Scholarly article on topic 'Typology of Malay Traditional House Rumah Lontiok and its Response to the Thermal Environment'

Typology of Malay Traditional House Rumah Lontiok and its Response to the Thermal Environment Academic research paper on "Civil engineering"

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Abstract of research paper on Civil engineering, author of scientific article — Yuri Hermawan Prasetyo, Muhammad Nur Fajri Alfata, Anikmah Ridho Pasaribu

Abstract Rumah Lontiok is one of the types of Malay traditional houses threatened to extinct since it have been abandoned by the local people. Located in Kampar–Riau, Rumah Lontiok has changed from its original form, particularly in using corrugated metal as rooftop material. The study aims to describe the Rumah Lontiok and its environment, and to investigate its thermal performance. Field experiment was carried out in this study. Thermal properties of material were measured by thermocouple and heat flux sensors, while surface temperature was gathered by thermocouple acquisitioned by datalogger. All thermal environment data were gathered for 24hours. Data of site situation was documented by recording and sketching on the worksheet. The result of the study figured out the situation of Rumah Lontiok and its environments affecting the thermal performance. The in-situ measurement found out that wall has thermal conductivity of 0.21W/m.K and the floor is 0.19W/m.K. The study shows that indoor thermal environment did not quite different compared to the outdoor thermal environment. The roof material is hypothesized as major source of heat gain into inside the building. Even though there are many openings, they cannot remove heat gain effectively.

Academic research paper on topic "Typology of Malay Traditional House Rumah Lontiok and its Response to the Thermal Environment"

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Procedia Environmental Sciences 20 (2014) 162-171

4th International Conference on Sustainable Future for Human Security, SustaiN 2013

Typology of Malay Traditional House Rumah Lontiok and its Response to the Thermal Environment

Yuri Hermawan Prasetyoa*, Muhammad Nur Fajri Alfatab, Anikmah Ridho Pasaribua

a Experimental Sub-station for Human Settlement Technologies Medan Office - Research Institute for Human Setlement, Indonesia b Laboratory of Building Sciences - Research Institute for Human Setlement, Indonesia

Abstract

Rumah Lontiok is one of the types of Malay traditional houses threatened to extinct since it have been abandoned by the local people. Located in Kampar-Riau, Rumah Lontiok has changed from its original form, particularly in using corrugated metal as rooftop material. The study aims to describe the Rumah Lontiok and its environment, and to investigate its thermal performance. Field experiment was carried out in this study. Thermal properties of material were measured by thermocouple and heat flux sensors, while surface temperature was gathered by thermocouple acquisitioned by datalogger. All thermal environment data were gathered for 24 hours. Data of site situation was documented by recording and sketching on the worksheet. The result of the study figured out the situation of Rumah Lontiok and its environments affecting the thermal performance. The in-situ measurement found out that wall has thermal conductivity of 0.21 W/m.K and the floor is 0.19 W/m.K. The study shows that indoor thermal environment did not quite different compared to the outdoor thermal environment. The roof material is hypothesized as major source of heat gain into inside the building. Even though there are many openings, they cannot remove heat gain effectively.

© 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.Org/licenses/by-nc-nd/3.0/).

Selectionandpeer-reviewunderresponsibility of the SustaiN conference committee and supported by Kyoto University; (RISH), (OPIR), (GCOE-ARS) and (GSS) as co-hosts

Keywords: Rumah Lontiok, thermal performance, field experiment, thermal conductivity

* Corresponding author Tel. +6281 320 574 941 E-mail address: yuri.h@puskim.pu.go.id

1878-0296 © 2014 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).

