Environmental performance and adaptation of chawls of Mumbai by msc.exhibition2019

Environmental performance and adaptation of chawls of Mumbai

University of Westminster, College of Design, Creative and Digital Industries School of Architecture and Cities MSc Architecture and Environmental Design 2018/19 Sem 2&3 Thesis Project Module

Tanvi Bobhate September 2019

Figure 0.1 Functional and adaptive passive design strategies in Verandas of Chawls. (Source: Author)

ABSTRACT

With the emerging urbanisation in Mumbai city, there still resides some of the old housing typologies including Chawls. Chawls represent society in the chaos of the city. During the change in time and contextual conditions, the chawls evolved. This urban vernacular Typology is very distinctive in terms of environmental design. In this study, the correlation between the changing lifestyle, use of the communal space and occupant’s comfort in chawls is aimed. Considering this aspect, the analytical work is conducted contemplating occupant’s concerns and devised adaptive solutions. The study focuses on achieving outdoor and indoor comfort in chawls to encourage the activities in communal spaces. It compares the performance in evolved chawls using dynamic thermal simulations and later to be improved using user adaptable and passive strategies. As the chawls are outdated and not maintained well, today they are demolished to be replaced by the high-rise building. Chawls cannot contain the density of a high-rise, but the transition from the “open-door culture” to “closed-door culture” is disappointing for the residents. Hence, this study further analyses the form of the building as a solution for density and environmental comfort. The form is evaluated in different orientations and height to width ratios. The research is conducted to resolve the chaos and concerns to improve the living of the society which indirectly affects the urban environment as well.

TA B L E O F C O N T E N T

   1.

ABSTRACT TABLE OF CONTENT ACKNOWLEDGMENTS INTRODUCTION 1.1 General Background 1.2 Contextual Background 1.3 Statement of Problems 1.4 Hypothesis 1.5 Research Methodology 1.6 Research Outcomes 1.7 Structure

LITERATURE REVIEW 2.1 Thermal comfort in Tropical climate 2.2 Climate responsive Design 2.3 Transitional and Social spaces 2.4 Chawls in Urban Mumbai 2.5 Urban Density in Mumbai 2.6 Conclusion and Research questions

CONTEXT AND PRECEDENT STUDY 3.2 Climate of Mumbai 3.3 Precedent study of Chawls 3.3.1 History and Evolution of Chawls 3.3.2 Typology Study 3.4 Precedent study for Building evaluation

FIELDWORK 4.1 Methodology 4.2 Case study – Tarabaug Estate Chawl 4.3 Qualitative analysis 4.3.1Observations 4.3.2 Occupancy 4.4 Quantitative analysis 4.4.1 Survey 4.4.2 Data loggers 4.5 Conclusion

ANALYTICAL WORK 5.1 Methodology 5.2 Indoor Comfort 5.2.1 Two Scenarios 5.2.2 Impact of Overhang 5.2.3 Thermal Analysis 5.3 Outdoor Comfort (Transitional Spaces) 5.4 Upgrading chawls 5.5 Design study 5.5.1 Massing Level 5.5.2 Unit Level 5.5.3 Design Recommendations

6.   

CONCLUSION REFERENCES APPENDICES AUTHORSHIP DECLARATION FORM

ACKNOWLEDGEMENT

It is a sincere pleasure to express my appreciation and gratitude to my Tutor Joana Carla Soares and Gonรงalves. Her support, prompt feedback, and ideas helped me in developing my dissertation. I would also like to express appreciation to our course leader Rosa Schiano Phan who guided and constantly supported us throughout the academic year. I am grateful for the exceptional tutors Kartikeya Rajput, Amedeo Scofone, Juan Vallejo for their valuable feedback and technical tutorials. Also, I appreciate Architects and Urban Planners from Mumbai Sulakshana Mahajan and Neera Adarkar for having brief discussions about my dissertation. Finally, I would to like thank my parents and friends for being supportive and helping me all the way through.

Figure 0.2 Life in chawls from book “Batatyachi Chawl” (Source: Google)

1 introduction

1.1 GENERAL BACKGROUND An urban planner in Mumbai points out, “Ultimately, any city or society is judged by how they treat those who aren’t privileged.” (Mehrotra, 2019)

Passive design is “using a house in a nomadic way”, which is described as housing different parts of the settlement in different times of the day. (Correa, 2013) The vernacular passive architecture of India is a big part of the distinguished Indian culture. The spaces in between these buildings are designed to bring residents and communities together. These collective spaces articulate the social as well as private functions as required by the context. The customs of the Indian civilization are based around these communal spaces. The socio-cultural connection in the settlements are as significant as the physical attributes of the built environment. These housing typologies still exist to represent the society, chawls being one of them from Mumbai. In warm and humid climates, the buildings and urban formation is organised to self-shade and ventilate more. The courtyards in chawls are distinctive than the larger courtyards in palaces or larger establishments. The main purpose of courtyards in chawl can be expressed as private narrow streets which allows winds and daylight separating two building wings for better ventilation and illuminance. Chawls, along with their communal spaces and urban form existing in Mumbai, function the same way. With fast-emerging real estate development, these fundamental factors are ignored.

Figure 1.1.2 the image showing the poor and rich housing in Mumbai (Source: Google)

1.3 RESEARCH QUESTIONS The research here questions the current evolution of chawls through the climatic and socio-cultural changes. The housing typology accommodated by the migrants before is still preferred by some residents, however the quality of life is being questioned by the occupants itself. The fieldwork sheds light on issues in chawls which follow other research questions •

Are the adaptive changes opted by the residents improving the living conditions or worsening?

•

Is it possible to achieve environmental densifications in chawls? How could that benefit current housing scenario?

1.4 HYPOTHESIS

Figure 1.1.1 Haveli in Rajasthan, India with passive vernacular architectural elements (Source : Google)

Lack of maintenance and development leading to adaptive modifications by the residents throughout the years does not prove beneficial to users as they believe. The microclimate of chawls is affected by the courtyards, and effectively the indoor comfort. The narrow courtyard will perform better, however appropriate aspect ratio should be examined. the Today’s crammed housing typology can be improved by breaking down the land with such open communal areas.

1 . 2 S TAT E M E N T O F P R O B L E M S With such rich passive architectural background, the preferred architectural option is a glass building or rectangle concrete block. The Housing is an issue in megacities like Mumbai, where rich and poor tell a different life story. Mumbai accommodates world’s second most valuable residence like Antilia and on the other hand one of the largest slums of world, Dharavi. The development scenario in Mumbai focuses on accommodating more people in less space, overlooking the environmental hazards. The ruined buildings in Mumbai are being replaced by a crowded high-rise tower s and skyscrapers. The low-cost high-rise towers has the worst living conditions which affect the users’ health. (Singh, 2018) Besides environmental conditions, these old settlements have social and cultural significance which has been getting neglected in the redevelopment scenario.

1.5 RESEARCH AIMS The main aim behind this study is to create a chawl for today. The chawls today are dilapidated, not maintained well and these conditions are causing people to dislike the typology along with its redevelopment in High rise towers. But as studies conducted imply, the typology of chawl is healthier and significant in environmental and social aspect. The social aspect of chawls is still appealing to the residents, which should replicate in future housing designs.

1.6 METHODOLOGY The research is carried out understanding the occupant’s behaviour and their spatial use of the communal and indoor spaces. It represents the way they occupied and modified the spaces as per their requirements, criticising some of the adaptations and strategically improving them. The applied strategies are passive, user friendly and affordable, So the applied solutions can be controlled and maintained further by users. The methodology and considerations while carrying out simulations are mentioned in the simulations, as they are better related to the context. The fieldwork studies are carried out using environmental measurement tools calculating dry bulb temperature, relative humidity, illuminance and surface temperatures as well as weekly monitoring using data loggers. The physical attributes of the studies chawls are modelled in various softwares for further analytical work. The evaluation of the environmental factors is carried out using environmental simulation programs like EDSL TAS, Optivent, Grasshopper, honeybee and radiance with Rhino as visualising software. The analysis is conducted to evaluate daylight, ventilation and thermal comfort. The final section of design study looks at the form and massing strategies. Design study refers the solar study, radiation, daylight and thermal studies using the same simulating tools.

design solution for the dense urban area, where the intent is to maintain the passive strategy with dense urban housing.

1.9 STRUCTURE The study is divided mainly in three sections – • Literature review • Fieldwork • Analytical work The literature review observes the research work and contextual background specified in chapter 2 and 3. The first part of literature review discusses broadly about architectural implications in hot and humid climate. It describes the experts research and opinions of the existence of old chawls in modernized urban Mumbai. The second part of literature review presents the characteristics of Mumbai climate, as it majorly affects the urban planning and architecture of the city. It also introduces the chawls with its evolution through time and present conditions, concluding with an evaluation of a residential building from similar climate as a precedent study. Further fieldwork analyses one of the chawls of Mumbai, Tarabaug Estate. It follows the qualitative and quantitative analysis method, by understanding from the observations and spatial movements also undertaking surveys and environmental measurements using data loggers. The main section of analytical work evaluates the studied chawl for its environmental performance and further design study of chawl typology. The case study analyses the indoor and outdoor comfort, while implementing the improvements. The indoor comfort is initially compared with the chawls as they were proposed and with the adaptive modifications proposed. After accumulating the issues, the chawls are upgraded to improve the performance and the design study is performed on the enhanced chawl form. The design study is conducted at massing and further in detail unit level. The derived form of chawl is suggested for the conclusion.

1.7 RESEARCH OUTCOMES The primary study of different housing typologies in Mumbai and specifically chawls, declare the negative impact of design structure on the occupant’s use of the space. The precedent study and fieldwork indicate the characteristics of chawls, the use of mechanical ventilation, daylight and various privacy issues. Proving the hypothesis, the results of the evaluations declare unacceptable environmental performance of strategies adopted by the users that are not benefitting them in any way. The further improved chawls facilitates in analysing the recommended chawl housing form. The conclusion from the study states a typology which consists of more density than chawls as required by today’s urban scenario. However, it maintains the environmental and social constraints of chawls.

1 . 8 S U M M A RY O F R E S U LT S The research studies the environmental efficiency of courtyards and veranda, looking into their physical attributes. Implications gathered based on the studies indicate the adverse effect of adaptive strategies on the comfort and energy consumption, eliminating the architectural essence of the typology. The form and specifics of these spaces show an impact on the microclimate and effectively on the indoor comfort. When densified furthermore , the identity of chawls gets lost . Hence an intermediate solution is derived after carrying out necessary simulations to achieve better environmental performance. The resulting design of chawl s is recommended further as an environmental 3

Figure 2.1 Contrast showing formal and informal housing implying unequal development. (Source: Google)

2 literature review

2 . 1 T H E R M A L C O M F O R T I N T R O P I C A L C L I M AT E Tropical climate regions deal with higher solar radiation and higher humidity throughout the year. The primary requirement with such climatic condition is adequate indoor air movement. The experts have criticized the international standards for Indoor comfortable temperatures as it ignores the adaptive potential. (Nicol, 2004) (Gou, et al., 2018) The occupants in tropical climates are inurned to higher indoor/operative temperatures and higher humidity. A study was conducted in a residential building in Singapore to analyze the adaptive behaviour of occupants and the measures they take. It states the two major “behavioural adjustments” (Gou, et al., 2018) as, increasing air velocity using mechanical fans and reduction in levels of clothing insulation. Activity and clothing considered for thermal comfort fluctuate as per the individual. Clothing and building create a barrier for heat flow, forming second and third skin, respectively. (Olgyay, 1963)There have been several studies for adaptive comfort. Specific arguments were brought forward after the necessary studies, questioning the parameters to be considered for the adaptive thermal comfort scale. The social and climatic context, physiological adjustment and the “behavioural adjustments” mentioned above are the important parameters as well. Fergus Nicol challenges ISO7730, based on Predicted Mean Vote (PMV) by Prof Ole Fanger. (Nicol, 2004) Limitations in his PMV model are stated in figure (2.1.1) focusing the six variables affecting the comfort.

Figure 2.1.2 Relation between Indoor and outdoor temperature (Source: Nicol, et al., 2012

Tcomf = 0.53 (To) + 13.8 The comfort range considered is ±2.5 °C, where factors like clothing, air movement varies.

