The renewable energy sources impact on vernacular architecture’s ability to be built sustainably: case study of Rumah Gadang

Rumah Gadang has the physical appearance of traditional architecture and was founded on human interaction with the environment. The natural resources of each area in Indonesia are said to have the greatest environmental effect on traditional vernacular architecture. Rumah Gadang is prominent for its ability to successfully combine elements of sustainability with a variety of other factors, including the environment, aesthetics, and social character. However, only a few studies discuss sustainability elements combination within Architecture Nusantara, Rumah Gadang. Therefore, this study will aim to reveal how these elements affect the sustainability of Rumah Gadang and how they contribute to the development of regional architectural styles. The qualitative method was used in this study with literature studies followed by descriptive analysis. The result of the study indicates two things, 1) The nature of these elements’ characteristics in Rumah Gadang fit with social, and environmental sustainability standards. 2) The descriptive analysis reveals that the impact of the variations in natural energy sources on these elements’ characteristics in Rumah Gadang is reflected in its physical appearance. The findings shown that Rumah Gadang’s architectural elements, including the Gonjong roof, wall linings, raised floor, openings, and stone foundation, respond to renewable energy sources based on sun, wind, and humidity factors. Rumah Gadang fulfills three pillars of sustainability: Social sustainability is achieved through traditional values and Minangkabau culture, while economic sustainability is achieved through regionally produced materials and construction methods. Lastly, the primary goal is to offer thermal comfort with minimal waste, making environmental sustainability the most crucial outcome component.


Introduction
Vernacular architecture is a reflection of how many civilizations around the world have historically interacted with their local environments [1].It shows how cultures have adapted to and used the natural resources available to them in a particular region, creating a distinctive architectural image from one region to the next.At the same time, it was successful in meeting the fundamental demands for protection from environmental hazards, addressing climatic issues, integrating social functions, and adding a physical and aesthetic distinctive look [2].
Vernacular architecture is sustainable because it brings harmony to every aspect of its structures, urban fabric, environment, building materials, culture, and climate [3].However, it is important to note that sustainability measures can change over time.Our current time's sustainability criteria may differ from those that are naturally found in vernacular architecture, so we must keep this in mind.
A survey of the relevant literature revealed a lack of scientific evidence about the role of renewable energy sources in developing Nusantara Architecture Rumah Gadang's perception of ecologically conscious vernacular architecture.While there is plenty of research on environmental sustainability in vernacular architecture in general, there are few studies on how renewable energy sources affect Nusantara Architecture Rumah Gadang's ability to project an image of an environmentally conscious vernacular architecture.
Additionally, there are few studies regarding the characteristics and appearance of Rumah Gadang's vernacular architecture, which restricts the researcher's area of inquiry to particular categories and universal prototypes of vernacular architecture in each country.However, the study will investigate the definition of vernacular, what influences vernacular architecture's form, and most significantly, how these influences relate to the characteristics that make vernacular buildings ecologically conscious.
The first stage of methodology will be data collection in a descriptive research approach method in the theoretical part of the study, followed by a qualitative, case study, and analysis research method approaches in the second stage of the methodology.Stages of the methodology include literature study, data collection through specifying case studies, and analyzing the findings in a descriptive-analytical approach.
This paper aims to define how vernacular architecture achieved sustainability by being environmentally responsive to a specific location in a specific period of time, as well as to explain how renewable energy sources contribute to shaping the form of vernacular architecture in Nusantara architecture Rumah Gadang.
This study will examine how the components and forms of Rumah Gadang are climate-sensitive in a way that provides the residents with human comfort in order to fully understand how vernacular architecture is sustainable.This study will concentrate on how renewable energy sources that are found naturally in the environment have a major impact on how the vernacular architecture's environmentally responsive forms are generated.This is why the corresponding of various vernacular architectural objects are significantly different from one climate zone to the others [4].

Vernacular architecture and Nusantara architecture
The Latin term verna, which implies the customary or regional, is where the word "vernacular" first appeared.The architecture that is prevalent throughout a civilization at a given period in relation to its culture and surroundings is known as vernacular architecture.Vernacular architecture is thought to make up 80% or perhaps more of all structures in the globe [5].Vernacular architecture, according to Oliver [6], is the effective outcome of an architecture that logically relates to the local construction materials, climate, and cultural requirements.He added that although there isn't really a precise definition of vernacular architecture, it might be a combination of architectural and human elements depending on the period, region, and history.
The vernacular architecture was characterized by another well-known scholar on the subject as the end result of the complete integration of a number of factors, including society, culture, environment, construction materials, and geographic location [7].Vernacular architecture and its relationship to the climate have been the subject of numerous literary works.In this context, vernacular architecture has been characterized as the organic incorporation of the architectural form as an aspect of its natural setting as the passive methods used in the naturally occurring forms -thanks to tradition and culture -are extremely beneficial at achieving a pleasant environment for the users [8].There are many names for Vernacular Architecture, in Indonesia itself, architecture that is closely related to tradition and culture is called "Nusantara Architecture".

