important.

I.4. Climatic Data and Building Characteristics in study area

I.4.1. Climatic Data

            This research was conducted in 3 different climatic regions. Surabaya and Surakarta represent lowland area, Malang (Tengger) represent upland area and Sumenep represents coastal area. The climatic condition in Surabaya shows that the coldest mont occurs in July. The average air temperature is 27,9 oC with maximum air temperatur is 33,9 o and minimum air temperature is 20,4 oC. The average air humidity in July around 73,4 % with maximum air humidity is 93,2 % and minimum air humidity is 43,8 5. The total horizontal radiation is 5550 Wh/m2 with precipitation level is 17,06 mm. The hottest month in Surabaya occurs in November. The average air temperature is 30,4 oC with maximum air temperature 36,9 oC and minimum air temperature is 22,9 oC. The average air humidity in the hottest month is 71,04 % with maximum air humidity is 96,2 % and minimum air humidity is 41,4 %. In detail, the climatic condition of each region can be seen on the table 2 and 3.

Table 2: Climatic Data in Study Area in the coldest month

Source: BMG Station : Perak, Karangploso, Kalianget

Table 3: Climatic Data in Study Area in the hottest month

Source: BMG Station : Perak, Karangploso, Kalianget

I.4.2. Building Characteristics

            From the preliminary studies, it can be known that commonly the building characteristics are differed 2 things, they are urban and rural region. In urban area there is no significant differences in using building material. Most building use heavyweight / lightweight material both for roof or wall, ceiling, various form and type of opening, and also use single and cross ventilation. There is no uniform building orientation. From the density side, the Coefficient of building base is around 50 – 70 %, even on the certain situation, the coefficient of building base is more than 70 %. It shows that the building density is categorized into dense and very dense environment.  In other side, in rural area there is rather different characteristic than those in urban area. Building material used in rural area is generally simpler, but relating to the modernization era, the influence of modern style of building has affected the building characteristic in rural area. Beside that, the population growing in rural area also influences to building density. In detailed, the building characteristics in area study can be shown in tables below:

Table 4 The Variants of House Living (Field Observation)

UPLAND-HIGH DENSITY

UPLAND-LOW DENSITY

LOWLAND-HIGH DENSITY

LOWLAND-LOW DENSITY

Source : HPTP final report

I.5. Thermal Comfort of Building

            Thermal comfort is one of the forms of comfort. The others are: acoustical, visual and air quality comfort (Santamouris, 1997: 129). The parameter of thermal comfort includes 3 aspects, they are: physical, psychological and external aspect (Francis Allard, 1998:5). In developing countries, like: Indonesia for instance, natural thermal comfort has to be fulfilled because of the health aspect and economical aspect (Aynsley, 1977).

            The relationship between health and thermal comfort actually has been stated since Hippocrates era, 400 BC, stating that to study the medicines, firstly people must study climate annually, secondly people must study the coldest wind and the hottest wind, and finally people must study water and health. It means that the health problem can be minimized by providing an adequate air flow, fresh air, and appropriate air temperature and air humidity in building.

I.6. Research Question

The research question is how far the thermal behavior of a settlement at high density environment influences to the building thermal comfort

II. Research Methodology

This research is a small part of whole research of HPTP (Hibah Penelitian Tim Pascasarjana). Operationally the research conducted in this previous stage consisted of 4 steps as follows:

1. Measuring the thermal performance on research object,
2. Observing thermal responses on each element, particularly wall and roof
3. Observing ventilation system and Air change rate
4. Comparation among the construction combination to obtain the illustration of important role of each variable

The field observation on upland and lowland with high and low density was done in the preliminary studies gave the recommendation of typologies and architectural variants on each location. The analysis of typologies and variants taken from direct field observation was carried out with model determination for simulation. Simulation programs used in the research are Harmonic Analysis for Thermal Simulation, AIOLOS as wind behavior simulation to predict Air Change Rate. From the simulation, it can be predicted the most suitable model for each region.

III. Result and Analysis

The simulation of thermal behavior on research model for condition in Surabaya that represents lowland area with high density was carried out to 15 models implementing 4 element variables of different building. The simulation was done in the hottest month, in November, and in the coldest month, in July. From the simulation result, the highest duration of comfort is the simulation result of A2 model (RL-WL-V1-C1). Meanwhile the lowest duration of comfort is the simulation result of A6 model (RL-WH-V1-C1).The determination of A2 model as model having the highest duration of comfort is when the comfortable temperature zone (22,9 – 27,7 oC) runs in the resting time (45,8 % in the hottest month, 58,3 % in the coldest month) and has a shorter overheating among the other models. The simulation of A6 model has the shortest duration of thermal comfort (4,2 % in the hottest month and 37,5 in the coldest month).

