Learning from the chawl

AA E+E Environmental & Energy studies programme Architectural association school of architecture Graduate school

M.arch Sustainable Environmental design Dissertation Project 2015-17

Learning from the chawl Design of low-cost social housing in Mumbai

Shruti Shiva January 2017

ABSTRACT Mumbai, India’s teeming metropolis experiences staggering rates of urbanization, causing an undue exploitation of the built environment. However, this growth is asymptotic to the needs of the city, failing to accommodate large numbers of rural migrants and causing a massive shortage of affordable housing. Although the government has proposed a program of rehabilitative schemes to relocate slum dwellers into high density towers, these buildings lack adequate light and ventilation, and fail to retain the existing ties within migrant communities.

It is within this milieu that chawls become a typological solution to the aforementioned problem. Chawls are historically built high density social housing, which were built by mill owners to house communities of migrant textile workers. Chawl architecture provided lively communal spaces and became synonymous with low-cost sustainable housing.

This paper studies the potential of this typology to be a precedent for passive design, while outlining the role and performance of key features, such as the corridor and the courtyard, in providing comfort and creating an enriching social environment.

Fieldwork and understanding of the occupant forms the crux of this thesis leading to the primary hypothesis of this paper, that the relationship between the corridor, the courtyard and the housing units lie at the crux of creating environmentally and socially sensitive spaces. The paper concludes by culling the learning from this typology, to propose a new outlook for sustainable high density housing through the preservation of urban communities.

Keywords : Mumbai, Chawl, transitional spaces, social housing, low-cost, community living

AUTHORSHIP DECLARATION FORM

Sustainable environmental design

Architectural Association School of Architecture Programme:

MArch Sustainable Environmental Design 2015-17

Submission:

Dissertation Project

Title: Learning from the chawl: low-cost social housing in Mumbai Number of Words: 14,141 words (excluding footnotes and references) Student Name:

Shruti Shiva

Declaration: “I certify that the contents of this document are entirely my own work and that any quotation or paraphrase from the published or unpublished work of others is duly acknowledged.�

Signature of Student:

Date: January 27th, 2017

Acknowledgments

Firstly, I would like to thank my tutor, Jorge Rodriguez, for his invaluable feedback, guidance and support, which helped me reach this dissertation to its full potential. I would like to thank Simos Yannas, Paula Cadima and all other SED tutors for providing great insights, engaging discussions and critiques which has contributed significantly to not just during the dissertation but also all through the course.

I’d like to thank my fellow SED colleagues, whose presence, feedback, compliments and critique have helped me hone my perspectives as an architect, among whom I’d like to make a special mention to Olivier Dambron and Paolo Flores for their technical inputs and Trishta Vardhan, Anusha Nanavati,Bhaavvyaa Rangarajan and Elias Anka for being my home away from home.

I would like to thank the occupants of the Government colony for their participation during fieldwork and for letting me into their homes with eagerness.

I would like to thank Sachit Ajmani for his tireless effort, patience, support and keen involvement in my project.

Lastly but definitely not the least, I’d like thank my parents, Hema and Shiva, and my family for their unconditional support, faith, encouragement and belief, without whom my rewarding and arduous journey through the masters would’ve never been possible.

Table of contents 1. Introduction 1.1. Introduction to Mumbai

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1.2. History of Mumbai’s urban growth 3 1.3. Current contextual scenario 5 1.4 SRA v/s Chawl 6 1.5 Primary research questions 7 1.6 Research Methodology 8

2.Climate analysis 2.1 Overview of climatic features 11 2.2. Climatic conditions 12 2.3.Comfort band 15 2.4. Passive cooling strategies 17 2.5. Passive cooling strategies 19 2.6. Transitional spaces 21 2.6a Courtyards 22 2.6b Verandas and Corridors 23 2.6c Balconies 23

3.Precedent study 3.1 What is a chawl 27 3.2. History of the chawl 28 3.3. Evolution of the chawl 29 3.4. About the typology 31 3.5 Materiality & typology 35 3.6. Universal applicability of the chawl type 36

4.Fieldwork 4.1 Fieldwork site 39 4.2 Interviews 40 4.3 Occupancy pattern 43 4.4 Gains charts 44 4.5 Outdoor study 45 4.6 Indoor Studies 46 4.6b.Data logger (april_summer week) 49 4.6c.Data logger ( july_rainy week) 50 4.7 Key inferences from fieldwork 51

