To Study Potentials of Earth Sheltered Architecture as Sustainable Alternative to DesignConstruction

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Study of the Potentials of Earth Sheltered Architecture as a Sustainable Architecture to Design Construction Karthik H Rao* 5th Year B.Arch. Student, Manipal School of Architecture and Planning (MSAP-MAHE), Manipal, Karnataka, India

A R T I C L E I N F O

A B S T R A C T

Keywords: Earth Earthen Architecture Earth Techniques Construction Material Historic Origin Sustainability Sustainable Architecture Importance of Earth Architecture Construction Techniques Rammed Earth

To study the benefits and issues related to Earth Architecture by studying its history and earlier construction practices, to use earth as a sustainable and ecological building material. We begin by Discussing the History of Earth Sheltered Buildings from their Origins; Modern materials, and construction techniques used for Earth Shelter Architecture; Literature Review: Analyzing the types if Earth Sheltered Architecture, with different benefits and construction styles; and the in the later portion of the research, we come up with diagrammatic analysis and findings, which tell us the advantages and disadvantages of earth Sheltered Buildings, w.r.t various factors, Hence, we discuss on how the Research has met the Intention of Defining Feasibility of Earth Shelter Architecture, It also supports the successful design of Earth Sheltered Buildings by comparing it to Conventional/Standard Housing.

Earth sheltered homes are an integral component of a sustainable and permaculture-oriented lifestyle. This approach emphasizes harmonious living with the natural environment while embracing simplicity and employing technology judiciously. Within this ethos, low-impact, traditional structures not only contribute to sustainability but also offer a means of providing affordable housing, granting individuals access to land and the ability to lead simpler, more ecologically sound lives. Earth sheltered, energy-efficient residences are well-lit, spacious, dry, and peaceful. While currently embraced by advocates of passive solar and sustainable architecture, the practice of earth sheltering has a historical presence dating back nearly as long as humans have been constructing their own dwellings. There are various ways to construct homes that go beyond the typical four walls and a roof commonly seen in suburban neighborhoods. Earth sheltered homes are constructed by using soil or vegetation to encase the walls or bury them underground. Earth sheltered homes are an excellent choice for homeowners seeking sustainable living spaces that offer better resilience against weather conditions compared to conventional homes. To embark on building one, it's crucial to grasp the various types of such homes and their reduced environmental impact [10-12].

Hence, the Research Questions include: • How can we enhance the usage of mud as a building material or by producing more earth shelters, by making it more feasible?

1. Introduction Earth is the most primitive material which is known to man. It is the origin of all life forms, but later, it became a support system for the survival. As time passed, man shifted from hunting and gathering to agriculture and farming [1,2]. This required permanent shelters, starting with caves, Later Earth was used as a major building material, scaling from small utensils to large cities, earth was used. However, with time, Earth was seen as a pre-modern, housing solutions to poor fragile material, there earth is the building material of bungalows offices, and many old buildings. The methods of developing with earth are developed each year. With big influence from new and modern technologies, these techniques became a bit forgotten. However, there are still people trying to go back living in harmony with nature and environment, making a lot of research to improve the quality of earth as a material and educate people and guide them towards a higher living standard [3–6]. Earth sheltering is a structural technique that involves using soil as a protective barrier against external temperature fluctuations. This method serves as an insulating cover to minimize heat loss and maintain a stable indoor temperature. Earth sheltered homes offer protection against temperature extremes, wind, rain, and harsh weather conditions.

They are known for their energy efficiency, sound insulation, resistance to freezing temperatures, and low maintenance requirements. Earth insulation has gained popularity in modern times among proponents of passive solar and sustainable architecture, but its roots can be traced back to the earliest human efforts in constructing shelter. [7–9] [11]

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What are the most effective configurations and arrangements for Mud Construction in terms of structural stability, cost efficiency, and make it more sustainable?

* Corresponding author.

E-mail addresses: harishrao20@gmail.com , karthik.rao7@learner.manipal.edu (Karthik H Rao), (Prof. Trupti Amit Kinjawadekar). https://doi.org/10.1016/j.conbuildmat.2023.133551 Received ; Received in revised form ; Accepted Available online 0950-0618/© 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/bync-nd/4.0/).

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With focus to the coastal Karnataka soil, how can we improvise on the soil stability and other aspects, that make it more feasible than the soils present in other states, and how it can be utilized to make it more eco - friendly building material in the coming years?

o

2. Background Study Earth, as a building material, encompasses a myriad of compositions and processing methods. Scientifically known as loam or clayey soil, it takes on different names in various applications, such as Rammed Earth, Soil Blocks, Mud bricks, or adobe. A building qualifies as earth-sheltered when its external envelope maintains significant contact with soil or substrate, where "thermally significant" denotes a tangible contribution to the building's thermal efficiency. Why does Mud Construction outperform conventional construction techniques? Because it offers strength, durability, and disaster resistance. It provides effective thermal insulation, is biodegradable and recyclable, boasting minimal carbon footprints through recycling and excavation. It demonstrates compatibility with varying climatic conditions, locations, and sizes, all while remaining costeffective. Given the evolving climate, there's an imperative shift from nonrenewable materials to ecological, renewable materials and techniques.

The paper gives a brief on the origin of Earth Architecture with its evolving construction techniques, the need of earth architecture and various related to earth as a building material. The paper also focuses on primitive construction techniques [10]

o

5. Research Gap Mud construction has been used for centuries in various parts of the world and offers several applications, such as Housing, Cultural centers, Public buildings, Landscape architecture, Artistic and Sculptural Applications, etc.

However, it is essential to note that mud construction requires proper design, techniques and maintenance to ensure its durability and longevity.

Factors like Climate, soil composition, and construction methods play a crucial role in determining the success rate of mud constructed structures.

3. Objectives of Study 1.

2.

The advantages of mud houses are numerous. They excel in thermal insulation, are eco-friendly and sustainable due to mud being a natural and renewable resource. Furthermore, mud houses are budget-friendly to construct and maintain, making them financially accessible for many. Their unique, natural aesthetic charm holds cultural significance and appeals to some. Additionally, mud construction can support local craftsmanship and traditional building techniques, preserving cultural heritage and knowledge. [25] In the realm of Mud Construction, various strategies come into play.

Stabilization and waterproofing, achieved using lime or cement, strengthen the walls. For waterproofing, external plaster or weatherproof coatings are typically applied. Given mud structures' excellent thermal insulation, strategic window placement can maximize airflow and natural light while minimizing direct sunlight.

Regular inspections and repairs of any mud wall or roof damage are imperative to ensure the structure's longevity. [10]

To understand the feasibility of earth as a building material, considering the soil present in Coastal Karnataka Region.

To provide a general construction guidelines of Earth Shelters in India, to find out the important parameters to be considered.

Although we already know that Hot-Humid and Hot-Arid are the ideal climates which can be used for building Earth sheltered homes, and in such regions, we do know that the riverbed/riverfront regions are more suitable for building Earth shelters, as the soil/ earth present in such places is more fertile, has more organic matter, such regions have been left vague or the soil from such regions are not utilized for Earth Shelters. There has not been an Initiative to start such Earth shelters near riverbeds in India.

