Experimental Numerical and Monitoring Tools

#### **Chapter 1**

## Reimagining Building Façades: The Prefabricated Unitized BIPV Walls (PUBW) for High-Rises

*Tianyi Chen, Chye Kiang Heng and Shin Woei Leow*

#### **Abstract**

In urban settings, building-integrated photovoltaics (BIPV) on façades prove more effective than rooftop installations, especially for tall structures with limited roof area. Yet, the absence of ready-to-use BIPV solutions restricts their broader use. This research presents a prefabricated unitized BIPV wall system, using light gauge steel structure prefabrication. The innovative BIPV system boasts a multifunctional, modular design, ensuring quick installation and meeting airtightness standards. The design process encompasses cross-sectional design, PV mounting, 3D modeling, and full-scale mock-up demonstrations in Singapore. Remarkably, the prefabricated units are preassembled and pre-wired, allowing three non-specialized workers to install from inside buildings, eliminating the need for scaffolding. The study offers insights into the new BIPV system's advantages, identifies its constraints, and suggests avenues for future enhancement.

**Keywords:** building-integrated photovoltaics, BIPV, solar energy, prefabricated construction, opaque PV, photovoltaics implementation

#### **1. Introduction**

Over the past decade, worldwide greenhouse gas emissions have surged, hitting unprecedented levels in recorded history [1]. Nations aligned with the Paris Agreement are committed to slashing their carbon outputs. As a result, they are formulating energy blueprints to shift their energy sources and diminish dependency on fossil fuels.

Unlike building-attached photovoltaics (BAPV) that need extra structures for installation, BIPV systems integrate photovoltaic modules directly into the building's façade, serving both as an envelope and a power generator. With silicon costs dropping, PV module prices are now on par with common construction materials like marble and aluminum cladding [2]. While rooftops offer solar exposure, their space is limited by infrastructure equipment. In contrast, building façades offer ample space for PV integration, making them ideal for BIPV.

In urbanized cities, tall buildings dominate the skyline. Their design influences material choices, demanding innovative construction and safety solutions. Currently, the main issue with tall structures and BIPV façades is accessibility. The installation

and construction require workers to use scaffolding or elevating platforms for PV module installations, often preceded by fixing aluminum cassettes. This process is not only tedious but resembles the construction approach of BAPV, emphasizing the challenges with time and costs previously noted [3]. Elevated BIPV work presents safety concerns, with PV components vulnerable to adverse weather, impacting performance and safety [4]. Some prefabricated curtain wall systems with PV technology offer installation from inside but compromise on power generation or integration areas.

Prefabricated construction is a method wherein building components are produced and assembled in an offsite factory before being transported to the construction site for erection [5]. This technology brings several advantages [6]. Primarily, it can expedite the process of on-site installation. Additionally, it allows for stringent quality control of construction in the controlled environment of the offsite factory, thus promoting material efficiency. Lastly, it mitigates the risk associated with laborers working in hazardous environments.

Presently, several studies are concentrating on the intersection of the photovoltaic industry with the prefabrication construction sector. RICS [7] proposed the concept of a prefabricated BIPV business model to reduce costs in industry development. Large prefabrication construction firms can establish dedicated PV departments, thereby eliminating the need for end-users to deal with contracts and maintenance of the PV system in their residences [8]. This arrangement also simplifies the process of accessing renewable energy subsidies. Further, Longas et al. [9] proposed the concept and prototype of a PV system featuring a laminated timber wood structure using prefabricated construction. Valckenborg [10] incorporated PV thin film within an aluminum folded structure to expedite construction. However, these current studies fall short of satisfying the requirements of high-density urban development when integrating with PV systems, as is the case in Asian countries like Singapore.

This study introduces a new design for a fully prefabricated BIPV wall suitable for tall structures, streamlining PV installation, and wall structuring without exterior scaffolding. The outcome is the prefabricated unitized BIPV wall (PUBW). This multi-layered, opaque BIPV wall minimizes on-site height-related risks, ensures efficient electricity generation, faster construction, cost savings, and protects PV components from prolonged adverse weather during building.

#### **2. Various BIPV building integrations**

The various types of BIPV building integrations introduced in the previous section can be mainly divided into two categories: roof system integration and façade system integration. The following illustrates the concept details of each type of building integration and the advantages and disadvantages when integrated with the PV panel.

#### **2.1 Roof PV systems**

Skylights use glazes to cover a part or entirety of a roof or atrium [11]. Skylights allow people to enjoy sunlight in an indoor environment. PV modules can replace glass to form semi-transparent or opaque parts in the skylight. By changing the density of the silicon crystal material on the glass, the indoor lighting and shading effects can be adjusted.

Cold roofs comprise an external cladding material, an air cavity, and a load-bearing substructure [12]. The ventilated air cavity dissipates the temperature of the outer

*Reimagining Building Façades: The Prefabricated Unitized BIPV Walls (PUBW) for High-Rises DOI: http://dx.doi.org/10.5772/intechopen.112878*

cladding material. It is also known as a discontinuous roof because the cladding material usually forms a watertight layer of tiles, slate, sheet metal, etc. PV can replace the cladding material and mimic its color and texture through external coatings, making it "invisible". This type of PV integration is widely used especially where the roof receives sufficient solar radiation and has a certain angle of inclination.

A shed roof is the external extension space of a building with climate protection functions, such as shelter from sun and rain. PV replaces the cladding or glazing material of the canopy and does not require the same thermal performance considerations as skylights.

#### **2.2 Façade PV systems**

A rainscreen wall comprises cladding, an air cavity and a substructure bearing the load. This type of wall uses a ventilated air cavity to dissipate solar heat; hence, it is also called a cold wall [13]. PV modules replace the external cladding material and increase the efficiency of electricity production, particularly silicon PV, owing to rear ventilation. Slits could be present between the PV cladding and other cladding materials; hence, no significant pressure difference occurs between the cavity and the exterior. The water that penetrates inside the cavity eventually drains out of the cavity through evaporation and natural outflow. The substructure bearing load is protected against water.

A curtain wall is a strong representation of the industrialization of the building façade, mainly comprising an extruded aluminum frame and filled glass or metal panels, which can be modularly manufactured and pre-assembled, such as unitized curtain wall, or assembled on site, such as stick curtain wall [14]. Curtain walls need to meet the function of resistance of horizontal load and transfer to the main structure of the building, such as wind force and earthquake, as well as airtightness, heat insulation, sound proofing, etc. They are self-standing structures and bear no dead load weights from the building, hanging from the edge of the floor slab by bracket components. PV usually takes the place of filled clear glass (vision window) or metal plate/opaque glass (spandrel).

A BIPV double skin comprises two layers of glass. The outer skin is mainly intended for lighting purposes, while the inner glass has an insulating effect. The distance between the two layers of glass varies from about 20 cm to 2 m, acting as heat insulation, thermal insulation, sound insulation, etc. The ventilation method (e.g., mechanical, natural or hybrid) and opening and closing time control of the air cavity can be adjusted depending on the climate conditions of the building for energy saving. PV replaces part or the entirety of the outer skin of the glass.

BIPV shading devices are generally placed on the external surface of a building façade to control the intensity of light and heat entering indoors [15]. Various configurations and functional options are available, such as providing shade from top sunlight, the east morning sun or the west sun in the evening. Thus, the power generation function of PV and shading can well complement each other.

#### **3. Prefabricated construction technologies**

There are various construction materials that can be utilized for prefabricated construction, such as concrete, laminated timber wood, steel, and light gauge steel. This research incorporates a light gauge steel structure as the principal structural system due to its recyclable nature, which makes it apt for application in high-density

**Figure 1.**

*From coiled steel to the creation of light gauge steel frames, the manufacturing process is automated in the factory, translating CAD models directly into finished products.*

urban areas like Singapore. **Figure 1** illustrates the automated fabrication process of light gauge steel frame components in the factory setting, utilizing data imported from the digital model.

In Singapore, prefabricated prefinished volumetric construction (PPVC) leverages a light gauge steel structure as its primary architectural element to enable the creation of high-level prefabricated buildings. The low embodied carbon of light gauge steel structures confers environmental advantages, with the added benefit of recyclability. For the design at hand, a C-shaped channel with a 2 mm thickness is adopted as studs. The study positions the load-bearing studs at intervals of 1000 mm. To counteract seismic and lateral wind load forces, as well as to sustain the weight of photovoltaic (PV) panels, three potential systems—X-bracing, sheathing panel, or a combination of both—are proposed as a means to withstand forces in the horizontal plane [16]. In this research, a blend of X-bracing and sheathing panel is utilized. Beyond their use in building façades, light gauge steel structures demonstrate high versatility as they can also be incorporated into roofs and partition walls.

Utilizing computer-aided design and automation, the C-channel structure can be tailored for specific lengths and hole placements, optimizing infrastructure embedding and PV panel holding, which reduces costs and time. For projects with substantial PV areas, one can either customize PV sizes or use automated tools to modify the light gauge steel structure to fit the PV dimensions and design. Being lightweight, these structures can be preassembled off-site and conveniently transported for on-site installation.

#### **4. The design of prefabricated unitized BIPV wall (PUBW)**

#### **4.1 2D cross-sectional design**

This research examines the environmental factors to identify the materials and sites associated with each layer of the BIPV façade, aiming to establish a standard 2D cross-sectional design. Such factors should be taken into account for PUBW. **Figure 2** presents the load-determining factors under consideration, which influence the selection of materials to be implemented in the construction system.

The strategy for weather control (including barriers against water, air, and vapor) aims to ensure the wall's water and air seal. PV, serving as the rain screen system's

*Reimagining Building Façades: The Prefabricated Unitized BIPV Walls (PUBW) for High-Rises DOI: http://dx.doi.org/10.5772/intechopen.112878*

#### **Figure 2.**

*Analysis of the functional layers in PUBW components.*

cladding, is naturally waterproof, preventing most rainwater from coming into direct contact with the external wall and wires. Additionally, the seals between units must uphold weatherproofing standards.