Selection and peer-review under responsibility of the SustaiN conference committee and supported by Kyoto University; (RISH), (OPIR), (GCOE-ARS) and (GSS) as co-hosts doi: 10. 1016/j .proen v .2014.03.022

1. Introduction

Indoor thermal comfort can be obtained by proper passive design to minimize energy consumption. The use of passive design could consider to passive design of traditional houses, since it has more sufficient indoor thermal environments than modern houses [1,2,3]. Indonesian traditional houses are believed as climate responsive buildings and enable to provide sufficient indoor thermal environment for the occupants through passive design. These conclusions also confirmed by number of researches carried out in Indonesia with various methods developed, such as field experiments in Nusa Tenggara Timur (NTT) [4,5,6], Bena - NTT [7], Javanese traditional houses [8], Bugis traditional houses [9], and by computer simulation in some of Indonesia traditional houses [i.e 10,11,12]. Although researches on Indonesia traditional houses had been performed, yet the study on thermal performance in traditional houses needs to be carried out intensively since Indonesia has various unique and different characteristic of traditional architecture. Among of them are traditional houses of Malay that consisted of four different forms: Lontik, Limas, Lipat Kajang and Lipat Pandan. This study was focused on Rumah Lontiok in District of Kampar, Province

Recently, Indonesia traditional houses have many changed. One of them is marked by using the contemporary building materials such as corrugated metal (zinc) as rooftop material due to the lack of reed and other materials from woods. It brings consequences to the thermal performance of traditional houses [13]. In addition, there are tendency to apply the elements of traditional houses on the modern houses to provide indoor thermal environment sufficiently [14]. Both tendencies require in-depth study to find out what traditional houses elements providing sufficient indoor thermal environment. However, study of thermal performance of traditional houses still need to be performed, so that the change of traditional houses and the use of its elements to modern house still provide sufficient indoor thermal environment for the occupants. The study aims to describe the one of Malay traditional houses and its environment, and to investigate its thermal performance.

Rumah Lontiok is one of the identified Malay traditional architectures in Indonesia and well-known as Lancang or Pencalang. The Rumah Lontiok is located in Blimbing village, District of Kampar, Province Riau (Fig. 1). Blimbing village is located nearby River Kampar and appointed by provincial government as a conserved traditional village. According to information by local sources, the Rumah Lontiok has been existed since the early 19th century. Nowadays, Rumah Lontiok is abandoned by occupants since the occupants prefer choosing to stay in modern landed houses.

Selection of research object is made by several criteria, such as originality (with few changes), the physically present building, and availability of local resources who can provide sufficient information related to the Rumah Lontiok, and the consent to measure the object directly. Field experiment was conducted by considering relative position of the sun against the earth, which is the sun perpendicularly located against the object (around March). It is hypothetically argued that the hotter solar radiation annually felt into the earth is reached at around month March.

Fig.1. Location of Province Riau

2. Method

Field experiment was carried out to measure thermal environments in and around the building, thermal properties of materials, and the site plan. The measured thermal environment parameters are air temperature (Ta), globe temperature (Tg), relative humidity (RH), wind speed (va), heat index (HI), and solar radiation (Rs). Air temperature, globe temperature, relative humidity and heat index were measured by IAQ meter QuesTemp 36, while wind speed was measured by Anemomaster Kanomax A031. The measurement was conducted during 24 hours with an hour in interval time in 23 different points at both inside and outside the building. The instruments were placed at 1.0-1.5 meter above the floor. The measurement point at inside the building consist of eight points divided to three zones namely Zone A, B and C. Moreover, measurement point of outdoor consists of nine points placed in the west side, north side, eastside, and south side of the building. Time measurement was started at 10 am on March 26th, 2013 and finished at 10 am on March 27th 2013.

A 2-minute measurement of temperature of building envelope was performed by thermocouple type J with data acquisition by datalogger HIOKI for 24 hours. This type of thermocouple could measure surface temperature up to 100oC with accuracy ±0.5%. Measurement was conducted at all surface building envelopes, both inside and outside surfaces. The measurement points are south wall, north wall, west wall, east wall, floor, and roof. Measurement was performed to determine the temperature difference between inside and outside surface of building envelope to describe its influence on thermal performance. An in-situ measurement of thermal conductivity of building materials was carried out by heat flux sensor acquitioned by TRSYS01 in 14 hours. This system is in accordance to ASTM C1155-95 (2007) about Standard practice for determining thermal resistance of building envelope components from the in-situ data. Installation of TRSYS01 system in building materials could be seen in Fig. 2. Thermal resistance is obtained by equation 1, while to validate the result of thermal resistance measurement, convergence test is used by equation 2.