4. Scope and Relevance of Study

Mud construction has been used for centuries in various parts of the world and offers several applications, such as Housing, Cultural centers, Public buildings, Landscape architecture, Artistic and Sculptural Applications, etc. However, it is essential to note that mud construction requires proper design, techniques and maintenance to ensure its durability and longevity. Factors like Climate, soil composition, and construction methods play a crucial role in determining the success rate of mud constructed structures.

Hence, we can see the gap clearly in our research. Such regions in India, in the present days can be utilized for constructing Mud-Structures, since we have been utilizing it from the past, were most of the Civilizations in the past have emerged near riverbeds (E.g., Mesopotamian Civilization: near rivers Tigris and Euphrates; or Egyptian Civilization: near river Nile).

Mud construction remains relevant for several reasons: o

Also, since Mud Architecture is Cost-Effective than the conventional techniques, there can be an initiation for constructing more sustainable Earth Shelters, keeping in mind the sustainability aspect. New ways of constructing in mud can help in more sustainable Low-cost houses, which can be initiated, which was not though of and initiated till date. [21] [22]

Sustainable and eco-friendly: Mud is a readily available and renewable natural resource, making it an eco-friendly building material that leaves a minimal carbon footprint. While mud construction does come with its share of drawbacks and constraints, its importance is rooted in offering sustainable, budget-friendly, and culturally meaningful answers to housing and infrastructure needs in specific situations. With the right expertise and contemporary engineering methods, mud construction can play a vital role in sustainable architectural and construction approaches. [10] [16]

6. Literature Study: 6.1. History of Earth Architecture: Earth construction techniques have a history spanning over 9000 years, finding application not only in residential structures but also in religious edifices across various ancient cultures.

The Stakeholders: (people) who benefit from our research include: o

Architects and Engineers, such as Researchers who can develop innovative techniques and designs for the people to create safe, durable, and aesthetically pleasing mud-built structures.

Understanding the material’s properties and behavior allows them to design more efficiently and explore its potential in various construction projects.

This approach to creating simple and minimalist shelters using readily available materials ranks among the oldest building techniques. Mudbased constructions took on diverse forms, often incorporating other natural elements like timber or stones, and occasionally integrating more contemporary materials such as cement and steel.

Other users include Construction Industry, Environment Organizations, Government and Policy makers, Non-Governmental Organizations, Homeowners and Individuals, etc.

The utilization of earth construction methods can be traced back to ancient civilizations such as Mesopotamia, Egypt, and China. These civilizations harnessed alluvial soils, readily accessible to them, to craft the earliest dwellings, fashioned from unfired bricks and rammed earth. [16]

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Fig. 1. Timeline of Building Materials Image Source: Architectural Dissertation Report - Mud and Lime as Building Material by Divya Saroja.R - Issuu

In Asia, As a result, the earliest large settlement using Earth construction materials, such as along the Tigris and Euphrates rivers, the settlement of Catalhoyuk, and those of Harappa and Mohenjo-Daro along the Indus River, seem to have developed with settled agriculture, using the river valley soil combined with the cultivated crops now available. [16] 6.2. Earth Architecture around the globe

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Fig. 2. Earth Architecture practiced in different continents from the past: a) Catalhoyuk, Turkey, b) Ancient Harappan Civilization, c) Mohenjo-Daro, d) Citadel of Bam, Iran, e) Kasbah in Asslim, Draa valley, Morrocco, SA, f) Temple of Ramses ii at Abu Simbel, Egypt, SA, g) Haus Rath, Weilburg, Germany, Europe, h) Huaca Pucllana, adobe pyramid in Lima, Peru,South America.

Image Source: (2)

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6.3. Earth Architecture in India

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Fig. 3. Earth Architecture practiced in many states of India: a) Jaisalmer School, Rajasthan, b) Khajuraho Group of Monuments, Madhya Pradesh, c) Jodh Bhai Palace, Uttar Pradesh, d) Bhunga - Traditional houses of Kutch region, Gujarat, e) Monuments, Houses and Resorts in Hampi, Karnataka, f) Traditional Houses and Resorts in Mangalore-Udupi, Karnataka, g) Monuments, Traditional Houses and Resorts in many parts of the states of Kerala and Tamil Nadu.

Image Source: (3)

6.4. Need of Earth Architecture The historical perspective of Earth Architecture reflects the admirable coexistence of past civilizations with nature, showcasing their harmonious relationship. Contrastingly, modern architecture has become heavily mechanized, spanning from material production to construction processes. This mechanization has driven up construction costs and amplified the carbon footprint associated with every architectural phase. Throughout the ages, mud has served as a versatile material for construction and various other applications. Amidst the quest for more environmentally sustainable materials within the technical dimensions of the construction industry, mud architecture emerges as one of the most viable solutions. The advantages and potential inherent in mud construction are boundless. A profound comprehension of this material and its associated techniques can facilitate its application in diverse construction scenarios. Building with mud not only addresses numerous housing challenges but also represents an eco-friendly alternative to the proliferation of concrete urban landscapes. [16]

3.

Silt: Silt constitutes a fine-grained sedimentary substance consisting of particles sized between those of sand and clay, typically falling within the range of 0.002 to 0.06 millimeters. Its formation arises from the erosion and weathering of rocks and minerals, and it's commonly located in riverbeds, lake bottoms, and regions where water decelerates, enabling particle settlement. Silt plays a pivotal role in enhancing soil fertility, with its impact on ecosystems and agriculture being variable and contingent on its distribution and concentration.

4.

Clay: Clay is a fine-grained natural soil material made up of exceedingly tiny particles, each with a diameter less than 0.002 millimeters. Its genesis is the result of prolonged weathering of rocks and minerals. Clay is renowned for its ability to become pliable when wet and to harden when dried or subjected to heat.

Its versatility finds application in numerous fields, including pottery, brickmaking, ceramics, and as a vital constituent in clay soils that prove conducive to agriculture. Beyond its utility, clay also exerts a significant impact on shaping landscapes and influencing soil's capacity for water retention and drainage.

5.

Organic Soil: Organic soil, alternatively referred to as peat or organic-rich soil, consists of a substantial amount of organic material resulting from the decomposition of plant and animal substances. It is commonly encountered in wetland areas, including bogs, marshes, and peatlands. This type of soil is identifiable by its dark hue, spongy texture, and notable capacity for retaining water.

6.

Mixtures: Mixtures are any of the above soils, e.g.: Sandy clay, Clayey sand, Clayey gravel, etc. [9] [10]

6.5. Comparative Study of Mud and Concrete A detailed comparative study was done, considering certain factors/ parameters like strength, stability, durability, etc. to find out which of the two are efficient and more feasible.

Comparative study link: [A] From the Above analysis we get to know that, even through the strength of concrete is more than mud, its longevity and durability is less, as compared to mud. Hence mud is more sustainable than concrete, and its strength can be improved when we process it.

6.6. Earth as a Building Material 6.6.1. Components of Earth

1.

2.

Hence the factors to be investigated while designing with Earth include:

Gravel: Gravel consists of small, rounded stones, pebbles, or rock fragments, typically ranging in size from 2 to 64 millimeters. It finds widespread use in construction, landscaping, and road-building thanks to its resilience and effective drainage characteristics.

Sand: Sand is a naturally formed granular substance comprising finely fragmented rock and mineral particles. Generally consisting of small grains measuring between 0.0625mm and 2mm in size, sand is prevalent on beaches, riverbeds, and deserts. It also serves as a valuable material in construction, glass manufacturing, and various industrial applications.