Figure 2.1.1 Limitation of Fanger’s PMV model (Source: Nicol, 2004)

The difference between Indoor and Outdoor air temperature should be minimized, as the higher difference may cause discomfort and could affect health. Humphrey mentions, “The Adaptive Process is fundamental, and the relation between the comfort temperature indoors and the outdoor temperature is a consequence of it.” (Nicol, et al., 2012) The graph in fig (2.1.2) shows the neutral temperature in a free-running building as a function of outdoor prevailing mean temperature. (Humphrey, et al., 1995) The observed neutral temperature is acceptable for users, as they adapt to different climate zones. The thermal comfort is achievable and preferable when indoors are in interaction with outdoors. The relation between Comfort temperature (Tcomf) and mean outdoor temperature (To) is expressed by the following equation (Humphrey, et al., 1995)

Thermal Comfort in Indian Context Indian Vernacular Architecture has been considerate of the user’s comfort. The spaces were made comfortable using passive strategies like Jaali (Perforated Screens), Courtyards, Evaporative cooling using Waterbodies. Even during industrialization, the urban fabric was designed to achieve outdoor and indoor comfort using open spaces. Later, the availability of resources and development lead to using energy for HVAC (Cooling). Flexible Building Design took priority over comfort and environmental consideration, as comfort could be achieved mechanically. (Lala, 2017) “Comfort cooling may be supplemented by radiant cooling and Buffer zones to assist in achieving comfort criteria and to reduce power consumption.” (CIBSE, 2017) With the Thermal comfort studies done so far, India lacks the focus on thermal comfort. There have been specific research in Adaptive comfort for different building typologies and recently customized performance evaluation approaches have been contributed for the Indian context. (Gupta, et al., 2019) The thermal comfort range is between the TSI (Tropical Summer Index) values 25°C and 30°C, as mentioned in the National Building Code of India. (NBC, 2016) The seasonal and diurnal changes have been ignored in this case; hence, a detailed analysis is demanded.

Continuous air movement in a hot and humid climate is necessary to maintain the minimum difference in Indoor and Outdoor air temperature. In case of higher difference, there are possibilities of condensation and mould leading to the deterioration of the building fabric. The typical strategies in tropical climates like cross ventilation and the use of mechanical fans are beneficial in this case. Undesirable conditions are not evident in an extremely humid climate, yet the higher humidity with higher temperature increases heat stress due to lack of conductive heat loss from the body and reduced evaporative cooling potential. (Indraganti, et al., 2012) Presence of airflow, in this case, can reduce heat stress. The studies in Windsor conference for varying Indian climates indicate the improved comfort temperatures with the use of mechanical fans and use of adaptive methods (air-coolers, windows, balcony doors). (Indraganti, et al., 2012)

2 . 2 C L I M AT E R E S P O N S I V E D E S I G N

Hot and humid climate requires specific design strategies and modifications for better passive design. For this research, I focused on three main environmental design parameters –

So eventually during evening and night when the temperature drops, the cold air inside helps in heat loss. In densely populated urban areas like Mumbai, creating an open layout is challenging to achieve. In the case of critical planning constraints where Wind and Solar parameters conflict, Ventilation should be prioritized in such a climate. (Givoni, 1994) Height to width ratio or aspect ratio is the ratio between the height of the building or vertical surface and distance between two buildings, i.e. distance between the two vertical surfaces. The space between buildings could be a street in an urban context or transitional area in building framework. As seen in the fig (2.2.2), length (L) can be infinite in terms of a continuous street, but in terms of courtyard Length to Width ratio matters as well. The aspect ratio is proportionally related to the sky view factor, i.e. the proportion of sky visible from a certain point. (Erell, et al., 2011) Higher H/W Ratio in tropical areas can help self-shading of building. Efficient H/W ratio can be achieved by analyzing sun positions for lower internal solar emission by reflection and absorption of solar radiation during peak hours.

•Building form and orientation •Solar control •Ventilation Building Form and orientation – In an urban scenario, building form with the surrounding context and open areas should be planned appropriately for better urban microclimate. Olgyay (1963) states, the importance of orientation of the building is mainly for the windows. As the studies shown in the fig (2.2.1) proves, most of the heat flow is through the windows. (Olgyay, 1963) In terms of a hot climate, the envelope surface area should be minimized so the solar conductive heat gain would be reduced. The self-shading of the envelope is beneficial to deal with higher solar radiation. Givoni recommends the open layout and crosses ventilation for buildings in a hot and humid climate. (Givoni, 1994) Cross ventilation keeps the Indoor and outdoor air temperature fluctuations similar.

Figure 2.2.1 Heat Flux through building Envelope (Source: Olgyay, 1963)

Figure 2.2.2 Relationship between SVF and H/W Ratio (Source: Erell, et al., 2011)

In hot climate naturally ventilated building, the factors affecting the indoor comfort are a lot, and they fluctuate throughout the day and during varying seasons. In this case, user interactive shading devices are beneficial, so that users can modify the shading as per their comfort conditions. These “active Facades” (CIBSE, 2017) can be mechanical or manual. Ventilation – Relationship of primary wind flow direction with the canyon axis is essential to determine the behaviour of secondary flow. Single-sided ventilation can be provided with a ventilator at a higher level as an outlet. This depends on the width of the room. With increased width and space, the double-sided ventilation preferably crosses ventilation is necessary. For residential layouts, cross ventilation for each room is challenging to achieve. The design should be planned considering the crossventilation through corridors and indoor open spaces. In complicated cases, the low-energy indoor air movement strategy used for tropical countries is ceiling fans. As noted from the adaptive thermal comfort study (Gou, et al., 2018), the use of mechanical fans is one of the occupant adaptive comfort strategies. The ceiling fans assist the air movement in the room, maintaining the stratification effect. In summer, the air movement affected by the fans helps evaporation from exposed human skin, which causes a cooling effect. The destratification caused by a slow reverse flow of the fans can circulate the hotter air in the room during the colder regions in tropical areas. (CIBSE, 2017)

Figure 2.2.3 Solar study by Le Corbusier for Unité d’Habitation (Source: Google)

Solar Control – While testing the orientation, solar penetration angles or solar azimuth and altitude should be considered based on the direction of the façade or window. The primary solar studies done by architects like Le Corbusier, Charles Correa, shows their strategies for solar access and control. With the study of the sun path of a specific location, the angles of the sun can be located to block or accept during certain hours of the year. The solar or daylight provision could be focused on the requirement for a particular activity of the room. Solar penetration through windows increases heat gains, which increase the indoor temperature even higher than the outdoor temperature. After the initial design, modifications like shading for the windows can be provided. In hot climates, achieving a balance between thermal comfort and daylight through available solar is essential. With different climatic context and energy parameters, it’s a designer’s responsibility to prioritize providing balanced daylight or thermal comfort. (Givoni, 1994) Different types of shading can be provided based on the orientation and location, as shown in the fig (2.2.4).

Figure 2.2.5 The representation of two altered wind flow pattern generated in urban street canyon with different primary wind flow. (Source: Erell, et al., 2011)

Figure 2.2.6 Stratification and destratification process affected by the ceiling fan rotation direction

Figure 2.2.4 Shading solutions (Source: CIBSE for Tropical Climate)

2 . 3 T R A N S I T I O N A L A N D S O C I A L S PA C E S

The study performed in 2012 shows the daily occupancy of people in the transitional spaces of chawls. It indicated more use of courtyards and Verandas than the streets (Gully) or public squares (nukkad and chawk) in the neighbourhood. The children and older people use the Verandahs to interact with each other, play cards or drink tea together in the evening. These studies indicate that “Chawls work as a whole network of spaces and thus function synchronously.” (Rane & Barde, 2012)

The social significance of chawls has been very influential for the residents and the community as a whole. This impact made chawls, the focus for the social, cultural and even political movements. (Adarkar, et al., 2011) Transitional spaces are necessary for tropical areas, as it defines a space between indoor and outdoor. The temperature difference between indoor and outdoor is less as the intermediate transitional space reduces the temperature.

Figure 2.3.1 Author’s representation of Lefebvre’ Spatial Triad (Source: Author) Figure 2.3.2 A study showing percentage of occupancy in social spaces of chawls. ( Source: Rane and Barde)

Social and communal integration Lefebvre explained the concept of “spatial triad” where social space is conceived, perceived and lived. “The social space works as a tool for the analysis of society.” (Lefebvre, 1984) The spatial practice of the spaces depends on their representation and presentation. Based on the ethnographic studies and interviews of the occupants, The chawls can be considered as a site of ‘spatial practice’ ( (Chatterjee & Parthasarathy, 2015) (Lefebvre, 1984) The current design solution for chawl redevelopment is a high-rise building. This is profitable for landowners and developers, but occupant’s opinion is neglected in such cases. This typology eliminates the social connection and contact between the residents. A survey was carried out focusing on the same issues in one of the chawls. Based on it, 85% of chawl occupants were unhappy with the high-rise or skyscraper solution. 83% of female occupants gave priority to the communal areas like a courtyard, and 98% of residents were unsatisfactory of their relocation to the suburban areas from city centres. (Rane & Barde, 2012) As children and women use communal areas like courtyard for playing or social gatherings. Some spaces are occupied by housewives, who have their small-scale businesses.

Figure 2.3.3 Visual connection in chawl culture (Source: Square one blog)

Visual Spaces – As per the story, the house is not just a shelter; it has a wall and roof – for windows. Windows are output for connection, which is to see and to be seen. (Hertzberger, 2017) The rooms and verandah face the courtyard, where children gather around and play. There is a visual connection, as parents can keep an eye on their children, and its a matter of safety as well. Such simple social link can mean a lot in terms of development and security of children. In skyscrapers, as Herzberger (2017) implies, you take the elevator from the ground floor to the 40th floor, and you have no awareness of neighbours or activities between these floors. Hence in apartmentculture, the neighbourhood connection is lost. Today, the residential buildings have children's play area allocated somewhere in common areas or on the terrace. Le Corbusier provided this space on the terrace in Unité d'habitation in Marseille, which is beneficial but overlooks the visual connection.

Figure 2.3.4 Children using social spaces on terrace of Unité d'habitation (Source: Google)

2.4 CHAWLS IN URBAN MUMBAI

Figure 2.4.1 Poor and rich housing of Mumbai (Source: Google)

The Urban extension in Mumbai grew towards the suburbs and further organically during the 19th and 20th century. The settlement developed in northern Mumbai as more people started migrating in the city. They settled in different locations in the town as per their economic classes, ranging from southern areas to north. The higher class settled in areas like Malabar hills; working middle classes contained chawls in Girgaon, Dadar etc. The poor accommodated the areas in the suburbs forming slums like Dharavi. (Adarkar, 2003) Addressing the issues of Mumbai, Mehrotra talks about “twoness of the city” (Mehrotra, 1991) The two worlds can indicate the difference in classes, occupancy patterns of spaces, infrastructure and opportunities. The city represents many historic British, Victorian, Art-Deco Architecture and famous monuments, on the other hand, it displays the poor informal settlements besides railways tracks. The chawls are an intermediate illustration of the urban fabric. Parts of old Bombay developed by the British was maintained and marked as a heritage town; however, housing density was boosted in other parts strategically and unintentionally. Adarkar discusses the growth of Mumbai when the urban fabric expanded unlike the “doughnut effect”. (Adarkar, et al., 2011) The city centre and suburbs both grew equally with time. The city centre is currently overcrowded with multiple high-rise commercial and residential buildings, insufficient open spaces between them, and diminishing green areas. The development regulations in the city are exploiting the built area as well. The municipality and building developers are focusing on maximum land use and maximizing built-up area. The latest proposed development plan 2043, shows the increased FSI (Floor Space Index) in the city up to 6.5 to 8 in central areas.

Mass housing in Mumbai– There were certain government proposals of low-cost mass housing from the mid-20th century, in the suburban areas of the city. Right from BDD (Bombay Development department) chawls by the British government to Kannamwar Nagar, Pratiksha Nagar by MHADA (Maharashtra Housing and Area Development Authority), the low-cost mass housing was established. With further increasing housing requirements, efficient planning was overlooked. As argued by architects in Mumbai, the proposed mass housing replacing chawls is of more inferior quality than the current living situation and unaffordable with additional higher maintenance charges for services. (Adarkar, et al., 2011) This eventually leads to residents selling the allotted flats and moving back to affordable slums or chawls. Town Planner and a part of MTSU (Mumbai Transformation Support Unit) Sulkashana Mahajan mentioned in a discussion, “Policy is not designed for good living conditions. Densification is the result of the policy.” (Mahajan, 2019) The study states that the policies by the government of Mumbai are ignoring the economic, social and environmental aspects. The rules were made in favour of government earlier; now they are helping developers earn incentives.