Each PV module is equipped with a module-level power electronics (MLPE) to enhance power generation, especially when PV modules experience partial shading. Having pre-wired and pre-installed MLPE devices simplifies the installation for workers without electrical expertise.

**Figure 3** depicts the standard horizontal and vertical cross-sections of PUBW. BIPV façade designs must meet core structural and weatherproofing standards to ensure a secure and cozy interior for inhabitants.

#### **4.2 Mounting design**

PV mounting systems greatly influence solar systems' esthetics and efficiency due to shading potential and load bearing. They fall into two categories: linear- and pointfixing systems [9]. Linear systems include mullion-transom and structural sealant systems. Mullion-transom systems have protruding elements causing potential for shadowing and debris accumulation. Structural sealant systems, without protrusions, use sealants for holding PVs and require extra precautions if above 8 m. Point-fixing systems are of three types: drilled spot, clamp fixing, and undercut anchor. Drilled spot systems demand specific PV types due to hole placements. Clamp fixing systems employ U-shaped clamps, while undercut anchor systems, reducing shading, need specialized glass types. This study's prototype employs the mullion–transom system for PV mounting.

#### **4.3 Joint design**

Joint design is crucial for functional continuity in independent prefabricated units [17]. It needs to ensure waterproofing, provide a "plug-and-play" assembly, and permit indoor manual installation without outdoor equipment like cranes. The PUBW's steel frame is consistently thin as it is non-structural. An "interlocking" design, like a

#### *Façade Design – Challenges and Future Perspective*

#### **Figure 3.**

*2D horizontal cross-section of the preassembled unitized BIPV façade.*

unitized curtain wall system, ensures seamless fitting and weatherproofing between adjacent units (**Figure 4**). This design uses male/female junctions for waterproofing and easy installation. Corners of the units allow for connections, making installations *Reimagining Building Façades: The Prefabricated Unitized BIPV Walls (PUBW) for High-Rises DOI: http://dx.doi.org/10.5772/intechopen.112878*

*Interlocking joints ensure a weatherproof and swift dry installation.*

possible with just manual labor. Post-installation, equipment like MLPE devices fit into reserved corners, protected by rock wool insulation, ensuring no overheating. Accessible plasterboards ease future maintenance. After assembly, the interior wall gets painted for visual consistency. This system's design offers architects flexibility, as shown in combined sections with different unit types.

#### **4.4 3D Modeling design**

3D models of the PUBW units are created for initial system validation, which displays each layer's representation, clarifying design details (**Figure 5**). Moreover, **Figure 6** provides a glimpse into the off-site pre-assembly, aiding in worker training for fabrication and installation.

**Figure 5.** *3D model of the PUBW.*

*Workers can be trained to understand the preassembly process through 3D models.*

*Reimagining Building Façades: The Prefabricated Unitized BIPV Walls (PUBW) for High-Rises DOI: http://dx.doi.org/10.5772/intechopen.112878*

**Figure 7.** *The mock-up of the PUBW.*

#### **4.5 System mock-up**

The "Modular Pod" prototype, made of light steel, showcased the PUBW on its eastern side (**Figure 7**). It was divided into two floors to replicate high-rise construction. Using standard building components and commercial PV modules, the prototype reflected actual dimensions. The installation was efficient, needing only three workers for assembly and PV wiring. After completion, the interior was painted for esthetics.

#### **5. Conclusions**

This research introduces a PUBW that combines architectural assembly and PV-powered energy, facilitating easy, scaffold-free installation on-site. Ideal for tall residential buildings with predominantly opaque façades on the west and east sides, this prefab façade shortens construction duration and simplifies BIPV system installation. Furthermore, it offers architects considerable design versatility and supports tailored mass production.

Technology can be adjusted to accommodate varying construction scenarios. If lifting or hoisting equipment is available on-site, the size of the PUBW can be scaled up to form a mega panel composed of several individual panels. Architects are free to design the material combination within the mega panel. For instance, they can integrate metal sheet panels with PV panels or modify the color of the panels. The larger size of the mega panel, compared to the standard size of PUBW, allows for faster and easier construction with the aid of hoisting machinery. This significantly increases the efficiency of on-site installation.

Furthermore, to enhance the efficacy of BIPV construction, it is of paramount importance to develop a comprehensive Building Information Modeling (BIM) digital library for PUBW or analogous BIPV prefabricated products. Digitized components within BIM can be viewed as a composite of multifaceted information, encompassing data on product logistics, associated costs, and photovoltaic performance metrics. By incorporating these digitized components into their BIM designs, architects can significantly economize on time, facilitate a more streamlined design procedure, and consequently accelerate the iterative process of design.

### **Acknowledgements**

This work was conducted under a Solar Competitive Research Program grant from the National Research Foundation Singapore (NRF) through the Singapore Economic Development Board (EDB). The project "Cost-effective high-power density BIPV modules" (R-712-000-083-272) is implemented by the Solar Energy Research Institute of Singapore (SERIS) in collaboration with the Department of Architecture in the College of Design and Engineering (CDE) at the National University of Singapore (NUS). SERIS is a research institute at the National University of Singapore (NUS). SERIS is supported by the NUS, the National Research Foundation Singapore (NRF), the Energy Market Authority of Singapore (EMA) and the Singapore Economic Development Board (EDB).

### **Author details**

Tianyi Chen1 \*, Chye Kiang Heng2 and Shin Woei Leow1

1 Solar Energy Research Institute of Singapore (SERIS), National University of Singapore, Singapore

2 Department of Architecture, National University of Singapore, Singapore

\*Address all correspondence to: tianyi@nus.edu.sg

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Reimagining Building Façades: The Prefabricated Unitized BIPV Walls (PUBW) for High-Rises DOI: http://dx.doi.org/10.5772/intechopen.112878*

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[5] Luong DL, Nguyen QT, Pham AD, Truong QC, Duong MQ. Building a decision-making support framework for installing solar panels on vertical glazing Façades of the building based on the life cycle assessment and environmental benefit analysis. Energies. 2020;**13**(9):2376. DOI: 10.3390/en13092376

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[12] Ahmadi MM et al. Towards sustainable net-zero districts using the extended exergy accounting concept. Renewable Energy. 2022;**197**:747-764. DOI: 10.1016/j.renene.2022.07.142

[13] Day G, Gasparri E, Aitchison M. Knowledge-based Design in

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#### **Chapter 2**

## Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations, Experimental Methods and Numerical Tools

*Mohammad Momeni and Chiara Bedon*

#### **Abstract**

This chapter explores the behaviour and performance of glass curtain wall systems under various dynamic mechanical loads, including seismic, wind and impulsive loads. The classification of glass façade systems, comprising framed and frameless types, is first shortly discussed, along with their core components such as glass panels and frames. The challenges posed by glass material, including its vulnerability to impact, stress peaks and extreme loads, are acknowledged. The study further delves into various design standards and regulations for glass façade systems under dynamic loads, addressing seismic events and wind and impulsive loads and hence outlining parameters for assessment, performance criteria, and design considerations in use of glass curtain walls. Additionally, numerical methods are explored as effective tools for simulating and analysing the mechanical response of glass curtain walls under dynamic loads. The utility of these methods is showcased through a case study involving the Finite Element (FE) modelling of a glass curtain wall system exposed to a lateral in-plane load. The results of FE analysis are then compared with literature experimental results, which indicates its capacity to anticipate structural responses and even complex mechanisms under dynamic loads.

**Keywords:** glass curtain walls, dynamic loads, finite element models, experiments, regulations

#### **1. Introduction**

In modern structural and architectural design of buildings, glass curtain wall (CW) systems have emerged as a defining building feature that brings aesthetics as well as functionality for specific purposes. These non-structural systems consist of assemblies of glass panels supported by metal structures, which are connected to the main

building through special connectors. Due to the relatively low tensile strength and brittle nature of glass as a load-bearing material in these systems, and with an increasing use of these systems in building designs, understanding their behaviour under various loads becomes important. This paper presents a review that explores the assessment of glass CW systems under different loads, including seismic, wind and impulsive loads. The first part of this paper looks into the fundamental principles of glass CW systems, distinguishing between framed and frameless configurations. The next parts delve into the realm of dynamic loads, encompassing seismic events, wind and impulsive loads such as blast and impact. The vulnerabilities and challenges posed by the glass material are then discussed, highlighting the need to address its relatively low tensile strength and susceptibility to brittle fracture. To this aim, an extensive review of available design standards for glass façade systems under dynamic loads as well as the classification of glass material based on their production methods is presented. The exploration of various design standards and codes underscores the collective efforts to ensure the resilience of these systems in the face of various dynamic forces. The utilisation of static and dynamic racking tests, wind tunnel experiments, shock tube tests and impact assessments elucidates the methodology behind ensuring the performance and safety of glass CW systems under dynamic loads. Moving beyond standards, the paper unfolds numerical methods that emerge as crucial tools for assessing structural responses under dynamic loads. Recognising the limitations and complexities of laboratory experiments, the significance of numerical methods, particularly finite element analysis, in comprehending the behaviour of glass CW systems under dynamic loading is also discussed. To validate the accuracy of numerical methods, an illustrative example of a finite element model is presented to evaluate the behaviour of a dry-glazed CW system under lateral inplane loading.