   The simulation of thermal behavior on research model for condition in Malang that represents upland area with high density was carried out to 15 models implementing 4 variables of different element building. The simulation was done in the hottest month and in the coldest month. From the simulation result, the highest duration of comfort is the simulation result of A6 model (RL-WH-V1-C1). Meanwhile the lowest duration of comfort is the simulation result of A1 model (RL-WL-V1-C0).The determination of A6 model as model having the highest duration of comfort is when the comfortable temperature zone (22,9 – 27,7 oC) runs in the resting time (66,7 % (16 hours) in the hottest month, 83,3 % in the coldest month) and has a shorter overheating among the other models (17,1 K and 0,7 K). The simulation of A1 model has the shortest duration of thermal comfort (8,3 % in the hottest month and 8,3 % in the coldest month) with overheating level is around 61, 5 K (in the hottest month) and 33,5 K (in the coldest month).

   Meanwhile, the simulation of thermal behavior on research model for condition in Sumenep that represents coastal land area with low density was also carried out to 15 models implementing 4 element variables of different building. The simulation was done in the hottest month and in the coldest month. From the simulation result, the highest duration of comfort is the simulation result of A4 model (RL-WH-V2-C1). Meanwhile the lowest duration of comfort is the simulation result of B6 model (RH-WH-V1-C1).The determination of A4 model as model having the highest duration of comfort is when the comfortable temperature zone (22,9 – 27,7 oC) runs in the resting time (54 % – 13 hours) in the hottest month, 63 % in the coldest month) and has a shorter overheating among the other models (52,5 K and 35 K). The simulation of B6 model has the shortest duration of thermal comfort (29 % in the hottest month and 50 % in the coldest month) with overheating level is around 51,7 K (in the hottest month) and 27.8 K (in the coldest month).

IV. Conclusion

From the analysis above, it can be concluded that :

1. Not all elements of building can provide adequate thermal comfort particularly in high density environment
2. Based on the climatic condition in Surabaya and the simulation result, A2 model with Lightweight Roof, Lightweight Wall, Single Ventilation, and Ceiling (RL-WL-V1-P1) is the most suitable model for Surabaya, meanwhile A6 model with Lightweight Roof, Heavyweight Wall, Single Ventilation, Ceiling (RL-WH-V1-C1) is the most unsuitable model for Surabaya (Lowland-high density)
3. Based on the climatic condition in Malang and the simulation result, A6 model with Lightweight Roof, Heavyweight Wall, Single Ventilation, Ceiling (RL-WH-V1-C1) is the most suitable model for Malang, and A1 model with Lightweight Roof-Lightweight Wall- Single Ventilation- Unceiling (RL-WL-V1-C0) is the most unsuitable model for Malang (Upland-high density)
4. Based on the climatic condition in Sumenep and the simulation result, A4 model with Lightweight Roof, Heavyweight Wall, Cross Ventilation, Ceiling (RL-WH-V2-C1) is the most suitable model for Sumenep, and B6 model with Heavyweight Roof-Heavyweight Wall- Single Ventilation- Ceiling (RH-WH-V1-C1) is the most unsuitable model for Sumenep (Lowland-low density)

Acknowledgement

Special thanks for Laboratory of Science and Environment, Institute of Technology Sepuluh November Surabaya and HPTP (Hibah Penelitian Tim Pascasarjana) Second Year (2006) that were facilitating and contributing  the research and funding. And also special thanks to Prof Mas Santosa, IG. Ngurah Antaryama, Ph.D and all member in HPTP team.

References

1. Aynsley, RM, 1977,Architectural Aerodynamyc, Applied Science Pub, London
2. Forsyt, Ann, 2003, Measuring Density: Working Difinition for Residential Density and Building Density, University of Minnesota, Minnesota
3. Francis Allard, 1998, Natural Ventilation in Building, James and James, London
4. Rapoport Amos, 1977, Human Aspect and Urban Form,Pergamon Press, London
5. Santamouris, 1997, Passive Cooling of Building, James and James, London
6. Santosa Mas, 2000, Specific Responses of Traditional Houses to Hot Tropics, Senvar – I ITS, Surabaya
7. Santosa Mas, 2006, Sistim Pendinginan Pasip pada Bangunan di daerah Tropis untuk upaya Pembambangunan Berkelanjutan, Laporan Akhir HPTP 2006, ITS, Surabaya
8. Sudiarso Budiyono, 2003, Penerapan pedoman Perencanaan Tata Ruang Kota- Diktat Supplemen,Jurusan Arsitektur dan Planologi UNKRIS/ UNTAR, Jakarta