Principles of Design for Sustainable Group Housing Projects in India

There are three rating systems available to assess the sustainability of Group Housing in India provided by three agencies, namely the Indian Green Building Council (IGBC), Green Rating for Integrated Habitat Assessment (GRIHA), and Eco Housing Assessment Criteria's. The parameters for all three rating systems have some differentials. The building rated under one rating system may not obtain a rating under another rating system. It means that designers' attention is restricted to the rating system's criteria and has lost the sustainable design process's true spirit. This paper aims to establish the Principles of Design that meet all the rating system's maximum criteria. The methodology followed for this paper includes a brief review of all rating systems and a comparative analysis of similarity and dissimilarity to understand the key focus areas of all three rating systems. The Principles of Design are applied to fulfill all the three-rating system requirements with each focus area. The applications of design principles in the project indicate that only a certain number of Principles of Design are applied to achieve the rating system in each project, and many Principles of Design are overlooked. This was due to the designer's approach to sustainable buildings as a product based on the rating system. The Principles of Design generated in this paper will be a ready source of guidance for India's sustainable housing design. The designer should initially approach sustainable design as a design process and, later on, achieve a sustainable design for a specific rating system.


Introduction
India's population has multiplied over the last few decades. There is a shortage of facilities in India at all levels; India's lack of accommodation is a significant problem. This housing shortage is more critical in urban centers due to rapid urban growth of 2.8 percent over 2001-2011, resulting in a rise in urbanization from 27.8 percent to 31.2 percent. Out of the 1.2 billion Indian population, the urban population is 377 million. The report submitted by the technical committee of the Ministry of Housing and Urban Poverty Alleviation (MHUPA) in 2012 estimated almost 18.78 million household shortages in India. [1] Rapid urbanization has put too much pressure on the city's finite resources. It has led to a shortage of essential services like potable water, sewage network, sanitation facility, electricity roads, waste disposal, and many more. Rapid urbanization has led to the destruction of green covers and water bodies. [2] The housing sector has a large share of rapid urbanization.
It is not possible to control the rapid urbanization. The only choice left to minimize the worst impact of rapid urbanization through sustainability. Sustainable Housing has an excellent opportunity to foster economic growth, environmental stewardship, quality of life, and social equity. [3] Sustainable housing would also reduce urban slums, harmful effects on climate change, and natural resources.

Aim
To generate principles of design of sustainable housing in India based on the rating system and understand the application of these principles of design in creating sustainable housing.

Objectives
a) To study the different concepts of sustainable development, the domains of sustainable development, the general principles of sustainable design. b) To study an overview of India's rating system for housing projects such as LEED, GRIHA, and Eco-Housing Assessment Criteria. c) To generate principles of design of sustainable housing in India based on a rating system. d) To understand the application of these principles of design in creating sustainable housing.

Significance of the Study
1. This study will provide the design principles for sustainable housing to meet all three rating systems' criteria. 2. This study will provide a concise form of sustainable design principles for architects, architectural students, owners, builders for ready reference rather than comprehensive and complicated rating systems. 3. The design principles for sustainable housing are not available in a standard format and are described by various authors based on their experience and expertise. The design principle based on the rating system of this paper will be treated as a standard format.

Scope and Limitation
This research is limited to a multi-story group housing project with low-rise and mid-rise apartments and does not cover high-rise housing projects. The principles of design for sustainable housing only overview and further in-depth study is required of these design principles by other researchers. This study deals only with the environmental domain of sustainability.

Sustainable Rating System of Housing in India: An Overview
It is essential to understand the basic definitions of sustainable development, the domain of sustainable development, and the principles of sustainable design to understand India's sustainable rating system, especially in the context of sustainable housing principles of design.