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Earth required for building can be taken the plot itself.

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The soil is collected after depth of 60cms only.

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Top layer soil is full of organic matter, it isn’t used.

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Below it is sand and clay that are dug out in heaps.

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Do not use hard rock.

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Soil to be used should be devoid of organic matter.

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Top should be replaced after excavating. [10]

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6.6.2. Design Consideration for Mud Construction

Hence designing mud construction requires careful planning to ensure durability and sustainability. Some of the key considerations include: 1.

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Fig. 4. Components of Soil Image Source: (4)

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Table 1 Pros and Cons of Earth Architecture

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Advantages

Disadvantages

Sustainability:

Susceptibility to Moisture:

The widespread availability of earth in most areas renders it a sustainable and environmentally friendly option for construction.

Earth-based materials left exposed may deteriorate or erode in the presence of excessive moisture, necessitating suitable maintenance.

Energy Efficiency:

Limited Structural Versatility:

Earth possesses exceptional thermal mass characteristics, aiding in the control of indoor temperatures and diminishing the demand for heating and cooling systems.

Certain limitations in terms of Structural integrity and design possibilities particularly in large-scale buildings.

Cost Effectiveness:

Certain earth construction techniques may not offer the same level of resistance to seismic activity as some contemporary construction materials.

Materials derived from earth are frequently more cost-effective than traditional construction materials such as bricks or concrete.

Negligible Transportation Costs:

Natural Aesthetics:

Adhesion:

Structures made from earth exhibit a distinctive and captivating aesthetic, harmonizing seamlessly with their natural environment.

Adhesion between earth and wood is relatively weak, which can make the construction of framed doors and windows challenging. Additionally, earth-based materials are prone to erosion from water.

design

and

as any shape is possible and choice of various techniques is available for construction and designing.

Low Embodied Energy: The manufacturing of earth-based materials consumes considerably less energy in contrast to energyintensive materials like concrete and steel.

6.7. Construction Techniques of Earth 6.7.1. Old Earth Wall Construction Techniques:

1. Earth Dug out: Excavation of the earth is employed to craft shelters.

Horizontal excavations form caves on the sides of hills, accessible through staircases and galleries, while vertical excavations on plateaus or plains create courtyards surrounded by rooms along their perimeters.

[16] 2. Earth Cut out: Used when soil is cohesive and contains concretions of carbonates. Soil is cut in the shape of blocks and used like bricks or stones. [16]

Labour-Intensive Construction: They often require handcrafting and specialized techniques.

in

13.

Vulnerability to Earthquakes:

because all the process are On-site.

Flexibility recyclable:

12.

Soil Selection: Choose the right type of soil with suitable proportions of clay, silt, and sand. Conduct soil tests to determine its suitability for construction.

Foundation: Ensure a stable foundation that can withstand settlement and moisture.

Mixing: Properly mix the mud with water and other stabilizers like lime to achieve the right consistency and strength.

Climate: Adapt the design to the local climate. Use overhangs, proper insulation, and ventilation to regulate temperature and moisture levels.

Protection: Apply protective coatings like plaster or whitewash to the exterior walls to shield them from weathering.

Drainage: Implement effective drainage systems to divert rainwater away from the structure's foundation to prevent erosion and water damage.

Structural Reinforcement: Depending on the structure's size and function, incorporate elements like buttresses or wooden supports for added strength.

Maintenance: Plan for regular maintenance to repair any erosion, cracks, or wear & tear Local Expertise: Involve local builders who are experienced in mud construction techniques to ensure best practices are followed.

Building Codes: Be aware of local building codes and regulations to ensure compliance with safety and structural standards.

Aesthetics: Consider the architectural and aesthetic aspects of your design to create an appealing and functional structure.

Resource Efficiency: Maximize the use of locally available materials and minimize waste to reduce the environmental impact.

Testing: Conduct structural tests and inspections during and after construction to ensure the building's safety and stability. [10]

3. Filled in/Earth Bag construction: This construction method, also known as sandbags or super adobe construction, initiates with digging a trench and establishing a foundation. Successive rows of woven bags filled with inorganic materials are stacked and secured together using barbed wire. [16]

Termite/Bacteria: Susceptible to Mechanical damage, rodents and burgles. New mud houses may have foul Odor of crushed leaves/animal waste.

Code And Regulatory Constraints: In certain areas, building codes and regulations might impose restrictions on the utilization of earth-based materials, which can pose difficulties in obtaining the necessary permits.

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[16]

(b) Fig. 5. a) Earth Dug out, b) Earth Cut out.

Image Source: (5)

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Construction Process of Adobe: 1.

Construct mold 2.

Mold is wetted and mix is poured inside. Mix must be of the right consistency.

3.

Molds must be lifted, and adobe is allowed to dry on the ground 4.

Blocks are kept with airtight polythene sheets for first 48 hours.

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Allowed to dry in the indirect sun until all the surface is dry.

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Sprinkle water over the blocks daily, as many times needed for 28 days

4. Covered Earth: In various regions around the world, soil has been employed as a roofing material to help regulate interior temperatures owing to its substantial thermal mass. Grass has also been utilized to cover roofs for similar purposes.

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Fig. 5. c) Filled in/Earth bag construction, d) Covered Earth.

Image Source: (5) Fig. 5. g) Adobe Blocks

5. Shaped Earth: Does not require molds of formwork as it uses plastic earth. Advantage of use of minimal and simple tools with a normal labor.

[16]

8. Extruded Earth: Used since long in fire brick industry, Stabilized earth is extruded through a machine to get the desired shape. Blocks are often hollow and are cut to desired length. [16]

6. Stacked Earth (COB): Cob, a natural building material composed of subsoil, water, fibrous organic material like straw, and occasionally lime, boasts fire resistance and resilience against seismic activity. Despite its reliance on economical materials, cob construction is notably laborintensive. The process often commences with the mixing and compacting of cob layers for the foundation. Historically, thick cob walls have proven effective as thermal mass, retaining warmth during colder seasons and keeping interiors cool in hotter weather. [16] Construction Process of COB Wall: 1.

Forming Stiff Mud and Molds 2.

Stacking the Molds 3.

Levelling and Trimming after every stage to prevent unlevelled walls 4.

Smoothening the sides 5.

Arrangement of Shuttering for Openings 6.

Layering the Cob strips [12]

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Fig. 5. h) Adobe Block: wall section

9. Wattle and Daub: A framework composed of bamboo and crane is constructed, known as wattle, to provide structural support. Over this mesh, a layer of mud, referred to as daub, is applied. When exposed to rainfall, the mud layer may wash away, but the underlying framework remains intact and can be re-plastered. While the construction and design are generally straightforward, they can demand significant labor.

Additionally, the drying process for the daub can be time-consuming. [16] 10. Rammed Earth: This approach evolved as an extension of the COB wall method to establish uniform wall thickness. Referred to as the rammed earth method, it involves using moist earth, a blend of mud, sand, and gravel, with the aim of enhancing wall strength through compaction. The optimal soil for rammed earth construction is ideally sandy or gravelly, rather than clay-rich soil. [16] Construction process of Rammed Earth: 1.

Formwork is built using plywood, vertical and horizontal timber and the rod, then we prepare the rammed earth 2.

