Investigation of colonial architecture’s influence on the resilience and sustainability of the limasan house in Ndalem Ngabean

Vernacular architecture is one of the symbols that represent a certain area through various aspects that fits to the condition of the built environment. One of the vernacular architecture in Indonesia is the Limasan house which originated from Yogyakarta with a pyramid-shaped roof as its hallmark. The purpose of this research is to identify the sustainability and resilience of the design of Yogyakarta’s Limasan house in Ndalem Ngabean in accordance with colonial architecture. The methods used in this paper are literature study, building observation on Limasan’s architectural features, and field study conducted in Yogyakarta. The result shows that there are visible features of colonial architecture in the physical appearance of the Limasan house. This indicates that the sustainability and resilience of Limasan House is influenced by colonial architecture.


Background
The Special Region of Yogyakarta is a province in Indonesia known for its historical and cultural identity that is not only found in the traditions but also in its traditional architecture.Ever since the Dutch came to Java and eventually colonized the land, acculturation between Western and Javanese culture has happened and created a lifestyle called the Indies culture [1].This culture that was raised through colonization affects the social and cultural aspect of the Javanese daily life including the container of urban space that is architecture [2].Through the development of building materials and methods in addition to the cultural impact that the colonizers brought, the Javanese started to build their houses with features of western architecture.The influence of colonial architecture was even shown in the residences of Yogyakarta's royal courtiers, one of the examples being in Kampung Kauman, Yogyakarta [3].
The complex of the studied object, Ndalem Ngabean Hotel and Resto, also has a history of being the residence of the royal member.The complex has a mass called Limasan which was previously built as the royal residence (Ndalem) for prince Hangabehi, the son of Sri Sultan Hamengkubuwana VII [4].In spite of the lack of information regarding the Limasan's built year, we can assume the possible range of IOP Publishing doi:10.1088/1755-1315/1351/1/012023 2 the built year by the reign of Sri Sultan Hamengkubuwana VII which is 1877-1921 where the Dutch have already been residing in Yogyakarta [5].Therefore, it is reasonable to say that the colonial style had influenced the style of Ndalem Ngabean's Limasan.
Aside from building appearance, colonial architecture can also affect the sustainability and resilience of the building.A sustainable building should incorporate ventilation so the building can breathe through its openings [6].The characteristic of colonial architescture that has numerous windows is an evident of colonial architecture's contribution to reach sustainability [7].Sustainable architecture can also be achieved through the material and construction usage in which colonial architecture influence, to be specific, will affect Limasan's comfortability and usability.Sustainable architecture has significance because it is in line with the principles of sustainability, which involves preserving natural resources to ensure their continuity and longevity [8].Indications of colonial influence in the architecture of Limasan lead us to further understand better the history of this Nusantara architecture house and the effect on the further development of Yogyakarta's traditional architecture.The principal purposes of this study were to: (1) study the aspects of Limasan House in Ndalem Ngabean and the influences of colonial style; (2) assess the impact of colonial architecture on the sustainability of the Limasan house in Ndalem Ngabean; and (3) identify potential sustainable design practices in vernacular architecture.

Research Methods
The method used in this paper is direct size measurement at the studied object and visual-based analysis using the photographed image obtained directly from the studied object.The sizes and visual identity of Limasan is then compared to the colonial buildings' data.The colonial buildings measured are Beringharjo market, Bank Indonesia, Pos Indonesia, and Gedung BNI 1946.The tool used for the measurement is a metric ruler.The data acquired is the thickness of Limasan's reinforced concrete wall which is used in the analysis of the building's sustainability and resilience.The descriptive-qualitative method is used to exclaim the influence of colonial architecture to the Limasan and analyze the sustainability principles with the support of the measurement data.The data for this method are collected through field observation, directly-documented pictures, and literature studies from journal and thesis.The discussion focuses on the architectural elements comparison such as window, door, roof, column, and wall to investigate traces of colonial style in Limasan.As for the sustainability principles discussed are the thermal environment, including the temperature and humidity of spaces, as well as the material resilience such as its life duration and withstanding to the local weather.