Figure 2.4.2 Land use map of Mumbai showing emerging built-up area (Source: Google)

As designers and planners can we contribute towards molding the physical form of Bombay to respond to the massive shifts in demography? Or translate in design terms the connection between social issues and physical form?

but also for the educational institutions, markets and other necessities. This encouraged more migrants to settle in chawls in Mumbai City. While construction, they used local construction material like timber, concrete and clay roof tiles. They share the toilet facilities, washing areas as well as spend the most time in common spaces. This occupant’s behaviour benefits the reduction of water, electricity and other energy use. The informal ways of living achieved comfort within the residents, so they share most of the things. The compact design of chawls shows efficient use of the space, where living space is provided with an open space to achieve better functionality and connection. The chawls have the scope for an “inclusive community”. (Jong, 2018) An inclusive community is an active community with good quality of life which contains excellent services, facilities and opportunities for the residents as well as promotes social capital. (Miller & Wilton, 2014) The effect of isolation, lack of facilities and services affects the resident’s health and quality of life. Hence this kind of communities with sustainable and collective living improve social and economic development. According to the report by Public Health England, “the community and its resilience is a part of a strategy to improve health and wellbeing.” (Miller & Wilton, 2014) These living conditions are similar to the Co-Living concept from UK and USA. The urban housing scenario of Mumbai is identical to that of London and New York. Many students and young people are migrating to the city for opportunities. Current housing alternative for them has shared apartments, which is affordable and flexible. Thus, this typology proves, it can be flexible in terms of time and user and be better than the current housing solution.

– Rahul Mehrotra (1991, p. 19) Effect on resident’s health – As we see through the land use of Mumbai over the years (fig 2.4.2), we witness reducing open spaces and just the infrastructure and property development. This is affecting the Urban heat Island and more pollution, affecting the urban environment and ultimately, resident’s health. The Low-cost mass housing with SRA (Slum Rehabilitation Authority) is a major ongoing construction scheme recently. According to the studies, these settlements have been proved unhealthier. A review of Three such settlements evaluates the association between the building design and patterns of tuberculosis in the occupants. (Singh, 2018) The study shows that daylight and natural ventilation limits the risk of airborne diseases like tuberculosis. Analytical studies were conducted to evaluate sky view factor, daylight, ventilation, which shows the effect of higher height to width ratio between buildings. The sustainable approach in Planning of Chawls The scheme of chawls began with a sustainable and affordable approach. It was constructed near the mills, which is convenient for the workers. Later, with urban development, this area became the prime location in the city. Proximity is not applicable not only for workspaces,

2.5 CONCLUSIONS AND RESEARCH QUESTIONS The spaces and their connection with the users establish their social value. The transitional areas in chawls are a significant part of the sustainable vernacular strategy. Urban composition, building fabrication, ventilation and daylight are to be focused in terms of maintaining healthier environments of occupants. As learned from the literature review, the climatic and social aspects affect the user’s health and wellbeing. The thermal comfort in this context and typology is yet uncertain. Relating the grasped literature review in associated context, these parameters and data can be combined with the chawl as a typology and social space. The preliminary research questions based on it are as follows – ·Is implementation of the passive strategies in typology like chawl practical? The occupants and architecture have some limitations which could be focused further. The strategies implemented should be practical and user-friendly. ·What factors are affecting the use of social spaces in chawls? As understood, thermal comfort is a primary factor, but the perception of the conceived and lived space is an important factor as well. The effect of these factors in the typology like chawls should be evaluated. ·How are the strategies implemented in chawls affecting the people’s comfort? Sustainable planning approach of chawls shows the overall benefits in terms of urban planning and wellbeing of occupants. The thermal comfort should be analyzed to maintain or improve it more. ·Is the typology adapting the evolution through time and socio-cultural changes? Born through industrialization and surviving the current concrete urban scenario, chawls and its occupants merged to be the part of the change.

LOCATION OF MUMBAI

INDIA MUMBAI

Equator

Figure 3.1 Location of India in world map with tropical line

Figure 3.2 Aerial View of Mumbai City

Latitude 19.0760° N Longitude 72.8777° E

3 context a n d precedents

3 . 1 C L I M AT E O F M U M B A I SEASON

MONTHS OF THE YEAR

SUMMER MONSOON

March, April, May June, July, August, September October, November December, January, February

POST MONSOON WINTER/MILD SEASON

AVG TEMPERATURE RANGE 24.56 – 33.30 25.37 – 30.58

AVERAGE PRECIPITATION 3 529

23.33 - 34.18 19.67 – 32.62

71 3

Figure 3.1.1 Seasonal variations in temperature and precipitation (Source: Author)

Mumbai is located in the west coast of India at latitude 19.0760° N and longitude 72.8777° E. It’s an Island surrounded by Arabian sea from South and west, and creek from east. In the north of the city lies Sanjay Gandhi National Park, which is topographically higher and broader forest known as “lungs of the city”. On further east of the metropolitan region, it is covered by Sahyadri mountain ranges. This geographical situation affects the climate of the city. India has a diversified climate According to Koppel climate classification; Mumbai has Tropical Dry Winter/Savanna Climate. Due to these climate conditions, it experiences hotter summer, slightly colder winters and rainy monsoon seasons causing it humid most of the time. As understood from the weather analysis from Metronome (data till 2017), the significant variations in climate are for the following period, which will be considered for review.

The adaptive building is need in terms of future climatic conditions. The rooms should have enough crossventilation and shading from direct solar gains to minimize the effect from higher outdoor temperature. Humidity – The terrain situation of Mumbai affects the climatic conditions, mostly humidity. Higher temperature and presence of water keeps the evaporative process continuous, maintaining humidity levels higher most of the times. Average humidity throughout the year varies by 63% - 80%. Winters/Mild Season has the lowest humidity, ad increases during summer and reaches 100% in Monsoon. Higher temperature with higher humidity in summer creates an uncomfortable situation for the residents in the city. But the evaporative process through human skin provides a cooling effect.

•May – Maximum Dry Bulb Temperature •January - Minimum Dry Bulb Temperature •July – Maximum Relative Humidity

Rainfall – Mumbai faces monsoon winds from the western sea, which brings rainfall, higher during monsoon season (June-September). During these four months, it rains most of the days with precipitation ranging from 295-786 mm. The winds from west and moisture in the air are evident. The winds cause higher waves, rough sea condition. Nowadays, the city faces unpredictable and heavy rainfall, which causes flooding scenario affecting the urban life.

The chart (fig 3.1.1) shows the division of seasons in Mumbai and other details. Temperature – Besides the three seasons, Post monsoon period is commonly termed as “October Heat”. During this period, the temperature and other factors are similar to the summer months. The dry bulb temperature is higher during the summer, post-monsoon and winter Afternoons. From June to September, i.e. monsoon season, usually, the temperature is in comfort zone. DBT exceeds 32 °C for 591 hours in a year. These are the most out of happy hours, in Summer and Winter Afternoons. The significant issues observed in thermal comfort are during summer, as the diurnal temperature difference is less. The difference in summer and mild season is the diurnal temperature difference as shown in figure (3.1.1) As the Temperature doesn’t decrease even during night in Summer months, adequate ventilation is necessary. The difference between Dry Bulb Temperature between the present (2017) and future (2050) shows more hightemperature scenario. Even though the temperature decreases during winter evenings, the higher temperature dominates more. The temperature exceeds 32 °C for 1532 hours in a year.

Figure 3.1.2 Flooding in Mumbai during monsoon season (Source: Google)

12 AM

6 AM

12 PM

6 PM

12 AM

WINTER

SUMMER

WINTER

Figure 3.1.3 Hourly Average Dry Bulb Temperature data in Mumbai for a year. (Source: Meteonorm)

12 AM

6 AM

12 PM

6 PM

12 AM

Figure 3.1.4 Hourly Average difference in Dry Bulb Temperature data of Present (2017) and Future (2050) in Mumbai for a year. (Source: Meteonorm)

Wind – The average wind velocity is 2.6 m/s, which has prevailing wind direction as southwest from the Arabian sea. Monsoon season has the highest wind speed of average 3.45 m/s. Even in summer, the wind velocity is average 2.66 m/s. The dense urban area limits the wind flow, affecting the temperature. The mild season has the lowest wind velocity of an average 1.8 m/s. Radiation –

Figure 3.1.5 Windrose for Mumbai (Source: Grasshopper)

Being in the equatorial region, Mumbai has higher Solar radiation throughout the year. It receives annual average global horizontal radiation of 5 kW/sq.m. Monsoon has the lowest sunshine hours, due to mostly cloudy hours. However, it receives diffuse radiation, which is average 2.87 kW/sq.m. In terms of vertical radiation, the north facades receive the minimum radiation as Mumbai is located in the northern hemisphere and gets the highest southern radiation. The radiation falling on east and west façade is higher throughout the year. Such higher radiation conditions need extreme shading for facades and streets. Suitable Comfort band – As understood from the literature review, the other adaptive comfort methods are not ideal for the tropical climates. According to adaptive comfort EN-15251 (2007 class II) method, the predicted comfort zone for Indian climate is 24.9 °C – 31.2 °C. As shown in fig (3.1.6) the adaptive comfort band from EN (Class II and III) is similar throughout the year, even though the temperature differs. The study by Sharma and Ali about Tropical Summer Index (TSI) shows the adaptive comfort people in tropical regions experience even in warmer temperature till 35 °C. (Sharma & Ali, 1986) The differing temperatures, diurnal changes and other valid parameters will affect the comfort band for every season. Psychrometric chart By using Nicol’s comfort equation with a comfort range of ±2.5 °C, as stated below, the average DBT of Mumbai is in comfort most of the time. Maximum DBT is out of the comfort band for the whole year. Tcomf = 0.53 (To) + 13.8

Figure 3.1.6 Radiation rose for Mumbai (Source: Grasshopper)

5.00 kWh/m2

4.00 3.00 2.00 1.00 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec North

East

South

West

Figure 3.1.7 Radiation data for Mumbai (Source: Meteonorm and excel)

Figure 3.1.7 Psychometric chart of Mumbai (Source: Grasshopper)

Figure 3.1.8 Dry Bub temperature with EN Adaptive comfort band (Meteonrom and Excel)

Figure 3.1.9 Dry Bub temperature with Nicolâ&#x20AC;&#x2122;s Adaptive comfort band and diurnal temperatures (Meteonrom and Excel) 21

3.2 PR ECED ENT ST UDY OF CH AWL S 3.2.1 HISTORY AND EVOLUTION OF CHAWLS

Background The typology of chawls is a mixture of from certain buildings from the world. The vernacular architecture of India inspires the Typology of Chawls. The Palaces and Wadas built for the royals from around 1100s, were later adopted to reside the common people in the emerging towns of India. The ‘Wadas’ are agrarian house-like residences for the ruling classes from each town, in Maharashtra. The main architectural elements and planning are like chawls. The fundamental concept is the rooms with verandahs facing the internal courtyard. The courtyard was used for social and cultural activities by the residents. The small windows form the courtyard kept the privacy, enabling the ventilation in the rooms and maintaining the visual connection of the courtyard. Later, East India Company by the British Government built military Barracks in Bombay; which can be considered as a precedent of the chawls. These were the residences for military men, with single rooms in a row connected by a corridor. It was a simple gothic construction fused with Traditional Indian architecture and locally used materials, like many British built structures in Bombay.

1750s

Figure 3.2.1.1 Vishrambaug Wada, Pune (Source: Google)

1800s

Figure 3.2.1.2 Military Barracks, Mumbai (Source: Google)

TENEMENT UNITS

1880 COOK -HOUSES

SHOPS

Tong Lau Tenements from Hongkong has a similar approach. These are mixed-used building typology with commercial spaces at the ground floor and tenant’s rooms on higher floors. Tong Lau is an urban shophouse which is influenced by Hong Kong’s urban policies, public policies and adapted with its local conditions and circumstances. (Yin & Distefano, 2016) The Density and characterization of Tong Lau evolved due to urbanization throughout the time. Hong Kong’s culture of living together in subdivided flats and sharing the washing areas, common balconies are incorporated in Tong Lau. It’s an urban housing where shops, residences and storage areas are stacked vertically. With time, chawls were built with commercial areas like shops or markets on lower floors. These vernacular architectural examples from the world contain characteristics and principles that are functional and substantial, which should be brought back to today’s modern society.