For each layer approx.. 15cm thick loose soil mix is poured in formwork. Then layer of moist soil is compressed using rammer 810cm 3.

Another layer of loose moist soil mix is poured in formwork 4.

Successive layers of moist soil mix is added and compressed 5.

Formwork is removed leaving back stable Rammed Earth. [12]

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Fig. 5. e) COB wall section, f) COB wall foundation: detailed section.

Image Source: (5)

7. Adobe: Adobe, as a construction material, boasts a rich history of use worldwide over the ages. These sun-dried blocks are well-suited for constructing two-story buildings. Typically, adobe blocks are crafted either by hand or within parallel wooden molds. This muddy soil mixture, frequently incorporating cut straw, is molded into blocks by filling timber formwork. An ideal clay content ranging from 20% to 40% is typically sought after for the production of adobe bricks. [16]

Fig. 5. i) Wattle and Daub: wall section Fig. 5. j) Rammed Earth: wall section Image Source: (5)

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6.7.2. New Earth Wall Construction Techniques:

1. Rammed Earth Panels: The introduction of Rammed Earth panels addresses the problem of horizontal shrinkage cracks seen in traditional rammed earth construction. A novel technique has been devised to create panels of one-story height, allowing for uninterrupted ramming.

Consequently, this approach effectively eliminates horizontal shrinkages, and vertical joints can be filled in one go after the shrinkage process is complete. [16]

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Fig. 6. e) Compressed Stabilized mud blocks (CSEB), f) CSEB on-site Construction.

2. Framed structure with rammed earth infill: A simple technique is developed to construct thin rammed earth infill panels. Pre-cast reinforced concrete was used for posts and ring beams. [16]

Image Source: (6)

7. Case Studies 7.1. Case Study 1: Prakash and Nishwath’s residence

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Architect: Chitra Vishwanath Firm: Biome Internationals, Bangalore Location: Eagle Bridge, near Bannerghatta Road, Bangalore Year of completion: 2006 Site: 80’x 65’ Built-up Area: 2,200sqft Mud construction Technique: Mud blocks and Rammed Earth

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Description: This Residence is built for a young couple that is sustainable and eco-friendly, with usage of Earth as a building material. (7)

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Construction Technique: Slipform Construction employs a unique construction technique where the formwork is crafted from prelaminated plywood and reinforced with mild steel angles to support the mud blocks. These mud blocks possess sufficient selfweight, eliminating the need for additional attachments or reinforcements. The mud blocks are meticulously positioned within the mud mortar, filling the space above the stone foundation's plinth beam. This careful arrangement allows for the flooring's skirting to seamlessly overlay the rammed earth without requiring any cutting.

To promote basement ventilation, a Jack Arch roof is incorporated between the panel walls. Interestingly, the soil excavated from the basement finds a purpose in the construction of the building.

Additionally, filler slabs are employed to reduce the roof's dead load, enhancing its structural efficiency while imparting a distinctive aesthetic appeal. [11] [17]

Fig. 6. a) Rammed Earth panel wall, b) Frame structure with rammed earth infill.

3. Earth wall construction with lost Formwork: Cost of framework is high, which makes use of a thin masonry wall or stiff thermal insulation, or lost formwork preferable. Thus, requires either no or one-sided formwork. [16] 4. Rammed Earth dome: Rammed earth dome was constructed using a rotating slip form, resulting in a dome with a thickness of 18cm at the base and 12cm at the top. The interior walls were also crafted from rammed earth and featured a hexagonal design.

Earth blocks, known as adobes, mud blocks, or sundried bricks, are fashioned by pouring wet earth into a formwork, a process typically carried out manually. Alternatively, when moist earth is compressed using a manual or powered press, they are referred to as soil blocks. Green bricks, produced by an extruder in an unbaked state, make up the third category.

Remarkably, these three block types generally share the same dimensions as baked bricks. [16]

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Fig. 6. c) Earth wall construction with lost formwork: Process, d) Rammed Earth dome.

5. Compressed Stabilized Mud Blocks (CSEB): In the early 19th century, Europe saw early attempts at using compressed stabilized earth blocks. These blocks are created by taking either raw or slightly moistened soil, placing it into a steel press, and then compressing it using either manual or motorized presses.

These blocks can be in their raw state or stabilized with the inclusion of cement or lime. The introduction of stabilizers enabled the construction of taller and thinner walls with impressive compressive strength and resistance to water. [16]

Fig. 7. Prakash and Nishwath’s residence: Views and Ornamental Details.

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7.1.1 Inference of case study 1:

1.

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Design Philosophy: This project prioritized ecology and sustainability, with a strong focus on minimizing the building's carbon footprint. Construction materials were carefully chosen to be renewable and locally sourced, effectively reducing the energy expended on transportation.

7.2. Case Study 2: Rajkumari Ratnavati Girls School • • • • • • •

Building Using Bricks Made At Site: The firm is committed to producing bricks on-site rather than transporting them from distant locations. This approach serves to prevent the depletion of resources from afar, curbs air pollution, and reduces energy consumption during transportation. Houses with basements offer an additional source of mud for crafting these blocks. The excavated soil undergoes a testing process, and a mixture is formulated to meet the required strength standards. A small quantity of cement or lime is introduced to stabilize the earth, guarding against shrinkage and water damage. These are commonly referred to as Stabilized Mud Blocks.

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3.

Using Buildings As Waste Sinks: The firm places a significant emphasis on waste management and consistently explores innovative techniques in this field. One of their inventive waste management approaches involves burying waste within the building's foundation, plinth, and sunken floors.

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4.

Using Waste For RCC Filler Slab: The utilization of filler slabs is a well-received concept in which economical and lightweight materials replace concrete below the neutral axis. This not only results in cost savings and reduced consumption of raw materials but also decreases the overall weight of the slab. An intriguing aspect of this approach in house construction is its ability to incorporate broken flooring tiles and stones, eliminating the necessity for plastering and repainting.

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Reusing Debris For New Construction: In situations where existing buildings are dismantled to make way for new construction, the debris can be repurposed effectively. Broken bricks can serve as a substitute for concrete aggregate in floor bases and flagging. They can also be crushed into a fine powder to replace sand in mortar, plinth, and lintel bands.

6.

Using Roofing Sheets Made Of Waste: Building material manufacturers are actively exploring the potential of waste utilization. They incorporate discarded tetra packs into roofing sheets and utilize recycled wood scrap to create composite wood products like hard boards and block boards. Moreover, they incorporate various forms of industrial and agricultural waste available in the market into their design processes.

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Architect: Diana Kellogg Architects Location: Rajkumari Ratnavati Girl’s School, Salkha, Jaisalmer, Rajasthan, India Climate: Hot and Arid Year of completion: 2021 Built-up Area: 3,560sqft Mud construction Technique: Sandstone Powdered Blocks Description: The Rajkumari Ratnavati Girl’s School is an architectural marvel designed by Diana Kellogg of Diana Kellogg Architects and commissioned by CITTA, a non-profit organization that supports development in some of the most economically challenged, geographically remote or marginalized communities in the world.