Elements of Yogyakarta Vernacular Architecture in Limasan House
The Special Region of Yogyakarta is located in the southern part of Central Java.It has a temperature range between 23°C -31°C and monthly average humidity range between 81% -90% [9].There are 2 seasons in the Special Region of Yogyakarta which is the summer season, starting from April to October and the rainy season from October to April.In the Special Region of Yogyakarta, there can be found various Javanese traditional buildings with different typologies.The architecture of traditional Javanese houses are distinguished by their roof, one of them being the Limasan House.These houses also indicate the social and economic status of the homeowner in which Limasan house is more widely used among Javanese residents compared to the Joglo house which is mostly owned by the upper-class community and the Keraton [10].Limasan House is a continuation of the development of the form of the existing building.Accordingly, there are 16 different types of Limasan Houses differentiated by the roof shape yet still forming a similar building known as Limasan House [11].The name of Limasan House is also taken by the typical form of the pyramid-like shape roof.
Limasan House structures as well as other vernacular building structures are generally made from natural and domestic materials such as wood and stone.The structural configuration of Limasan House is also almost the same as Joglo yet there is no arrangement of beams called tumpangsari in the Limasan structure.The word limasan itself is taken from the word lima-lasan, which is adapted from the Javanese Language and is a simple calculation of the measurement of the structural elements: molo 3 m and blandar 5 m.Furthermore, if the molo is 10 m, then blandar must be using a size of 15 m (limasan = fifteen = 15) [11].Molo is the beam that is located at the very top and is considered the head of the building while blandar is the pillar that supports the roof.
The structural system in the Limasan House consists of several components that work simultaneously so each component has a function differently and consists of a column, beam, roof, and umpak that holds the roof.Correlating with the resilience and sustainability aspects, the structure of the Limasan which is made of full walls (not an open space) creates good insulation for the occupants.

Elements of Colonial Architecture Style
In the context of the time period, Yogyakarta was under the government of the Dutch therefore the colonial architecture style carried specifically is the Indische architecture during the 18th and 19th centuries.This style then developed into Indische Empire architecture, the more adjusted to local context version, after the reign of H. W. Daendels who brought the influence of the French Empire architecture style [12].It was then developed further into transitional architecture style during 1890-1915 [13].The Dutch continued to introduce modern colonial architecture style from 1915 to 1940 [12].
There are certain characteristics of every colonial architectural style.The floor plan of Indische Empire architecture is determined by a symmetrical plan with a terrace [12].Symmetrical shape offers easy spatial connections and the terrace is a form of adaptation to the local climate [14].The column style in the Indische Empire style was heavily influenced by Greek architecture and the influence reduced during the transitional era.A colonial building built in this era in the same city as the studied object is the Bank Indonesia building.The transitional style's characteristics still bear resemblance to the Indische Empire style in terms of the floor plan.Besides, Indonesia's design and spatial layout has remained relatively unchanged [15].However, the facade appearance consists of gevels and towers.The material used is mainly bricks for both columns and walls and wood for horses, frames, and doors.However, the use of glass material was not as popular during this era [13].The structural system uses bearing wall construction.The material and structural system is used according to the original colonial building in the place it came from which was constructed to withstand the extreme weather of the subtropical climate.An example of buildings built in this period is the POS Besar office building in Yogyakarta and Lawang Sewu in Semarang.
Lastly, the modern colonial architecture style's floor plan is more varied and creative.Symmetrical plans are no longer used, as well as terraces around the building are rarely used anymore.Terraces, on the other hand, are still used as an architectural element to protect the building from direct sunlight and to provide comfort.The facade is simple in design, looks more clean, and reflects the idea that form follows function.The material and construction system were primarily made of concrete, which had never been used before [16].

The Influence of One Architecture Style to Another
Through diverse historical occurrences, decision making in designing also has always been influenced by different factors.Take an example from Kampung Kauman, Yogyakarta [3].Due to the colonization by the Dutch, residences of the abdi dalem have the silhouette of a traditional Javanese house but with the features of a colonial house as seen in its Roman pillars, Italian hanging lamp, and large main entrance.These western features were considered a symbol of power.There are also modern javanese houses in the village due to the advancement of construction technology and the changing trend of dwellings.The influence is shown in the shape and material of the houses where most have substituted its wooden walls and columns with concrete ones as well as the addition of geometric shapes in the facade.
Another example of acculturation of styles can be found in the influence of Chinese style on Javanese houses in Lasem.In Kauman the Javanese style can be seen in the building's silhouette, in Lasem it can be found in the layout and ornamentation of the house.Meanwhile the Chinese architecture mainly takes over the structural elements such as the roof shape and construction [17].To sum up, the embodiment of more than one architecture style can be seen on some of the elements: the silhouette, facade, material, construction, layout, and the ornamentation of the building.