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The term "Nusantara Architecture" refers to the art and understanding of the built environment that originates from the whole Indonesian archipelago, from Sabang to Merauke.An understanding of architecture that was centered on Indonesia's diverse range of cultures, customs, and climate.diverse ideals and viewpoints from diverse socioeconomic cultures are represented by Nusantara Architecture [9].The architecture of Nusantara, which was created by and for the local populace, reflects distinctive, unique, and diversified local content and identity values.The local culture, which often emerges from tiny settlements, is extremely closely related to this architecture.Architecture cannot be separated from cultural development since it is designed to be able to meet human requirements and improve the level of living [10].

Defining sustainable architecture
Since vernacular architecture can result in structures that can incorporate sustainable architectural principles, as was indicated in the introduction, readings, and publications have led to the notion that vernacular architecture is sustainable.The sustainable architecture of today makes many references to historical instances of vernacular architecture, despite the fact that sustainability may appear to be a relatively new notion [11].In order to better grasp this theoretical portion of the study, we must first identify sustainability and its guiding principles.Then, we must investigate natural energy sources.This research will examine how vernacular architecture implemented sustainability components into their structures.
The term "sustainability" has been defined in a large body of literature; however, the definition provided by the World Commission on Environment and Development (WCED) in 1987 [12] is perhaps the most widely used when discussing "sustainable developments" or "development that meets the needs of the present without compromising the ability of future generations to meet their own needs."In order to maintain continuity and placemaking, sustainability is described as the complete interaction of nature and humans [13].
As he states that sustainability is a means of fully integrating the environment, society, and economy together to sustain a better life, Phillip Sutton defines sustainability as a means of improving the quality of life as well as providing means of survival and continuity [14].He also mentions the full integration of the three aspects of sustainability.The social, economic, and environmental pillars-as Sutton previously mentioned-form the cornerstone of every sustainable design plan.It is clearly obvious that sustainability centers around these three fundamental pillars [11].
In light of what has been said thus far, it is clear that vernacular architecture has succeeded in achieving the three pillars of sustainability: social, economic, and environmental.The social pillar is defined by the participation of culture and society; the economic pillar may be defined by the use of local materials and building methods.The following section of the research will provide readers a better idea of how it was done by focusing on environmental sustainability issues and how natural energy forces are incorporated into traditional architecture to meet human comfort needs.

Types of renewable energy sources
The sun, wind/airflow, humidity, and lastly the natural construction materials present in the surrounding area of the given context are some examples of renewable energy sources that deal with the ensuing architectural form within a particular context.Each of those elements directly influences the architectural forms that are produced.
The Sun factor, which is regarded as the primary source of heat in all temperature zones, is one of the main renewable energy sources that a human being has to adjust with in order to achieve comfort in his house.The orientation of a building in relation to the sun must be carefully considered while designing a structure in order to determine where the sun will be at each hour of the day throughout all days and seasons, but notably during the summer.As well as taking into account the sun's energy that is reflected off nearby structures and surfaces, or that is absorbed by them, which helps to create a unique microclimate.To effectively harness the sun's energy, it is crucial to locate the ideal orientation [7].This use would help the home's passive heating, passive cooling, and natural lighting systems work more efficiently.
Buildings can ensure natural air circulation through two main principles that directly rely on the wind as a renewable energy resource.First, differences in air pressure occur due to different air velocity, which causes the air to circulate from the high-pressure area to the low-pressure area.Second, the hot, lighter air travels up and the colder, denser air descends down, providing natural air circulation.Natural convection forces depend on the difference in air density caused by various temperatures.The third aspect is humidity, often known as water.Water is crucial for boosting humidity, especially if we want to make hot climatic zones more comfortable for people [7].
The last consideration is the local natural materials that can be found in the environment.Since vernacular architecture was developed using local materials unique to a particular area, it is crucial to understand how these materials are expressed in vernacular buildings' forms and how they are best used in construction to provide comfort to users.Additionally, using local resources is more environmentally and economically sustainable than using materials from abroad since they are less expensive, naturally accessible, and need less energy to transport to the building site.
Local builders developed the greatest building construction techniques on their own to provide comfort using the local resources that were accessible, for instance, using wood and palm fiber from the local forests.The methods utilized in conventional vernacular architecture are intriguing since they are by definition sustainable [15].