Definitions of Sustainable Development
Sustainable Development is a vast domain. There are various definitions available for sustainable development, which are described below: a). Defined as "the continued ability of a society, an ecosystem, or any such interactive system of function without exhausting key resources and without adversely affecting the environment." b). "Development that meets the needs of the present without compromising the ability of future generations to meet their own need"-from the World The term "Sustainable design "is an extensive discipline that encompasses various fields, including product design, architectural design, interior design, graphic design, and many more. Sustainable design is a design process that can integrate an environmentally friendly approach and consider natural resources as part of the design process. Mr. Smith Lewis defines sustainable design in the architectural sector as follows: "Sustainable design is the practice of designing buildings in such a way that they function in harmony with natural systems." [13] According to Jason F. McLennan, "The Philosophy of Sustainable Design," 2004, there are six principles of sustainable design, as listed below: [14] i. Learning from natural systems (Biomimicry Principle) ii.
Respect for energy & natural resources (Conservation Principle) iii.
Respect for people (Human Vitality Principle) iv.
Respect for a place (Ecosystem Principle), v.
Systems thinking (Holistic Principle) H.P. Thanu and Dr. C. Rajasekaran, in their research paper titled "Comparative study on Indian building assessment tools and its limitations," discussed assessment approaches of different rating system for environmental, economic, and social aspects of sustainability. The study concludes that there is a considerable gap between sustainable building assessment tools at the regional level, and the implementation of international tools in India would have shortcomings. They also conclude that these rating systems are useful for streamlining the process but do not reliably calculate the environmental effect of Building Energy. [9] Iliyas Ikbal Sande and N. S. Phadtare, in their research paper titled "Comparative Study of LEED and GRIHA Rating System," disused assessment methods; scopes, and performance criteria, and energy rating scales of LEED and GRIHA rating system. The study concludes that both rating systems have different parameters, so there is a possibility that the same building rated differently. The rating systems are complicated and do not offer a clear picture of project sustainability effectiveness, often confusing the architects and builders. The study recommends a simple and straightforward agenda for small contractors to understand and implement the project's rating system. [10] Thus, to conclude, the rating systems do not have similar criteria and do not guarantee the implementation of all sustainable design points. These are very complex and difficult for stakeholders to understand. Their effectiveness in the Indian context, particularly with so much regional variation, is highly questionable. There is a need to develop a single rating system that completely blends all aspects of sustainability.
The literature review may also conclude that no study has addressed design principles based on comparing rating systems to include all parameters. There is still no specific study available for housing-specific rating systems. This study will be unique to address all the criteria of three rating systems in one, and also, this study will be first to discuss the rating system specific to Housing.

Methodology
The primary purpose of the methodology is to fulfill the aim and objectives of the research problem. The rating system does not cover the entire spectrum of sustainability, so there is a need to establish sustainability and sustainable design vision in the Indian context through literature review. The literature review helps to discuss the different concepts of sustainable development that ultimately help recognize sustainability in a broader sense. The definitions of sustainability discussed in the paper are not provided by individuals but are defined by different commissions at the international level. The different domains of sustainability and sustainable design principles have been discussed in this paper through the literature review.
The various broachers and manuals available for housing rating agencies, such as IGBC, GRIHA, and Eco Housing Assessment Criteria, are used to study the various sustainable rating systems. The rating agency divides the entire manual into different parts, and further, these sections are divide into different criteria, and the points are allocated to each criterion. It is essential to study the priority of the different sections available in the rating system. The rating system is studied based on the different significant sections divided by the rating agencies, the number of criteria and points available in each section, and the weighting of the percentage of those sections. The certification process was also addressed quite briefly.
All rating systems have similarities and differentials in different sections, their weighting. The comparative analysis is essential for understanding similarity and dissimilarity and to list all the areas of focus of the different ratings, the weighting provided by each rating system in these areas of focus. For further study of the detailed rating system, focused areas are defined.
The rating systems treat design as a product, and Principles of Design treat design as a design process. Therefore the conversion of the criteria of the rating system into Principles of design is essential. All rating systems are compared under focused area site planning, energy consumption and daylighting, sustainable building materials, water conservation, and waste management. All other focused areas will be put in under the Miscellaneous head Categories. The Principals of design have been worked out to address all criteria under each rating system.
The case studies are performed to understand the applicability of Principals of Design in Housing projects. All case studies selected are small-site projects of not more than 5 acres, low-rise, and medium-rise housing projects. In the one case study T Zed homes, selected for IGBC ranking, the author had visited the site personally and interacted with users. The other two case studies are the latest GRIHA's rated housing project and are carried out through a literature review. Case studies are explored in all focused areas, as discussed in the Principles of Design, such as site planning, energy and daylight use, sustainable building materials, water conservation, and waste management.