#### **2. Glass CW technology**

A CW is a peripheral structure for buildings, which is composed – in most of cases - of metal supporting structures (aluminium or steel frame members) and plates (which can be composed of glass, aluminium, slate, ceramics, sandwich panels, etc.). When the panel is made of glass, as it is for CWs major functions of load-bearing capacity and architectural impact are expected. The classification of glass façade systems is based on their structural support, hence resulting in two main types: framed or frameless glass façade systems. Framed systems are typically designed using extruded aluminium components, although earlier versions used steel. On the other hand, frameless systems are restrained using bolted spider arms and steel supports, which serve as crucial architectural elements blending stability and aesthetic impact. The metal frames offer an efficient point support for glass panels but include various point-fixed joint options for truss and cable-supported systems. In these cases, typical systems comprise four key components: glass panels, bolted fixtures, glass support attachments (spider arms) and the main structural support frame [1]. Examples of framed and frameless glass façades are shown in **Figure 1**.

In this context, it is worth to remind that a glass CW represents a non-structural, exterior wall system that is used to clad buildings [2]. It is designed to separate the interior environment of a building from the external space while allowing light to enter and providing an important aesthetic appearance. Unlike more solid alternatives such as masonry, CWs are notably lightweight solutions of large use in modern

*Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations… DOI: http://dx.doi.org/10.5772/intechopen.113266*

**Figure 1.** *Examples of glass façade; (a) framed glass façade, and (b) frameless glass façade.*

constructions and derive their name from the resemblance to hanging curtains. Glass CW systems come then in two main forms: stick-built and unitised solutions, each with distinct structural attributes [3]. Stick-built systems involve on-site assembly of framing and glazing components, while unitised systems are typically pre-fabricated into CW units before installation. These constructional methods and technologies result in varying mullion-to-transom joints, where stick-built systems use aluminium shear blocks and unitised systems rely on direct screw connections. The unitised version also employs specific mullion profiles for easier on-site assembly and improved drift capacities under in-plane lateral loads, compared to stick-built systems. The choice between dry-glazed and structural sealant-glazed (SSG) configurations for glass panels is another parameter that further influences the mechanical performance of the assembled system [3]. Dry-glazed systems utilise rubber gaskets for compression, water resistance, and air infiltration prevention, while SSG systems are based on structural sealants to enhance water intrusion resistance and restrict the movement of glass panels. In addition, anchorage attachments play also a significant role, which is mostly influenced by factors like span lengths, temperature fluctuations, design loads and considerations for seismic or wind events and determining the size, shape and placement of attachment anchors. These attachments lead unavoidably to diverse responses during wind and seismic events, accommodating movements and rotations while maintaining flexibility. Overall, the interplay of these assembled components largely shapes and governs the complex behaviour of glass CW systems, underscoring the need for comprehensive engineering analysis, thoughtful design and construction considerations.

#### **3. Glass material**

The utilisation of glass in constructing envelopes has garnered substantial attention from researchers in recent decades [4]. However, it is important to remind that glass itself, despite its prevalent mechanical use, still poses challenges when overloaded, due to its relatively low tensile strength and brittle nature. This becomes particularly

evident in the context of glazing windows and façades, which constitute delicate and breakable elements within a building structure. This vulnerability is especially pronounced when the design anticipates extreme loading conditions or the potential for such conditions arising over the structure's lifespan, as these glass envelopes serve as the primary barrier between the interior and exterior environments [5]. Finally, it is important to emphasise that glass components are the most vulnerable component in these systems, but an optimal structural design should pay attention for many other CW components [3]. With a focus on glass material, common types are classified based on their production methods into three categories [6]. AN glass material stands out for its cost-effectiveness due to its relatively straightforward production process. However, in terms of strength, it lags behind HS and FT glasses. Through the method of heating and gradual cooling used to transform AN glass, HS glass is formed, which is characterised by a certain surface compression within the glass panels. This results in a significant strength boost, compared to AN glass, and approximately doubles its strength. This arises from the harmonious distribution of thermal strains across the glass thickness during the heating and cooling phases, leading to a surface compressive stress raising up to about 30 MPa. On the other hand, elevating AN glass temperature to around 700°C and rapidly cooling it generates FT glass. In this case, the surface compression stress is notably high, exceeding 69 MPa as per ASTM C1048 standard [7]. This remarkable surface compression endows FT glass with a strength that is about 4 to 5 times greater than AN glass. Unlike AN and HS glasses, FT glass possesses stored elastic energy. Consequently, when broken, it fragments into numerous small, fine glass cubes (**Figure 2**). This unique behaviour is responsible for FT glass being commonly referred to as "safety glass" [8]. Worth noting is that under circumstances involving high-strain rate loads like explosions or impacts, FT glass, despite its safety characteristics, does hold the potential to break into larger pieces.

It should be noted that research studies and regulations emphasise the remarkable strength of glass material under high strain rate loads, with a dynamic increase factor of approximately 1.78, resulting in a compressive strength of 80 MPa for glass when subjected to impact or explosion [9, 10].

**Figure 2.** *Fracture pattern in AN (left), HS (middle), FT (right) glass material [8].*

*Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations… DOI: http://dx.doi.org/10.5772/intechopen.113266*

#### **4. Selection of design standards and experimental protocols for glass façades under dynamic loads**

Dynamic loads refer to forces that fluctuate in strength and direction over time. Such loads stem from sources like earthquakes, explosions, impacts, and sudden shifts in motion. They can induce extra stress on structures, materials, and components, necessitating their consideration during engineering and design to prevent fatigue, resonance, and other dynamic effects. In recent decades, significant events have caused substantial consequences for buildings and their envelopes. Notably, major earthquakes like the 1995 Northridge Earthquake prompted professionals to delve into improved glazing system design for enhanced safety, where the damage of glass façades was extensively observed, and more than 60% of the panes were broken [11]. Furthermore, recent explosion incidents have amplified the need for designing blastresistant buildings, particularly those featuring CWs, to safeguard occupants from external explosions. Regrettably, many of these events have led to casualties, injuries and substantial financial losses, underscoring our built environment vulnerability (i.e. explosions in Tarragona, Spain 2020 [12], and Beirut, Lebanon in 2020 [13]). This underscores the necessity of considering blast loads when designing structures with CWs located near such facilities. Conversely, other loading types, such as wind and fire, should also be accounted for in glass CW design. It is worth noting that in areas with high wind velocities, wind governs the structure design, requiring the entire glass CW and its connections to withstand wind loads. Consequently, these components (i.e. glass CWs) typically face a multi-risk environment, subject to different types of loading as given above, and have often incurred significant damage, posing threats to life safety and incurring economic losses due to repair expenses and downtime.

#### **4.1 Seismic events**

During seismic events, the glass panels within the CW framing system experience in-plane displacement due to increasing story drift from the seismic forces. As stated in ASCE 7-16 [14], engineers are obligated to ensure that the relative seismic displacement (drift) of a considered glass CW component, *DpI*, remains below the relative seismic displacement at which glass fallout from the CW, storefront, or partition occurs. This means that *Δfallout*, as presented in Eq. 1, should respect the condition:

$$
\Delta\_{\text{fallout}} \ge \max \left\{ 1.25 D\_{p1}, 13 mm \right\} \tag{1}
$$

It should be also noted that *DpI* = *DpIe*, where *Dp* is the relative seismic displacement that the component must be designed to accommodate, and *Ie* is the importance factor (1.00, 1.25, 1.50 for increasing importance). However, there are some exceptions in ASCE 7-16 to describe states that do not comply with this requirement. In this regard, glass panels with sufficient gap from the frame, such that physical contact does not occur at the design drift do not need to satisty Eq. 1. Instead, the focus shifts to meeting the following criteria:

$$D\_{clear} \ge \mathbf{1.25D}\_{pl} \tag{2}$$

where *Dclear* signifies the relative seismic displacement at initial glass-to-frame contact. For rectangular glass panels, *Dclear* is determined by Eq. 3 as follows:

$$D\_{clear} \ge 2\mathbf{c}\_1 \left( \mathbf{1} + \frac{h\_p}{b\_p} \frac{c\_2}{c\_1} \right) \tag{3}$$

where the rectangular glass panel height and width are denoted by *hp* and *bp*, respectively, and *c1* and *c2* represent the clearances between the frame and the vertical and horizontal edges of the glass, respectively. These parameters are shown in **Figure 3**.

As many other national and international standards for structural design, ASCE 7-16 uses "risk categories" to find an appropriate design wind velocity for determining the corresponding pressures and thus design structures and building components [14]. In this context, fully tempered monolithic glass in risk categories I, II and III and located within 3 m of a walking surface is exempt. Also, annealed or heatstrengthened laminated glass with an interlayer of at least 0.76 mm, mechanically captured in a wall system glazing pocket and secured to the frame by a wet-glazed elastomeric sealant perimeter bead (minimum 13 mm glass contact width), or an approved anchorage system, is not subjected to this requirement. It should be noted that different global codes present diverse performance criteria for CWs [16]. Eurocode 8 [17] offers permissible inter storey drift ratio values for damage control in non-structural elements under various conditions: 0.5%, 0.75% and 1% for brittle nonstructural elements attached to the structure and for ductile non-structural elements or those integrated without obstructing structural deformation, respectively. New Zealand standard for structural design actions, NZS 1170.5 [18], dictates that a glass CW is considered to have failed when the relative displacement attains the larger of