Research methods
In the theoretical portion of the study, the first step of methodology will involve gathering data with historical research using a descriptive research approach technique.One type of research methodology that offers material from the past is historical research.Historical researchers must investigate, evaluate, and develop conclusions in order to uncover evidence from eras and worlds other than their own as "things from the past" cannot be objectively accessible [16].
The second stage of methodology will involve a qualitative, case study, and analysis research method approach.The primary focus of qualitative research stems from its ability to assess the quality and holistic aspects of life.This also naturally makes the design and layout more flexible, which enables customization to be carried out during the study process.In this way, it is very useful to understand human nature and the processes of human activity and artifice [16].This portion has two stages: gathering data by designating case studies and applying a descriptive-analytical approach to analyze the results.
The researcher will use Rumah Gadang, a well-known Indonesian vernacular home, as a case study.This section of the study will take an analytical descriptive approach to provides a comprehensive understanding of the characteristics from both sustainable architecture and Nusantara architecture: rumah Gadang then explain how its form and features are responsive to local renewable energy sources in a way that promotes environmental sustainability and user comfort.

Result and discussion
Traditional societies of West Sumatra, like the Minangkabau People, also have laws and practices that they adhere to for a very long period.The Minangkabau People are an Austronesian tribe whose culture was shaped by the blending of both the ancient and modern Malay cultures with other influences.In Nusantara, Austronesians are mostly housed in homes, temples, community centers, and storage facilities.Similar to those categories, there are four different types of structures in Minangkabau culture: Rangkiang (storage), Balai Adat (community hall), Surau (place of worship), and Rumah Gadang (home) [17].The arrangement of spaces and shapes of rumah Gadang reflects the hierarchical organization of Minangkabau architecture [15].Rumah Gadang is a Minangkabau traditional house that has a long rectangular plan with multiple gable roofs that create ends like buffalo horns, which can be seen in figure 1.Typically, Rumah Gadang is constructed near the former family home.Thus, there is typically still a familial link in a region [18].Deliberation and announcement of the construction of a Rumah Gadang in a hamlet are part of the process of building one.
Rumah Gadang is a type of vernacular housing found commonly in humid, tropical areas of Padang, West Sumatra.The average temperature in Padang, West Sumatra is between 20 and 30 degrees Celsius.In the city of Padang, the dry season is often brief and hot while the rainy season is similarly condensed with significant rainfall.From May to September, there are 4.3 months of dry weather.June has an average of 9.6 days with at least 1 millimetre of precipitation, making it the month with the fewest rainy days in Padang City.From September through May, the rainy season, which lasts 7.7 months, has a probability of rain on any given day of more than 48%.November has the wettest days in Padang City, with an average of 19.3 days with at least 1 millimetre of precipitation [19].
The house's eastern and western halves are referred to as the base and the end, respectively.Doors and windows commonly face north and south [20].Because they are not directly in the path of the rising and setting sun, doors and windows avoiding east and west are deemed advantageous because they let in enough natural light without overheating the space.The roof of Rumah Gadang consists of multiple gable roofs which is called Gonjong [15].Due to its form, it's easier to drain rainwater and reduce heat.Volume for the insulation and transitional areas is created by the space on the roof.
As seen in figure 2, two varieties of rumah Gadang are born out of two harmonies, signifying the disparities in customs.There are platforms with tiers of floors at both ends of rumah Gadang Laras Koto Piliang (Aristokat).In the meanwhile, there is no platform in the rumah Gadang Laras Bodi Caniago (Democrat) home, and the floor is level rather than layered [15].6 Rumah Gadang's walls are made up of two linings.The house's inside is lined with wooden planks.Sakapiang boards are used to build the complete internal wall of the home, which are arranged upright.Like the exterior walls, the inside plank walls have carvings.Planks of braided bamboo or wood cover the ceiling.They employ sculpted wrought iron or wood to support the link where the pillars meet the ceiling.Wooden planks make up the front of the wall lining, while Sasak Bugih, a woven bamboo sheet, is typically used for the left, right, and rear sides.The side walls are referred to as Dindieng Hari, while the front wall is known as Dindieng Tapih [15].The front of the wall lining can be seen in figure 3 below.The wall's construction elements allowed additional lightning and enough airflow to pass through the space between the wooden planks.Rumah Gadang is a home on stilts because there are between 1 and 2 meters between the ground and the floor surface, as seen in figure 4. Additionally, the floor surface is built of wooden planks on a wooden frame with spaces between the planks to permit slow-moving air to enter and depart.Rumah Gadang's floor and ground are separated by a gap, which facilitates the passage of wind through the home's foundation and lowers the interior temperature.This wooden-framed, earthquake-resistant stilt house was built as a single, cohesive building.Rumah Gadang has a stone slab, captured in figure 5, supporting each pillar.Every pole is set up on a rock that slopes from 1-4 degrees.There are eight or twelve sides to these pillars.The Tapi pole, Temban pole, Tangah pole, Dalam pole, and Saluki pole are the four lengthy rows and the five consecutive columns that make up each Rumah Gadang.Each row of pillars has a name that is appropriate for its purpose and significance.Every home has a Tuo pole, also known as a Tiang Tuo or a Panjang si Majolelo pole, which is the tallest Tangah pillar in a row [21].The wooden bolts and pins system utilized in beam connection systems is shown in figure 6. Author's Personal Collection.) The materials used in building Rumah Gadang from wood, bamboo, and palm fibers are all collected from the local forests.The local residents usually hold a ceremony to deliver the first Tiang Tuo.The rest of the materials are transported by river and/or carried on foot [20].Nowadays, Rumah Gadang uses concrete frame and brick wall instead.However, the forms and principles of the house are still being preserved.