Analysis and Discussion
The analysis and discussion are divided into three parts; the first part consists of defining the focus area of the study using a comparative analysis of the rating system; the second part consists of drawing up the concepts of sustainable housing design through means of a detailed comparative analysis of the rating system in a targeted area. The third part consists of studying the applications of these derived principles of design in sustainable housing projects.

Analysis of Sustainable Rating Systems for Housing in India
There are agencies such as the Indian Green Building Council (IGBC), the Green Rating for Integrated Habitat Assessment (GRIHA), the Eco Housing Assessment Criteria, which evaluate sustainable designs for different parameters and offer various building certifications, as shown in Table 2, Table 4 and Table 6. They are called the rating system, and these agencies are called rating agencies. These evaluation systems remain silent on the design process and are more interested in the product; of course, many design processes have recently been integrated into the GRIHA rating system. However, it is not easy to identify sustainable design principles through the rating system, so there is a need to establish design principles to fulfill all the rating system specifications.

IGBC Rating System for Housing
Indian Green Building Council (IGBC) has launched the rating system, the name of "IGBC Green Residential Societies recently." IGBC Green Residential Societies rating system consists of six sections, namely Green Facilities, Operation and Maintenance, Water Management, Energy Conservation, Waste Management, Resident Health & Wellbeing, Exceptional Green Practices as shown in Table 1. [15] Table 3. There are 30 criteria and a total of 100 points under these six sections. Out of these 30 criteria, three are mandatory, eight are partially mandatory, and others are optional. [16]  The various ratings are awarded as per the following table.  The rating system's comparative analysis of the focused area is given below to understand all three rating systems' similarity and dissimilarity, as shown in Table 7. It is concluded that four focus areas tend to be similar and that other focus areas are different. The Sustainable Building Materials are standard in two rating systems, and it can be included as one more focus area. Hence, five common focused areas will be studied in the rating system, and all other focus areas will be put as a Miscellaneous category. There will also be a similarity and dissimilarity between different rating systems for the selected five focus areas that will be addressed while generating design principles for sustainable housing in the next section.

Principles of Design for Sustainable Housing in India Based on Detailed Comparative Analysis of Various Rating System in India
The analysis of the rating system suggests that not all three rating systems have the same standards for housing ratings. Many criteria are similar in all three rating agencies, and many are entirely different. All criteria need to be included in the Principles of Design for Housing so that specific housing is suitable for sustainable housing under all three rating systems. There are five core design-focused areas, i.e., site preparation, energy consumption and daylighting, sustainable building materials, water conservation, waste management, and the other focused area will be put in under the Miscellaneous head Categories The various criteria related to the Selection of sites of all three rating systems are shown in Table 8. The various criteria related to Natural Features, Landscaping, and Soil Conservation of all three rating systems are shown in Table 9. The planning and construction should be carried out in such a way as to retain natural elements such as dense tree clusters, water sources, topographical features such as steep slopes, or peaks. iii.
The plants may be removed for construction; they may be transplanted if necessary. If it is appropriate to remove a few trees, the new trees must be planted at a ratio of 1:5. iv.
The topsoil is very important to preserve because It has fertile value for all types of vegetation.
During the construction, this topsoil should be preserved at some location and used for vegetation later on.

Utility Corridor and Site Circulation
The various criteria related to the Utility Corridor and site circulation of all three rating systems are shown in Table 10.  Surface shading is essential to minimize the heat effect of the island; at least 50 percent of non-roof impervious surfaces should be shaded on-site, including parking lots, walkways, and plazas. iii.
At least 50 percent of the overall paved surface of the area should have a reflectance of .5.