STREET

Figure 3.2.1.3 Tong Lau, Hongkong (Source: Yin & Distefano, 2016)

1800s

Figure 3.2.1.4 Khotachi Wadi, Mumbai (Source: Google)

1920

In terms of urban housing, it resembles with the highdensity urban typology from Brazil known as Corticos, i.e. tenements. The earliest urban form from São Paulo, Brazil appears in the large cities of Brazil housing poor working-class people, as a result of rapid urbanization. (Kestler-D'Amours, 2014) It accommodates multiple families which share the toilet and other facilities. However, the corticos have undesirable living conditions, unhealthy sanitary conditions and lack of facilities. (Kestler-D'Amours, 2014) Many families accommodate these tenements and other informal housing due to its proximity to the city centre and other resources.

Figure 3.2.1.5 BDD Chawl, Mumbai (Source: Google)

1950

Figure 3.2.1.6 Cortico, Sao Paulo, Brazil (Source: Kestler-D'Amours, 2014)

Figure 3.2.1.7 Busy façade of on old chawl in Mumbai (Source: Google)

History of chawls in Mumbai – Urbanization of Mumbai started with the industrialization during the British era. Many migrants, merchants, millworkers were accommodated in the city for emerging employment opportunities. This initiated low-cost housing like Chawls built by private trusts and government. While comparing the major mass housing movements in the world, Florian Urban states “The chawls were the architectural response to the rapid industrial growth and the Indian equivalent to the Glasgow tenement or the Berlin backyard building.” (Urban, 2012) Locals or the private trusts of Mumbai built the houses in natural approach in the city in the early 1800s, called wadis. Wadis are agrarian houses, comparatively low-densified, a low-rise example of chawls. It’s a complex of few bungalows-similar together, housing people from the same cultural and ethnic background. The wadis were named after the cast or family keeping the culture alive. Khotachi wadi is a heritage housing village in Mumbai, accommodating many families of diverse communities. These houses are 1-3 storied timber frame structures with vernacular detailed elements like a sloping roof with tiles, projecting balconies, ornate façade elements etc. This village is sustained well due to its high cultural and architectural significance. Chawls can be termed as an elaborated version of Wadis by densifying with comparatively higher

floors. The basic idea of Chawl is a series of compact rooms opening in the courtyard with shared toilet facilities at the end of it. Many chawls were later built using these materials for the mill workers and then for working-class immigrants. More subsequently, more lowcost mass housing using stone and cement was developed by the British government like BDD (Bombay Development Department) Chawls on the reclaimed lands. BDD Chawl (Worli) is a cluster of 121 buildings in Central Mumbai with a dense room with shared toilets, veranda and open spaces between buildings. It is one of the oldest mass housing which is on the verge of redevelopment now. Rent control act was passed in 1947, which froze the rent of the hotels and lodging rents. Chawls were mostly owned by a private landlord, who lost the concern in a property after the act. Maintaining the property was not profitable for the landlords, so through the time chawls started falling apart. Existing tenants and some landlords paid the maintenance charges, but low-income groups couldn’t afford it anymore. The migrants rented Chawls and lodging in the city. After the rent control act, the facilities limited, and migrants shifted to cheaper slums. According to the Planning commission report (20022007), the rent control act is the reason behind the escalation of chawls in the city. (Mahajan, n.d.) Today, the chawls are being redeveloped by MHADA and relocating the residents to far suburban areas of the city. 23

Chawls of today â&#x20AC;&#x201C;

Government mass housing complex (Kannamwar Nagar) â&#x20AC;&#x201C;

Chawls are a functional and social urban housing typology of Mumbai. Residents of chawls, using the spaces for generations, still prefer those spaces. The communal living, safety, neighbourhood and of course, the centralized location makes a more significant impact on the occupantâ&#x20AC;&#x2122;s mindset. Architects and urban planners are keen about these constructions and are trying to implement its features in the recent housing proposals. Till now, this approach of housing is applied in some places for low-cost, highly dense settlements. The government planned certain Mass housing complex in suburban areas from 1950s. These complexes are like a small sustainable town in the areas.

Kannamwar Nagar is one of a biggest housing colony in India built in 1960s which consists of more than 300 MHADA buildings. It is acknowledged as one of largest workers housing colonies in Asia. It is located in suburban area of Mumbai besides eastern express highway, giving easier access to the city. It is in proximity to the Navi (New) Mumbai as well, which directs way out of the city. The complex has educational facilities, hospitals, Recreational areas like gardens. With such services and proximity to major locations of the town, this housing complex can be considered as a sustainable approach to planning. The buildings are 4-5 Storied with courtyards and corridors. It is considered as an endeavour of higher density housing with better environmental conditions. The open internal courtyards surrounding the rooms and corridor achieve required cross ventilation in the rooms. The unit sizes are similar like chawls, but the tenement density is more and feasible in suburban areas.

Figure 3.2.1.8 Building Layout (Source: Author) Corridor Rooms Toilets

Building A Housing Complex

Figure 3.2.1.9 Building external view (left) External corridor (Right) (Source: Author)

Figure 3.2.1.10 Location map of Kannamwar Nagar (Source: Author)

Figure 3.2.1.10 Concept of Project Udaan (Source: SP+a)

Udaan (Sameep Padora)– SP+A (Sameep Padora and associates), an Architecture firm based in Mumbai proposed a low-cost mass housing in extended suburban areas of Mumbai, inspired from the social aspects of chawls. It is part of “Housing for All” policy of the government. An attempt of attaining the social connection and environmental approach in housing schemes of densely urbanized areas is carried out. The main concept, as shown in fig (3.2.1.10) designing horizontally instead of repeating the layouts vertically. The presence of social and interactive space in intermediate levels achieve the required connection. As understood from fig (3.2.1.11), the implemented strategies are the architect’s

interpretation of the chawls. The design is flexible with the unit layout and is constructed with precast pods, which gives further flexibility for the users. The indoor corridors with open interaction space and added internal courtyard-similar space enables the cross-ventilation required for hot and humid climate. The project is still under construction; however, the precast construction can reduce the onsite construction period. Architect Kamy Iyer discusses the complexity of applying such housing proposals in the city and suggests more exploration about building affordable housing alternatives for the city. (Sriram, 2016)

Figure 3.2.1.11 Section showing the implemented design strategies (Source: SP+a) 25

3.2 PR ECED ENT ST UDY OF CH AWL S 3.2.2 TYPOLOGY STUDY Chawls were built for the low- and middle-class residents, mainly Migrants. The architecture and planning of chawls focus on the essential required spaces for the occupants. It is a formal housing with tenements facing each other around the courtyard. The Verandas (Corridors) connecting the collinear rooms with shared toilet blocks at the end of the it. The Rooms from chawls were previously built to be occupied by a single worker. The rooms or kholis are usually a single space of around 15-45 sq. m. Floor area, containing the living room, kitchen, bedroom, washing area. Chawls differ on the location, period of construction in the characteristics, which will be discussed further in detail. The communal spaces like courtyard and Verandas are significant regarding the architectural and social correlation. The courtyard creates a central shaded space which enables the air movement in the veranda and effectively in the units. The comfort of these spaces allows residents to utilise spaces for cultural and social gatherings. As shown in fig (3.2.2.5) the courtyard is used for festival celebration or recreational purposes. Veranda and other spaces like staircase lobby are used for more than just transitional spaces. Fig (3.2.2.3)

Building Fabrication – Chawls having a sustainable approach, the construction materials used are mostly vernacular or Local materials. Some of the low storeyed chawls are timber constructions; having have an absolute vernacular expression. However, some of the old Brick-timber unprotected chawls have been disappeared now. The retained concrete chawls have some load-bearing construction with thick walls. Environmentally, brick fabric with timber is a lightweight envelope with better possible performance. Later, the concrete or loadbearing constructions developed by the private or government companies were preferred. These constructions required less maintenance and last longer, yet eliminates the significant qualities of chawl typology. Generally, the windows have side-hinged openable wooden shutter with the ventilator on top. The wooden doors usually have the ventilators as well.

Figure 3.2.2.2 Front façade of chawl (Source: Google)

TENEMENTS • •

15-45 sq.m. area Facing each other creating community life

COURTYARD

Open social space at ground level

Verandas (Corridors) Connecting private and communal spaces together TOILET BLOCKS

Figure 3.2.2.1 An example of chawl typology (Haji Kasam Chawl) (Source: Author)

Common toilet facilities 26

Communal spaces

Figure 3.2.2.3 Veranda (Source: Author)

Figure 3.2.2.5 Festivities in Courtyard (Source: Google)

Figure 3.2.2.4 Staircase Lobby (Source: Author)

Figure 3.2.2.6 Courtyard as playground (Source: Google)

3.2 PR ECED ENT ST UDY OF CH AWL S Types of chawls

The chawls in Mumbai vary in terms of its forms and characteristics. The fig (3.2.2.7), (3.2.2.8), (3.2.2.9) show basic types of chawls, baithi (rowhouse) chawl, bar chawl and courtyard chawl. Baithi chawl can be referred to as a beginning of the chawls, having rooms at ground floor with front and back courtyard. The front courtyard is used as a social space, whereas the back courtyard is used as a service space for the residents. Bar chawls are linearly parallel building with a courtyard in between. It has a veranda on the inner side, and in some cases on both sides of the room. The courtyard chawl has an open courtyard in front of the building, which is usually Cshaped looking into the courtyard.

Figure 3.2.2.7 Baithi chawl (Source: Gupte, 2011)

For a detailed understanding, four different chawls from Mumbai has been examined in various aspects. Numerically, it looks into population density, no of floors, the ground coverage area, Floor to Area Ratio (FAR) and standard room sizes. The height to width ratio of own courtyard is mentioned in the sections. Bhatia chawl is located in the prime crowded market place, with one faĂ§ade facing the main road. The entrance from the internal street leads to a narrow gate towards the courtyard. The private verandas look into small 4 m courtyard. This chawl has verandas or balconies facing the road, which acts as a solar shade as well. Swadeshi chawl has unique design and building occupancy, with the crowded market at lower floor and residential blocks at the upper level. The chawls have one wider social courtyard and narrow courtyard as a service area in between other blocks as seen in section. Tarabaug estate, on the other hand, is a complex of tall chawl buildings. It has a typical chawl form, which shows a compact densified typology.

Figure 3.2.2.8 Bar chawl (Source: Gupte, 2011)

The British government developed BDD chawl for workerâ&#x20AC;&#x2122;s housing. It is a massive complex in city and suburban areas, which is concrete construction. The internal roads between the buildings act as a courtyard, providing open space. Verandas or corridors are internally planned so this represents an earlier concrete block housing typology. Figure 3.2.2.9 Courtyard chawl (Source: Gupte, 2011)

HEIGHT TO WIDTH RATIO

Figure 3.2.2.10 Bhatia chawl drawings (Source: Google and Author)

0.22 people/

Building Height – 12 m

m²

Density

No of Floors

GROUND COVERAGE

60 %

FAR

2.23

SQ.M.

20-53 m²

Room Size

Road

Single Building Chawl

Bhatia chawl Swadeshi market chawl

Chawl Complex of 8

Buildings

0.19 people/ m² Density

No of Floors

GROUND COVERAGE FAR SQ.M.

Room Size

2 47 %

1.2 Building Height – 6 m

1.2

RESIDENTIAL LEVEL

1.95 14.5-40 m²

MARKET LEVEL Figure 3.2.2.10 Swadeshi Market Chawl drawings (Source: Google and Author) 30

Figure 3.2.2.11 Tarabaug chawl drawings (Source: Google and Author)

1.8

HEIGHT TO WIDTH RATIO

Building Height – 15 m

0.22 people/ m² Density

No of Floors

GROUND COVERAGE

49 %

FAR

2.44

SQ.M.

20-40.2 m²

Room Size Chawl Complex of 4

Buildings

Tarabaug Estate BDD chawl

Chawl Complex of 42

Buildings 0.25 people/ m²

Density

Building Height – 12 m

No of Floors

GROUND COVERAGE

12 m 31

36.8%

FAR

1.47

SQ.M.

