thermal performance optimation - ITS

Samodra : THERMAL PERFORMANCE OPTIMIZATION

THERMAL PERFORMANCE OPTIMIZATION OF SKIN CONSTRUCTION DESIGN FOR JAVANESE VILLAGE HOUSES FX Teddy Badai Samodra Environmental Architecture Researcher/Architect Alumnus of Department of Architecture-ITS E-mail: [email protected]

ABSTRACT The climate in tropical humid area is the most difficult aspect which can be solved by architectural design method. In fact, thermal contribution would not happen if building design, construction system and environmental consideration met human being’s need or is very subjective. This paper reports a study on Javanese village houses because this type of house has typical characteristics which can be recognized from the materials used, dimension and building shape. This study aims to find out the influence of architectural design and building construction system on thermal performance optimization, recognizing characteristics of village houses which indicate thermal performance optimization as well as recognizing components of village houses which influence thermal performance most. Computer simulation using AIOLOS and ARCHIPAK software was used from this simulation to gain analyzing architectural design by determining comfortable duration and degreehours value in the coldest month (August) and the hottest (November). The result shows that architectural design and building construction can optimize thermal performance. And with kloneng wall (combination of 0.8 metres height of brick in the lower and 2 metres height bamboo in the upper) as building skin construction system, the thermal performance will be the best and the important influential factor. Keywords: humid tropical climate, material simulation, skin construction, thermal performance, village houses

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ARCHITECTURE&ENVIRONMENT. Vol.5, No. 1, April 2006 : 66-76

INTRODUCTION Thermal performance for Javanese village house has been more effective than the other typologies such as colonial and modern. Javanese village house has lightweight material (Nirwansjah dan Hariadi, 1988). In the range of village image that are roof style and dimension, material at the time variable, and also characteristic of Javanese village house plan, it has potential to have material simulation by optimizing the roof, building skin construction system and orientation from the point of view of thermal performance. This method is one of architectural design strategies for Javanese village houses.

THERMAL BEHAVIOUR OF BUILDINGS In the area that has small variations in dry air temperature and relative humidity, daily or annually, some factors determine building thermal behaviour. They are capability as thermal resistance from building skin construction, solar radiation (direct or indirect), number of air change, and internal heat gain (Santosa, 1993). This environmental problems will take a lot of variables. Sub variables or components of variable have complex relation. In this case, designer as decision maker must decide for specific condition. Thus, the optimization is needed. Computer simulation is commonly used for optimization tool. In that way, iteration is conducted to obtain optimized value. Thus, on appropriate optimization software is need for analyzing thermal performance of building.

ARCHITECTURAL DESIGN IMAGE OF VILLAGE Javanese village house has specific characteristics as identity. That images can be used as range of design simulation for obtaining thermal performance optimization. It must be done on that range, so the simulation design can not neglect village image (Table 1). Based on the village image study, elements of the village house, which potential for optimization are roof, building skin construction system, and orientation, or see Figure 1; 1. Roof; in the thermal performance, optimization for the roof is the material, but in limited alternative. It is only taken from surroundings area. 2. Building skin construction system; it is consist of wall and openings (window, door). Its material is also taken from surroundings area. 3. Orientation; Javanese village house orientation has not specific regulation, so that all of orientation can be taken on the simulation.

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Table 1. Village Architectural Design Image No. Elements of Design Explanation 1. Roof Style Roof has kampung pokok style like brunjung on joglo and there are emper on it. 2. Dimension The dimension of building appropriates with nuclear family. Material Material would be taken from surroundings 3. environment. Source: Gunadi and Prijotomo, 1979

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SKIN CONSTRUCTION SYSTEM

ORIENTATION

Figure 1. Javanese Village House Elements

Skin construction system becomes a very important element for analyzing thermal performance. It is showed as method of architectural design. It can determine performance of building on these criteria: opening, material, and orientation. In the Javanese village house, wall has specific phenomena. They are material ventilation of wall; bamboo (gedhek), wood (gebyog). The material role has ventilation for air change, good for healthy and optimization for environmental design of building. Identification of Skin Construction System Skin construction systems in the region of observation, Blitar, East Java (Figure 2), developed as 6 combinations (phases). They consist of 3 types of wall material and 2 types of roof material. It is shown on Table 2. Wood, The first material application (gebyog) in the Javanese village houses has been existing material. Bamboo was recognized as new technologies of welitan system after wood application. As the last of skin construction system of Javanese village houses design, kloneng was implemented after the brick founded. Kloneng is a specific name of Blitar Javanese

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village house wall. Usually, it is constructed by about 0.8 metres height of brick in the lower and 2 metres height bamboo in the upper. Kloneng was found by Javanese people in the last phases. It is shown on Table 2.