Renewable Energy Sources
The various criteria related to Renewable Energy sources of all three rating systems are shown in Table 12. There should be renewable energy sources of 1kWp per 500 sqm of total built-up area. iii.
All motors and transformer should be at least a 3-star BEE rating. iv.
Automation is recommended for outdoor lighting to minimize the saving of energy. v.
It is highly recommended that the lighting fixture be used not to create light pollution, which may not be suitable for humans, trees, and animals. For more significant projects, a lighting consultant should be appointed. vi.
The solar water heater should be used in the Housing campus and other similar projects per project requirements.

Energy Consumption and Daylighting
The various criteria related to Energy Consumption and Daylighting of all three rating systems are shown in Table  13. The orientation of blocks should also be done to allow optimize the wind flow in all units.
iii. The distance between blocks should be calculated to allow winter sun and stop the summer sun. The mutual shading and self-shading of blocks should be worked to ensure minimizing the heat gain in summers. iv.
The units should be oriented in such a manner to reduce heat gain in summer and allow heat gain in winter. v.
The surface to volume and perimeter to area ratio should be calculated, and it should be minimum to have a less exposed area in a hot climate. vi.
The staircase, toilets, etc. should act as buffer spaces to reduce heat gain for the main areas such as living, dining, bedrooms, etc. in summers. vii.
The window size should be determined based on the amount of light required and the amount of wind needed in a building. viii.
The shading of the window and another opening should be done as solar path analysis. ix.
All areas should be designed in such a manner to receive a sufficient amount of light. 1 daylight factor = 80 lux. Kitchen=2.5 Living = .625 Study Room = 1.9 Circulation = .313 etc. x.
The computer simulation tools may be used to check thermal comfort by measuring the airflow, temperature, and humidity.

Sustainable Building Materials
The various criteria related to Sustainable Building Materials of all three rating systems are shown in Table 14.
Design Guidelines: i.
The used materials should have low embodied energy. ii.
The life cycle assessment of materials should be compared in selecting the materials. iii.
The material should be environmentally friendly and do not harm the environment. The used material to have low carbon emissions and comparative analysis should be done before selecting the material. iv.
The R-value and U value are significant in selecting the materials so that these can act as good insulation materials v.
The use of pozzolana material along with cement for R.C.C and other purposes should be encouraged. vi.
Alternative structural systems such as Ferro cement and/or pre-cast components should be used for columns, beams, slabs, staircases, lofts, balconies, and roof. vii.
The convention bricks should be avoided, and the alternate building materials should be used, e.g., fly ash bricks, lime bricks, industrial waste bricks, aerated lightweight concrete blocks, gypsum-based blocks, lato blocks, etc viii.
The use of natural wood should be avoided, and the new low energy, recycled material should be used. To promote the installation of low environmental impact materials in the building interiors and reduce the usage of virgin material. iii.
To promote the use of low-VOC and lead-free interior paints; low-VOC adhesives and sealants; composite wood product without urea-formaldehyde to maintain good indoor air quality for the occupants.
IGBC i. Use certified green building materials, products, and equipment, to reduce dependence on materials that have associated negative environmental impacts ii.
Provide occupants with descriptive guidelines that educate and help them implement and maintain green design features Eco Housing i.
To reuse /recycle waste products and prevent landfills. ii.
To reuse /recycle waste Products iii.
To reuse /recycle waste products and prevent landfills. iv.
To use lesser quantities of materials and to reduce site wastages, thus reducing the amount of resource extraction. To promote the use of traditional/vernacular construction techniques v.
To use energy-efficient building material and materials from renewable sources Source: IGBC, GRIHA, Eco Housing Assessme nt Criteria's Manual To reduce the overall water demand of the building through system optimization, which includes the installation of water-efficient systems such as low flush toilets equipped with dual flush functionality and water faucets with aerators. Additionally, this criterion emphasizes on reducing the landscape water demand through the use of regionally appropriate, xerophyte (low water using native species of flora) plant species and efficient irrigation systems iii.
To ensure the availability of appropriate facilities for tertiary-level treatment of wastewater generated, artificial groundwater recharge and rainwater storage; and maximum utilization of treated and harvested water within the project site to reduce the overall dependence on freshwater supply from concerned authorities iv.
To ensure that a monitoring mechanism is in place for the supply of freshwater from concerned authority and at STP outlet line IGBC i. Enhance groundwater table and reduce municipal water demand through effective rainwater management ii.
Encourage continuous monitoring to enhance the water performance of the residential society, thereby save potable water iii.
Measure and reduce the per capita water consumption in the residential society, thereby saving potable water iv.
Enhance the efficiency of water fixtures, thereby minimizing potable water use v.
Treat wastewater generated on-site, to avoid polluting the receiving streams by safe disposal and reduce the burden on Centralised municipal water treatment plants vi.
Reuse of treated wastewater to meet the Landscaping / Flushing demand or both. The greywater and black water of sewage may also be treated in a treatment plant. The water should be reused after treatment for various purposes such as flushing and landscape etc. iii.
The water consumption should be minimized during the construction.
iv. All fixtures and faucets should have low flow rates not exceeding 8lpm. v.
All W.C to be provided with a dual flush system to avoid wastage of water. vi.
The native species should be planted to consume less water, and the gardening area should be minimized to reduce the water for landscaping. vii.
There should be a sprinkler and drip irrigation system for outdoor landscape areas to reduce water consumption.