Conclusion
The discussion throughout the paper described how renewable energy sources operate and how many vernacular features respond to those resources, and below is the conclusion of the discussion.The research problem was based on how the form of the vernacular architecture was generated in a way that showed how it responded to the renewable sources found on site.
Most of the characteristics of Rumah Gadang's vernacular architecture are the result of the sun's influence.The house's orientation, which determines where its doors and windows should be placed in relation to the west and east, provides enough lighting while shielding it from the heat of the sun's rays directly overhead.A sufficient amount of light can also enter the home through the opening between the wooden planks that make up the exterior lining of the wall.
Rumah Gadang has several wind-responsive elements.The numerous windows at Rumah Gadang allow for large openings without worrying about overheating.The design of the roof allowed for good ventilation inside the dwelling.The large, many-gable roofs offer transitional areas for ventilation to lessen heat within the dwelling.The massive, multiple-gable roofs provide transitional space for airflow to reduce heat within the house.Natural ventilation is also provided by the small gaps between wooden planks for wall lining and flooring.In addition, Rumah Gadang's adaptation of a home on stilts style was advantageous because it allowed the wind to travel through the bottom of the house and further decreased the heat inside.
The unique shape of the roof is mostly a result of humidity.There was enough room on top of the home due to the numerous gable roofs with points like buffalo horns, preventing hot, humid air from being trapped within.Because of its shape, the rainwater is easily drained from the top of the house.Regarding the good airflow that Rumah Gadang has already attained, it keeps molds from growing, which might cause the wood to decay.
The following is a summary of how Rumah Gadang's architectural elements respond to renewable energy sources.The elements include the Gonjong roof, wall linings, raised floor, openings, and stone foundation.These elements are evaluated based on their response to three factors: sun factors, wind factors (airflow), and humidity factors.Additionally, all elements are considered suitable for accommodating building materials factor which is an indicator that the materials used are local materials.The result indicates that the Gonjong roof and wall linings are responsive to all three factors, while the raised floor and openings are responsive to sun factors and wind factors (airflow).The Stone Foundation is only responsive to sun Factors and wind Factors.
The Rumah Gadang has been able to incorporate a sustainable design and has strong environmental resilience while being designated as a traditional dwelling.Rumah Gadang's environmentally friendly architecture is a reaction to the local environment, climate, and terrain.Rumah Gadang's design is modified to reflect local beliefs and traditions.The three sustainability pillars are obtained from many elements of Rumah Gadang.Social sustainability is obtained because Rumah Gadang represents traditional values and is heavily influenced by the local culture of Minangkabau.Due to the use of solely regionally produced building materials and construction methods, economic sustainability is always achieved.Since the primary objective is to provide thermal comfort with the least amount of waste possible, environmental sustainability is the most significant outcome component.