5.Pre-design studies 5.1 Courtyard 55 5.1a. shape optimization 57 5.1b. Aspect ratio 59 5.1c. Material study 61 5.1d. Activity pattern and courtyard usage 63 5.1e. Effect of trees, vegetation and water bodies 64 5.2. Unit studies _base case description 65 5.2a. Unit strategies 66 5.2b Unit studies_top floor analysis 70 5.2c Orientation studies 71 5.2d Unit performance conclusion 72 5.3 Corridor analysis 73 5.3a. Case study summary 73 5.3b. Depth and shading analysis 75 5.3c. Daylight analysis 77 5.4 Conclusions 78

6. Design application 6.0. Design strategies 82 6.1. Unit design 83 6.2. Building Block design 86 6.3. Elevation design 87 6.4. Views 91 6.5 Site Analysis 95 6.5a Site selection 96 6.5b. Site mapping 97 6.6. Massing strategies 99 6.7. Master plan 103 6.8 Views_outdoor 105 6.8a. Design assessment 107 6.8b. courtyard assessment 109 6.9. Summary of performance 111

7. Conclusions 115

8. Post Design 8.1 Green Roof system 8.2 Bamboo shading making 8.3 Cost benefit Analysis

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List of figures and tables 1.Introduction Figure. 1.2.1. Mumbai’s growth from an archipelago to a unified city.

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Figure. 1.2.2. Mumbai’s oldest known chawl, the multi tenant social housing

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Figure. 1.2.3. The decline and dilapidation of chawls

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Figure. 1.2.4. Towering privately owned real estate dwarfing the chawl

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Figure. 1.3.1. Article cutout reporting the failure of the SRA building scheme and consequent vacancies

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Figure. 1.3.2. Slum rehabilitative process, schematic representation

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Figure. 1.4.1. Preliminary comparative analysis of the chawl and the SRA type; urban, building and unit level

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2.Climate and passive strategies Figure. 2.1.1. Location of Mumbai city and satellite image of the city

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Table 2.0. Summary of seasons and their characteristic temperature range

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Figure. 2.1.2. climatic overview of Mumbai city; temperature, radiation, humidity and precipitation)

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Figure. 2.1.3. Precipitation in mm 13 Figure. 2.1.4. Radiation rose with sunpath to indicate which direction receives what proportion of radiation

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Figure. 2.1.5. Prevailing wind speed and direction 14 Figure. 2.1.6. Solar angles and sunpath 14 Figure. 2.3.1. summer months psychrometric chart 15 Figure. 2.3.2. Rainy months psychrometric chart 15 Figure. 2.3.3. Increase in outdoor comfort band in tropical countries

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Figure. 2.3.4. Study on comfort in tropical countries 16 Figure. 2.3.5. Adaptive opportunities used by locals to maintain comfort; left to right- low Clo values, sitting under a tree, sleeping outside under shade and using water for increasing comfort 16 Figure. 2.4.1. summary of passive cooling features 17 Figure. 2.5.1. Physiological cooling through movement of air

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Figure. 2.5.2. Irregular plan to induce more ventilation 19 Figure. 2.5.3. single room linearity promoting cross ventilation

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Figure. 2.5.4. Useful depth of a space to promote and benefit from cross ventilation

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Figure. 2.5.4. Diagrams to indicate the flow of wind when parallel to opening versus oblique.

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Figure. 2.5.6. Wind flow with respect to position of inlet and outlet in section

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Figure. 2.5.7. Wind flow with changed inlet outlet proportions; where a is equal, b outlet greater than inlet and c is inlet 20 Figure. 2.5.8. Shading as per orientations 20 Figure. 2.5.9. Wind flow through shading devices 20 Figure. 2.6.1. Jharoka or gallery in Rajasthan mansion, India

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Figure. 2.6.2. Traditional gujrati courtyard house, Pol house

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Figure. 2.6.3. Uncovered courtyard 21

Figure. 2.6.4. Covered court/atria 21 Figure. 2.6.5. Balcony/external corridor 21 Figure. 2.6.6. enclosed corridor 21 Figure. 2.6.7. Day time courtyard mechanics 22 Figure. 2.6.8. Night time courtyard mechanics 22 Figure. 2.6.9. Schematic diagram showing cooling effect of courtyard

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Figure. 2.6.10. Schematic representation of the effect vegetation to inbound breeze

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Figure. 2.6.11. Traditional Indian courtyard with colonnaded corridors

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Figure. 2.6.12. Schematic representation of the verandah promoting ventilation)

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Figure. 2.6.13. Diagram showing heat loss through formation of thermal bridges in cases of balconies

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3.Precedent study Figure. 3.1.1. Mumbai’s heritage chawl, Jer Mahal