Material: Sandstone Powdered Blocks: The local sandstone is the main component of construction. This provides protection from extreme heat during the day, and warmth during evening hours. The inner walls of the building have plastered with lime, which insulates the building. (8) (a) Construction Technique: Wet Method of Natural Sandstone Powdered Brick: Wet installation stands out as the prevailing technique for natural sandstone brick applications. The key consideration lies in choosing the optimal method from the array of installation options provided within the wet process. This approach encompasses the Direct Adhesion Method and the Spot Bonding Method as two primary techniques.

Direct Adhesion Method: The most prevalent wet method, known as the Direct Adhesion Method, relies on a liquid latex blend with a cement-based filler powder to create cement mortar. This mortar is thinly layered and applied to the surface, eliminating the need for onsite drilling. It is noteworthy for being the most cost-effective among the various installation methods available.

Spot Bonding Method: As a result of this installation technique, gaps or air pockets are intentionally introduced between the stone and the wall. These gaps and air pockets effectively lower the likelihood of water staining. [18]

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Rainwater Harvesting And Wastewater Management: They have adopted a rainwater harvesting system aimed at decreasing reliance on the grid for water supply. Additionally, they actively explore wastewater treatment and its subsequent reuse for purposes like gardening and car washing. Their approach involves implementing a root zone treatment system that is both uncomplicated and environmentally friendly, consuming less energy.

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(b)

(d)

Fig. 8. Ratnavati’s Girls school, Rajasthan. a) aerial view, b) isometric view, c) sandstone powdered bricks, d) sectional elevation of the building Image Source: (8)

Reducing Local Impact: The firm endeavors to reduce the impact of their projects and foster local biodiversity. They integrate gardens and terraces whenever feasible, providing a habitat for a diverse range of flora and fauna. They also prioritize the preservation of existing trees on the site, incorporating them into their design plans. (7)

The use of local materials to create the infrastructure helped reduce carbon emissions. The skilled craftsman working on sandstone made the construction process economic. The material protection from extreme heat during the day, and warmth during evening hours.

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Advantages of Wet bonding: • The method is cheap.

• The technique does not require on-site drilling.

• No on-site drilling prevents cracks on the walls.

• Bond between the stone and cladding is entirely made throughout the area. No space is left between them.

• More even look is achieved. [18] Disadvantages of Wet Bonding: • The later expansion is not possible due to the edge-to-edge bonding.

This limitation results in the buckling of the natural stone. Hence, this method requires adequate expansion and contraction joints.

• Improper bond between the wall and the adhesive or the mortar can make the stone to fall off.

• The cladding stone may absorb water from the mortar. This makes the stone to change its color.

• The wet method, though, is easy, can consume a lot of time. [18]

Fig. 9. Soil stratification, (a) laterization on soil made up of gneissic granites (b) showing different zones of the laterite profile. Image Source: (9) 7.3.1.2. Analysis of Soil study:

The soil samples gathered from different locations exhibit a notable fines content, particularly a high silt content. When saturated, these elevated levels of silt content and increased ion hydration or dissociation of sheet minerals have an impact on the soil's strength parameters. The high silt content reduces the plasticity, and lesser the plasticity of the soil, lesser will be its rigidity, as the clay content in the soil binds all the particles together. [21] During the monsoon season, as water permeates this layer, the silty soils break apart and behave akin to a liquid, often leading to the erosion of fine soil, the creation of voids, and occasionally resulting in significant settlement and sliding of the upper layers under applied loads. Hence It is necessary to improve the properties of lithomargic clay and the dispersive nature of soil with suitable ground improvement techniques. [21]

7.2.1. Inference of case study 2

Building Orientation: The building's orientation is optimized to harness the prevailing wind while minimizing direct sunlight exposure.

Additionally, the design incorporates solar panels to generate electricity for lighting and fans within the building.

Water Harvesting System: The design efficiently utilizes local ancient water harvesting methods to maximize rainwater collection and recycle gray water within the school. Consequently, the courtyard within the complex has the capacity to harvest and store up to 3.5 lakh liters of water.

Vernacular design process: Utilizing locally sourced materials for constructing the infrastructure played a pivotal role in curbing carbon emissions. The expertise of craftsmen proficient in working with sandstone contributed to the cost-effectiveness of the construction process. Additionally, the material offered natural insulation, shielding occupants from extreme daytime heat and providing warmth during the evening hours. However, to ensure ample ventilation, adjustments were made to the architectural plans, resulting in larger classrooms and office spaces.

Solar Canopy: The solar panels positioned on the upper level of the structure serve a dual purpose, functioning as a shading canopy while also supplying power to the building. To enhance cooling efficiency, the system taps into geothermal energy during the night to cool the building during the day. Furthermore, a solar canopy with a metal framework on the roof serves a playful function as a jungle gym, featuring seesaws, swings, and monkey bars for the girls to enjoy.

Fig. 1 0 . Lithomargic Clay Samples collected from various locations in Udupi region Image Source: (10)

Usage of Jali's: Jali's contribute to heat reduction, and the elliptical shape of the building enhances sustainability. As a result, this configuration fosters a cooling airflow system, in conjunction with passive solar cooling, even in areas where temperatures can soar to nearly 120 degrees. (8)

7.3.1.3. Inference

Utilizing Lithomargic clay directly for construction in Earth shelters within coastal regions poses significant challenges, particularly when it encounters water. Additionally, the limited availability of stronger local fill materials for replacement presents a hurdle. [21]

7.3. Case Study 3: Udupi Mane 7.3.1. Possibility of Earth sheltered homes in Udupi region 7.3.1.1. Soil Study of Coastal Karnataka: Literature study

Therefore, one potential solution involves enhancing its strength through Chemical Stabilization using Lime and Granulated Blast Furnace Slag (GBFS). This approach can pave the way for the feasibility of constructing Earth sheltered houses in areas like Udupi and the coastal regions of Karnataka. [21] [22]

The coastal area of the Udupi-Mangalore region features a diverse range of soils, each with distinct properties. Among the most prevalent and abundant soils are lateritic soil and lithomargic clay.

These lithomargic clays are found beneath the lateritic formations, situated at shallow depths, positioned between the underlying granitic gneiss and the firm lateritic crust above. [21] Lithomargic clay is generally found below the lateritic soil along the coastal belt of Karnataka. This soil boasts a significant silt content and displays dispersive characteristics, making it susceptible to erosion and landslides. Hence, Lithomargic clay is a type of problematic soil, which needs a thorough study to make it suitable to sustain any engineering structures such as buildings, earth shelters, etc. [21]

Lime Stabilization: Lime stabilization is a ground improvement method that entails the introduction of lime into the soil to enhance its characteristics. This enhancement takes place through a process wherein the right quantity of lime is added to a reactive soil, facilitating ion exchange. Lime, being rich in calcium, contributes significantly to bolstering the stability of the soil. [23]

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Fig. 1 1 . Adding Lime stabilizer to collected soil sample.

Image Source: (11)

Fig. 1 3 . Characterization of mineralization and compounds; (a) XRD analysis of Manipal Sample; (b) quantification of compounds.

Image Source: (13)

2. Granulated Blast Furnace Slag (GBFS): GBFS (Granulated Blast Furnace Slag) is obtained through the rapid cooling of molten iron slag from a blast furnace. India alone produces over 10 million tons of GBFS annually, necessitating effective disposal methods to mitigate environmental impact. Leveraging GBFS as a stabilizing material not only addresses the disposal issue but also promotes sustainability.