12-15 m²

Room Size Figure 3.2.2.12 BDD Chawl drawings (Source: Google and Author)

3 . 3 P R E C E D E N T S T U D Y O F B U I L D I N G E VA LUAT I O N

The energy consumption with mechanical ventilation is not as distinctly higher than Naturally ventilated flat. The limitation indicted here states the small number of flats assessed might have affected the results. As well as the use of mechanical ventilation is, in a controlled manner. The image shows the temperature in the rooms with AC and without AC. The temperature profile and values in the flat using mechanical ventilation is similar to the freerunning flat. The Comfort band by ASHRAE 55 and NBC (National Building Code, India) has been used while comparing the temperature trend. The minimum temperature monitored in AC and NV flats is frequently in the comfort band but is regardless of the comfort otherwise. This indicates the crucial requirement in the study of thermal comfort in the Indian context.

A Building Performance Evaluation (BPE)study was recently conducted in a certified green building in Chennai, India, which has a similar hot and humid climate like Mumbai. This study shows similar occupant behaviour and related conclusions from the fieldwork of chawls. The typology and age of the buildings are entirely different, yet the performance and concerns are comparable. Gupta criticised when IGBC (Indian Green Building Council) claims that India has 2nd largest registered footprint of green buildings in the world. As the post evaluation of these buildings is not mandatory in any of the Indian green building rating systems, there is no proof that these buildings are performing better after a certain period, or if the occupant’s use if affecting the performance. The BUS survey was conducted for occupants from 38 flats, and I-BPE was conducted in certain selected 29 flats in different levels during a summer month. I-BPE method for this study included a review of design, technical survey of the building, energy evaluation, environmental monitoring and occupant’s feedback. (Gupta, et al., 2019)

The building has a common corridor where the living room and kitchen windows open. These areas were planned as a potential social, communal space for the residents. The POE/BUS Survey shows, the occupants keep the windows closed for privacy from the corridors, which reduces thermal comfort effectively. The BUS survey results indicate the failure of the design strategies when implemented irrespective of the user’s requirements and lifestyle. The survey also states uncomfortable air quality and indoor comfort due to lack of ventilation. The flats in lower floors have issued of low daylight due to surrounding buildings, which was probably ignored in the green building certification process. It can be stated that better air movement between outdoor to indoor helps the heat loss, as similar to the use of mechanical ventilation for a limited period.

Figure 3.3.1 Relation between temperature and energy consumption in AC and NV flats (Source: Gupta , et al., 2019)

Figure 3.3.1 Temperature profile in respect of comfort band (Source: Gupta , et al., 2019)

Figure 4.1 Courtyard in Tarabaug Estate (Source: Author)

4 fieldwork

4.1 METHODOLOGY In an “inclusive community” like chawl, the architecture relates to the user. Fieldwork was conducted to understand occupant’s behaviour in different spaces of chawls and frame a hypothesis based on it. This specific chawl, “Tarabaug Estate” was chosen as it has a dense urban complex of buildings, and has a typical form of the chawls. The fieldwork was carried during a week in Summer (May), as this is the critical period when occupants feel most thermal discomfort. It is divided into qualitative and quantitative analysis of microclimate, occupant’s behaviour, their comfort. Qualitative analysis The behaviour and use of space imply the comfort of users. During the site visit, some observations and Interviews were carried out. The observations of the building show the use of the spaces and the practices that can cause issues in the building performance. Occupants’ interviews made the author understand their behaviour. Through interviews, the author followed the problems tackled by residents and the qualities they appreciate about their existing spaces. Quantitative analysis A survey was conducted based on the observations, social and environmental issues seen. The study performed provides statistical information to form further conclusions. Spot measurements and weekly climate monitoring were done, to relate occupant’s perception and further analytical work. These measurements are taken for a unit and the adjacent veranda, as these are the most occupied space. The spot measurements were carried out to measure temperature, humidity, wind speed, Illuminance and surface temperature using environmental measurement instruments. For weekly monitoring, three Data loggers were installed in the occupied spaces like veranda, living room and kitchen. Later, microclimate studies were performed using simulation tools, to understand the relation with the use of the space as observed.

4 . 2 C A S E S T U D Y â&#x20AC;&#x201C; TA R A B A U G E S TAT E C H AW L

ARABIAN SEA Figure 4.2.1 Location of Tarabaug Estate with Sun path of Mumbai (Source: Author and Grasshopper)

Figure 4.2.2 18 m wide Main road (Source: Google)

Figure 4.2.3 12 m wide internal road (Source: Google)

Figure 4.2.3 Internal street (Source: Author)

Built spaces

Location-

Open and Recreational spaces

Like most of the chawls of Mumbai, studied chawl “Tarabaug Estate” is in the southern Mumbai – City. It is located in Girgaon, which is culturally rich and diverse. Tarabaug Estate was built by a private owner in 1963, as mentioned in the entrance gate of the estate. The estate is well connected with the railway station (Charni road) and main sea face road. Its proximity to the ocean and beach, known as Girgaon Chowpatty, affects the microclimate. Being a prime location in the city, this neighbourhood has all the facilities and amenities easily accessible from the site. The adjacent buildings in the north of the estate can block the ventilation; hence the courtyards are beneficial as an open space in the cluster. The railway station and adjacent road as seen in fig (4.2.2) and (4.2.3) are very crowded and source of high pollution. However, a pedestrian’s perception while entering Tarabaug estate changes as the internal street and further courtyard changes the microclimate. The transition from crammed road and walkways out of the estate to calm shaded street and courtyard is apparent. These qualities change the microclimate and perception of the chawls in a jam-packed city. The estate consists of 4 buildings, with three c-shaped buildings with courtyard and one additional single building block. Overlying sun path of Mumbai shows the sun movement access, which indicated the sun positions for the year with higher temperature. The higher temperatures in mid-year and summer show concern, which will be studied explicitly in the analytical work. The orientation of the building appears to be utilizing the self-shading. Further Solar Radiation analysis is conducted to work out the relation between sun movements and the configuration of Tarabaug estate.

Figure 4.2.4 Keyplan of Tarabaug Estate (Source: Author)

VERANDA Width – 1.6 m TENEMENT Floor Height – 3m

COURTYARD Courtyard width – 8 m

Figure 4.2.5 Key section of Tarabaug Estate wing F (Source: Author)

POROUS ENVELOPE

Overview of the Building – The Building is C-shaped with a courtyard in the centre. The shaded verandahs of both wings facing the courtyard and rooms on the other side (fig4.2.6). The staircase lobby in the north of the building block is open for air circulation, so the probable cross-ventilation from there achieves a porous envelope for the building. The building has five floors, with a sloping roof. Each level has 21 residential units of varying room configuration. The overall layout of the units is similar. The shared toilet facilities lie on the south of the building block, at the end of the corridor. The analyzed unit is located on the first floor in the middle of the west wing.

STUDIED UNIT

Figure 4.2.6 Wing F Layout (Source: Author)

Overview of a unit – The analyzed unit is occupied by Bhavsar family of 3 people, a male (41), female (31) and a child (10). The unit is 20 sq. m. with a living room and kitchen in it. As learned from the precedents, the spaces in the tenements are multi-functionals. The rooms are used as a bedroom, study rooms as well. The previously provided washing area has been enclosed to be used as a bathing area. The family has been renting the house for the past two years; the owner owns the house from around 50 years. The living room opens in veranda and kitchen faces outside the estate. Above the kitchen window, a loft is provided for storage, as seen in the section (fig4.2.7). The partition wall between living and kitchen area is open from the top. Veranda and internal spaces in the kitchen are used to dry the clothes.

Living room

4.3 QUALITATIVE ANALYSIS

Kitchen Washing/bathing area

4.3.1 OBSERVATIONS Figure 4.2.7 Plan (Below) and section (above) of studied unit of chawl (Source: Author)

During the transition in more than 50 years, Tarabaug Estate went under many changes. The fabrication, use and routine of the spaces revised as per user’s requirements. Observations made through the fieldwork expresses the effect of evolution. Communal spacesResidents use communal spaces for more than just a transitional space. As seen in fig (4.3.1.1) they use even the staircase mid landing as a resting place, since it is open and comfortable during a hot summer day. The Verandas as seen in fig (4.3.1.1) is used as a storage space as well, more like an extension of the unit. Even though verandas are shaded, the additional overhang was added by the residents to prevent the rain and solar radiation in the veranda. Windows and doors –

Figure 4.3.1.1 Observed use of communal spaces (Source: Author)

Windows and doors are wooden framed with a net or wooden shutters. The net encloses Even window opening for security reasons. The living room doors are kept open usually, as part of the “chawl culture”. Due to privacy, some of the windows are closed, dodging daylight completely (fig4.3.1.2). In some of the cases, the windows facing out has other buildings right in front of it, which invades the privacy from the other side as well, effectively creating a scenario from fig (4.3.1.2). AC units – Air conditioning units are used nowadays due to thermal discomfort in most of the units. The AC takes the space above the window (fig4.3.1.2), and the compressor occupies space of the ventilator, which reduces the window aperture. The AC emits heat outside in veranda affecting the temperature in veranda as well.

Figure 4.3.1.2 Observed issues in internal layout (Source: Author)

4.3.2 OCCUPANCY

Figure 4.3.2.1 Illustration of different use of one room space (source: Alcamo, et al., 2013)

The adaptive thermal comfort was explained in an interactive way with “the habits of hobbits” (Humphrey, et al., 1995) from “the Lord of the Rings” films. The behaviour of hobbits is revised as per the seasonal climatic changes; it gives a clear idea of their comfortable temperature profile. Similarly, the courtyards and verandas are occupied based on the habits of the residents. The study was performed during the summer days when children had holidays so effectively; they used the spaces more than other days. Children and women use transitional spaces more than workers or working women in some cases. During the weekends, the spaces are used the most.

OCCUPANT 1 MALE (Employed)

00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

WEEKDAY OCCUPANCY HOURS WEEKEND OCCUPANCY HOURS

OCCUPANT 2 FEMALE (Stay at home mom) 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

WEEKDAY OCCUPANCY HOURS WEEKEND OCCUPANCY HOURS

OCCUPANT 3 CHILD (Attending school) 00:00 01:00 02:00 03:00 04:00 05:00 06:00 07:00 08:00 09:00 10:00 11:00 12:00 13:00 14:00 15:00 16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00

WEEKDAY OCCUPANCY HOURS WEEKEND OCCUPANCY HOURS Figure 4.3.2.2 Occupancy hours of the users of studied unit (Source: Author)

residents occupying the spaces

Figure 4.3.2.3 Occupied courtyards by children (left) and senior citizens (right) (Source: Nanaware, n.d)

Figure 4.3.2.4 Indoor adjustments and lifestyle (Source: Google)

Figure 4.3.2.4 Occupied communal spaces (left) and room (right) (Source: Nanaware, n.d)

4.4 QUANTITATIVE ANALYSIS 4.4.1 SURVEY

Figure 4.4.1 Children playing in verandas (Source: Google)

Few interviews and survey were conducted of the residents in the chawl. As learned from an occupancy survey from the literature review, courtyard and veranda spaces were used more than other areas of chawl (Rane & Barde, 2012). Further, with hypothesis formed based on this, a survey was made to understand the current use and further improvement potential expected from the occupants. Some people still prefer to live in chawls; however, due to lack of maintenance, water and toilet facilities, some dwellers prefer to shift to the apartments. (fig 4.4.3) When interviewed, the residents mentioned how communal spaces help social bonding.

10%

2.55 People/sq.m.

30% 50%

85% of residents appreciate the community and social interaction. Due to these connections, they have a support system from the neighbours. A dweller in his 70s mentioned that this is the best place to grow up. He could adapt through the transition during more than 70 years of life in chawl, and this provides a better support system for older people. Residents stated the importance of the prime location of the chawl, as most of them use public transport, which is affordable to within proximity. Understanding the indoor space utilization, density per unit varies in the chawl. Some units are occupied by a single person and some by joint families.