Re = Y™=1hTsk/Y,t=1qk (1)

CR1 = (Re(t) - Re(t - 1 ))/fle(t) (2)

with Re(t) is final measurement and Re(t—1) is previous measurement (every 60 minutes in interval time). Thermal conductance is calculated using equation 3. Time-lag and decrement factor was calculated using the difference between outside and inside surface temperature of building envelope measured by thermocouple temperature sensors. Meanwhile, data of site situation was documented by recording and sketching on the worksheet. The dimension of building was measured by laser distance meter.

k = ± R

Fig. 2 Measurement of thermal conductivity using TRSYS01 System

Data analysis was performed by descriptive analysis by comparing indoor and outdoor temperature. Heat transfer analysis was used to describe the thermal performance of building envelope. Heat Index (HI) also accounted to

describe the effect of indoor thermal environment on the occupants. HI is the function of air temperature and relative humidity. Thermal comfort indices such as PMV, PPD, effective temperature (ET), are used to evaluate thermal comfort, and they were calculated with ASHRAE Thermal Comfort software. Thermal comfort is interpreted through comparing with standards such as Indonesia National Standards (SNI) and ASHRAE, and the other results of researches on the naturally-ventilated building in Indonesia such as Feriadi's [15,16]. This method was carried out since existing Rumah Lontiok was not inhabited so it was difficult to gather data of thermal response of the occupants. As function of mean outdoor air temperature (To), the thermal neutrality of ASHRAE is calculated as follow:

Tn(A) = 11.9 + 0.534To (4)

3. Results

3.1. Description of the typology traditional Architecture Rumah Lontiok

Rumah Lontiok get its name from the roof form of the house, which is in native language called by Lontiok. The Rumah Lontiok is situated at 0°19.682' N and 100°57.134' E with altitude of 50 m above sea level. The Rumah Lontiok generally has orientation facing toward Northeast and prolonged from Northwest to Southeast. Rumah Lontiok is typically a stilt house, an elevated first floor above ground level. Formerly, stilt house form was selected aiming to avoid flood and wild animal (Fig. 3a). Space under stilt house usually functioned as corral, barn, boat storage, playground, timber storage, etc. The form of wall facade Rumah Lontiok tilted out at the top and the cantilever of walls and roof beams curved look like a boat-shaped (Fig. 3b). Both edges of the roof looming have ornaments usually called Sulo Bayung. Another ornament in the house placed at the end of the fourth Lontiok roof is called Sayok Lalangan. Both edges of the cantilever wall have many varying decorative carving forms such as a crescent moon or buffalo horn (Fig. 3c).

Fig. 3 (a) Stilt house and boat-shaped roof form; (b) wall tilted out at the top (c) ornaments motive buffalo horn

Originally, building structures, windows, doors, and walls used wood materials that locally named by Kulim, while rooftop material use organic material such as Ijuk, alang-alang (reeds) or Nipah leaf. Now, rooftop material used corrugated metal (zinc) for durability reason but the wall and building structure remain using wood material. Walls use timber panel assembled in a vertical way, but originally it was used woven bamboo named tadie with timber frame. Another characteristic of Rumah Lontik is a terrace with roofed staircase in front of the building called anjung that represents transitional space among outdoor and indoor space. Rumah Lontiok house can be accessed through two main accesses in rear and front of building. Staircase constructed from wood and always has odd number such as five, seven, and so on. Besides functioned as a house, Rumah Lontiok is also used in traditional ceremony such as marriage and feasting.

Building layout was divided into three zones, they are main zone (zone A) considered as sacred place, private zone (zone B) and services zone (zone C) (See Fig. 4). The main zone is functioned as a meeting room for traditional or custom events, and occasionally functioned as parents and children bedrooms. Private zone is used as a family gathering space and for women who were married. Service zone is used as food storage, kitchen and dining

room. There is no bathroom/toilet in Rumah Lontiok since the people concentrated their activities in river Kampar. Spatial pattern of traditional village is randomly clustered following access road. Between one house and another is separated by open space filled up by various trees and vegetations. Type of trees dominated by high tree and fruit tree such as coconut tree, mango tree, durian tree, rose apple tree, and so forth. Thus, Rumah Lontiok also surrounded by open space whereas many kind of trees and vegetations lied within.