The National Slag Association (NSA) has conducted extensive research affirming that the utilization of these slags in construction activities poses no risks to both human health and the environment.

To enhance the stability of Lithomargic clay for creating Earth blocks onsite, specific proportions of both Lime and GBFS stabilizers must be incorporated. [23]

Fig. 1 4 . Future 3D views of Earth-Shelters, combined with traditional architecture styles of Coastal Karnataka Image Source: (14) 7.3.2. Current Scenario of Earth Shelters in Coastal Karnataka

Examining the historical context of Udupi, a community-oriented setting, it becomes evident that the majority of the constructed buildings relied heavily on ancient earth construction methods, primarily utilizing Laterite soil. These structures typically adhered to a maximum height of two storeys. [25] In the superstructure's fundamental framework, primary components included wooden members, mud walls, and thatched roofs. Below ground level, the substructure incorporated compacted earth, granite slabs, pebbles, and earth. In certain instances, lime plaster was applied to the walls. With the progression of technology, later additions introduced laterite stone walls or baked bricks, eventually replacing the thatched roofs with Mangalore tiles. [25] Over time, a noticeable transition has occurred wherein many of these mud structures have been supplanted by reinforced concrete wall construction. Architectural styles have also shifted from traditional to encompass modern and postmodern influences.

Such houses adhere to standardized norms and guidelines, irrespective of the specific context or region. They tend to consume a substantial amount of energy and often lack semi-public spaces conducive to social interaction. These designs prioritize aesthetics that may not necessarily resonate with the local context but are borrowed, resulting in a lack of distinctive identity or the charm of traditional architecture. While they may gain in terms of social status, they often forfeit cultural and sustainability aspects. [25]

Fig. 1 2 . GBFS Stabilizer Image Source: (12) 7.3.1.3. Inference from Soil study experiment

• • •

•

•

•

The optimum percentage replacement of lithomargic clay by granulated blast furnace slag is 20%.

The optimum percentage of lime to be added to lithomargic clay is 4%.

For 80% lithomargic clay, 20% GBFS with addition of 4% lime, for 28 days cured samples, there is significant increase in unconfined compressive strength, cohesion and angle of internal friction when compared to that of lithomargic soil alone.

From X-ray diffraction (XRD) studies, it is identified that compounds such as CASH, CSHH, CAOH, gyrolite, gismondine are responsible for binding the soil particles together to form a hardened skeleton matrix, thus increasing the strength of the soil. [21] During the monsoon, silt within the soil dissolves and behaves like a liquid, often getting washed away and leading to the formation of voids. In some cases, this results in substantial settlement and sliding of the upper layers under applied loads.

Therefore, there is a necessity to enhance the soil properties through stabilization methods. [21] [22]

As a response to this shift, there has been a transition towards designing with the community in mind rather than catering solely to individual needs. Consequently, numerous architecture firms in Udupi and Mangalore are now dedicated to exploring innovative Earth shelter designs. They aim to extend the use of processed clay and enhance the stability of earth structures through their endeavors.

Hence, we can see a shift, From conventional to new eco-friendly building techniques coming up by renowned architects in Mangalore, and rooting back to the culture, by using traditional building elements.

So we can say that new earth shelter projects are coming up and are still in the development stages. [25]

Therefore, the is a scope/possibility of using Lithomargic clay for constructing Earth blocks, when it is perfectly stabilized with soil stabilizers like Lime and GBFS, etc which can bring about an initiative for producing more Earth-shelters in the near future, in the Coastal regions of Karnataka, which also makes it a very eco- friendly approach towards sustainability, since the building material as a whole has less embodied energy, because there is less Carbon Dioxide is released to the Atmosphere. [24]

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7.3.3. Case study 3: “Udupi mane”, residential villa

• • • • •

Architect: Praangana Architects Location: Udupi Climate: Hot and Humid Year of completion: 2021 Built-up Area: 2,000sqft

8.1.2. Findings: Factors/Parameters with respective Benchmarks

10 9 8 7 6 5 4 3 2 1 0

25 20 15 10

• •

•

• •

• • • •

5

Mud construction Technique: Processed Clay Blocks ( using Lithomargic Soil ) Description: The need of this project came up when the dilapidated ancestral house was demolished. The project had to recreate that vernacular ambience of client's ancestral home and be the epicenter of family ties. The design had to respect the confines of Vaastu which became more important due to the presence of temple.

Construction Technique: This house stands out for its commitment to traditional construction methods. The foundation and walls are constructed using lime mortar, following a local traditional recipe. The incorporation of arches, including corbelled arches, plays a pivotal role in creating a fully load-bearing structure.

Furthermore, lime plaster has been applied to the walls, a factor contributing to the remarkable coolness and comfort maintained within the house during the scorching coastal summer weather. [19] This approach also significantly prolongs the life of the structure. The use of cement and steel was notably limited, with a conscious effort to procure most materials from local sources to reduce the overall carbon footprint.

Other features of its make are: Intermediate slab was made with reclaimed wooden beams and planks topped with bricks and finished with red-oxide. (All wood used are reclaimed for demolished buildings).

Sloping Mangalore tile roof made of reclaimed tiles.

Fixed furniture's finished with green and yellow oxides. [15]

0 Strength and Durability (kPa)

Time consumed (in months)

0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0

5 4 3

2 1 0

Water resistance: Liquidity Index

Fire resistance

60

3

50

2.5

40

2

30

1.5

20

1

10

0.5

0

0

Ideal cost of 1 brick (rupees)

Density (in gm/cc)

2.71 2.7 2.69 2.68 2.67 2.66 2.65 2.64 2.63 2.62

Fig. 1 5 . Front Elevational View of “Udupi Mane”.

Image Source: (15)

120 100 80 60 40 20 0 Specific gravity

Cohesion (in kPa)

8. Analysis 140 8.1. Soil Feasibility Analysis of case studies: To achieve Objective 1

120

Objective 1: “To understand the feasibility of earth as a building material, considering the soil present in Coastal Karnataka Region.”

100

•

60

•

1000 900 800 700 600 500 400 300 200 100 0

80

A Feasibility Analysis was done by considering 16 factors, and each factor w.r.t a particular soil study was given benchmarks to conclude which soil is more feasible as per the factors.

Note: 4 points given so that we can produce the percentage efficiency for each of the case studies.

40 20 0

• • •

Specific Heat Capacity (in J/kg.K)

Thermal Resistivity (in rho)

Good : if value achieves benchmark or goes beyond it Moderate : if value is near to benchmark Bad : if value obtained is below benchmark

LEGEND: 1.

2.

3.

4.

8.1.1. Detailed Comparative Analysis of Case Studies Comparative study link: [B] 11

Red Clayey Soil Dessert Soil Lithomargic Soil Benchmark Line

1

2

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Continue…Findings: Factors/Parameters with respective Benchmarks

8.2. Survey Analysis: To achieve objective 2

12

Objective 2: “To provide a general construction guidelines of Earth Shelters in India, to find out the important parameters to be considered.”

25 10 20

8.2.1. Questionnaire for survey: Google Form Link:

8

15

[C]

6

10

4

5

2

0

Based on the different aspects of the existing researches, literature reviews and discussion with the guide, the questionnaire is completed.

The questionnaire is to be filled/completed by Architecture students, or Architects, Engineers, researches, etc with the help of which we can determine the impact assessment of earth shelters and Earthen architecture (restricted to India only, for this research).