Structure and Construction
The colonial architecture influence to the resilience and sustainability of Limasan House can be identified through its structure and construction.Vernacular buildings in Yogyakarta using wood as its main structure to hold the building in place [11].Wood is used as a structure to build vernacular architecture buildings as well as limasan houses that are built using teak wood [11].As for now, some vernacular buildings have changed their structural component using reinforced concrete instead of wood, this happened because of the building technology advancement that was brought by the colonizers [18].This advancement brought more durable material but in the construction, maintenance, disposal, and operation phase steel reinforced concrete produces more emission [19].On the contrary though, the longer a building stands, the more carbon emission is reduced for every 5 years and wood life span is shorter in high humidity places such as Indonesia as it will deteriorate the material unlike concrete [19] [20].

Wall
The wall acts as a structural aspect.The wall at the pringgitan perimeter is 50 cm thick double stack brick wall and the rest of the walls separating the spaces are 15 cm thick brick wall.The thick wall provides a noise blocking feature, creating a private space for the user inside the house.The wall material and thickness also work as a micro-climating strategy to provide thermal comfort to the occupant inside the house.
Double stacked brick walls mainly respond to the thermal aspect as Netherland has 4 seasons which typically have lower temperature compared with the Limasan that have higher temperature.The original traditional Limasan wall is not supposed to be structural and the materials used are wood (Gebyok), bamboo (Gedhek), or brick (Tembok) [21].The full use of brick and the existence of bearing wall construction indicates that this aspect of Ndalem Ngabean's Limasan is influenced by Colonial Architecture.
In comparison to the outdoor area, Ndalem Ngabean's Limasan House has a lower average around 07.00 UTC+7 to 15.00 UTC+7 and a more steady graph with a peak temperature reached around 30⁰C in 13.30 UTC+7 and the minimum temperature reached around 26⁰C at 05.00 UTC+7 (Figure 5).Furthermore, the interior humidity of the Limasan house has a more stable chart and a slightly greater humidity between 07.00 UTC+7 and 15.00 UTC+7, with the highest humidity reaching around 80% and the lowest humidity reaching around 60% [22].In the realm of thermal conductive adjustments, thicker wall constructions showed a more pronounced advantage compared to the thinner part.This advantage manifested in elevated flame speeds and an enhanced capacity to endure greater heat losses without succumbing to extinguishment [23].The thicker walls possess a greater amount of material to obstruct the heat received by the building.These thicker walls would diminish the heat flow between the interior and exterior environments.This results in enhanced energy efficiency and the maintenance of optimal temperatures within a structure, as Limasan in Ndalem Ngabean does.

Column
The structural system that supports the front part of the roof over the emperan space is wooden column and beam.The wooden columns are also connected to the wooden terrace fence similar to the traditional design.The columns in the connecting hall to the Joglo's pendhopo also have traditional wooden design with umpak (stone base) with traditional Javanese carving on it.Yet at the center of the Emperan, supporting the roof along with the bearing wall, there are two concrete columns.The using of this concrete column because of limasan structural system in the building influenced by the colonial which makes it more sustainable in term of durability because of concrete characteristic that is not getting material degradation because of biological attack in wooden material that can result in failure of the structure itself [20].The design of the concrete column is similar to the colonial doric column with the visible vertical line work.A similar other example of this is the upper part of Pasar Beringharjo's entrance column, which Pasar Beringharjo is one of the colonial buildings preserved in Yogyakarta.This indicates the influence of colonial architecture on half of the structural system of the Emperan.