Waste Management
The various criteria related to Waste Management of all three rating systems are shown in Table 16. Ensure effective organic waste management, so as to prevent waste being sent to landfills. iii.
Ensure effective dry waste management, so as to prevent waste being sent to landfills.
Eco Housing i. To efficiently manage wastes and recover resources, Segregation of waste at source/ Reduce the quantity of waste to be collected by the local urban body, To adopt scientific methods for designs of collection /storage bins from a public health point of view. ii.
To efficiently manage the wastes and recover resources. iii.
To promote ' Zero Wet Waste' concept To efficiently manage the wastes and recover resources iv.
To promote the ' Zero Wet Waste' concept and Recover resource Source: IGBC, GRIHA, Eco Housing Assessment Criteria's Manual Design Guidelines: a). There should be Segregation of solid waste and other waste at the source. b). There should be a proper procedure to be worked out to collect the waste, and the schedule must be worked out to dispose of different kinds of waste. c). On-site treatment of organic waste should be done in large housing complexes. Energy and manure should be recovered from waste. d). Construction waste should be utilized on-site as much as possible. e). Spill prevention and control plans should be made to stop the source of the spill, contain the spill, and dispose of the hazardous waste and contaminated materials.

Miscellaneous
Design Guidelines: a). There should be proper safety measure during the constructions for workers b). The noise control and air pollution should be taken care of at the time of construction activity. c). There should not be any contamination of the water table and a minimum standard of living for construction workers. d). There should be at least two techniques to reduce water consumption during construction, such as using treated water or rainwater for construction activities or using an additive to reduce the curing water. e). To promote the adoption of a measure for the project to make it universally accessible. f). To create awareness of sustainability among the residents and visitors. g). There should be proper sanitation /safety of construction workers on-site, and there should be an appropriate mechanism to reduce the air pollution on-site during construction.

Case Studies: Applications of Principles of Design for Sustainable Housing in India
The three case studies were chosen to analyze the applications of the derived Principles of Design (as mentioned in the last section) for a housing project; the first case study Tzed homes, Bangalore, is considered to be a live study due to site visits and interactions with users of by author; the other two case studies are conducted through the internet.