#### *Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations… DOI: http://dx.doi.org/10.5772/intechopen.113266*

two values: either 1/250 of the span or twice the width of the glass clearance. Here, the span represents the height of the story for the CWs attached to the building, while the glass clearance corresponds to the width of the silicone adhesive bar inserted on each side of the glass panel. In FEMA 273 [19], diverse configurations of glazing systems involve subframes attached to the main structure, either field-assembled or prefabricated. These systems are sensitive to deformations, and drift analysis is crucial to ensure compliance with performance levels. Failures, particularly in dry glazing, can result in shattering or detachment. Visual evaluation encompasses factors like glass support, mullion arrangement, sealants and connectors. Acceptance criteria revolve around force provisions and displacement for varying levels, with drift limits set at 0.02 and 0.01 for Life Safety and Immediate Occupancy performance levels, respectively. In FEMA P-58–2 [20–22], a fragility class is assigned to each category of glass CW, serving as a valuable point of reference for seismic design and calculations. In other words, FEMA P-58 employs repair costs instead of structural parameters to assess seismic performance. Fragility and repair cost functions are linked to vulnerable building components, showing the probability of surpassing damage thresholds at specific engineering demand parameter values. These functions, combined with peak structural responses, predict damage states and estimate economic losses. Other codes such as Chinese [23, 24], Canadian [25] and Japanese [26] establish varying limits tied to earthquake load intensity. In Chinese design codes [23, 24] for CWs, a distinct recommendation is presented. It stipulates that the in-plane peak drift of the CW should exceed three times the elastic deformation limit of the main structure. The Canadian code [25] assigns a value of 0.02 applicable to all structural types, which is a conservative approach across various building categories. It is understood that the glass panel loses its functionality immediately upon breakage. As per the Japanese code [26], glazed systems must be designed to adhere to inter storey drift ratio limits of 1% for severe earthquakes, 0.5% for moderate earthquakes, and 0.33% for low earthquakes. While the international codes' approaches mentioned above pertain to seismic requirements for glass CWs, the challenge persists in evaluating the CWs' capacity under various limit states. Generally, the codes emphasise the necessity of conducting experimental tests to address this concern. In the following, existing experimental tests to determine the lateral capacity of CW under seismic loading are discussed.

To evaluate the seismic performance of CW systems, various experimental protocols including shaking table test, in-plane racking test and so on can be found in the literature. These protocols serve as essential tools in understanding the dynamic behaviour of CW systems and contribute to more resilient and reliable structural designs. Shaking table testing stands as a foundational approach in assessing the seismic performance of CW systems. This technique involves subjecting scaled models or prototypes to simulated seismic motions, enabling insights into dynamic properties, system responses and failure modes under controlled conditions. Standardised codes such as AC156 [27] establish guidelines for seismic qualification tests of non-structural components and systems, which are adaptable for glass CW systems meeting specific criteria (i.e. systems with fundamental frequencies greater than 1.3 Hz). Similarly, FEMA 461 [28] guides the fragility evaluation of systems sensitive to dynamic motion. Despite not being explicitly tailored for shaking table testing of CWs affixed to buildings with multiple attachment points at neighbouring floor levels, this protocol nonetheless offers valuable insights into the testing of such CW systems. In-plane racking test serves as a pivotal method to assess the drift capacity of glass CW systems under dynamic loads. Standards like AAMA 501.4 [29]

and AAMA 501.6 [30] focus on the in-plane draft capacity of framed glass façade systems as shown in **Figure 4**, offering methods for both static and dynamic testing. In AAMA 501.4, a horizontal static monotonic displacement is applied to the glass CW specimen up to a designated displacement. This facilitates the assessment of serviceability limit states, including factors like air infiltration, water penetration and structural integrity.

The second procedure, AAMA 501.6, takes a dynamic approach by subjecting the glass CW system to cyclic horizontal forces. This dynamic assessment, conducted with incremental concatenated sine waves following a crescendo pattern as depicted in **Figure 5**, mimics the stress dynamics experienced during seismic events. According to the protocol (more details about the incremental step loads can be found in [15]), the crescendo test should continue until one of these conditions is met: (1) a glass piece with an area of at least 645 mm<sup>2</sup> falls out, (2) the drift index (defined as the lateral displacement at the top of the glass panel divided by the glass panel height) is equal to or exceeds 0.1 (equivalent to 10%) or (3) a maximum racking displacement of

#### **Figure 4.**

*Schematic drawing of racking test facility designed for mock-up of glass CWs [15].*

*Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations… DOI: http://dx.doi.org/10.5772/intechopen.113266*

152.4 mm is reached. These criteria determine when the test concludes. In the case of condition (1), the displacement at which the glass fallout transpires is designated as *Δfallout*.

By obtaining this dynamic data and incorporating it within the equations supplied by ASCE 7-16, as explained earlier, one can establish the system capacity to withstand seismic forces while adhering to specific relative drift limits.

#### **4.2 Wind load**

Eurocode 1 [31] outlines wind load calculations for façades in part 1–4, aiding structural design for buildings up to 200 m tall and to bridges having no span greater than 200 m. Wind forces are specified for the entire structure and components like cladding units. As a convention, the fundamental basic wind velocity is the 10-minute mean wind velocity with a return period of 50 years. It should be noted that traditional buildings have experienced extreme weather events, revealing the inadequacy of the current guidance, where the design values often fall below actual wind loads observed over decades, as reported in [5] for many regions of Europe, the US, as well as the Asia-Pacific region. On the other hand, many instances still exist where the code fails to offer satisfactory answers. For such situations, wind tunnel experiments or, in exceptional cases, full-scale experiments can provide solutions [32]. Wind tunnel experiments serve as an alternative to codes of practice when dealing with scenarios beyond their scope or when a more precise assessment of wind loading is deemed essential. Within a wind tunnel, the wind, the structure, its environment and occasionally its actions are replicated at a reduced scale. This allows for the measurement of wind speeds, pressures, forces, moments, accelerations and so on. Common test protocols are used to evaluate the performance of glass CWs against out-of-plane loads and weather conditions, both in laboratory and field settings. These protocols, such as ASTM E283 [33], E330/330 M [34], E331 [35], E783 [36], E997 [37] and E1996 [38], cover various aspects including air leakage, structural performance, water penetration, glass breakage probability and impact resistance. These tests are conducted using an air pressurised test chamber as can be seen in **Figure 6** for both glass CW specimens and structural glass panels. Controlled air pressure differentials simulate wind pressures, both static and cyclic, along with additional conditions like debris impacts and water pressures. These conditions aim to replicate realistic scenarios during windstorms.

It is worth mentioning that the design of glass CWs is an open-ended process, requiring engineers to consult various design guides for handling out-of-plane

loading. In addition, the conjunction of wind load with other climate changes like rain [40], hail [41], flood [42] and so on often negatively affects building façades' performance and durability. This includes surface material degradation, frost damage, salt efflorescence, structural cracking, interior harm, and other concerns, and hence, careful consideration should be taken into account for these aspects.

#### **4.3 Impulsive loads**

Impulsive loads are sudden and high-intensity forces or pressures applied to a structure within a short duration. These loads can result from events like explosions, impacts or other abrupt occurrences. Impulsive loads are characterised by their rapid rise in force and are typically short-lived but can exert significant stress on the structure [43–45]. Examples of impulsive loads include the shockwaves from explosions, the impact of heavy objects on a surface or the force exerted during a sudden collision. Due to the abrupt nature and intensity of an impulsive load, it can lead to structural damage, material deformation and even failure if not adequately considered in design and engineering. Engineers often need to account for impulsive loads when designing structures and their envelopes that are prone to encountering these sudden and highenergy events [46]. Mitigating the effects of impulsive loads requires careful analysis, materials selection and structural design that can absorb or distribute the impact forces effectively. It is important to note that a majority of casualties resulting from a blast incident are linked to injuries caused by glass fragments [5]. Therefore, extra caution should be exercised when considering glass façades in blast-prone scenarios.

#### *4.3.1 Blast load*

The progress in blast protection design achieved during the Second World War resulted in the release of an engineering manual by the United States Army Corps Of Engineers, which is labelled as UFC 3–340-02 [47] after many revisions, and it is widely used by researchers in the field of blast-resistant structures. The manual outlines blast parameter calculation and design techniques for protective construction in facilities involving explosive materials. Its strategies can be adapted for various types of structures directly, or by modifying via experimentation and numerical analyses. Notably, Section 6-27 of this manual focuses on designing glass panes under explosive conditions, providing instructions and graphs based on panel dimensions (thickness, width and height), time duration and blast pressure. These graphical representations are derived to aid in designing and assessing glazing ability to withstand prescribed blast loads with a failure probability not exceeding 0.001. Failure is assumed when maximum deflection of pane exceeds ten times the glazing thickness, preventing edge disengagement of the plate while staying within Von Kármán plate equation limits. In addition, further explanations are given in this manual as design criteria for the glass façades specifically for sealants, gaskets, beads, glazing setting, frame loads and rebound (which is the response to the dynamic loading will cause the window to rebound (outward deflection) after its initial positive (inward) deflection). The most important criteria as maximum allowable limits for frame design are: i) Frame members' relative displacement should be limited to the smaller of 1/264th of the span or 1/8 inch; ii) Maximum stress in any member and fastener should not exceed material yield stress divided by 1.65 and 2.00, respectively, and iii) The deflection of the building should not impose deflections on the frame greater than 1/264th of the length of the pane edge. Also, other codes such as HOSDB, 1997 [48]; GSA TS-01 [49]; ASTM *Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations… DOI: http://dx.doi.org/10.5772/intechopen.113266*

F1642 [50] and ISO 16933 [51] can be found in the literature regarding glazing systems subject to air blast loadings.

It is important to emphasise that the conventional regulations and building guidelines do not adequately address potential threats that could arise, such as explosive incidents. In order to ensure the protection of constructed infrastructure, there is a need to develop methodologies that can effectively quantify the capacity of structural elements to withstand explosive loads. Additionally, assessing the risks associated with the failure of these elements is crucial. To achieve these goals, a combination of experimental studies and numerical approaches is essential. This combined effort will not only provide practical solutions but also equip engineers with decision-making tools to enhance the security of vital infrastructure. In the realm of testing the blast resistance of glazing materials, two primary methods are commonly employed: shock tube [52] and arena test [51]. Shock tubes are capable of generating relatively moderate pressures over extended durations, making them well-suited for assessing the effects of larger-scale explosive devices, such as vehicle-borne improvised devices and industrial explosions. Conversely, arena tests simulate scenarios involving smaller charges detonated at close range or vehicle-borne improvised explosive devices. Examples of shock tube testing and arena testing of full glass windows under blast loading can be seen in **Figure 7**. It is noteworthy that variations in design codes need to be considered when designing building façades to withstand blast events. In this regard, a comprehensive analysis was conducted to compare the different existing standards for testing blast-resistant windows and glazing materials, as referenced as [55].