Fig. 4 Layout of Rumah Lontiok

3.2. Thermal properties of materials

Building materials used in Rumah Lontioks is predominantly constructed by wood. Wall and floor use the same kind of wood. The only difference is in the thickness of those elements. Wall has 2-cm thickness while floor has 2.5 cm. Material properties of wood can be demonstrated by thermal conductivity, time lag and decrement factor. Heat flux measurements and calculated thermal resistance of wall and floor material are shown in Fig. 5. Using equation 1, it is obtained that thermal resistances of wall during in-situ measurement are 0.106 m2K/W and 0.084 m2K/W and thermal resistances of floor are 0.137 m2K/W and 0.124 m2K/W. Thus, the average thermal resistances of wall and floor are 0.095 m2K/W and 0.131 m2K/W respectively. Using equation 3, thermal conductance of wall and floor are 10.703 W/m2K and 7.671 W/m2K respectively. Thermal conductivity of materials is calculated by multiplying results above by the actual thickness of materials (0.02 m and 0.025 meter respectively for wall and floor). Thus, it is obtained that thermal conductivity of wall is 0.214 W/mK and floor is 0.190 W/mK. Convergence test using equation 2 proved that measurement results have CR<0.1, so that it fulfill convergence requirement and the result is valid to estimate the thermal conductivity of building materials (see Table 1). The thermal conductivity of roof materials in Rumah Lontiok is determined by literature review. According to ISO TC 163/SC 2 or ISO/FDIS 10456:2007 (E), thermal conductivity of zinc is about of 110 W/mK, while the time-lag is 0 minutes and decrement factor 1.00. It means that corrugated metal transfers heat from the outside into inside surface without any interval of time and the entire heat flowed through the material without any heat dissipation [17].

To determine time-lag and decrement factor of wall and floor material, data of surface temperature of wall and floor materials were used. From the calculation, time lag (9) and decrement factor of wall and floor materials are 6 minutes and 0.933 respectively. It means that heat transferred through the wall from outside to inside occurs relatively fast. Decrement factor showed that about 93.3% of heat from the outside of the building will be transmitted into indoor environment and only few heat dissipate in the building materials, either stored or disposed by the materials (about 6.7%).

Fig. 5 Heat flux and thermal resistance of (a) wall material and (b) floor material

Table 1 Convergence test results

Convergence

CR1 CR2 CR1 CR2

Re -2-Re-3 0,00789 0,00631 0.09623 0.06224

Re -1-Re-2 0,00230 0,00738 0.01448 0.03935

Re -Re-1 0,00782 0,00721 0.01722 0.02076

3.3. Thermal performance

Thermal performance of Rumah Lontiok is described by evaluating thermal performance of building envelope and comparing indoor and outdoor thermal environment. Measurement of roof surface in Rumah Lontiok was carried out at the North side and south side, while at wall was carried out in three different sides: South, North, and West. Profile of roof surface temperature can be seen in Fig. 6a. The figure illustrates that the surface temperature of the roof start increasing significantly at around 8 am and reaching its peak at 12.30 pm. After 13.30 it starts decreasing and stable after 7 pm. Between 9 am and 3 pm, the outside surface had higher temperature than inside surface. The maximum temperature difference is about 5.4oC in North-side and 11.8oC in South-side. Meanwhile, there is no significant difference in both sides of roof surface at 4 pm to 9 am. The highest surface temperature at north-side and south-side were 67.5oC and 71.5oC respectively. It means that roof has large number of heat transferred from outside to inside the building, thus highly contributing to internal heat gain. The south-side of roof has greater contribution in heating the room than north-side roof.

Fig 6 (a) Surface temperature of roof and (b) Surface temperature of wall

Wall surfaces temperature is described in Fig. 6b. It has the same pattern as roof surface temperature, where the temperature starts increasing at about 7.30 am and reaches its peak at 1.30 pm then declining continuously. Interestingly, the north-side and south-side of wall have nearly same surface temperature. The average difference temperatures of both sides at 8 am to 1.30 pm are about 1.8oC and 1.9oC respectively. In addition, both sides have relatively high surface temperature (reaching to about 40oC at outside surface and 37-38oC at inside). Meanwhile, west-side wall has the lowest surface temperature. These findings imply that north and south side of wall have higher contribution in heating indoor environment of the buildings compared to west-side. It is probably caused by different vegetations shading the building. The distance of the building to the vegetations and trees at west-side relatively narrower compared to north and south side. Hence, at south and north side, there is more open space than others so that allow those sides receive more solar radiation and heat from outside. Meanwhile, west side of wall is perfectly shaded by vegetations and trees.