Case Study 1: Tzed Homes, Bangalore (Live Study)
The project statistics of T-ZED Homes, Bangalore, are shown in Table 17.  The parking is offered in the sunken courtyard, open on the driveway, and connected to other sections of the ground. It did not feel like a basement, and no artificial means are required for lighting and ventilation at this parking level, as shown in Fig 2. This can be considered a good save on electricity than parking in the basement, causing more electricity usage. [18] d). Landscaping: The site is very linear. The plot is divided into two zones, the north zone, and the south zone, by a road on the central axis. In the southern section, the blocks are deliberately situated a little farther apart, and the landscape areas have been worked out between the blocks, called the e-zone, as shown in Fig 3 & Fig 4. There are recreational zones for children's games, seating areas, etc. Thick vegetation and other features of the landscape are planted in this area. [19] Fire tender road is a mandatory requirement all around the site, and it can be used only in case of fire. This fire tender road is almost at the road level of entrance, so the residents do not use it for parking. This road is landscaped so that only the part of the wheel is paved, and the in-between space is treated with grass, as shown in Fig 5. Source: Gaurav Gangwar  75% of the total construction waste is recycled or reused on-site, which is an excellent achievement and also reduced the construction cost. Approximately 82% of the total material used was manufactured and extracted regionally to minimize transport costs and reduce environmental pollution. [18]

Energy Consumption and Day Lighting
The design of the building is incorporating passive principles of design to ample daylight available at every home. [19] The orientation of the four-story blocks is so that the longer axis is facing north-south, and the opening in the units is facing north and south, as shown in Fig 6. This will allow for less heat gain in the summer and more heat gain in the winter. This will also affect the lower energy usage within the building. [18] The unit plans' arrangement has more opening of the room faces to the north and south, as shown in Fig 7. There is a bedroom, a dining room, a kitchen on the south side, a living room facing east, and the other rooms facing north. This also allows the proper daylighting in all rooms, and 87% of regularly occupied spaces have necessary daylight. The soil stabilized blocks, laterite blocks are used on exterior walls that provide good thermal insulation and long-lasting materials, as shown in Fig 8. To reduce cement and steel used, filler slabs are used in the roof and fly ash blocks. Rubberwood, non-forest wood, is used in place of natural wood for door shutters and flooring. These are local materials that use less incarnated energy and are very useful for reducing carbon emissions. This has saved roughly 20,000 tonnes of carbon emissions in savings capital and 1500 tonnes of carbon emissions in operational savings. This may be the first residential project to seek credit from CER, as stated by BCIL. [19] Source: Gaurav Gangwar

. Water Conservation
There is no sewage connection on this campus. All black water from the toilet and bathroom continues to the sewage treatment system, where the decomposition of 70% of the biological matter is by anaerobic processes, as shown in Fig 9. [19]  All wastewater (greywater) is treated in the plant, as shown in Fig 10, filtration, aeration, and ozonization. This usage of treated wastewater is in the water closet of individual housing units and gardens. 95% of the wastewater is reused. [17] Low-flow dual-flush toilets, sensor-based urinals, and other low-flow fixtures are installed to minimize water consumption by 20%. [19,20] 4.3.1.6. Solid Waste Management Solid waste segregation is done as per the different categories of waste, as shown in Fig 11. The first category of waste is plastic, metal, and tetra pack; second is paper and cardboard, third is newspapers, fourth is digester (kitchen waste), the fifth is e-waste, and sixth is glass bottles. A proper schedule worked out the collection of different categories of waste. The digester is collected daily, and e-waste is collected only once a month. Similarly, the other schedule has been worked out for other waste categories. [21] The waste from the kitchen is divided into two parts: organic and inorganic waste. Organic waste goes to vermicomposting pits where it has been processed into Vermicompost, a nutrient-rich natural fertilizer, and a soil conditioner. This fertilizer is used in the garden. [19,20] Source: Gaurav Gangwar Figure 11. Container for Solid Waste Management

Case Study 2: Palladio, Pune (Internet Study)
The project statistics of Palladio Pune are shown in Table 18. For soil erosion control on-site, appropriate measures have been adopted, and the fertile topsoil was preserved for the use of vegetation. The existing mature trees have been protected and preserved on site. The services are planned in such a manner to create a minimum disturbance on site. [22] Source: https://www.javdekars.com/projects/ongoing-projects/palladio-wakad.ht ml

Energy Consumption and Daylighting
The planning of all residential units around the landscape area on the podium layout takes care of daylighting., as shown in Fig 12. Openings were sufficient in size for daylight, and 85 percent of the habitable spaces had proper daylight. [22] Various techniques such as horizontal shading devices, balconies, and treatment in terraces, appropriate glazing to reduce heat, reduces the direct heat gain by 45%, as shown in Fig 13. Fly ash bricks are used for enveloping and application of heat-reflecting paint on the roof to minimize heat gain. [22]