Figure 2. Javanese Village House Location As presented on the Table 2, kloneng has been growth as “the young material”. Why it can be found in the last period? By field study, kloneng has been found after brick recognized by the people. In the beginning, Javanese people used wood for wall and sirap (wood shingles) roof for their houses. After that, the people used bamboo and kloneng in the end. In this research, study for thermal performance focused on the wall analyzing as skin construction system design. Combination wall and roof has been decided into phase 1, 2, and 3 or 4, 5, and 6. Due to take optimization, genteng has been chosen as roof material with various wall combinations.

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Table 2. Material Application Phases of Javanese Village Houses Phases Combination Explanation Walls Roofs 1 Wood Sirap - The first material application(gebyog) - Existing material combination 2 Bamboo Sirap - Recognition of welitan system (bambu-gedhek) 3 Kloneng Sirap - Recognition of new system; brick 4

Wood

5 Bamboo Kloneng 6 Source: Field Study, 2005

Genteng

Genteng Genteng

-

Recognition of cast system; genteng Last material application

RESEARCH METHOD The research involves three main phases for environment temperature prediction to the Javanese village houses: 1. Identification and specification phase; evaluation for characteristic of village houses and fixation for simulation object. 2. Simulation phase; realization for simulation model and optimization system on the building design with AIOLOS v1.0 (ventilation simulation) and ARCHIPAK v4.0 (thermal simulation) software. 3. Optimization phase; evaluation for obtaining the optimization model as recommended design in the thermal performance. The object in this research is Javanese village house which still in original condition. The house must be occupied by not more than 5 persons; it is described as nuclear family and consist of father, mother, and 3 children. This condition determines number of rooms and areas, distribution of air change, and internal heat gain. Survey location for Javanese house would be taken on the area which has village characteristic, rural (see Figure 3). The study was conducted by doing direct observation about the available building materials, occupant characters and environmental condition in Kedawung, Blitar, East Java, which is determined on the basis of comparable data obtained from Meteorology and Geophysics Centre of Karangploso, Malang.

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Figure 3. Javanese Village House Environment Source: Field Study, 2005 Table 3. Javanese Village Houses Simulation Description Simulations Variables Wall a). SIMULATION 1 Roof Orientation Wall b). SIMULATION 2 Roof Orientation Wall Roof c). SIMULATION 3 Orientation

Explanation Wood Genteng South = 1800 Bamboo Genteng South = 1800 Kloneng Genteng South = 1800

Based on field study, the number of material simulation, which can be done to optimize thermal performance, reaches 3 (Table 3). To gain comfortable period and degree-hours value in the coldest month (August) and the hottest (November), based on data obtained in the year 2000-2004, computer simulation using AIOLOS and ARCHIPAK software was used from this simulation, the best thermal performance can be determined. In this paper, thermal performance of wood, bamboo, kloneng as skin construction system can be compared. Orientation has less influence than the other element in the low-rise building. Main orientation of building (North, East, South, and West) has

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no significant difference of air change (Samodra, 2005). The phenomena can determine temperature of building into slightly difference.

Figure 5. Skin Construction System

Figure 6. Javanese Village House Simulation Models

RESULT AND DISCUSSION Comfort period In the coldest month, comfort period of simulation 2 and 3 has the same value in active period time, that is 15 hours (Figure 7). Substitution the bamboo and kloneng wall can improve the performance by wood material; in fact, it increase from 13 hours to 15 hours. In the hottest month, 16 hours in active period of Javanese village house give 15 hours in comfort (about 94%) for all simulations. The conditions indicate that thermal performance of skin construction system has optimized. From this simulation, simulations 2 and 3 with bamboo and kloneng have optimized.

