LOCAL WISDOM OF STRUCTURE AND BUILDING SYSTEM TRADITIONAL ARCHITECTURE IN RESPONDING TO NATURE

[15] ABSTRACT Traditional architecture was built on a tradition inherited from one generation to the next. As a country which has hundreds of tribes, Indonesia has hundreds of traditional architecture designed by the ancestors to fulfill the function as well as responding to natural context. The aim of this research is to find out how the structural and building system traditional architecture in this country respond its natural conditions as the context. The method used is qualitative descriptive with the analysis of some traditional architecture which have been visited and conducted a theory review. The results showed that the traditional architecture in Indonesia had been designed to respond to nature as context. From the discussion, it can be concluded that traditional architecture in each region has an approach in aligning themselves with nature as context.


INTRODUCTION
Indonesia is an archipelago which has a very diverse geography. Geographic conditions in Indonesia produces natural conditions which are different from one another, including culture, and ethnicity.
According to Ronald (2002:5) there are more than three hundred tribes in Indonesia which can be further divided into several customs, which each of them has its own house and bring Indonesia as a country which has hundreds of diverse customary houses.
On the other hand, Mangunwijaya (1992) said that the concept of architecture of the archipelago is the adjustment and the tunings with nature. This study aims to find out how the traditional architecture in Indonesia

DISCUSSION
There are four basic elements of a building; building structure, building systems, building services, and building management (So and Chan, 1999

Responding to Earthquake
Indonesia is a country which is prone to natural disasters because it is located around of the ring of fire (Wijayanto, 2016).This condition makes Indonesia is prone to earthquakes, especially for islands located in the ring of fire. Figure   1 shows the earthquake zone map indicating areas in Indonesia, which is  Pudjisuryadi, et. al. (2007) showed that Omo hada has a very stable structure system. The foundation system as a base isolation has ability to reduce the internal forces as well.  Figure 3 shows how load of Tongkonan is distributed to the ground.
Most Tongkonan houses use bamboo as its roof material. However, one type of Tongkonan house use stones as its roof material ( Figure 4). This local material tied up using bamboo skin on a roof structure so as not to fall during earthquakes. When an earthquake is happening roof covering material will move following the earthquake forces and re-stabilized after the shaking stops (Manurung, 2011). This type of Tongkonan is also known as Stone

Responding to Climate
Indonesia is a country that has a humid tropical climate. In tropical countries, temperature and humidity becomes a problem in the architectural design process, as mentioned by So and Chan (1999), external temperature can be around 35 degrees Celsius with humidity ranging from 90% to 100%. Furthermore, they said that too hot or too cold temperature can be dangerous to human life; it shows that human thermal comfort becomes an important things that must be considered in any design process.
In the beginning of the design process, the local climate should be considered to produce the design which is energy conscious and efficient in energy use (Iyendo, et.al. 2016). A research conducted by Iyendo, et.al  design of vernacular buildings more sustainable than modern buildings. As a country that is located below the equator, Indonesia has a hot humid climate.
Every region in Indonesia has related differences in climate and humidity levels. Climatic conditions responded in different ways by our ancestors in producing traditional architectural design in Indonesia. As Lechner (2015) said, in hot and dry climates, window size is smaller so that the hot air does not get into the building, while in the heat and humid climates size of the window is larger. In hot and dry areas flat roofs shape is relevant due for low levels of rainfall in this area, the opposite occurs in hot and humid area ( Figure 5) Research on the influence of traditional roof shape in Central Java (Purwanto, et.al., 2006) found that the roof shape the which has no air circulation in the roof, contributing the heat in the room below, which affect the thermal comfort.
The main Limasan roof modifications are widely used in modern buildings.
However, without an effort to provide good air circulation, will reduce the performance of the building itself. The