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Figure. 3.2.1. Hinterhaus or backyard house in Berlin

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Figure. 3.2.2. Picture of a chawl in Old Bombay

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Figure. 3.2.3. Art deco apartments in Mumbai 28 Figure. 3.3.1. Drawings of the baithi chawl 29 Figure. 3.3.2. Drawings of the 2-3 storey chawl 29 Figure. 3.3.3. Drawings of the government chawl

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Figure. 3.3.4. schematic drawing of current chawl

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Figure. 3.3.5. Baithi chawl 30 Figure. 3.3.6. 2-3 storey chawl 30 Figure. 3.3.7. BDD chawl 30 Figure. 3.3.8. government chawl 30 Figure. 3.4.1. diagram of the unit 31 Figure. 3.4.2. diagram of the courtyard 31 Figure. 3.4.3. diagram of the corridor 31 Figure. 3.4.4. Unit interiors 32 Figure. 3.4.5. children playing in the courtyard 32 Figure. 3.4.6. corridor being used for socialising and thoroughfare

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Figure. 3.4.7. Children playing human pyramid during a festival in a courtyard

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Figure. 3.4.8.The corridor is uniformly lit up during a festival giving a communal common aesthetic

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Figure. 3.4.9. The diagrammatic scheme of surrounding spaces near a chawl

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Figure. 3.4.10. Space usage study summary 34 Figure. 3.5.1. Timber and brick construction chawl 35 Figure. 3.5.2. Concrete construction chawl 35 Figure. 3.6.1. Bouca housing by Alvaro Siza 36 Figure. 3.6.2. Aranya low-cost housing complex by BV Doshi

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Figure. 3.6.3. The winding corridor of the Pedrogulho housing with the brise soliels visible at the back

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4.Fieldwork Figure.4.1.1. Site of fieldwork, Government colony chawl

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Figure. 4.1.2. Figure ground of site complex 39 Figure. 4.1.3. schematic plan diagram of the fieldwork building to demarcate the various spaces

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Figure. 4.2.1. percentage of satisfied versus unsatisfied occupants

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Figure. 4.2.2. Key demographics of the occupants and snippets of the interviews

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Figure. 4.2.3. a)-f)Collection of pictures depicting chawl life and some quotes to illustrate occupants’ views

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Figure. 4.3.1. Occupancy patterns as informed by observation, literature and interviews

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Figure. 4.4.1. Equipment gains, usage pattern of appliances and heat gains due to activity and occupancy

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Figure 4.5.1 location of spot measures schematic section

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Table. 4.0. Summary of spot measures taken through the day in court and corridor_April

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Table. 4.1. Summary of spot measures taken through the day in court and corridor_July

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Figure 4.5.2 location of spot measures - C- courtyard , B-Corridor

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Figure 4.5.3 Thermal imaging of the facade showing heat loss through corridor

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Figure 4.5.4 Thermal imaging of the facade showing heat loss through corridor

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Figure 4.5.5 Thermal imaging of the corridor 46 Figure 4.6.1 Thermal imaging of the kitchen 47 Figure 4.6.2 Living space unit interiors 47 Figure 4.6.3. Living space unit interiors 47 Figure 4.6.3. View of the unit 47 Figure 4.6.5. Section indicating spot measures of day light levels in Lux

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Figure 4.6.6. Plan indicating spot measures taken at 9am

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Figure 4.6.7. Plan indicating spot measures taken at 1pm

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Figure 4.6.7. Data logger reading _summer week 49 Figure 4.6.8. Data logger reading _rainy week 49 Table 4.3. Key inferences and design guidelines 52

5.Analytic work Table 5.0. Factors impacting comfort in a courtyard

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Figure 5.1.1. Chawl typologies and court types 57 Figure 5.1.2. Radiation testing for different forms of the courtyard for 21st march

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Figure 5.1.3. Summary of the analytic work by Das regarding impact of aspect ratio on wind velocity

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Figure 5.1.4. Some of the chawls that were included in the analysis

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Figure 5.1.5. Graph plotting average incident radiation against aspect ratio to generate a tendency curve

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Figure 5.1.6. Graph plotting average wind velocity against aspect ratio to generate a tendency curve

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Figure 5.1.7. Ground materials that were tested; grass, mud, concrete paving, paver block & terracotta tiles

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Figure 5.1.8. courtyard with patches of ground materials

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Table 5.1. Compiled data for material analysis for 2pm