Resulting Guideline: The developed guideline stages can be briefly summarized as: • To assess the effective parameters of Earth Buildings and finding the most important parameters in India.

• To assess which parameter has maximum effect.

• Providing general guidelines for earth shelters. [D]

0 Plasticity Index

Maintenance

25

50

20

40

15

30

10

20

8.2.2. List of Survey Questions:

10

1. To what extent would you describe your level of interest in?

5 0 0

Annual Environmental impact (in %)

2. How important is it to have a National code for building Earth shelters in India?

• Level of Importance (in %): 0-20 20-40 40-60 6080 80-100

Sound insulation (in db) 60

1600 1400 1200 1000 800 600 400 200 0

50

3. Of the current existing national codes of building Earth shelters, which are you aware of (commercial or residential)?

• I am not aware of any national code • Others(s), Please specify

40 30 20

4. To what extent do you think a national guideline will influence the building industry in a shift towards more earth sheltered building development in India?

• Degree of Influence ( in %): 0-20 20-40 40-60 6080 80-100

10 Indoor Air Quality (in ppm)

0 Silt Content (in %)

5. How important is it that buildings of India seek full earth building accreditation/ recognition?

• Level of Importance (in %): 0-20 20-40 40-60 6080 80-100

Overall Soil Feasibility Chart 60 50

6. What can be your reasons for using the national guidelines of earth building and earth architecture?

• Being able to access the environmental impact of buildings • Building comparisons at national and international level • Social and environmental responsibility to create vernacular buildings • Others(s)- please specify

40 30 20

7. In your opinion, what are the obstacles to shifting from conventional to Earth shelters?

• Perceived higher upfront costs • Lack of Education and awareness • No fiscal incentive • Different accounting methods of construction • No coordination • Politics • Other(s)- please specify

10 0 Feasibility Analysis Red Clayey soil

Dessert Soil

Laterite/Lithomargic soil

8.1.3. Findings: Overall Soil Feasibility Analysis

From the each of these soils will give us a percentage of how feasible the soil is. ❖ From the above, we can conclude that the soils: 1.

2.

3.

8. What do you believe are the economic reasons/benefits of earth shelters?

• Lower lifetime and Operating costs • Higher building value • Helping to transform the market • Higher return on investment

Red Clayey soil: achieved 50% feasibility Dessert soil: achieved 40% feasibility Lithomargic soil: achieved 50% feasibility, w.r.t each of the factors considered.

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9. What do you believe are the environmental reasons/benefits of earth building?

• Protection of the environment • Reducing climate change and emissions • Minimising ecological impact of buildings • Improving indoor environmental quality • Waste reduction

7. NBC for Earth shelters must be used for accessing the environmental impact of buildings as well as to create more vernacular buildings.

10. What do you think are the social reasons/benefits of earth building?

• Greater Health and well-being • Support of India’s economy • Tenant productivity • Improved learning environments • Aesthetically pleasing • Moral imperative of being “sustainable” [D]

8. 72.5% people believe that lack of awareness is the main reason for shifting from conventional to old shelters, hence need to educate the mass about the positive aspects of Earth shelters.

8.2.3. Survey Observations and Analysis:

1. Total Responses: 40 2. Age Groups: Mostly response by Architecture Students 95%, Architects and Engineers in India 5% 3. Level Of interest in Topic: 60-80% Sustainability, Earth Architecture 40-60%, Earth building tools 60-40%, Earth materials 60-80%

9. Ecological Benefits of Earth Shelters: Higher building value, and lower lifetime cost, which in turn helps to transform the building industry market

4. Importance of NBC for Earth shelters in India: 60-80% 10. Environmental Benefits of Earth Shelters: Helps to minimise the ecological impact of buildings, reducing on carbon emissions and in turn protects the nature.

5. Degree of Influence of NBC towards building more Earth Shelters in India: 40-60%

11. Social Benefits of Earth Shelters: Earth Shelters provide greater health and well-being and is aesthetically pleasing. Due to its lower building cost, it can support India’s economy in the coming years.

6. 60-80% importance that buildings in India to seek full recognition for Earth Shelters

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8.3. Some Important Guidelines for building Earth Shelters in India 1. SEISMIC STRENGTHENING OF LOAD BEARING BUILDINGS: for Collar Beam and Horizontal Band

3. HOLDFASTS, OTHER ALTERNATIVES AND APPLICATIONS: The earthen walls may be kept no more than 400mm thick. To improve their behaviour, steel holdfasts of Z-shape may be screwed to the wooden posts at least one for each triangle and be built into cladding earthen wall.

As an alternative to wooden frames, steel pipe or iron frames of equal strength may be used. The internal bracing system will also be appropriately suitable for the seismic safety of random rubble or brick work in mud mortar constructions. Such frames should also be inserted in existing low strength masonry houses for retrofitting them against collapse in future earthquakes. [E]

WALL

Two horizontal continuous reinforcing and binding beams or bands should be places, one coinciding with lintels of door and window opening, and the other just below the in all walls and seismic zones 2,3,4, and 5. Proper connection of ties places at right angles at the corners and junctions of walls should be ensured. Where the height of the wall is not more than 2.5m, the lintel band can be avoided, but the lintels should be connected to the roof band. The bands could be in the following forms: • Unfinished rough cut or sawn (70 x 150mm in section) lumber in single pieces provided diagonal members for bracing at corners.

• Unfinished rough cut or sawn (50 x 10mm or 70 x 70mm in section) lumber two pieces in parallel with halved joints at corners and junctions of walls placed in parallel. [E]

4. METHODS TO REDUCE TERMITE AND BACTERIAL EFFECTS IN THE EARTH SHELTERS: Elevate the structure's foundation to minimize contact with the ground, where termites are typically found.

Inspect your mud structure regularly for signs of termite activity, such as mud tubes or wood damage.

Apply a thick layer of lime plaster or cement mortar to the lower portion of the walls to create a barrier against termites and moisture.

Use natural repellents like neem oil or aloe vera near the foundation to deter termites.

Ensure efficient drainage around the structure to prevent water buildup, which can attract bacteria and contribute to structural decay.

Consider applying an eco-friendly sealant or coating to the exterior walls to provide an additional layer of protection. [E]

Fig. 1 6 . a) REINFORCING LINTEL UNDER FLOOR BEAM: 1: Good position of Beam 3: Lintel band of wood

2: Avoid this position 4: Additional Lintel

9. Inference

b) Footing on firm soil

•

The Soil present in the Coastal region is more efficient as compared to soils present in other regions. Hence, we can utilise it for producing more Earth Shelters reducing on the Carbon Emissions.

•

As per the Comparative analysis, the structural Limitations of Laterite/ Lithomargic soil is it is susceptible to erosion. Due to the technological Advancements, we are seeing an improvement, by adding certain number of Stabilizers to the soil, that increase the strength, make it stable by water-proofing, and help to add more comfort, by making the interior spaces cool during the summers.

c) Footing on soft soil

ADEQUATE CONFIGURATION OF EARTHEN BUILDING: 6) Stable foundation 7) Good Lime mortar 8) Floor level 9) Ground level 10) Waterproof layer All dimensions are in millimetres

2. INTERNAL BRACING SYSTEM IN EARTHEN HOUSES:

Through the Soil study experiment (From reference paper):

Earthen houses are intrinsically very weak under lateral load, hence require very special techniques to make them collapse proof in seismic intensities VIII and IX areas such as vertical tension members as well as diagonal braces The frames will also restrain the walls from disintegrating completely. There are 3 systems: • System A: The whole building plan may be framed as one piece and the external walls built keeping the wooden frame as the inner walls built keeping the frame on one of its faces, preferably one bedroom side.