Ornament
The Limasan House primarily used wood for its materials in order to utilize local resources because it was more affordable [24].However, due to material development over time Limasan began to use a combination of brick and wood walls.This material combination enables the home to regulate air comfort which removes excess humidity, making the thermal comfort closer to standard [20] (Figure 9).The use of wooden material produces less emission in its life cycle compared to steel reinforced concrete material in overall [19].However, the sulfur oxide emission for wood maintenance is higher than steel reinforced concrete yet the maintenance stage only takes less than 9% of the whole life cycle so it is still less emission compared to the operation and construction phase in which steel reinforced concrete produces more carbon emission, nitrogen oxides, and sulfur oxide in.Aside from that, ornamentation is not a necessity to make the building stand therefore in terms of resilience it does not matter [19].Despite that,the wood ornamentation is more sustainable in terms of material production compared to masonry and concrete.The colonial architecture ornamentation is known for its doric pattern.Meanwhile, the ornamentation of this Limasan are traditional sculptures as its ventilation and patterned tile on its wall.This aspect of Limasan still maintained its original traditional design.Nonetheless, the colonial architecture influence can still be seen in the Limasan house's column ornaments (Figure 9).

Roof
Roof is an important structure to withstand rain and provide thermal comfort to the users by blocking sunlight and having sloped shape helps minimize rain that is forced onto the structure.Furthermore, it also minimizes the chance of structural damage by giving aerodynamics ability to the shape.According to the philosophy of the Javanese people that have a simple lifestyle, the roof structure of Limasan House is made less complicated by removing tumpang sari as part of the structure to reduce construction time, making it more cost-and-energy-efficient than regular Joglo.The roof of the Limasan House is normally constructed of clay tiles in order to allow hot air to vent [24].The heat conductivity in clay roof was also proven to be able to cause a difference up to 10° celsius between indoor and outdoor temperature, keeping the indoor thermal environment closer to comfort standard [25].
The Pos Besar Office in Yogyakarta is an example of a building constructed during the same period with the Limasan House that has the style of transitional colonial architecture.Pos Besar Office was built in 1912 [26], and at the time, the Dutch architect felt it was necessary to incorporate elements of Indonesian traditional architectural culture [20].Therefore, in this case the colonial building was the one that is influenced by the tropical architecture feature thus making the Limasan roof bears no resemblance to the colonial architecture (Figure 11).

Colonial Architecture Influence on The Limasan House
Based on the results and discussions of the Limasan house analysis, there are some similarities due to the influence of colonial architecture

Conclusions
Based on our analysis on the Limasan House, it can be concluded that there is colonial influence in the features of Ndalem Ngabean's Limasan.The colonial style in the structure and construction of the Limasan house can be seen in the building structure that mainly uses wood in the past to concrete and brick which also affected the sustainability in the building due to durability of the material.Walls in the limasan house have differentiated due to colonialism by the change of its main material that originally used wood to use brick as its main element.The brick material however, increases the performance of the wall to maintain a stable temperature indoors.The column material also originally mainly used wood but now uses concrete, causing the overall structure to be more sustainable in the long run by having more durability against biological degradation.On the other hand, the ornament has not been impacted by colonialism as seen in the traditional wooden carving.This material, however, is more sustainable compared to masonry and concrete.The roof is also not affected by the influence of colonial style due to its characteristic that suits the tropical conditions of Indonesia, therefore it remains in its original form.
From the analysis we did on the Limasan house of Ndalem Ngabean, as a result it can be stated that some aspects of the Limasan house were influenced by colonialism as seen in the column, wall, IOP Publishing doi:10.1088/1755-1315/1351/1/01202310 structure, and construction.Aside from that, there are two elements that are not affected: ornament and roof.The colonial style influence increases the material resilience of Ndalem Ngabean's Limasan compared to an authentic traditional Limasan and affects the house's sustainability through the comfortable thermal condition provided by the thermal mass of the double brick wall.
For future research it would be better to improve the variability of the factors from our investigation, and benefit to further research including analysis on the type of colonial architecture that was adapted to the Limasan, as well as preceding data regarding the history of Ndalem Ngabean's renovations.

Acknowledgement
This research is part of the Final Project on Nusantara Architecture Class, Department of Architecture, Institut Teknologi Sepuluh Nopember 2022.The research is part of Penelitian Dana Mandiri Institut Teknologi Sepuluh Nopember 2023.The authors gratefully acknowledge this financial and technical report.

Figure 6 .
Figure 6.Traditional wooden wall in a Limasan house near the Palace of Yogyakarta.

Table 1 .
Analysis of the Architectural Element on Limasan House 9