Since the Rumah Lontiok is a stilt house, then the floor is one of the building envelops element. The surface temperatures of floor of Rumah Lontiok have lower temperature than other building envelopes. Unlike the others, inside surface temperature of the floor was relatively higher than the outside (see Fig. 7). It implies that heat transmitted from inside to outside surface of floor. Thus, a little amount of heat was disposed to outdoor environment through the floor whilst heat was transmitted into indoor environments at other building wrappers. Fig. 7 also demonstrated that outside surface temperature is more fluctuative and much lower than inside. It probably comes from the fact that outside of system boundary of the building in floor side is an open space that unexposed directly from any heat resources such as direct solar radiation, indirect radiation, etc. In addition, wind under stilt house flowing all day and night long so that there is cooling effect on the outside surface of floor.

-Outside surface

15 ........................................................ ............... ....................

Fig. 7 Profile of surface temperature of floor

The profile of indoor and outdoor thermal environment is illustrated in Fig 8. The measurement results showed that air temperature of indoor and outdoor of the building was not significantly deferent. Neither did for the relative humidity. The recorded lowest indoor air temperature (Ta) was around 24.5°C (at around 6 am) and the highest temperature was around 32.7°C (at around 3 pm). The temperature difference is about 8.2°C. The indoor air temperatures at three different zones inside the building also look like uniform (see Fig. 8a). The outdoor relative humidity ranged from 55% to 97% and the indoor humidity is about 61% - 95%. The outdoor RH has the same as indoor except at 10 am to 6 pm where outdoor RH has little bit higher than indoor (See Fig. 8b). Furthermore, average wind velocity outside the building relatively higher than that of inside the building. The average wind velocity in zone A is higher than that in zone B and zone C, and zone C has the lowest average wind velocity. Indoor wind velocity fluctuated between 0.02 to 0.45 m/s with average speed of 0.10 m/s, and the wind velocity outside the building is between 0.01 to 0.40 with average of 0.17 (see Fig. 8c).

Many openings at building envelope are considered as main cause the outdoor and indoor air temperature was not quiet different. As an open thermal system, energy (heat) and mass (relative humidity) from outside can enter into the system freely, and vice versa. Thus, there is no difference between indoor and outdoor air temperature and the relative humidity. The use of loose and opened partition make the air temperature and relative humidity distributed evenly throughout inside the building, but wind velocity did neither. Eventough it uses loose and opened partition in every zone, the air volume could not flow within the building freely. The front façade of building that contain many openings make that allowing more air from outside the building infiltrated into zone A (main zone).

Fig 8 Comparison of outdoor and indoor (a) air temperature, (b) relative humidity, (c) wind velocity; and (d) Heat Index

Thermal performance of building also can be evaluated from Heat Index (H.I). H.I is obtained from direct measurements using instruments QuesTemp 36. The HI in Rumah Lontiok is illustrated in Fig. 8d. Fig 8d showed that from 9 am to 9 pm the HI in Rumah Lontiok lied at 33-41oC. It means that the occupants should extremely vigilant since at that time the indoor thermal environment could make occupants heat cramps and very exhausted. Long and continuous activities within could make heat stroke to the occupants. At remaining time, the occupant still need aware since long and continuous activities at HI 27-32oC could make people heat cramps.

3.4. Thermal Comfort

To evaluate thermal comfort, SNI to be compared is SNI 03-6572-2001 of Standard for planning of ventilation system and air conditioning system in buildings. According to the SNI, thermal comfort level is distinguished into two different categories: dry season (operative temperature 22.5-26.0oC); and wet season (20.0-23.5oC). The neutral temperature used adaptive standard ASHRAE 55 by following equation 4. In addition, calculation of PMV with assumption of metabolic rate 1.0 met and clothing 0.27 clo [16] also carried out to predict thermal comfort in the Rumah Lontiok.