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Figure 5.1.9. Surface temperature_9am 62 Figure 5.1.10. Surface temperature_2pm 62 Figure 5.1.11. Surface temperature_6pm 62 Figure 5.1.12. courtyard activity usage and pattern 63 Figure 5.1.13. Microclimate analysis to test the effect of trees

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Figure 5.2.1. Base case description 65 Figure 5.2.2. Location of the base case and solar angles

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Figure 5.2.3. Graph of typical summer week to test window to wall ratio strategy

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Figure 5.2.4. Graph of typical summer week to test night ventilation strategy

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Figure 5.2.5. Graph of typical summer week to test addition of screens

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Figure 5.2.6. Graph of typical summer week to test changing material

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Figure 5.2.7. Summary of cooling strategies measured with annual cooling loads

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Figure 5.2.8. Graph testing combined strategies of thermal mass, screen and ventilation_summer week 69 Figure 5.2.9. Graph of roof system performances

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Figure 5.2.10. Sections of roofing system 70 Figure 5.2.11. Graph showing the thermal performance of the unit in different orientations

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Figure 5.2.12. Solar gains through the windows for different orientations

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Figure 5.3.1. Effect of wind and solar radiation on thermal sensation

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Figure 5.3.2. Summary of diagrammatic inferences of effect of depth of forecourt

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Figure 5.3.3. Average incident radiation on vertical surface on obstruction by overhang

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Figure 5.3.4. Graph showing the relationship between radiation and increasing depth of corridor

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Figure 5.3.5. Different activities as imagined in the corridor

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Figure 5.3.6. Shading devices used; left to right- bamboo trellises for vegetation, movable bamboo shutters, bamboo woven screens. 75 Figure 5.3.7. Radiation analysis of the impact of shading in reducing solar gains

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Figure 5.3.8. Shading masks of various shading devices

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Figure 5.3.9.Diagram showing alternating corridor strategy to maximize daylighting

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Figure 5.3.10.Daylight analysis of unit through various shading

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6.Design application Figure 6.1.1.Dimensions and plan of the unit 83 Figure 6.1.2.Section and summary of GFRG panel features

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Figure 6.1.3. Unit design_locating the GFRG panels 83 Figure 6.1.4. Unit design, windows, front facade material and design

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Figure 6.1.5. Wind flow through the unit section

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Figure 6.1.6. Unit design showing location of spaces and foldable flexible furniture

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Figure 6.1.7. Unit design showing location of main corridor, private extension space and shading devices

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Figure 6.2.1. Diagram showing position of corridor, private extension communal space

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Figure 6.2.2. Diagram indicating inversion of the corridor location

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Figure 6.2.3. Diagram indicating replication of alternating scheme

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Figure 6.2.4. Diagram indicating location of core and additional staircases that wrap around the building

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Figure 6.2.5. overall building spaces diagram 86 Figure 6.3.1. East and west elevation design 87 Figure 6.3.2. South elevation design 87 Figure 6.3.3. North elevation design 87 Figure 6.3.4. View of building block 90 Figure 6.4.1. Corridor view 91 Figure 6.4.2. Corridor view 92 Figure 6.4.3. Interior view : day time view 93 Figure 6.4.4. Interior view : night time view 93 Figure 6.5.1. Aerial view of the site 95 Figure 6.5.2. Views and imaginations of the redevelopment of the chosen site.

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Figure 6.5.3. Chosen site and details of site 96 Figure 6.5.4. Microclimate analysis of the site 96 Figure 6.5.5. site mapping 97 Figure 6.5.6. Overshadow analysis of the site 98 Figure 6.6.1. Studies of trying to establish the height beyond which the relationship with the ground is lost

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Figure 6.6.2.Applying the aspect ratio to the site as grids

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Figure 6.6.3.Extruding the built form 100 Figure 6.6.4. Cutting pedestrian axes through the extruded grids.

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Figure 6.6.5. opening the courts to the axes 100 Figure 6.6.6. Analysis to test the optimum location for cutouts

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Figure 6.6.6. Optimizing massing for windflow 101 Figure 6.6.9. Optimizing massing for overshadowing 101 Figure 6.6.8. Overshadow tests (source: after ladybug) 101 Figure 6.6.10 .Relationship diagram showing the proportional relationship of the functions

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Figure 6.6.10 . Final massing form showing the built form, the open spaces and the zoning of spaces

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Figure 6.6.11 .comparative built up of existing chawl, proposal and SRA

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Figure 6.7.1 .analysing and combining massing, ENVIMET simulations and single block design to arrive upon masterplan 103 Figure 6.7.2 .Master plan of the housing complex 103 Figure 6.8.1 . View of market plaza courtyard 105 Figure 6.8.2 . View of garden courtyard 105 Figure 6.8.3 . View of a wedding taking place in one of paved courts