20%

Chawl Apartments

15.30 People/sq.m. 50% 0.13 People/sq.m.

30%

Chawl similar Apartments

0.39 People/sq.m.

Figure 4.4.2 Survey results showing population density (Source: Author)

Figure 4.4.3 Survey results showing preferred housing typology (Source: Author)

4.4.2 MEASUREMENT

300 250 200 150 100 50 0

33 32 31 30 29 28 27

Veranda

Living Room

Kitchen

Figure 4.2.2.1 Section showing spot measurements (Source: Author)

Data loggers – The veranda temperature is higher as it is exposed to external climate. Living room and mostly kitchen have a lower temperature. Air conditions are used average 2-3 hours at night, during the hottest days. Remaining hours, the rooms are naturally ventilated, which is mostly out of comfort zone. The indoor temperature with mechanical cooling is not lower than 29°C, which confirms the achieved comfort even at 29°C. They use mechanical fans and AC at the same time is to improve air circulation, as it is one of the other adaptive strategies. In terms of humidity, internal rooms have more humidity during the daytime; however, at night, the enclosed room has less humidity. Even during summer, the humidity reaches 70 % has observed in the climatic analysis.

Illuminance (lux)

Temperature (c )

Spot MeasurementsSpot measurements taken during summer midday shows higher indoor temperature similar to the external temperature in the courtyard. The spot measurements are done at one unit on the first floor. Due to more solar exposure on the fourth (top) floor, the temperature is 1°C more than lower floors in Verandas. The indoor illuminance levels are much lower as observed. The closed windows and dark interiors affect the daylight as well. The surface temperature of the floor is lower in the kitchen as its less exposed; however, the floor is a slightly lower temperature than the external temperature.

Figure 4.2.2.2 Data logger measurements showing temperature profile (Source: Author)

Figure 4.2.2.3 Data logger measurements showing humidity profile (Source: Author)

5 case study â&#x20AC;&#x201C;

analytical work

5.1 METHODOLOGY

01 Indoor comfort

02 Outdoor comfort ANALYTICAL WORK

03 Upgrading Chawls

04 Design Study

Unit level

Massing level

Environmental Perception of Design Figure 5.1.1 Process of analytical work 48

The studied exemplar case of Tarabaug Estate represents the chawls of today, which will be evaluated for their performance in today’s climatic and urban context. Based on the conclusions and hypothesis from fieldwork, further analytical work is conducted to evaluate the result of adaptive strategies by the occupants and recommends environmental design strategies further. This analytical work focuses on studying the two scenarios of chawls, evaluating comfort in transitional spaces and resolving the primary issues observed. With the aim of environmental retrofit, a design study was conducted to evaluate the form at massing and unit level. The studied chawl was modelled in Rhinoceros software, to visualize the results from ladybug and honeybee tools from Grasshopper plugin. Initial Ventilation studies were conducted using Optivent tool whereas EDSL Tas software was used for dynamic thermal analysis. The process of analytical work (fig 5.1.2) is explained further in detail –

Grasshopper

Indoor Comfort – The modifications in building and climate with time affected the indoor comfort in Chawls. In this section, adaptive scenario is compared with the original proposed design of the chawl. The noted physical parameters of the existing chawl have been considered while evaluating to reveal performance of the existing chawls. The simulations are carried out for May (Summer) and January (Winter) months to analyze the varied performance of the building. Analysis focuses on – • Passive Ventilation • Solar Radiation • Daylight • Thermal comfort

Ladybug

Honeybee

Figure 5.1.2 Simulation tools used

Design Study – This concluding section of the analytical work evaluates the chawl building form (C-shaped) at Massing and Unit level. In massing level, the form is analyzed in 4 different orientations and 3 Height to width ratio of the courtyard. The irregular sun penetration in the courtyard with varying orientations and height to width ratio eliminates few scenarios. The annual comfortable hours in other scenarios are evaluated to finalize one ideal orientation and height to width ratio. This concluded example is used to evaluate the performance at the unit level. The previously studied unit is evaluated with the current aspect ratio and orientation, implementing passive strategies to improve indoor performance. The analysis focuses on – •Solar Study •Radiation study •Daylight •Thermal Comfort

Outdoor Comfort – In this section, the comfort in transitional spaces like veranda and courtyard has been evaluated to reveal the comfortable hours to use these spaces. The simulations indicate the comfortable hours in transitional spaces throughout three seasons of year. Analysis focuses on – • Thermal comfort • Universal Thermal Comfort Index (UTCI) for Outdoor Comfort Upgrading chawls – Observing the thermal comfort issues in indoor and outdoor spaces of chawl, upgradation of chawls is suggested. Initially, few primary strategies to resolve existing comfort issues are evaluated. Further design study suggests the overall form upgradation, which can be incorporated while designing such typology. In this section, the analysis is focused on the materials of the building and surrounding which directly affects the comfort. The analysis is compared with the base case study from previous section to indicate improvement. Analysis focuses on – • Indoor Thermal comfort • Universal Thermal Comfort Index (UTCI) for Outdoor Comfort 49

5.2 INDOOR COMFORT 5.2.1 TWO CASES The original design and the adapted design throughout the time is evaluated to observe the degraded performance of the typology. The second case, which is the resultant living situation, is due to the measures taken by residents. Occupants look for quick and easy solutions, to get rid of the discomfort, which is not time-consuming. (Heerwagen & Diamond, 1992) In this middle-class housing, the solutions cost-effective as well. The resultant situation is compromising the design and declining the performance of chawls. In view of this, an analysis of case 1 reveals the performance of original design application. In contrast, case 2 shows the performance with design solutions pointing out the negative and positive consequences. The residents occupy the Verandas as an extended area of the room. As it had issues with penetrating rains with wind and higher solar radiation, users put an aluminium sheet overhang with basic framing. The overhang is 900 mm in depth with 45° slope, which blocks more area. (fig 5.2.2) Case 1 has an open layout with equal cross ventilation. The washing/bathing area was used for washing dishes or clothes (fig 5.2.1). It is separated by a 3’ wall and 0.5’ threshold to prevent water from entering kitchen space. The same space is used for bathing. The cultural impact on architectural planning is clearly visible here. The old practice indicates that women of the house wake up early in the morning, take a bath and start cooking for the families. The men of the family later use the bathing space. Through time, this practice changed as people needed privacy. They enclosed the walls of the washing/bathing area. Case 2 altered the internal walls by enclosing them for privacy.

Figure 5.2.1 Image showing Case 1 kitchen layout

Section with 0.9 m overhang on veranda Figure 5.2.2 Implementation of Overhang in Veranda

CASE 1

CASE 2 Enclosed walls for privacy

3.4 M

3M 6.8 M

3.4 M

Ac units occupying the ventilator space

Figure 5.2.3 Detailed image of both Unit cases 50

OPTIVENT Case 1 has more window and effective aperture area, as case 2 blocks the Living room ventilator area with AC unit. The internal layout in case 2 is confined due to the enclosed walls. This separated the whole big space, as seen in fig (5.2.5) to two different rooms (fig). These two significant changes affect the internal airflow. Optivent from case 1 shows around 50% required airflow achieved for cooling, which can be improved more. (fig) However, Case 2 shows a decline in the airflow, with insufficiency of around 75% airflow required for cooling. (fig 5.2.5)

Optivent tool was used to explore the ability of both scenarios of chawls for effective natural ventilation during Summer month (May), as it is considered a critical season for thermal comfort. The inputs for temperature, Wind flow are based on the fieldwork measurements. The internal gain inputs are based on the fieldwork as described in detail in TAS Analysis.

3.4 M

3M 6.8 M

3.4 M 3M

Buoyancy driven

Figure 5.2.4 Results from Optivent for Case 1 (Source: Optivent)

Figure 5.2.5 Results from Optivent for Case 1 (Source: Optivent) 51

5 . 2 C O M PA R I S O N O F U N I T S C E N A R I O S 5.2.3 IMPACT OF OVERHANG As learned from the climate analysis of Mumbai, solar radiation is higher throughout the year. Radiation is higher in mild season from the south than in summer. Open verandas are self-shaded, yet they receive a lot of radiation. The additional overhang in self-shaded veranda reduces solar radiation but decreases direct sunlight. Further radiation and daylight analysis are performed to evaluate the impact of overhang in veranda and the unit, as diffused radiation still accessible.

Radiation â&#x20AC;&#x201C; The impact of adaptive strategy of overhang for veranda is evaluated at all levels of the building, for both cases to observe the reduced radiation. Daily average radiation can be interpreted better for the exposure by using Ladybug tool from Grasshopper., The average solar radiation for daytime hours (8:00-18:00) is calculated for 21st of May (Summer) and 21st of January (Winter), as radiation is higher even during winter. Application of overhang shows a massive reduction of average 95 wh/m2 radiation during summer. The decline in mild season is higher for west wing up to average 82 wh/m2, due to orientation and lower winter afternoon angles. Overall, Lower floors receive lesser radiation since narrow courtyard control the sun penetration for lower floors. As an impact of orientation, verandas in east wing receives lesser radiation than from west wing.

0.9 OVERHANG ON VERANDA

Figure 5.2.6 Solar radiation results in Veranda (Source: Rhino, Grasshopper)

REDUCED RADIATION WITH OVERHANG

REDUCTION

AVG 95 Wh/m2

AVG 96 Wh/m2

73 wh/m2

149 wh/m2

47 wh/m2

161 wh/m2

33 wh/m2

139 wh/m2

201 wh/m2

130 wh/m2

196 wh/m2

79 wh/m2

156 wh/m2

60 wh/m2

SUMMER (21ST MAY 8:00-18:00) REDUCTION

AVG 26 Wh/m2

REDUCTION

AVG 82 Wh/m2

144 wh/m2

218 wh/m2

86 wh/m2

184 wh/m2

70 wh/m2

146 wh/m2

MILD SEASON (21ST JANUARY 8:00-18:00)

112 wh/m2

90 wh/m2

124 wh/m2

94 wh/m2

125 wh/m2

99 wh/m2

DAYLIGHT The analysis is performed considering the existing scenario, where residents close windows for privacy, which affects indoor daylight, additionally to poor daylight conditions. Hence, the windows have closed wooden shutter and Ventilators with glass. As poor daylight conditions are known, one of the lower floors, i.e. the first floor is tested. The interiors are occupied by crammed furniture and the dark coloured walls as observed in case study. Useful Daylight Illuminance (UDI) analysis was performed to relate the percentage of occupied hours that meet the target illuminance needed throughout the year. This study indicates the areas with excess or lack of illuminance required in certain parts of the building. The transmittance and reflective input values along with materials of the component are stated in the fig (). As mentioned in the rating guide by Indian Green Building rating system, minimum 50% occupied space should receive 110 lux. (IGBC, 2017) The minimum threshold for illuminance is considered 150 lux, as mentioned required for kitchen spaces. (CIBSE, 2015) The impact of overhang affects daylight in the veranda, yet the required daylight is achieved, avoiding the possibility of glare. Glare possibilities (more than 2000 lux) are more towards the ends of the veranda. The illuminance in the living room is always less than 150 lux.

Materials Walls Floor Ceiling Windows Ventilators Overhang

Dark colored walls Dark Stone flooring White Ceiling Wooden shutters Single glazed glass Aluminium sheet

Reflectance Transmittance 0.3 0.2 0.7 0.1 0.9 0.1

UDI below 150 lux

UDI 150 -2000 lux

LEGEND

UDI above 2000 lux

LEGEND

Figure 5.1.2 UDI Results in veranda

UDI below 150 lux

UDI 150 -2000 lux

LEGEND

Figure 5.2.8 UDI Results with overhang in veranda (Source: Rhino, Grasshopper, Radiance)

Figure 5.2.7 Building Materials and Its values for the analysis

LEGEND

UDI above 2000 lux

LEGEND

5.2.3 THERMAL ANALYSIS (TAS) A centrally located flat from chawl is analyzed for thermal analysis using EDSL Tas software, studying the resultant temperature profiles in the unit. The inputs considered for this analysis are mentioned further in detail, evaluating the base case performance, compare the performance of both scenarios and comfort in transitional spaces like veranda. Also, thermal studies are conducted to see the effects of implemented basic approaches for improving building performance.

C A S E 1 – Basecase

C A S E 2 – Revised Case (Without Cooling)

W1 AREA – 20.3 Sq. m.

AREA – 11 Sq. m.

W/F RATIO – 20%

W/F RATIO – 22%

AREA – 9.3 Sq. m. W/F RATIO – 17%

Figure 5.2.3.1 TAS inputs for chawl model in both cases

U- Value (W/m²K)

ENVELOPE

APERTURE S

External Wall Internal Wall Flooring Roof

230-300 mm thick Brick walls with plaster

Living room Window (W1) Kitchen Window (W2)

Glass as wooden shutter with Glass ventilator

Main Door (D)

Wooden door with Glass ventilator

110 mm thick Brick walls with plaster Kota stone flooring Mangalore tiles on Wooden Joists and Battens

Glass as wooden shutter with Glass ventilator

Figure 5.2.3.2 TAS inputs for materials in both cases

1.9 0.9 2.2 2.2

R- Value

G- Value

Window Window Area Opening (%) (Sq.m.)