Fig. 9a showed that most of indoor operative temperature of Rumah Lontiok was higher than that standardized (above upper limit of thermal comfort), except for that are from 12 pm to 8 am. It means that 2/3 of time a day in Rumah Lontiok is uncomfortable. Comparing to Feriadi's study, the thermal environment of Rumah Lontiok was much above of thermal neutrality for naturally ventilated building at from 9 am to 7 pm, and out of thermal comfort range at from 10 am to 6 pm. Feriadi's range of thermal comfort is between 27.5-30.9oC. Using eq. 4, it is obtained that neutral temperature of ASHRAE is about 26.4oC. This temperature closes to the upper limit of thermal comfort according to the SNI. Thus, mostly indoor air temperature of Rumah Lontiok was higher than ASHRAE's neutral temperature, except at 11 pm-8 am (see Fig. 9b). Ranges of thermal discomfort time by SNI and ASHRAE Standard 55 are longer than the reference by Feriadi's study. Although Feriadi's study following adaptive thermal comfort as ASHRAE's, but the neutral temperature and the range of thermal comfort according to Feriadi's still longer than those of ASHRAE's

Predicting thermal comfort using Predicted Mean Voted (PMV) and Percentage Predicted Dissatisfied (PPD) showed that thermal neutrality (PMV=0) and thermally comfortable (PMV=±1) are predicted held from 7 pm to 9 am. In this situation, more people are predicted to be lower dissatisfied (PPD below 10%). Starting from 8 am, the thermal environment is predicted slightly warm and getting hotter in the daytime, and the hottest time (PMV=+3 with PPD about 100%) is reached from 2 pm to 4 pm. It means that during daytime, the indoor thermal environment of Rumah Lontiok is predicted to be warm to hot and the occupants would feel more comfortable at night to morning time (10.00 pm-08.00 am) rather than another time (daytime).

Fig. 9 Comparation of indoor thermal environment to thermal comfort according to (a) SNI and Feriadi's study in operative temperature and (b) ASHRAE Standard-55

Fig 10 PMV-PPD based thermal comfort in Rumah Lontiok

The findings of this research disagree to other previous related studies on traditional houses in Indonesia. Several researches [i.e 1,4,5,6,7] showed that traditional houses able to reduce outdoor air temperature so that traditional houses could maintain its indoor thermal environment lower compared to outdoor's during daytime. Evaluation of thermal comfort in traditional houses [i.e 5,6] also concluded that traditional houses able to create thermal comfort inside the building. These findings probably because Rumah Lontiok uses corrugated metal as rooftop material so that affecting thermal performance of building in a whole since the roof provide the biggest influence on thermal comfort. The open space and the vegetations existed around the building can not help lowering indoor thermal environment. The macro climate of Province Riau that has high average air temperature and solar radiation is also considered make the building relatively has poor indoor thermal environment.

4. Conclusions

Many studies showed that the traditional house has good termal performance compared with the modern houses. This study disagree to those studies by showing that the Rumah Lontiok has a poor thermal performance because there is no significant temperature difference between indoor and outdoor thermal environment. Comparation study to analyze thermal comfort also was carried out by both prescriptive approach and adaptive approach. The results showed that during daytime, the occupants are thermally uncomfortable and predicted to do so. In contrary, the

occupants would be more tolerable to the thermal environment at night time. This study also figured out that rooftop material (corrugated metals) has significant contribution in heating indoor rooms. The north and south side of wall also contributed in heating the rooms due to the orientation of building and the thermal properties of wall material. The open space and vegetations existed around the building cannot help lowering indoor thermal environment effectively. Further study needs to be performed by computer simulation to simulate the effect of use of organic materials (especially reeds as roof cover) to the indoor thermal performance.

Acknowledgements

Authors would like to thank to Experimental sub-station of human settlements technology, Research Institute for Human Settlements for funding this research through National Budget in Fiscal Year 2013. Many thanks also attributed to Laboratory of Building Sciences - Research Institute for Human Settlement for supporting measurement instruments and human resources. Many thanks are also given to the research team leader Asnah Rumiawati and supporting researcher Nanda Pratama.

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