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HOURS

Degree-Hours In the Degree-hours analysis also can be seen the difference condition because of calculate analyzing. This method explains total number of overheating (UH) and underheating (OH) temperature or total number of difference temperature between indoor temperature and the upper or lower comfort limit line. 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Simulation 1 Simulation 2 Simulation 3

Coldest month

Hottest month

SIMULATIONS

Figure 7. Comfort Period in the Coldest and Hottest Month The simulations involve genteng roof indicate difference thermal performance from simulations. They show that underheating problem has been dominant (Figure 8), with bamboo and kloneng wall, the value are -4.2 and -4.6 in the coldest month. Exactly, in the wood wall simulation, the underheating value is only -2.8. However, all of simulations that involve genteng roof, the overheating values are not different so much; maximum value is 1, it just for simulation 1. Like coldest month, in the hottest month, simulation 3 with kloneng wall has thermal performance are better than the others because overheating value is lowest (OH = 0,4) although underheating is higher than simulation 1 (wood wall). This capability of the kloneng is suitable in the hot humid tropical climate. Its material has U-value = 2.62 W/mK (brick), it is lower than wood (U-value = 2.92 W/mK) or bamboo (U-value = 3.69 W/mK). In the other things, Tlag (time lag) of kloneng is 4.2 hours, higher than wood (1 hour) or bamboo (0.19). It is sure that kloneng has capability in the thermal resistance, it is important in the coldest and hottest month. Kloneng has bamboo in upper sides, it has ventilation for air change. This capability is good for healthy too.

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Figure 8. Degree-hours in the Coldest and Hottest Month Temperature Fluctuations In the coldest and hottest month, the optimization Javanese village house has capability for reducing the thermal condition of environment and the other village house models. In the hottest month, it is in warm condition, but it still can reduce the overheating value or its condition. At 06.00 a.m. (coldest and hottest month) is in underheating (Figure 9), it has been indicated by any factors, such as: 1. Opening schedule shows 1 (opened) at 05.00 a.m. and influence dynamically the condition at 06.00, it has also been determined by underheating condition of the environment. 2. Solar radiation has not influence to the building. 3. Material characteristic is heat loss, so that building in underheating condition. 30

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Figure 9. Temperature Fluctuations of Javanese Village house with Kloneng Wall

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CONCLUSION Architectural design in the Javanese village house simulations has fixed value for optimization. That design elements are shape and dimension, building construction indicates about the material. From the discussion, combination for material (roof and wall) can improve the environment and existing building design. In the thermal performance simulation, kloneng wall has showed as optimal local material for Javanese village house (especially in the Blitar region). It capabilities was indicated by: 1. Long period of comfort duration; 15 hours of 16 hours = 94% 2. Minimum value of underheating in the coldest moth (UH = 4.2) and overheating in the hottest month (OH = 0.4) This local material has characteristics for obtaining thermal performance optimization, they are: 1. Minimum value of U-value = 2.62 W/mK 2. Maximum value of Tlag = 4.2 hours The tabulation and graph illustration indicate that it has significant difference on the wall substitution in the coldest month only. It indicates that environmental condition is underheating. The wall substitution and combination with orientation have influence also, but the contributions are lower than in the roof. By analyzing comfort period and degree-hours, wall optimization by kloneng can be obtained as alternative and contribution for architectural, environmental design and construction.

REFERENCES Allard, F. (1998), Natural Ventilation in Buildings, James & James LTD, London Aynsley, R.M. (1977), Architectural Aerodynamics, Applied Science publishers LTD, London Frick, H. (1997), Pola Struktural dan Teknik Bangunan di Indonesia, Kanisius, Yogyakarta Gunadi S., Prijotomo, J. (1979), Perkembangan Arsitektur Pedesaan, FTA - ITS, Surabaya Ismunandar, R. (1997), Arsitektur Rumah Tradisional Jawa, Daahra Prize, Semarang Nirvansjah, R. dan Hariadi, D. (1988), Study Faktor Kenyamaman dan Kenikmatan Bangunan Kolonial di Surabaya, Pusat Penelitian ITS, Surabaya

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Samodra, F.X.T.B. (2005), Thermal Performance Optimization for Javanese Village Houses, Proceedings SENVAR2005, September 19-20. pp 15-25. Samodra, F.X.T.B. (2006), Thermal Performance of Kloneng as Local Material for Javanese Village Houses, Proceedings INTA 2006, April 3-5. pp P11-1 – P116 Santosa, M. (1993), Sistem Informasi Aspek Panas dalam Rancang Arsitektur, Lemlit ITS, Surabaya Santosa, M. (2000), Specific Responses of Traditional Houses to Hot Tropic, Proceedings SENVAR 2000, October 23-24. pp 13-17. Santosa, M. (2003), Totalitas Arsitektur Tropis, Orasi Pengukuhan Guru Besar ITS, Surabaya Swami, Chandra, (1988), Correlation for Pressure Distribution on Buildings and calculation of Natural-Ventilation Airflow, ASHRAE Transactions, vol. 94. no.1 Szokolay, S.V. (1987), Thermal Design of Buildings, RAIA Education Division, Canberra

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