**Figure 7.** *Examples of testing full glass windows under blast loading; a) shock tube blast testing [53] and b) arena testing [54].*

**Figure 8.**

*Conventional impactors for glass CWs: (a) twin-Tire and (b) Spheroconical bag (SB, with dimensions in mm) [61].*

#### *4.3.2 Impact load*

Impact loads represent a prevalent form of dynamic forces that can inflict significant damage on brittle materials in a short duration of time. Present regulations do not have enough guidance to accurately assess the resistance of glass elements to various types of impact loading. The classification of impact loading, as outlined in [56], distinguishes between hard body and soft body impact, a division particularly pertinent to glass due to its vulnerability when interacting with harder materials. However, there are only a limited number of regulations such as HR EN 12600 [57], HR EN 356 [58], DIN 18008-4 Annex A document [59] and CWCT TN 76 [60] that detail methods for testing glass resistance to impact. Two commonly used impactors are the spheroconical bag (SB) and the twin tire (TT) which are widely used to assess the performance of glazing under soft body impact. The SB contains glass spheres and weighs 50 kg, while the TT consists of two pneumatic tires inflated to 3.5 bar air pressure, with an additional 50 kg steel mass inside (see **Figure 8**). The International HR EN 12600 standard introduced the TT pendulum protocol to replace the SB impactor. German regulations also permit FE numerical simulations using the TT impact instead of full-scale experiments. Some standards such as CSTB 3228 [62], CWCT TN 76 [60], ACR[M]001 [63] and ANSI Z97.1 [64] still advocate for the SB impactor. These standards evaluate the glass system performance after impact, assessing its ability to withstand breakage, cracks and fragments. The primary regulations influence façade designers and manufacturers to adhere to the original SB approach.

#### **5. Numerical analysis of in-plane seismic load effects**

As for many other constructional and structural issues, engineers have consistently turned to numerical methods, encompassing simpler techniques or complicated finite element analysis, to account for intricate nuances in their models. In addition to mitigating the financial burden associated with laboratory testing, these numerical methods facilitate parametric studies involving diverse input variables.

A huge number of research studies can be found in the literature regarding performance evaluation of glass elements and façades under different types of loadings.

#### *Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations… DOI: http://dx.doi.org/10.5772/intechopen.113266*

There are different methods including single degree of freedom (SDOF), multi degree of freedom (MDOF) and finite element (FE) methods that are widely used to find the response of such structures. SDOF methods are always used to find the response of a single member under extreme dynamic loads like blast and impacts [65, 66], while MDOF [67, 68] and FE methods [69–73] not only can be used for single members but also can be utilised for other complicated structures where more details should be taken into consideration. Besides, engineers are always seeking simpler solutions (instead of experimental and numerical analyses) to solve problems that can provide more straightforward analytical approaches for investigating the issue. As a result, analytical methods (which themselves have been validated and calibrated using accurate experimental and numerical results) have also gained importance among researchers, and examples of these can be observed in [16, 74, 75]. Exploring this topic in depth within the confines of this chapter is not feasible; however, more comprehensive explanations can be sought in the technical literature.

In the following, to show the accuracy and applicability of FE models to find the response of a glazing under lateral loading, a numerical model based on Abaqus software is used to evaluate the response of a dry-glazed CW façade under lateral load, based on validation towards literature tests. In this regard, the experimental investigation conducted by Shirazi [76] is taken into account. The schematic of selected experimental test is shown in **Figure 9**. The CW arrangement depicted in **Figure 9**

**Figure 9.** *Considered glass CW configuration for mock-up test [71].*

features an annealed monolithic glass panel measuring 1829 mm in height, 1524 mm in width, and 6 mm in thickness, which was dry glazed within a Kawneer 1600 aluminium CW frame. It is important to mention that the clearance between the glass and the frame was taken as 11 mm. The pressure plate profiles are affixed to the mullions and transoms using screws spaced at intervals of 9 inches centre-to-centre, and these screws are tightened to a required torque of 10.7–11.3 N-m to secure the glass in position. The CW was subjected to a lateral racking displacement at the top corner of the frame.

To simulate the glass CW, all components (including mullions, transoms, pressure plates, gaskets, perimeter gaskets, thermal gaskets, setting blocks and glass panel), are individually modelled and meshed using C3D8R elements. The particular aspect of the present application – compared to a multitude of literature examples which are based on the use of rough geometrical simplifications – is in fact a full three-dimensional description of CW elements. These parts are then assembled to construct the final configuration. It is important to highlight that the minimum dimension of solid elements is 2 mm, which is primarily applied to gaskets, where higher deflection is anticipated. **Figure 10** shows the CW modelled in Abaqus software.

The FE modelling takes into account various interactions among distinct components, encompassing the interactions between i) glass, transoms and mullions; ii) glass and gaskets; iii) glass and setting blocks; iv) rubber parts (i.e. gaskets, perimeter gaskets, thermal gaskets, setting blocks) and aluminium parts (i.e. mullions, transoms, pressure plates) and v) the semi-rigid connections linking transoms and mullions. In cases (i) and (iii), the normal hard contact and frictionless tangential behaviours are used to define the contact property. In case (ii), the hard contact is used for normal behaviour, while the penalty method with a friction coefficient of 0.65 is used to define the tangential behaviour of contact property. In case (iv), the tie constraint strategy is used, and for case (v), the u-joint connection type is implemented to define

**Figure 10.** *Glass CW modelled in Abaqus software.*

*Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations… DOI: http://dx.doi.org/10.5772/intechopen.113266*

the connector in connecting transom and mullion parts. The U-joint type connector, which is used to connect two reference points at each location (i.e. the connection of the transom to the mullion) by the wire, fixes all translational degrees of freedom and the rotational degree of freedom about the global y-axis.

The glass panel characteristics are defined with a modulus of elasticity of 72 GPa, Poisson ratio of 0.25 and mass density of 2500 kg/m<sup>3</sup> . For the aluminium parts, values of 69 GPa for the modulus of elasticity, 0.33 for Poisson ratio, and 2700 kg/m<sup>3</sup> for mass density are utilised. Regarding the gaskets, the modulus of elasticity is approximated at 4.4 MPa, with Poisson ratio equal to 0.3 and mass density of 1300 kg/m<sup>3</sup> .

The results of FE analysis are compared with the reference experimental results in terms of load-drift relationship, as demonstrated in **Figure 11**. The figure reveals that there is a rather good agreement between the FE outcomes and the experimental findings. In other words, this signifies that the FE modelling can anticipate the structural responses at particular drift levels during the analysis, in accordance with the experimental findings. These structural behaviours encompass three essential aspects (which are shown in **Figure 11**) including: 1) starting the plastic deformation of the gasket, 2) starting the contact between the glass and the frame and 3) the occurrence of frame and glass failure. Furthermore, the model proficiency in faithfully replicating the glass movement within the glazing pocket enables accurate representation of how the glass comes into contact with the frame, and all these aspects have a kay role in structural performance and capacity assessment for similar systems.

Assured that the FE model like in **Figure 10** can be further optimised and simplified to enhance its computational efficiency, it is worth noting that major challenges are related to the accuracy of simplified restraints and boundaries, given that they have a major influence on the stress and strain distribution in glass. Obviously, special modelling assumptions should be taken into account under various loading configurations. However, the goal of ongoing investigations is to capture and define a harmonised modelling strategy for glass façades in general. Also, another important aspect which is presently under investigation is the possible definition of standardised performance indicators that could be used for a given curtain wall exposed to various

**Figure 11.** *Comparison of load-drift relationship obtained from FE model with experiment.*

mechanical loads and for structural health monitoring purposes, diagnostics and life cycle assessment of façades in buildings.

### **6. Conclusion**

A comprehensive exploration of glass curtain wall systems under various dynamic loads, including seismic, wind and impulsive forces like blasts and impacts, is provided by this paper. Regulations, experimental methods and numerical simulations have received special attention, and the essential need for meticulous design, advanced materials and rigorous testing to ensure the structural integrity and safety of these architectural features is emphasised. The array of design standards, regulations and codes available to guide engineers in addressing these dynamic loads is illuminated by the paper. The necessity of a multidisciplinary approach, encompassing elements of structural engineering, material science and architectural design to create glass curtain walls capable of withstanding dynamic loads, is highlighted. Additionally, the role of numerical methods, particularly finite element analysis, in simulating and predicting the behaviour of glass curtain wall systems under dynamic conditions, is underscored by the study. These methods offer cost-effective and efficient means of assessing complex interactions, enabling the evaluation of structural responses and contributing to design optimization. As the boundaries of modern architecture continue to be pushed by architects and engineers, the insights presented here serve as a valuable guidance to ensure the optimal performance of glass curtain wall structures when confronted with dynamic challenges.