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Figure 6.8.4 . View from the corridor, watching people play in a playground courtyard

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Figure 6.8.4 . thermal assessment graph for summer week

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Figure 6.8.5 . thermal assessment graph for rainy week

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Figure 6.8.6 . annual cooling load moth wise for unit performance

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Figure 6.8.7 . Assessment of courtyards, 21st march, 6pm 109 Figure 6.8.8. Assessment of courtyards, 21st march, 9am 109 Figure 6.8.9. Stratification of air temperature 110 Figure 6.8.10.Stratification of wind speed 110 Figure 6.9.1. Summary section of environmental performance of the spaces, 9am 111 Figure 6.9.2. Summary section of environmental performance of the spaces, 11am 111 Figure 6.9.3. Summary section of environmental performance of the spaces, 3pm 112 Figure 6.9.4. Summary section of environmental performance of the spaces, 5pm 112

7.Conclusion Figure 7.0.0. Aerial view of the proposal 115

8.Post design studies Figure 8.1.1. Process of producing Amrit mitti 119 Figure 8.2.1. Women weaving with bamboo 120 Figure 8.2.2. Bamboo woven shading 120 Figure 8.2.3. Cost comparison of materials 121

01 1.1 1.2 1.3 1.4 1.5 1.6

Learning From The Chawl

Introduction Introduction to Mumbai History of Mumbai’s urban growth Current contextual scenario SRA versus the Chawl Primary research questions Research methodology

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AA School: Susatainable Environmental Design

Chapter 1. Introduction

1.Introduction 1.1 Introduction to Mumbai Contemporary India is a landscape of duality. While almost 68% of the population continues to live in a rural setup (Urban Agglomerations, 2014) India is also home to some of the largest growing metropolises in the developing world. One such city is the city of Mumbai.

Mumbai is the largest metropolis in India. According to the 2011 official census, Mumbai is home to over 18 million people, accounting for a miniscule 4.5 sq.m per person. The city’s urban fabric is in a state of context flux, characterised by striking polarity of informal settlements and high rise luxury apartments. This can be attributed to a variety of historic socio-political factors, a prelude of which is to create the contextual basis for the argument of this dissertation.

Learning From The Chawl

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1.2. History of Mumbai’s urban growth In its conception, Mumbai was a cluster of seven islands (figure 1.2.1),with agriculture as the inhabitants’ primary occupation. Due to its significant geographic position along the west coast, the city boasted of important ports and fishing also became an important occupation. This led to the formation of villages, comprising of people of the fishing and agrarian communities and thus, the city’s housing was characterised by small bungalows within these larger communal settlements.

This period was followed by the advent of the colonial empire, under which the city began to see new industrial growth owing to its natural harbours.

This facet of the city was further exploited during the turn of the19th century, when the American civil war ended textile supply from America to the British empire and they were forced to look for other avenues for production. Mumbai then began to be developed as a textile production centre. This heralded growth in the direction of industrial and transport infrastructure and soon enough, it prompted the proliferation of textile mills over the cityscape. (Shetty et al, 2007) The mills caused an increase in the demand for labour in the city and began to attract migrant blue collar workers from all over the country. Migrants in search for a better living, found themselves in the city looking for jobs. However, it soon became apparent that there was a lack of housing to accommodate the work force.

(Arunachalam, 1978). Thus, the multi-tenanted shared utilities housing typology was born (figure 1.2.2). This low cost housing, which was primarily built by mill owners and other landowners, became an idiom for social housing. They later came to be known as ‘chawl’ colloquially. (Shetty et al., 2007)

Figure. 1.2.1. Mumbai’s growth from an archipelago to a unified city. (Source: after Vosburgh, 2014)

Figure. 1.2.2. Mumbai’s oldest known chawl, the multi tenant social housing (Source: Fernandes, 2008)

Soon after India became independent from colonial rule, economic growth and employment rates continued to grow in Mumbai with the increasing presence of the textile mills in the centre of it. A political party established a union to ensure a strong political base in the textile industry (Hutchison & Brown 2001) This however, monopolised the nature of industrial growth in the city. In order to promote diversification, policies were introduced to curb the expansion of mills and to encourage production from cottage industries and the power sectors. (Hutchison & Brown 2001) And thereby leading to the demise of the mills in the late 70s (D’Monte, 2002)

Figure. 1.2.3. The decline and dilapidation of chawls (Source: Mahankal, 2015)

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Chapter 1. Introduction

Despite the fall of the mills, the city’s growth kept accelerating due to the development of other industries (the film industry being a noteworthy proponent of this age) and continued to attract migrant workers.