0.5 0.34 0.34

0.9 0.9

0.34

0.9

1.78 2.25 0.54 (Ventilato r)

95% 95% 95%

Figure 5.2.3.3 Thermal comfort analysis model with surrounding (Sourc: EDSL TAS)

Figure 5.2.3.4 Thermal comfort analysis model of chawl building (Sourc: EDSL TAS)

EQUIPMENT GAINS Area Season Summer Monsoon Mild season

Days of the months

Hours

2952 2929

Refrigerator

2880

washing machine*

Hob*

200

1st January - 28th February 1st November - 31st December 4th June - 30th September

Ceiling Fan

1st March - 3rd June 1st October- 31st October

Sensible energy

Figure 5.2.3.5 seasonal inputs for analysis in TAS

20.4

43.6

359.6 EQUIPMENT GAIN *Energy consumed by per cycle in a day Figure 5.2.3.6 inputs of Equipment gains 56

17.6

BASECASE PERFROMANCE STUDY

The preliminary analysis of base case (Case 1) compared all floors during two days in March and May. This shows the comparison between all floors in the building on 16th march highest external temperature day and 21st May typical summer day. The diurnal temperature difference in march is more than May. The higher external temperature during daytime in march loses heat during nighttime, however in May heat is stored indoor due to similar external temperature at night. The difference between the 3rd and 4th floor, i.e. top floor shows the effect of lightweight roof construction. The temperature is increased earlier in the top floor than floors below. Figure 5.2.3.7 Keyplan of the building

DIURNAL TEMPERATURE DIFFERENCE

Resultant Temperature of the Rooms

41 40

1°C difference

1.5°C difference

38 37

1.5°C difference 4°C difference

36 35

EFFECT FROM LIGHTWEIGHT ROOF

34 33 32 31 Ground Floor

1st Floor

2nd Floor

3rd Floor

4th Floor

Floors 16th March 21st May External Temperature (16th March)

16th March – Highest External Temperature 21st May- Typical Summer day

External Temperature (21st May)

Figure 5.2.3.8 Comparison in all the floors on two days at 15:00 (peak hours) (Source: EDSL TAS)

As observed in the previous study, the diurnal temperature difference in May is less. The maximum difference is approximately 4°C on lower floors and 7°C on the top floor. During peak hours, the temperature in the top and lower floors is 2°C. Nicol’s adaptive comfort band has been used to relate the comfort with resultant temperature. The comfort lies between 27°C-30.7°C in May, which shows the resultant temperature out of the comfort zone most of the time. However, the external temperature during the night is in the adaptive comfort zone. The Adaptive comfort, according to Nicol’s comfort equation, lies between 24.3°C-29.2°C in January. Winter week shows daytime external temperature in comfort, but resultant temperature 2 degrees higher. As during night, external temperature is under comfort zone, when windows are 60% open, the indoor temperature exceeds even more than daytime. This indicates the need for ventilation even during the mild season.

R e s u l t a n t t e m p e r a t u r e (summer season week - may) 40 35 GROUND FLOOR

30 25 20 15 40 35 30

SECOND FLOOR

25 20 15 40 35

FOURTH FLOOR

30 25 20 15

Adaptive Comfort Band (Nicol)

Figure 5.2.3.8 Basecae Temperature variations for summer week (Source: EDSL TAS)

R e s u l t a n t t e m p e r a t u r e (winter/mild season week â&#x20AC;&#x201C; January) 40 35 GROUND FLOOR

30 25 20 15 40 35

SECOND FLOOR

30 25 20 15 40 35

FOURTH FLOOR

30 25 20 15

Adaptive Comfort Band (Nicol)

Figure 5.2.3.9 Basecase Temperature variations for winter week (Source: EDSL TAS)

COMPARISON OF BOTH CASES The annual comfortable hours were tested for both cases, to compare the performance considering the annual comfort band of 24°C – 30.7°C (Nicol’s Adaptive Comfort Equation). Learning from the base case assessment, windows are considered open 98% (2% frame and net factor) throughout the year for the analysis. The first case reveals the main issue mainly during summer and monsoon, as it shows more than 50% overheating hours. Case 2 indicates an increase in uncomfortable hours, mostly in mild season. This out of comfort indoor condition encouraged the occupants to use mechanical ventilation. As seen from data loggers, they use ACs during the night, which might increase their cooling loads up to 798 kW/h/m2, which increases by 14% from case 1.

C A S E 1 – Basecase

C A S E 2 – Revised Case (Without Cooling) SUMMER

Top level (West) Middle level (West) Lower level (West) Top level (East) Middle level (East) Lower level (East)

Top level (West) Middle level (West) Lower level (West) Top level (East) Middle level (East) Lower level (East) 0

% of Hours Within Comfort

100

% of Hours Within Comfort

% of Hours Overheating

100

% of Hours Overheating

MONSOON

Top level (West) Middle level (West) Lower level (West) Top level (East) Middle level (East) Lower level (East)

Top level (West) Middle level (West) Lower level (West) Top level (East) Middle level (East) Lower level (East) 0

% of Hours Within Comfort

100

% of Hours Overheating

% of Hours Within Comfort

100

% of Hours Overheating

MILD SEASON Top level (West) Middle level (West) Lower level (West) Top level (East) Middle level (East) Lower level (East)

Top level (West) Middle level (West) Lower level (West) Top level (East) Middle level (East) Lower level (East) 0

% of Hours Within Comfort

% of Hours Below Comfort

100

% of Hours Overheating

% of Hours Within Comfort

% of Hours Overheating

Increase in overheating 60

Figure 5.2.3.10 Comparison in annual comfort hours in both cases (Source: EDSL TAS)

100

5.3 OUT D OOR COM FORT (Tra ns i ti on al sp ac e s) 5.3.1 VERANDA

YEARLY (% of hours out of comfort zone) Fourth Floor Veranda (East)

Second Floor Veranda (East)

Ground Floor Veranda (East) 0

% of Hours Within Comfort

% of Hours below Comfort

100

% of Hours Overheating

Figure 5.3.1.1 Annual comfort in three levels of Veranda (Source: EDSL TAS)

is affected mainly due to fluctuations in mean radiant temperature, and during winter afternoons due to solar gains. In peak hours of summer and monsoon, the verandas are overheating. In these seasons they can be usually used during night time after 7 p.m. When the external temperature goes below comfort during winter nights, veranda temperature is higher than external temperature yet below comfort. However, during peak hours in winter and other seasons, veranda temperature is 1-2°C more than the external temperature.

Resultant Temperature (c)

Thermal comfort in Verandas have been evaluated in TAS annually and daily profile basis. The annual comfort in fig (5.3.1.1) indicated the comfortable hours in Ground (Lower) floor, Second (Middle) floor and Fourth (Top) floor. The difference replicates the indoor temperature profile indicating higher temperatures on the top floor. The veranda shows 65-70% comfortable hours annually. In terms of understanding daily comfortable hours, fig (5.3.1.2) displays a daily profile from 3 seasons for an intermediate (second) floor. The resultant temperature

40 35 30 25 20 1

Hours

Comfort Band (24°C- 31°C) Figure 5.3.1.2 Daily temperature profile of 3 seasons showing Veranda temperature 62

5.3.1 COURTYARD

The UTCI (Universal Thermal Climate Index) analysis is performed during different hours of the day, to understand the effect on UTCI stress during peak hours and after peak hours. The courtyard is shaded well during some hours as visible in fig 5.3.1.2. It receives direct solar radiation during certain hours of the day. Ground reflectivity (albedo value) of sandstone is 0.6. Inputting this value in UTCI for different seasons, we achieve strong heat stress and very strong stress during peak hours. Fig 5.3.1.2 indicates the variations in UTCI from 9:0018:00 throughout three seasons. Morning and evening hours show the heat release ability of the courtyard, which shows equal stress in Summer and monsoon. Heat loss in winter nights achieves moderate heat stress during winter mornings. Lower winter angles restrict solar access in the courtyard keeping it in comfort most of the time. Following fig indicates current usable hours of the season in the studied courtyard. Figure 5.3.1.2 Existing Courtyard of the site

VERY STRONG HEAT STRESS

Average UTCI (degree c )

STRONG HEAT STRESS

36 34 32

MODERATE HEAT STRESS

30 28 26

NO THERMAL STRESS

Figure 5.3.1.1 Daily temperature

22 20 09:00

11:00

12:00

13:00

14:00

Hour Monsoon

Mild season

Figure 5.3.1.2 Comfort of courtyard in different seasons based on UTCI analysis

Summer

15:00

18:00

Outcomes The indoor temperature is higher throughout the year. 75-80% of overheating scenarios in summer creates critical unsatisfactory living conditions. In terms of lowcost housing, the potential outcome of the use of mechanical cooling is improper. The transitional spaces like veranda and courtyards are more comfortable than the rooms, yet the required comfort is not achieved. The overheating in veranda might increase more as the heat emission from ac compressor release in the veranda, which is not evaluated in the analysis due to simulation limitations. The possibility of the comfortable hours and the preferred occupied hours by the residents do not meet. Due to higher sun angles in May and July, the courtyard always receives sun, and under extreme thermal stress. Some measures are required to avoid such conditions. The diurnal temperature difference in different seasons implies the necessity of ventilation during summer. The structure of the roof affects indoor temperature, which has the potential for improvement. This Urban Vernacular architecture typology was designed for that specific time and user requirement. However, throughout the time with all the economic, social and other modifications, the building goes through certain adaptive changes as we saw. The whole family later occupied Chawls, mainly built for the mill workers, a room for single-tenant. The chawls evolved with time, but it has its limitations yet.

Positive points to consider

Shaded transitional spaces

Negative points to consider

Maximum airflow throughout the year

VENTILATION

Open layout works better

Resolving observed issues

Improving Roof to avoid ENVELOPE overheating

Appropriate Aperture size

VENTILATION

Natural ventilation using passive strategies SHADING

SHADING

Shading required in all veranda

Better shading materials

Materials with more thermal PERFORMANCE resistance

5.4 UPGRADING CHAWLS

COURTYARD - MATERIAL Average UTCI (degree c )

Existing material of courtyard is a stone (Sandstone), which indicates very strong heat stress condition based on previous studies. The heat emission from the ground is higher with the use of stone. This study is performed to understand different surface material’s heat emission and choosing better material in the courtyard. The methodology is similar to previous UTCI study by analyzing the UTCI stress from morning to evening contemplating the changes. The comparative study is performed with three materials – Concrete, stone and soil. The albedo value of the ground surface material indicates the reflection of solar radiation, which ranges from 0 to 1. Albedo value of selected material are as follows –

SUMMER 21ST May

40 35 30 25 20 09:00

11:00

12:00

13:00

14:00

15:00

18:00

Hour Concrete

Soil

Stone

Concrete – 0.7 Stone (Existing) – 0.6

MILD SEASON 21ST January

Soil/ Terracotta soil – 0.3 Average UTCI (degree c )

The results of the analysis indicate the gradual difference with concrete being highest and soil lower UTCI degrees. Heat loss by all the materials is similar; however, the emission during peak hours varies. Alteration in material is not improving the comfort conditions as required. Shading the courtyard is necessary to avoid extreme solar exposure.

40 35 30 25 20 09:00

11:00

12:00

13:00

14:00

15:00

18:00

15:00

18:00

Hour

Average UTCI (degree c )

Concrete

Soil

Stone

MONSOON 21ST July

40 35 30 25 20 09:00

11:00

12:00

13:00

14:00

Hour Concrete

Soil

Stone

Figure 5.4.1 UTCI analysis comparing impact of different ground materials

Design Solution alternatives for shading courtyard space In warm climates like Mumbai, the public or open spaces are shaded to avoid excess solar radiation. These examples from other countries as well as India, display different solutions for shading adapted or planned. The colours of fabric or cool shadow from a tree are used to improve outdoor comfort in the simplest ways.