### **Author details**

Mohammad Momeni and Chiara Bedon\* Department of Engineering and Architecture, University of Trieste, Italy

\*Address all correspondence to: chiara.bedon@dia.units.it

© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

*Review on Glass Curtain Walls under Different Dynamic Mechanical Loads: Regulations… DOI: http://dx.doi.org/10.5772/intechopen.113266*

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[59] Siebert G. DIN 18008 Glas im Bauwesen–Bemessungs-und Konstruktionsregeln: Grundlagen und Konzept der Normenreihe. Stahlbau. 2019;**88**(1):32-35

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[64] A. Z97.1. American National Standard for Safety Glazing Materials Used in Buildings—Safety Performance Specifications and Methods of Test. McLean, VA, USA: Accredited Standards Committee (ASC); 2015

[65] Feng R-Q, Ye J-H, Wu Y, Shen S-Z. Nonlinear response spectra of cable net facades. Soil Dynamics and Earthquake Engineering. 2012;**32**(1):71-86

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analysis of dry-glazed curtain walls. Journal of Architectural Engineering. 2011;**17**(1):24-33

[72] Caterino N, Del Zoppo M, Maddaloni G, Bonati A, Cavanna G, Occhiuzzi A. Seismic assessment and finite element modelling of glazed curtain walls. Structural Engineering and Mechanics. 2017;**61**(1):77-90

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[76] Shirazi A. Development of a Seismic Vulnerability Evaluation Procedure for Architectural Glass Curtain Walls. Ph.D. thesis. University Park, PA: Pennsylvania State Univ.; 2005

#### **Chapter 3**

## The State of Housing, Drinking Water, Electricity, and Sanitation Facilities of Scheduled Tribes in Eastern Uttar Pradesh, India

*Poonam Singh Kharwar, Devesh Kumar, Abhishek Kumar and Abhinav Kumar*

#### **Abstract**

Façade design, drinking water, electricity, and sanitation are critical basic human needs for a decent life in the modern period. The development and implementation of these regulations are necessary for socioeconomic advancement and protect tribes, particularly women, from significant public health, environmental, and security issues. Despite the government's intentions to address their backward status through special constitutional provisions, tribes in eastern Uttar Pradesh remain severely underserved regarding these services. The design of façades has a favorable impact on the lives of socioeconomically deprived citizens of developing countries like India. The present chapter examines the façade design, drinking water, electricity, and sanitation services provided to Scheduled Tribes in the eastern Upper Peninsula and potential improvement initiatives. Façade design impacts the types of businesses that thrive in a given location. The majority of scheduled tribes rely on the informal economy for a living. The majority of ST families (43.9%) still live in jhuggis, only 27.12% have both tap water supplies and electricity, the majority (92.15%) use hand pumps for drinking water outside the home, 77.4% of STs do not have latrine facilities inside the premises, and the surrounding sanitation is inadequate. Although government is taking steps for piped water supply, ST families are still deprived of this facility due to the scattered nature of remotely placed *kaccha* houses and lack of proper attention from responsible authorities.

**Keywords:** scheduled tribes, housing, sanitation, drinking water, electricity facility

#### **1. Introduction**

Tribes are different from the general population because of their different way of living and community life. Tribes as custom-bound communities in India are facing numerous problems like geographic separation from mainstream of the masses such as unemployment, poverty, poor health, alcoholism, various kinds of exploitations, natural calamities, and naxalism in present global area. Their inclusive growth can be

achieved only by bringing them into the national mainstream and, at the same time, preserving their culture and traditions. Nomenclature of the Scheduled Tribe (ST) fully emerged under the Government of India Act of 1935 and the Constitution of India to bring them into the mainstream of national development by their equitable and balanced progress [1].

Except for Africa, India has the highest concentration of tribal people worldwide. According to the 2011 census, tribes made up approximately 8.6% of the total Indian population, with 89.97% of them living in rural areas. Uttar Pradesh (U.P.) is the most populous state. However, it is also one of the least developed, with a Human Development Index (HDI) value of 0.380 (2007–2008), lower than the national average of 0.467, placing it 18th among Indian states/U.T.s. It ranks 17th among all Indian states regarding the number of S.T.s. According to the 2011 census, 1.13 million indigenous people made up 0.6% of the overall population of the U.P. The eastern section of the state was home to around 84% of the population. Sonbhadra district accounted for more than one-third (33.94%) of the total S.T. population, while Ballia and Deoria accounted for more than half (53.34%) (2013) (Government of India) [2]. Although HDI improvement in India was estimated to be greater (0.633) in 2021, it was relatively slow (0.592) in Uttar Pradesh, which ranked 32nd out of 33 states [3].

At present, there are 15 notified tribal communities in U.P. *Gond* tribe accounts for first highest number of tribes followed by Kharwar as second most populous tribal community. After 2002 proclamation, Gonds were categorized as ST in 13 districts only, and in other districts, they were renamed SC. In 2011, the Gonds, along with the sub-ethnic groups namely Dhuria, Nayak, Ojha, Pathari, and Rajgond, were the largest and most prominent tribal population, accounting for 50.2% of all STs and occupying 18 districts in eastern Uttar Pradesh. According to the 2011 census, Kharwar is the second most populous tribe, accounting for 14.6% of the state's ST population. These two tribes accounted for nearly two-thirds of the total ST population in the Upper Peninsula. Tharu is the third largest community, with a population increase of 26% from 83,544 in 2001 to 1,05,291 in 2011. Their percentage share of all STs has declined from 77.4 in 2001 to 9.3 in 2011. *Saharya* is the fourth largest tribe, found mainly in Lalitpur district accounting for 6.25 of all STs followed by Chero (3.7%). Thus, according to census 2011, all these five tribes constitute 83.6% of ST population of U.P. *Baiga and Pankha/Panika* constituted 1.5 and 1.4%, respectively. *Agariya and Bhuiya/Bhuinya* constituted 2.6 and 2.2%, respectively. Population share of Bhotia (0.5%), Buksa (0.4%), Janusari (0.3%), Raji (0.1%), Parahiya (0.1%), and Patari (0.01%) contributes to minimum in ST population. Sonbhadra district constituted more than one-third (33.94%) and along with Ballia and Deoria more than one-half (53.34%) of total ST population of the U.P. [4].

Welfare programs directed for the development of these STs have not resulted in any visible positive impact. Given the common backwardness and suffering of the S.T. people in the eastern U.P., it is critical to study and uncover the underlying correlates that make their lives so wretched. Façade design, drinking water, electricity, and sanitation are crucial basic human necessities for a decent life in the modern day, and the development and implementation of these provisions are critical for the socioeconomic uplift of these less fortunate parts of society. Population of STs is less in eastern U.P. So it has not drawn attention of researchers in the past. No extensive field study has been reported on STs in socioeconomically backward regions of eastern U.P. Hence, there is an urgent need to conduct such study to fill up the gap of knowledge and to provide guidelines and strategies for formulation of sustainable development program for the overall betterment of these deprived community.

*The State of Housing, Drinking Water, Electricity, and Sanitation Facilities of Scheduled… DOI: http://dx.doi.org/10.5772/intechopen.113046*

#### **2. Objectives**

Present study was conducted among families of different ST communities in Deoria, Ballia, Ghazipur, Varanasi, and Sonbhadra districts of U.P. with following objectives:


#### **3. Review of literature**

Belshaw [5] mentioned that though a lot has been done for tribal's social and economic betterment, a great deal remains to be done.

Sharma [6] mentioned that 20% of the tribal population has been uprooted and displaced in less than 50 years; they have lost their rights because of their political powerlessness. The magnitude of land and number of displaced persons has been increasing since then.

Sharma [6] mentioned that 20% of the tribal population has been uprooted and displaced in less than 50 years; they have lost their rights because of their political powerlessness. The magnitude of land and number of displaced persons has been increasing since then.

According to Singh [1], the tribals in India are the most adversely impacted ethnic group due to post-independence development, and the new economic policy is likely to worsen their situation. As a result, more earnest efforts are required to salvage and enhance their socioeconomic situation within the restrictions and possibilities of their existential circumstances, including rural, illiteracy, poverty, ill-health, and unproductive agriculture. The government's efforts to improve tribal welfare through protective developmental measures have had little impact on tribal development. Mehta [7] gave a comprehensive analysis of tribal development initiatives used during the twentieth century, revealing that the government failed to provide them with basic survival needs.

Mondal and Mete [8] noted that tribes are not able to appreciate modern concept of health and sanitation due to illiteracy and ignorance. Based on NITI Aayog estimates (2011–2012), U.P. stands among states having 30–40% population below

poverty line and it is better only to Jharkhand and Chhattisgarh. Deshmukh [9] revealed that the existing welfare strategies did not help the tribal overcome from inferiority and atrocities on them.

Although welfare plans such as subsidizing housing (façade designed by the government as multistory building) like *Lohia, Indira, and Kashiram Awas Yojna* exist for the poor in rural area, tribes are not getting benefits and they are victims of inequality, exploitation, and oppression. Their economic situation is worse than other communities in society, the majority of them are deprived of the basic needs of life. Compared to urban areas, situation of tribal living in remote area is worse [10].

Access to adequate drinking water and sanitation services is intimately linked to public health. Consumption of contaminated drinking water, poor disposal of human excreta, a lack of personal and food hygiene, and improper solid and liquid waste disposal have all been identified as causes of numerous diseases in developing nations such as India. According to the 2011 Census of India, almost 70% of India's population (650 million) lives in rural and slum areas. It increases the population's vulnerability to water-borne and vector-borne diseases. It is also due to a need for more basic sanitation facilities, contaminated water, and unsanitary living conditions.

According to the 2011 census, 40.62% of STs live in good-conditioned houses with sustainable façade designs. Meanwhile, 6.2% live in crumbling façade-designed dwellings, compared to 53.1% and 5.35% for all socioeconomic groups. The availability of drinking water portrays a dismal perception, with only 19.72% of STs having a drinking water source inside their premises and 33.59% having it outside their premises. The other group does better (46.6 and 17.6%, respectively). The hand pump is the primary drinking water source for STs and all categories—all categories (33.5%) and STs (39.2%). Tap water from treated sources is the second most available source for all social group households (32%), whereas in case of STs, it is water from uncovered wells (19.1%).