This increased the demand for housing in the affordable and social sector. In order to keep tenantbased housing affordable, the rent control act1 was introduced, which levied a cap on the amount of rent that landlords could elicit from tenants (Department of housing, 2000) While the rent was capped, the rate of industrial growth continued to accelerate and soon the cost of living grew as well. This meant that landlords were not making a profit by constructing chawls, which led to the subsequent neglect of the existing structures (figure 1.2.3). The demand thus spilled over to the uncontrolled private-builder sector, where the housing deficit would be then met through agencies and cooperative societies.(Shetty et al, 2007) Privately owned buildings2 now began to characterise the market(figure 1.2.4). The migrant populace, however, could not afford real estate through this sector, and with no affordable housing being made, slums began to proliferate across the city fabric With a clear lack of required low-cost social housing that could prove to be a checking force towards the growth of informal settlements, slums continue to grow and till today, stand as a manifestation of systemic failure.

Figure. 1.2.4. Towering privately owned real estate dwarfing the chawl (Source: Gupte, 2011)

1) The rent control act dictates that the landlord of a cess buildings, that is, ones built before the 1940s, must fix the rent that the tenants must pay. The landlord is obliged to increase the rent only for purposes of taxes, repairs and other maintenance work. He/ she may also increase the rent by a maximum of 4% per annum with tenant consent. The landlord is bound to make structural and maintenance repairs of the building.

2) Co-operations and private landholdings grew further due to the implementation of the Urban ceiling act (1976). The act stated that excessive hoarding of land under private parties was forbidden, thereby ensuring adequate land for infrastructure and public housing. Contrary to the intention of the act, this caused land to remain locked and prompted corruption and bribery amongst officials and private builders. Land thus became more and more scarce and prices began to soar. Privately owned buildings now began to characterise the market.

Learning From The Chawl

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nearly 25% of the tenements (figure 1.3.1) being left

Figure. 1.3.1. Article cutout reporting the failure of the SRA building scheme and consequent vacancies (Source: Bhattacharya, 2016)

1.3. Current contextual sceanario In order to provide a suitable solution for the growing number of illegal settlements, the government announced a housing scheme, Slum rehabilitative scheme, under the Slum Rehabilitative authority (SRA).

Figure. 1.3.2. Slum rehabilitative process, schematic representation

The rehabilitative scheme ushered in the year 1995, in an attempt to rid the city of illegal settlements. Under the scheme, if 70% of squatter dwellers give their consent, the slums are demolished and new towers are constructed into which the slum inhabitants would be relocated. Builders who choose to build within the scheme are given a floor space index (FSI) of 4 to develop the proposal and an excess FSI generated after all the slum dwellers have been relocated, can be sold off by the builder for commercial or luxury residence purposes (figure 1.3.2).

While this seems like an innocuous solution to the aforementioned problem, the buildings themselves, fail to provide for basic features such as adequate light, ventilation, green and community sensitive spaces.

The abysmal quality of the SRA buildings has resulted in

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vacant. While the SRA towers fail to provide a decent built quality, they are also asynchronous with the needs of the slum dwellers in a social capacity. Most inhabitants of the slum are migrant workers who come from rural backgrounds, where the societal fabric is very rich and important one. The slum then becomes a village within a city, providing them opportunities to form communities and relations in an unfamiliar environment. By not acknowledging this in its architecture, the SRA towers do not provide the support migrants require into order to assimilate into the city and its fabric.

It is within this milieu that chawls become a typological solution. Chawls are a low cost social housing typology.

Built in the early 50s, this housing type consisted of single room tenements flanked around a corridor encasing a courtyard, with the primary motive to house the migrant workers who worked in the mills. Due to its vibrant social fabric, the chawl earned itself the moniker of an urban village.

While it remained the singular solution to low cost housing needs between the 60s through to the demise of the mills in the 70s, the production of this typology nearly stopped once the rent control was established.

The building of chawls became unprofitable and the existing ones were left to dilapidate, making them structurally inhabitable.

The following section conducts a preliminary examination of the potential of a chawl over the SRA building as a precedent.

AA School: Susatainable Environmental Design

SRA BUILDING

CHAWL

Chapter 1. Introduction

1.4 SRA v/s Chawl A preliminary set of studies was conducted to understand the urban character, the form and the unit performance of the chawl in comparison to the SRA building.

Figure 1.4.1 illustrates the urban and built form comparisons between the two.