Figure 5.4.2 NID Ahmedabad, India (Source: Google)

Figure 5.4.3 Ledras Street in Cyprus (Source: Google)

Figure 5.4.4 City Palace, Udaipur, India (Source: Google)

Figure 5.4.5 Indian Habitat Centre (Source: Google)

Figure 5.4.6 Metropol Parasol, Seville, Spain (Source: Google)

Average UTCI (degree c )

COURTYARD - SHADING One of the solutions is tested to analyze the effect after shading. An exemplar wooden shading is designed for chawl courtyard, as required by environmental and social constraints. The pergola-like slender structure maintains the visual connection between veranda and courtyard. But the form of the pergola blocks the direct sun. As the centre of the courtyard receives more radiation all the time, the pergola is denser in middle and permeable at both ends. The space between pergola and building lets the heat pass through without obstruction. The outdoor comfort improved by 3Â°C in summer peak times and 6Â°C in mild season peak times.

40 35 30 25 20 09:00

11:00

12:00

13:00

14:00

15:00

18:00

Hours Courtyard

Courtyard (With Shading)

Average UTCI (degree c )

Figure SUMMER 21ST may

40 35 30 25 20 09:00

11:00

12:00

13:00

14:00

15:00

18:00

Hours Courtyard

Courtyard (With Shading)

Average UTCI (degree c )

Figure MILD SEASON 21ST January

40 35 30 25 20 09:00 11:00 12:00 13:00 14:00 15:00 18:00 Courtyard

Hours

Courtyard (With Shading)

Figure MONSOON21ST July

Figure 5.4.7 Conceptual sketch of proposed shading (source: Author)

Figure 5.4.8 UTCI analysis showing improvement with shading

Without shading

With shading

Figure 5.4.9 UTCI results of both cases

Figure 5.4.10 View of courtyard with proposed roof and reduced UTCI values. 68

IMPROVING BUILDING ENVELOPE

Ventilated pitched roof

Frosted Glass

Fabric Window shading

Figure 5.4.11 Suggested improvements in the envelope

The major issues in building envelope observed in indoor comfort analysis are roof and overhang. User-friendly and affordable materials and constructions are applied to improve performance. The poor daylight conditions are observed due to dark interiors and closed windows for privacy. This can be improved with the application of frosted glass to enhance the indoor daylight conditions even when they are closed to maintain privacy. The frosted glass has higher solar resistance and performs better in daylight distribution. In the case of overhang, a fabric material with higher G-value and R-value can be recommended to increase penetration restricting the sun access. The water-resistance fabric used for outdoor shading materials like PVC fabric, which needs less maintenance as well. The revisions in the material properties and values can be referred from fig (5.4.12). The improved UDI considering changes can be referred from the appendix (), and it will be discussed further precisely in the unit level analysis.

Change in construction…. ROOF – Air gap 150 mm Wood fiber insulation 8mm thick Change in u value and r value

OVERHANG – Aluminium material to Textile with more G-Value and R-Value

Materials Walls Floor Ceiling Windows Ventilators Overhang

Reflectance Basecase

Final Case

0.3 0.2 0.7

0.5 0.2 0.7

Dark colored walls Dark Stone flooring White Ceiling

Transmittance Basecase

Final Case

0.1 0.9 0.1

0.7 0.9 0.6

Wooden shutters Single glazed glass Aluminium sheet

Figure 5.4.12 Reflectance and transmittance values of building materials

ROOF (improved performance)The lightweight wooden roof affects adjacent indoor spaces when exposed to the sun. The construction of the roof is improved by using wood fibre insulation to restrict heat flow and further allowing airgap between the construction. The air gap allows air to pass from the heated roof, which is known as a ventilated pitched roof. The implementations in overhang and roof show the improvement on all floors. As we compare it to the existing indoor performance, significant improvement is visible in monsoon and mild season.

SUMMER

FOURTH (WEST) SECOND (WEST) GROUND (WEST) FOURTH (EAST) SECOND (EAST) GROUND (EAST) 0

% of Hours Within Comfort

100

% of Hours Overheating

MONSOON FOURTH (WEST) SECOND (WEST) GROUND (WEST) FOURTH (EAST) SECOND (EAST) GROUND (EAST) 0

% of Hours Within Comfort

100

% of Hours Overheating

MILD SEASON FOURTH (WEST) SECOND (WEST) GROUND (WEST)

Comfortable hours in Case-2 Increase in comfortable hours

FOURTH (EAST) SECOND (EAST) GROUND (EAST) 0

% of Hours Within Comfort

100

% of Hours Overheating

Figure 5.4.13 Improved thermal performance with envelope improvement 70

5.5 DESIGN STUDY

DESIGN STUDY massing level

solar study solar radiation Comparison in chosen cases for indoor comfort Concluding with ideal orientation and aspect ratio

5.5 DESIGN STUDY The sun angles for 4 hours of summer and mild season day (21st May and 21st January) are achieved using sun vectors from sun path analysis of Grasshopper. Due to the location of Mumbai, the sun path shows fewer hours of the sun reaches the façade from the north. The altitude and azimuth of every angle have been considered and illustrated in the sections.

O1 – (N-S)

O2 – (W-E)

O3 – (NW-SE)

O4 – (NE-SW)

Figure 5.5.1 3D sunpath showing 4 orientations

5.5 DESIGN STUDY

O1 – (N-S)

Current scenario of chawls is not suitable to the changing lifestyle and urban development. Therefore a design study is performed for the retrofit of the chawls for today, which analyses the building form for better

O3 – (NE-SW)

O4 – (NW-SE) N

O R I E N TAT I O N

MASSING LEVEL

H / W R AT I O

(COURTYARD TO BUILDING)

A 4.25 : 1

B 2.1:1

C 1.4:1

UNIT LEVEL STUDY

SHADING

UNIT LEVEL

performance. This study evaluates the chawl building form in different orientations and aspect ratios. The aspect ratio or height to width ratio of the courtyard to the building affects the comfort in courtyard and effectively indoor comfort of the rooms. Planning the building with correct orientation is the fundamental passive design strategy implemented to reduce energy consumption, significantly for low-cost residential settlement like chawls. The courtyard is analyzed in 4 orientations with typical ‘C-shaped’ 5 storied building form. The three aspect ratios observed from the case studies of Chawls in Mumbai are explained in 4 orientations.

O2 – (W-E)

APERTURE SIZE

INTERNAL HEIGHT

Figure 5.5.2 Design study methodology

SOLAR STUDY - METHODOLOGY

The partly cloudy sky appears almost regularly during the wet season (35â&#x20AC;&#x201C;45%). Overcast sky occurs during only 20% of the time over a year during the rainy period. Effectively, solar radiation is comparatively less during monsoon. Hence, the solar radiation is performed for the extreme seasons, summer and Mild season (Winter) day. The radiation analysis is compared for a single day of both seasons, i.e. 21st May (Summer) and 21st January (Mild season/Winter) with average daily solar radiation values in facades and verandas. Solar analysis with sun penetration in the courtyard is studied for 12 scenarios of orientations and aspect ratios. The performance of both wings varies depending on the orienting direction. The radiation in corridors, exposed facades and shaded facades affect the internal solar gains, irrespective of the insulation of the building envelope. The detailed solar radiation of verandas can be referred from appendix section_. The solar penetration and its effect on radiation on facades are explained further.

WING 2

WING 1

RADIATION IN CORRIDOR N

O2 N

RADIATION ON FACADES

EXPOSED FACADES COVERED FACADES 75

O1 – (N-S)

5.5 DESIGN STUDY 5.5.1 MASSING LEVEL

SOLAR STUDY EXPOSED FACADE Mild Season_Wing B

181

Mild Season_Wing A

122 237

Summer_Wing B 171

Summer_Wing A

SHADED FACADE

100

200

250

300

350

400

450

Vertical Solar Radiation (wh/m2)

15 0 10

33 28

150

Vertical Solar Radiation (wh/m2)

12:00

12:00 15:00

15:00

09:00

12:00

15:00

15:00 09:00

18:00

09:00

15:00

18:00

09:00

18:00

WING A

Courtyard width – 4m H/W Ratio – 4

WING B Courtyard width – 8m H/W Ratio – 2

EXPOSED

SHADED

EXPOSED

SHADED

EXPOSED

SHADED

EXPOSED

SHADED

WING B

WING A

EXPOSED

18:00

WING A

WING B Courtyard width – 12m H/W Ratio – 1.5

SunVectors on 21st May (Summer) SunVectors on 21st January (Mild Season/Winter)

Figure 5.5.1.1 Solar angle penetration study and solar radiation analysis on facades of O1. (Source: Grasshopper)

O2 – (W-E)

5.5 DESIGN STUDY 5.5.1 MASSING LEVEL

SOLAR STUDY EXPOSED FACADE Mild Season_Wing B

392

Mild Season_Wing A

24 86

Summer_Wing B

108

Summer_Wing A 0

100

150

200 250 300 Vertical Solar Radiation (wh/m2)

350

400

450

6 48

12:00

Post-Afternoon sun access (Summer)

12:00 15:00

09:00 18:00

SHADED

EXPOSED

SHADED

Post-Afternoon sun access (Summer)

Afternoon sun access (Mild Season)

WING A

Courtyard width – 4m H/W Ratio – 4

WING B

Courtyard width – 8m H/W Ratio – 2

18:00

EXPOSED

18:00

EXPOSED

SHADED

15:00

18:00 18:00

SHADED

09:00

18:00

WING B

09:00

Afternoon sun access (Mild Season)

12:00

09:00

WING A

15:00

09:00

EXPOSED

12:00

15:00

Vertical Solar Radiation (wh/m2)

EXPOSED

SHADED

Vertical Solar Radiation (wh/m2)

SHADED

EXPOSED

Post-Afternoon sun access (Summer)

Afternoon sun access (Mild WING A Season)

WING B

Courtyard width – 12m H/W Ratio – 1.5

SunVectors on 21st May (Summer) SunVectors on 21st January (Mild Season/Winter)

Figure 5.5.1.2 Solar angle penetration study and solar radiation analysis on facades of O2. (Source: Grasshopper)

O3 – (NW-SE)

5.5 DESIGN STUDY 5.5.1 MASSING LEVEL

SOLAR STUDY EXPOSED FACADE Mild Season_Wing B 282

Mild Season_Wing A

56 193

Summer_Wing B

161

Summer_Wing A 0

100

150

SHADED FACADE

350

400

450

12:00

09:00

09:00 18:00

SHADED

Post-Afternoon sun access (Summer)

Afternoon sun access (Mild Season)

WING A

Courtyard width – 4m H/W Ratio – 4

WING B

Courtyard width – 8m H/W Ratio – 2

A 78

EXPOSED

18:00

EXPOSED

SHADED

12:00

18:00

WING B

15:00

18:00

Post-Afternoon sun access (Summer)

15:00 15:00

09:00

15:00

18:00

EXPOSED

09:00

15:00

Afternoon sun access (Mild Season)

Vertical Solar Radiation (wh/m2)

12:00

09:00

WING A

12:00

15:00

Vertical Solar Radiation (wh/m2)

EXPOSED

SHADED

Vertical Solar Radiation (wh/m2)

SHADED

EXPOSED

48 32

SunVectors on 21st January (Mild Season/Winter)

300

SunVectors on 21st May (Summer)

250

16 23

200

Vertical Solar Radiation (wh/m2)

Post-Afternoon sun access (Summer)

Afternoon sun access (Mild WING A Season)

WING B

Courtyard width – 12m H/W Ratio – 1.5

C Figure 5.5.1.3 Solar angle penetration study and solar radiation analysis on facades of O3. (Source: Grasshopper)

O4 – (NE-SW)

5.5 DESIGN STUDY 5.5.1 MASSING LEVEL

SOLAR STUDY EXPOSED FACADE Mild Season_Wing B

Mild Season_Wing A

423 182

Summer_Wing B 103

Summer_Wing A

SHADED FACADE

100

150

200

250

300

350

400

450

Vertical Solar Radiation (wh/m2)

57 56

5 10

5 14

13 17

Vertical Solar Radiation (wh/m2)

15:00

Vertical Solar Radiation (wh/m2)

15:00 15:00 12:00

12:00

18:00

09:00

12:00

09:00

Afternoon sun access (Mild Season)

WING B

SW Morning and midday sun access (Summer)

Afternoon sun access (Mild Season)

WING A

Courtyard width – 4m H/W Ratio – 4

WING B

Courtyard width – 8m H/W Ratio – 2

SHADED

EXPOSED

SHADED

EXPOSED

09:00

18:00

WING A

09:00

18:00

09:00

18:00

Morning and midday sun access (Summer)

12:00