In India, 77.4% of STs do not have access to a latrine, compared to 53.1% of the general population. Only 46.9% of all homes, including 22.6% of ST households, have a latrine. Human night soil removal is still used by up to 0.3% of all households and 0.1% of ST households. While just 49.8% of total households utilize open defecation, 74.7% of ST households still practice it [2].

The disparity in terms of access to household amenities like tap water and latrine is sharp across states. While facility of tap water is as high as 89.5% in Himachal Pradesh and 85.4% in Sikkim and Goa, it is only 27.35% in U.P. Facility of drinking water within the premises is as high as 85.9% in Punjab, it is only 51.9% in U.P. The government initiated a new project supported by the World Bank called as National Rural Drinking Water Programme, which aims to provide safe, 24 7 piped drinking water supply to 7.8 million rural population in four low-income states namely Assam, Bihar, U. P., and Jharkhand that have the lowest piped water supply and sanitation facilities.

While access to and coverage of latrine facilities is only 35.7% in Uttar Pradesh, it also attempts to promote excellent hygiene and cleanliness among people by launching Solid and Liquid Waste Management initiatives in villages, towns, and cities. Since the commencement of the Swachh Bharat Mission, sanitation progress has accelerated. According to the NSSO, sanitation coverage has increased to roughly 48.8% as of December 2015. The mission's intended outcomes are the maintenance of installed toilets and their use by beneficiaries [11].

Jaiswal [12] found that more than 55% of tribes stay in *kuccha* houses façade design made of mud and natural local amenities, half of the population lack pure water; more than 60% tribal areas are not electrified.

*The State of Housing, Drinking Water, Electricity, and Sanitation Facilities of Scheduled… DOI: http://dx.doi.org/10.5772/intechopen.113046*

Bano and Ara [13] found only 22% literacy in Kharwar tribe of Sonbhadra, the majority of them (66%) were agriculturists followed by labor work (30%), mostly (92%) living in semicemented houses. Their economic status was pulling them down due to backwardness in education, lack of ideas and techniques, lack of knowledge and skill production, and inability to manage their income.

#### **4. Methodology**

All ST communities living in eastern U.P. comprised as universe of the study. Five districts of eastern U.P. namely Sonbhadra, Varanasi, Ghazipur, Deoria, and Ballia were selected randomly to conduct the study. With the assistance of health specialists and related experts, the author created a semiconstructed questionnaire based on perspectives regarding general health, education, and socioeconomic level markers. Section A contains 22 socioeconomic status questions developed by Aggarwal et al. [14], a scale suitable for all segments of society. Section B includes questions about the general health and education of the head of the household and family members. Section C contains questions about general health, education, and socioeconomic status variables. Present research project, being extensive field study, was performed by survey research method based on the primary as well as secondary data collected by observation and interview. Field surveyors used the semiconstructed questionnaire to collect the data from the study sample, which consists of selected 11,416 families residing in 474 villages of five districts. Field surveyors also subjected them to scheduled information interviews and observation techniques as needed. The secondary data were collected from the relevant published documents. Data were compiled in Excel sheet of SPSS version 16, analyzed, and subjected to vigorous statistical treatment for analysis as needed.

#### **5. Results**

#### **5.1 Housing**

#### *5.1.1 Type of house used for living in family*

Analysis of different types of houses used for living by families in study districts is presented in **Figure 1**. Most of them live in either *jhuggis* (43.9%) or own houses with 1–2 rooms (45.5%), and only 10.5% own houses with 3–4 rooms but none have five or more room houses.

#### *5.1.2 Facilities of tap water supply and electricity*

Analysis of tap water supplies and electricity in families in study districts is presented in **Figure 2**. It reveals that only 27.12% of ST families have both tap water supply and electricity and 43.7% have none of it. Sonbhadra families are without tap water supply and electricity connection is limited to 22.5% only.

#### *5.1.3 Drinking water supply source, distance, and purification status*

Analysis of drinking water supply and purity status of families in study districts is presented in **Table 1**. Most of the ST families (92.15%) collect drinking water directly

**Figure 1.** *Graph showing type of house used for living in each district.*

#### **Figure 2.**

*Graph showing water and electricity facilities in each district.*


*The State of Housing, Drinking Water, Electricity, and Sanitation Facilities of Scheduled… DOI: http://dx.doi.org/10.5772/intechopen.113046*


**Table 1.**

*Drinking water supply source, distance, and purification status.*

from hand-pump followed by submersible boring (2.94%), well (3.18%), and tap water (1.64%). Pond is still source of drinking water for 0.07% of Sonbhadra families; they are devoid of tap water supply and submersible boring. The majority of drinking water supply is within house (53.34%) or in neighboring area (36.51%), but in Sonbhadra, it is mostly in neighboring area (81.3%) or outside away (18.1%). Almost all (98.35%) drinking water supply is untreated, the remaining 1.6% is bleaching chlorinated.

#### **6. Sanitation**

#### **6.1 Facility of in-house sanitary latrine**

**Figure 3** presents family possession of sanitary latrines. Only 9.1% of ST families have sanitary latrine facility that is nil in Sonbhadra.

#### **6.2 Sanitation status out of home**

**Figure 4** presents sanitation status outside the home of family. It shows that sanitation outside the home is satisfactory in only 46.95% of families.

#### **7. Discussion**

#### **7.1 Housing**

#### *7.1.1 Type of house used for living*

Majority of ST families live in either *jhuggis* (43.9%) or their own house with 1–2 rooms (45.5%), followed by own house with 3–4 rooms (10.5%). These findings

**Figure 3.** *Graph showing in-house sanitation facilities in each district.*

**Figure 4.** *Graph showing out house sanitation facilities in each district.*

affirm the observation made by Singh that ST has very low level of physical conditions of living [1]. Sharma added that 20% of the tribal population has been uprooted and displaced within 50 years, they have lost their rights because of their political powerlessness, and the magnitude of land and number of displaced persons have been increasing since then [6].

Census 2011 data reveal that 40.62% of STs lived in good-condition houses and 6.2% lived in dilapidated houses compared to 53.1 and 5.35%, respectively, of the allsocial groups [15]. In the present study, 54% of ST families in Sonbhadra lives in *jhuggis*, which is still high in comparison to 19.57% in general population of Sonbhadra. Similar is the status of houses of ST families in other districts (Ghazipur 23.3 and 6.22%, Ballia 80.18 and 8.66%, Deoria 15.84 and 8.54%, and Varanasi 61.7 and 2.15%). Present finding is in conformity with the finding of Jaiswal that more than 55% of *Kharwar* tribe stay in kuccha houses [12]. These findings reinforce the fact related to

*The State of Housing, Drinking Water, Electricity, and Sanitation Facilities of Scheduled… DOI: http://dx.doi.org/10.5772/intechopen.113046*

houses of *tharu* made of mud and brick, using and thatching wooden rod, traditionally, *tharus* house making system, agriculture system, cooking system was based on the nature of law, which is why the environmental balance never distorted in past. Culture of tribes is eco-friendly because of their deep relation with nature, which is also reflected in their living conditions [10].

Rai [10] reported that plans (such as *Awas Yojna*) are underway for the poor in rural areas but benefits are not transmitted to the beneficiaries due to several factors, including corruption. Some tribes do not have BPL cards in spite of their eligibility, and some have BPL cards but their name is not on the BPL list therefore they do not get benefit of such plans [10]. Present finding is also comparable to the observation presented by Bano and Ara [13] that most (92%) of *kharwar* tribe live in semicemented houses [13].

#### *7.1.2 Locality of family residence*

Most of the ST families are living either in rural localities (54%) or in *jhuggis*/slums (43.9%), devoid of basic facilities to live and earn. Most of them are slum dwellers due to hill terrain (Sonbhadra 53.9%), flood-affected area (Ballia 80.4%), and urban slum (Varanasi 61.7%) because of displacement and compulsion of temporary nature of livelihood while those of Ghazipur (81.7%) and Deoria (83.2%) in rural locality. Finding in the present study shows much higher percentage of locality of slum dwelt by families in study districts in comparison to that of general population as reported in census 2011. Finding in the present study shows much higher locality of *jhuggis*/slums dwelt by families in study districts in comparison to that of general population as reported in census 2011 (Sonbhadra 54% in study and 19.57% in census 2011, Ghazipur 23.3 and 6.22%, Ballia 80.18 and 8.66%, Deoria 15.84 and 8.54%, and Varanasi 61.7 and 2.15%, respectively).

#### **7.2 Facilities of tap water supply and electricity**

Only 27.12% of ST families have both tap water supplies and electricity and 43.7% have none of it. Sonbhadra families are without tap water supply and electricity connection is limited to 22.5% only, electricity connection in Sonbhadra at the present study is comparable to that of 20.94% in general population of Sonbhadra as reported in census 2011. Electricity supply observed as 45.6% in Varanasi, 24.9% in Ghazipur, 32.8% in Deoria, and 31.3% in Ballia families is comparable to those of 62.04, 20.15, 31.64, and 24.87%, respectively, to general population reported in census 2011; hence, almost all families are lagging behind the supplies of these essentials at present. Present finding is also in conformity with Economic Survey Report (2015–2016), which mentions that the disparity in terms of access to household amenities like tap water is sharp [11]. Facility of tap water is 89.5% in Himachal Pradesh, and 85.4% in Sikkim and Goa but only 27.3% in U.P. Present finding is also in conformity with observation of Jaiswal that more than 60% of tribal areas are not electrified [12]. Both clean energy and drinking water are included in SDG and countries, including India, are committed to achieve it, but there is no desirable progress in ST families [16].