U R B A N CHARACTER

SUNPATH & SHADE M A S K

WIND

FLOW

TYPOLOGY

UNIT

FORM

The chawl behaves like an urban catalyst by promoting the growth of amenities around it. The SRA is situated in the midst of slum clearings, with no amenities around it to facilitate the growth of a community.

The shading mask diagram reveals the lack of adequate open spaces between the buildings in a SRA scheme. The chawl has large open spaces in the form of enclosed courtyards.

The wind diagram shows that wind flow is diverted around the SRA building due to its form, while the courtyards facilitate in channeling wind flow through the chawl’s built form.

A quick study of the unit performances gives a notional idea of the problems in an SRA building.

It can be noted that the floor area, and the occupant density in both units is similar.

The chawl unit has provisions for cross ventilation and a marginally larger opening to facade ratio, while the SRA plan is doubly loaded , providing no scope for cross ventilation. There are no buffer or transitional spaces in the SRA, reducing the adaptive opportunity of the occupant.

This when coupled with the lack of communal spaces which foster the growth of urban communities, gives insight into the staggering vacancies in SRA buildings.

Thus it can be concluded that the chawl forms a better precedent to be studied further.

U N I T DIMENSIONS

Figure. 1.4.1. Preliminary comparative analysis of the chawl and the SRA type; urban, building and unit level

Learning From The Chawl

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1.5 Primary research questions The theoretical review of the need for studying the chawl, the background of the city and contextual groundwork lay the framework for a primary set of research questions and agenda, through which a more comprehensive set of research questions will be culled further on, they are as follows : How does the chawl form a precedent for designing lowcost social housing?

What is the environmental and social benefit of preserving the ‘chawl culture’ ?

What are the learning and shortcomings of this typology?

Scope and objective The scope of this thesis is : to create environments which are thermally and visually comfortable, with occupant behavior, aspiration and adaptability at the centre of the strategies. provision of multiple comfortable spaces such as the living units, the corridors and the courtyards, to provide many opportunities for occupants to achieve comfort. balancing density with environmental and architectural quality to propose a new outlook on low-cost mass social housing in Mumbai. the master plan includes design development plans of shops, market places and communal facilities like daycare, laundry and study rooms. These are not studied in detail for environmental performance.

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1.6 Research Methodology

Chapter 1. Introduction

Introduction : Understanding context of the city and need for the research of chawls.

Climate & Passive cooling theory : Understanding and theorotical of the climate type of Mumbai.

Literature review of passive cooling strategies that are applicable to the climate type.

Precedent & state of the art : Theory study of the chawl as a precedent; the typology, the social relevance, the evolution, materiality and universal applicability Fieldwork: Fieldwork and analysis of an existing chawl. Study of its various elements, its thermal performance, comfort of transitional spaces, understanding occupancy patterns and requirements.

Pre-design Analysis : Analysis of the various elements of the chawl and addressing key issues arrived upon through fieldwork. Establishing design guidelines.

Design : Application of learning from all the above to arrive upon a design driven by adaptibility and passive strategies Conclusions

Learning From The Chawl

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02 2.1 2.2.

2.3.

2.4.

2.5.

2.6.

2.6a 2.6b 2.6c

Learning From The Chawl

Climate analysis Overview of climatic features Climatic conditions Comfort band Passive cooling strategies Passive cooling strategies Transitional spaces Courtyards Verandas and Corridors Balconies

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Figure. 2.1.1. Location of Mumbai city and satellite image of the city (source : After google earth)

2.Climate analysis

2.1 Overview of climatic features Location & Topography Mumbai is a peninsular city located towards the west coast of India at latitude 18°58′ N and longitude 72°49′ E. It is surrounded by the arabian sea on three sides. Lying on the windward side of the western ghats (mountain ranges marking the west coast of India) Mumbai finds itself in the tropical coastal region of india, called the Konkan belt. (figure 2.1.1)

Seasons and climate By the Koppen-Geigar classification (Mcknight et al., 2000), Mumbai falls under the tropical wet and dry climatic zone, with the following seasonal periods, each characterised by specific temperature and precipitation ranges.