Water Conservation
The installation of the sewage treatment facility on-site for wastewater treatment, and its usage is for landscaping. Native plant species are used for land use to reduce water needs, and a drip irrigation system is used to allow effective use of water for landscaping. There is a reduction of approximately 55.74 percent of water demand for landscaping. [22] There is a provision of low-flow fixtures, and the use of STP Treated water for flushing through dual flush reduced the building water demand by 25.93 %. There is rainwater harvesting provision of recharge pits to collect 100% runoff from the groundwater recharge roof. [22]

Sustainable Building Materials
Fly ash was added in Ordinary Portland cement (OPC) and Rich Mixed Concrete (RMC) to reduce cement and better strength. [22] There is the use of recycled steel and fly ash bricks for building. Fly ash based on PPC and mortar is used, including the use of plaster containing toxic waste. [22] There are aluminum window frames and vitrified tiled having recycled contents, low -VOC paints, adhesives, and sealants are used in construction. [22] 4.3.3. Case Study 3: Devraai Phase -II, Pune The project statistics of Devraai, Pune are shown in Table 19. The site area is very small, still the 51 no native species of tree planted along the periphery of the site to enhance biodiversity as shown in Fig 14. [23]

. Energy Consumption and Day Lighting
The window wall ratio (WWR) was maintained at 14.39 percent for good daylight in the building as a visual connection between the occupant and the outside environment, as shown in Fig 16. Approximately 85 percent of the habitat spaces are well lit and comply with the daylight factors specified by the National Building code of India. [23] The longer face is facing east and west, as seen in Fig 15, so there are double walls built on the envelope to minimize heat gain, and several energy-efficient steps have taken to reduce the Energy Performance Index (EPI) by 84.5 percent, i.e., 15.5 kW / m2 / year compared to the GRIHA benchmark EPI. [23] A solar hot water system has been installed to offset 96% of the conventional demand for hot water to reduce conventional energy demand. There is an installation of 3 kW solar panel capacity to meet the building's common area lighting requirements. [23]

Sustainable Building Materials
There were Fly ash bricks with a minimum content of 70.89 percent of ash for 100 percent of the total volume of bricks. Portland Pozzolana Cement (PPC) with a fly ash content of 30% by weight was used in the plaster and masonry mortar project. [23]

Water Conservation
The installation of low-flow plumbing fixtures lowered the demand for building water by 34 percent compared to the GRIHA baseline. The installation of a drip irrigation system saved 75% of the landscaping water demand. [23]

Conclusion and Recommendations
The study of the rating system suggests that there are similarities and dissimilarities in all three rating systems. The similarity and dissimilarity are seen in the comparative study of the rating system. The creation of Principles of Design is to meet all the criteria of the three rating systems. There are five focus areas for sustainable design principles, namely site planning, energy and daylight use, sustainable building materials, water conservation, and waste management. The other areas are grouped under the miscellaneous heading.
Tzed homes have a Platinum rating, the highest in IGBC ratings, which is the best practice of IGBC in this paper. The Palladio is again not a very large project and has earned a 4-star rating that is one step below the highest rating in GRIHA. Devrrai Phase -II received a 3-star rating despite a minimal project, and there is not much scope for site planning. The three case studies carried out in this paper indicate that there are different parameters for each study due to a variety of factors, such as the designer's approach to achieving a specific rating system and considering sustainable building as a design product, project estimation, project site potential, and other factors. It is not the designer's responsibility since the client wished to achieve a specific rating system, and the designer should meet the requirements of a specific rating system. The designer's role has become minimal, and many Principles of Design for proper Sustainable Housing have been overlooked. The Principles of Design outlined in this paper serve as a ready guideline for designers to implement the maximum Principles of Design to determine the true spirit of sustainable design and obtain the building rating. It is advised that other researchers could further explore the Principles of Design.