#### **7.3 Drinking water supply source, distance, and purification status**

Most (92.15%) of ST families collect drinking water directly from hand-pump followed by submersible boring (2.94%), well (3.18%), and tap water (1.64%). Only 0.07% of them collect it from pond. Drinking water sources from ponds in 0.07% Sonbhadra families and no tap water supply and submersible boring is matter of public health concern. Sonbhadra ST families use hand pumps (80.95%) comparatively higher than general population (62.2%), but no tap water against 14.57% used by general population reported in census 2011. Findings in Ghazipur and Varanasi are also comparable to census 2011 general population. Findings in Ballia are lower (mainly tap water and boring) in comparison to census 2011 general population mentioning tap water (15.56%) and boring (0.31%) [15]. Hence, present finding reveals very low achievement of piped tap water supply in ST families in comparison to general population and they are more dependent on hand pump for drinking water.

In the present study, the majority of drinking water supply is either within house (53.34%) or in neighboring area (36.51%) on average but in Sonbhadra it is mostly in neighboring area (81.3%) or outside away (18.1%). Almost all (98.35%) drinking water supply is untreated, and only 1.6% is bleaching chlorinated due to direct collection from hand pump. The current results are consistent with census 2011 data, which note that the availability of drinking water paints a dismal image because just 19.72% of STs have a source inside their buildings, while 33.59% have one outside. In this aspect, the other group does better (46.6% and 17.6%). As the primary source of drinking water, hand pumps are used by both STs and all categories (33.5%) and 39.2% of STs, respectively. For all homes in social groups, treated tap water ranks as the second most accessible source (32%), while for self-taught people (19.1%), the most accessible source is untreated healthy water.

Almost all (98.35%) drinking water supply is untreated due to direct collection by hand pump. Although government is taking steps for piped water supply, ST family lacks it due to their scattered nature of remote placed *kaccha* houses and lack of proper attention from responsible authority. Untreated drinking water taken from uncovered wells and polluted ponds is an important public health problem.

Present finding is also in conformity with Economic Survey Report (2015–2016) related to drinking water supply mentioned earlier. Facility of drinking water within the premises is as high as 85.9% in Punjab; it is only 51.9% in U.P. The National Rural Drinking Water Programme launched a new project, supported by the World Bank, to provide a safe, 24 7 piped drinking water supply to 7.8 million rural people in four low-income states, namely Assam, Bihar, Uttar Pradesh, and Jharkhand, which have the least piped water supply and sanitation facilities [11]. Jaiswal also mentioned that half of the ST population lacks availability of pure drinking water [12].

#### **7.4 Sanitation**

#### *7.4.1 Facility of in-house sanitary latrine*

Present finding of possession of sanitary latrine of only 9.1% is comparable to the national average, which mentions that in India, an exceedingly high 77.4% of STs do not have latrine facility inside the premises as compared to 53.1% of all population. However, it is very low in comparison to Government of India 2013, which mentioned that only 46.9% of all households out of which 22.6% of ST households have latrine facility within the premises and 74.7% of ST households are still going for open defecation [2]. Present finding is in conformity with the Economic Survey, 2015–2016 report that presented that only 35.7% of population in U.P. had access to and coverage of latrine facilities, which was as high as 95% in Kerala and 91% in Mizoram. Achievement of sanitary latrine in present study is dismal in spite of the fact that the

*The State of Housing, Drinking Water, Electricity, and Sanitation Facilities of Scheduled… DOI: http://dx.doi.org/10.5772/intechopen.113046*

Government of India launched *Swachh Bharat Mission* and sanitation coverage, which stood at 40.6% as per NSSO, has risen to around 48.8% (as of December 2015) [11].

As per census 2011, more than 72% of the rural population defecates in rural area, which is even more in ST population. Lack of sanitation facilities puts at risk not just public health and pollution but also security, particularly for vulnerable women, leading to severe crimes such as rape, sexual assault, and eve-teasing. Lack of sanitation services leads to pollution, health challenges, and, most importantly, security issues. Women should practice open defecation, which puts them more exposed to crime. Rape, sexual assault, or eve-teasing frequently occur in the dead of night, and the screams of anguish are never heard [15].

Sonbhadra ST family in the present study did not possess sanitary latrine in contrast to that of 25.83% in general population. All of Sonbhadra ST still go for open defecation in contrast to 74.18% in general population of Sonbhadra as reported in census 2011. Possession of sanitary latrine in the present study in Ghazipur (18.5%) is still lower in comparison to 21.89% in general population of Ghazipur reported in census 2011. Possession of sanitary latrine in the present study in Ballia (2.9%), Deoria (11.1%), and Varanasi (10.1%) is still very low in comparison to 26.88% in general population (26.98, 22.8, and 55.91% as reported in census 2011. Figure of open defecation by ST families in the present study (Sonbhadra 100%, Ballia 97.1%, Deoria 88.9%, Ghazipur 81.5%, and Varanasi 89.9%) is still higher than that of general population (74.18, 77.2, 77.75, 76.69, and 43.83%) as reported in census 2011 [15, 17].

#### *7.4.2 Sanitation status out of home*

Sanitation of neighboring surrounding is unsatisfactory in 53.05% of families. Census of India 2011 revealed "lack of basic sanitation and unhygienic living conditions, as around 70% of India's population (650 million) lives in rural and slum area." Present finding of poor sanitation in surrounding is associated with location of their residence predominantly in slum area/*jhuggi* (43.9%) and rural locality (54%) having unhygienic drainage and surface sanitation as well as their nonpossession of sanitary latrines (90.9%) leading to open defecation [15]. Jaiswal also reported that they do not have any proper sanitation facilities. Their knowledge of health and sanitation is very poor, they are poor at cleaning their own house [12].

#### **8. Conclusion and recommendations**

Most ST families still live in either *jhuggis* (43.9%) or own houses with 1–2 rooms (45.5%); they are living either in rural locality (54%) or in slum (43.9%), devoid of basic facilities to live and earn. Such poor conditions due to the terrain of hill and flood, displacement, and compulsion of temporary nature of livelihood; low standard locality is due to the effect of forced migration and urbanization. Although welfare plans such as subsidizing housing like *Lohia, Indira, Kashiram Awas Yojna. PM Yojna* exists for poor in rural areas, but tribes are not getting benefits; their housing condition continues to remain worse compared to previous census data and other social categories. Some tribes do not have BPL cards in spite of their eligibility; therefore, they do not get benefit of such plans.

Only 27.12% of ST families have both tap water supplies and electricity and 43.7% have none of it, facilities are much lower than general population; this disparity is more marked in Sonbhadra. In spite of the government's commitment to achieve both clean energy and drinking piped water as part of SDG, benefit is slow among ST families in eastern U.P. They have very low (1.64%) achievement of piped tap water supply in comparison to general population and they are more dependent on hand pump (92.15%) for drinking water. Digging of small pit in the land locally called "*kuhaad,*" which collects water from drains and spring in it, along with pond water (0.07%) in Sonbhadra district pose their exposure to contaminated water not only with germs but also excess iron, fluoride, and heavy metals, leading to deformity and increased mortality [18].

Access to drinking water source is only 53.34% within home and they are dependent on neighbor as high as 81.3% in Sonbhadra, which remain distant compared to general population in spite of drinking water mission. Almost all (98.35%) drinking water supply is untreated due to direct collection by hand pump. It is due to the scattered nature of remote placed *kaccha* houses and lack of proper attention from responsible authority. Necessary corrective measures are needed to provide pure potable water to address highly prevalent water-born public health problem.

As high as 77.4% of STs do not have latrine facility inside the premises as compared to 53.1% of all India and 64.3% of U.P. general population, and achievement of sanitary latrine is dismal in spite of the *Swachh Bharat Mission*. Figures of open defecation by ST families are still higher than general population reported in census 2011 and it is a matter of great concern, a problem throughout the Indian subcontinent. It poses not only public health and pollution problems but also security problems especially for vulnerable women leading to serious crimes such as rape, sexual assault, and eve-teasing. Provision of adequate sanitation facilities will lead to improvement not only overall status but also reduction in serious crimes against the weaker society, which is still very high among these communities. Sanitation in their neighboring area is unsatisfactory in 53.05% of families mainly due to unhygienic drainage and surface sanitation in slum area. The construction of drainage system, village sanitation infrastructure, personal toilets, and the environmental measures to control mosquito breeding should be included in the MGNREGA scheme and completed on priority basis in Scheduled Areas [15, 19, 20].

Due to low education and economic factors, tribes are victims of inequality, exploitation, and oppression. Tribes of backward eastern U.P. are living in conditions of deprivation; their economic condition due to subsistence low level of economy and standard of living are very low, as most of them do not have land, assets, and education. Protective developmental measures have not yielded any remarkable impact on tribal development; special budget provision remains unutilized largely. Although rich limestone hills in Sonbhadra have given establishment of cement and other allied factories and giant thermal plants, native tribes are not getting desired benefit. The low representation of tribes to the total population often excludes them from development processes hence their adequate political representation is required for their uplift and empowerment. There is an urgent need for robust institutions to not only bridge wide gaps between ST and general population in rapidly changing socio-economic conditions but also strengthen social inclusion.

#### **Acknowledgements**

I would like to acknowledge the IOE Banaras Hindu University and Indian Council of Social Science Research, New Delhi, and express my special gratitude for collaboration. I wish to thank various people for their contribution to this project.

*The State of Housing, Drinking Water, Electricity, and Sanitation Facilities of Scheduled… DOI: http://dx.doi.org/10.5772/intechopen.113046*

#### **Funding**

The author received financial support from Indian Council of Social Research, New Delhi for the research of this article.

#### **Declaration**

The author declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

#### **Author details**

Poonam Singh Kharwar<sup>1</sup> \*, Devesh Kumar<sup>2</sup> , Abhishek Kumar<sup>3</sup> and Abhinav Kumar<sup>4</sup>


© 2023 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Section 2