• System B: Each room may be framed individually, thus external walls will have the frame only on their inner face, the internal walls will have the frames on both faces, preventing the fall of inner wall either way, This system will have the advantage of permitting any plan shape without the problem of torsion of frames and much greater safety of cross walls. It will however consume more timber since all frames on the inner walls will be doubled.

• System C: In the third system, the frames of system B may not be joined across walls making it a stronger whole building frame, Such a system will have advantages of both A and B systems and can be adopted from the more important buildings such as those built for community services. [E]

•

3. HOLDFASTS, OTHER ALTERNATIVES AND APPLICATIONS: The earthen walls may be kept no more than 400mm thick. To improve their behaviour, steel holdfasts of Z-shape may be screwed to the wooden posts at least one for each triangle and be built into cladding earthen wall.

•

• •

•

•

14

The optimum percentage replacement of lithomargic clay by granulated blast furnace slag is 20%.

The optimum percentage of lime to be added to lithomargic clay is 4%.

For 80% lithomargic clay, 20% GBFS with addition of 4% lime, for 28 days cured samples, there is significant increase in unconfined compressive strength, cohesion and angle of internal friction when compared to that of lithomargic soil alone.

From X-ray diffraction (XRD) studies, it is identified that compounds such as CASH, CSHH, CAOH, gyrolite, gismondine are responsible for binding the soil particles together to form a hardened skeleton matrix, thus increasing the strength of the soil [21] [22] Therefore, the is a scope/possibility of using Lithomargic clay for constructing Earth blocks, when it is perfectly stabilized with soil stabilizers like Lime and GBFS, etc which can bring about an initiative for producing more Earth-shelters in the near future, in the Coastal regions of Karnataka, which also makes it a very eco- friendly approach towards sustainability, since the building material as a whole has less embodied energy, because there is less Carbon Dioxide is released to the Atmosphere.

Ecological Benefits of Earth shelters include Sound Insulation, Thermal mass, Durability, Processed clay for higher strength, Low maintenance, Environmentally friendly, Biodegradable, and Reduced Carbon emissions.

Karthik H Rao

10. Conclusion

10

Time to bring a Change!

Carbon emissions is a major issue, automobile industry is the biggest polluter for carbon emissions and next is the built structures. The automobile industry is making changes to the motorized vehicles by changing it to electrical vehicles, so it is time to use our earth for construction and reduce the carbon emissions.

Earthen materials are natural and is not an environment pollutant, hence it is very safe and is important to save these ecofriendly practices to save ourselves. Using earthen materials like mud, lime, stone, wood and other natural fibers for construction can make major changes to our environment and our personal wellbeing. This dissertation contains the most important things we need to know when we want to build our homes with sustainable way of thinking using as much as we can say the simplest natural material - earth. There Is a lot of information all over internet about earth architecture, so I tried to show the ones which are useful for people.

Even with regulation and education problems as well I believe that people should know how to combine the economy and ecology meanwhile, they live in healthier and more comfort environment in their homes.

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CRediT authorship contribution statement

19

Karthik H Rao: Conceptualization, Methodology, Formal analysis, Investigation, Writing – original draft, Writing – review & editing, Visualization. Prof. Trupti Amit Kinjawadekar: Investigation, Supervision, Review & editing.

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12 13 14 15 16 17

18

21

Declaration of Competing Interest 22

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

23

Data availability 24

The data that has been used is confidential.

Acknowledgments This research did not receive any specific grant from funding agencies in public, commercial, or not-for-profit sectors.

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References 1

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A. Benardos a; I. Athanasiadis b; N. Katsoulakos c. (26 Nov 2013). Modern earth sheltered constructions: A paradigm of green engineering. https://www.sciencedirect.com/science/article/pii/S0886779813001922 Trevor, A. (27 Mar 2023). Earth Sheltered Multifamily Housing. https://www.proquest.com/openview/4f1645e9859c026edf5c734117b9d77a/1?pq -origsite=gscholar&cbl=18750&diss=y R. L. Wendt. (April 1982). EARTH-SHELTERED HOUSING; AN EVALUATION OF ENERGY-CONSERVATION POTENTIAL. https://www.osti.gov/biblio/5203877 Milanovi, A. (11 Oct 2018). Earth-Sheltered House: A Case Study of Dobraca Village House near Kragujevac, Serbia. https://www.mdpi.com/2071-1050/10/10/3629 Thomas, N. (July 1980). ENERGY ANALYSIS OF EARTH SHELTERED DWELLINGS. https://shareok.org/handle/11244/32097 Parisa, D; Baran, M; Hossein, O. (2022). Using Thermal Potential Of The Earth To Optimize Energy Consumption In Architectural Structures. https://www.nveo.org/index.php/journal/article/view/4226 Bramjot Kaur, Ar Vinod Tripathi. (April 2017). Earth Architecture, Innovations in earth construction and its potential. Earth Architecture: Innovations in earth construction and its Potential by Brahmjot Kaur - Issuu Jideofor, A. (29 Aug 2021). A Study of the Energy Conservation Potentials of Earth Sheltered Housing for purposes of Urban Scale Developments. https://www.researchgate.net/profile/JideoforAkubue/publication/335231169_A_Study_of_the_Energy_Conservation_Potentials_of_ Earth_Sheltered_Housing_for_purposes_of_Urban_Scale_Developments/links/5d59c8 e392851cb74c7601ef/A-Study-of-the-Energy-Conservation-Potentials-of-EarthSheltered-Housing-for-purposes-of-Urban-Scale-Developments.pdf Forowicz, T. (1 Jul 2017). THE INFLUENCE OF CLIMATE ON THE HEAT TRANSFER FROM EARTH-SHELTER BUILDINGS. http://www.ibpsa.org/%5Cproceedings%5CBS1995%5CBS95_236_245.pdf D V, Berezin. (1988). Earth-sheltering effect on dwelling in cold climate: simulationbased and theoretical approaches. https://iopscience.iop.org/article/10.1088/1757899X/687/5/055042/meta Pearlmutter, D; Erell, E; Etzion, Y. (10 Oct 2011). Monitoring the Thermal Performance of an Insulated Earth-sheltered Structure: A Hot-arid Zone Case Study. https://www.tandfonline.com/doi/abs/10.1080/00038628.1993.9696727 Deepak Nayak; Purushotham G. Sarvade; Udaya Shankara H. N.; Jagadeesha B. Pai. (19 April 2023). Mineralogical Characterization of Lithomargic Clay Deposits along the Coastal Belt of Udupi Region of South India. J. Compos. Sci. | Free Full-Text | Mineralogical Characterization of Lithomargic Clay Deposits along the Coastal Belt of Udupi Region of South India (mdpi.com) K. Mahesh Bhat; Sitaram Nayak. (16 April 2021). Experimental Studies and its Application using PLAXIS-2D for Lithomargic Clay Stabilized by GBFS and Lime.

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