Table 2.0. Summary of seasons and their characteristic temperature range

Season

Period

Average Temperature range (°C )

Summer

March-May

24.3- 32.7

133.2

Monsoon (south- June-September 24.9- 30.5 west)

541.2

Retreating monsoon

11

OctoberNovember

22.2-33.5

Average Precipitation (mm)

36.3

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temperature (°C)

Chapter 2. Climate and Passive strategies

Relative humidity (%)

90 80 70 60 50 40 30 20 10 0

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

OCT

NOV

DEC

Figure. 2.1.2. climatic overview of Mumbai city; temperature, radiation, humidity and precipitation (source: after SED_climate consult) Direct solar radiation (w/sq.m) Diffuse solar radiation (w/sq.m) Comfort band

Outdoor temp (°C) Relative humidity (%)

2.2. Climatic conditions Temperature Mumbai has mild temperatures throughout, owing to its tropical climate and favourable location, benefitting from the sea. The hottest months are the summer months, between march and may, when the maximum can reach up to 35°C. In the rainy season, the prevailing winds lower the temperature and the maximum drops to 30°C coupled with the ambient effect of high rainfall. The winters are not significantly colder, as they temperatures remain mild within the range of 24-32°C, with the lowest sometimes dropping to 18°C and the highest reaching 33°C (figure 2.1.2).

Humidity Mumbai being a peninsular city that is surrounded by water on three sides, experiences high humidity. It average ranges between 55-75% between the months of December and may. The coastal location of the city causes the humidity to drastically rise during the monsoon periods as the average for that period ranges between 83-100% (figure 2.1.2).

Learning From The Chawl

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Rainfall Mumbai receives high rainfall as it lies on the windward side of the western Ghats.

The average precipitation through the year is 242.2 cm. The summer and winter months receive minimal rainfall averaging to 150mm and 40mm respectively.

The highest rainfall is received in the rainy season when the southwest monsoon winds bring in averaging 550mm of precipitation over a span of four months of june to september (figure 2.2.1)

Figure. 2.2.1. Precipitation in mm (source: after meteonorm 7)

Radiation Mumbai receives high solar radiation subject to the seasons and position of the sun. During the months of march, April and may, Global radiation ranges a maximum between 190-200kwh/sq.m, making solar protection an important factor in comfort. Figure 2.2.2 shows that the maximum radiation that is received on a vertical surface is from the south, followed by the west and east directions, however, the radiation dome highlights that while the south is exposed to high intensity of radiation, the duration under solar duress is lower than the east and west, thus creating a hierarchy in shading requirements.

Figure. 2.2.2. Radiation rose with sunpath to indicate which direction receives what proportion of radiation (source: after Grasshoper-ladybug)

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Wind speed and direction

Chapter 2. Climate and Passive strategies

Mumbai lies on the west coast of India, receiving winds from the Arabian sea side. The prevailing winds thus, are from the South-west. The average wind speed remains between 2-4m/s (figure 2.2.3) Data from Meteonorm suggests that the highest winds are average around july/ august at 4.2 m/s and the lowest are recorded in ocotber at 0.9m/s, during the retreating monsoon period.

Figure. 2.2.3. Prevailing wind speed and direction (source: after Grasshopper-ladybug)

Solar Angles

46°

68 ° 78 °

The sunpath reveals that the solar angles as illustrated in figure 2.2.4, incident on Mumbai are not low, assuring sun light access through the year. However, being close to the equator the solar angle gets high, causing a lot of incident radiation on the horizontal surface. Thereby making the roof and the ground plane important factors in desining for comfort.

21ST JUNE

21ST DEC

21ST MARCH

Figure. 2.2.4. Solar angles and sunpath (source: after Grasshopper-ladybug) Learning From The Chawl

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2.3.Comfort band In order to derive a comfort equation for Hot and humid region, a literature review of comfort analysis of this region was done. While ASHRAE 55 is followed in most of India, Ghosh (2014) suggest through analytic work that the comfort band suggested is unsuitable for tropical climates like Mumbai. Thus it becomes essential to find an equation which is suitable for the inhabitants of a tropical climate.

Nicol et al (2012) discuss in their book the usability of adaptive comfort and take into account the possibility of fun-running buildings aided by natural ventilation. The EN15251 standard developed for European buildings by the Comite Europeen de Normalisation (CEN) much like the ASHRAE sets a comfort range for buildings not only in mechanical mode but also in a free-running mode, which is derived from the following equation : Tcomf = 0.33Trm + 18.8 where the comfort equation is a function of the running mean of the outdoor temperature (Trm) The equation proposed by Humphreys as discussed

by Nicol (2004) describes the adaptive comfort equation for free-running buildings in hot and humid provides a target temperature which is a function of the outdoor temperature. The equation is as follows :

Figure. 2.3.1. summer months psychrometric chart (source:after Climate consultant)

Tc = 0.534 To + 12.9 where Tc is comfort temperature and To is outdoor temperature.

The comfort range is indicated as 2-3°C on either side of the optimum temperature. It is also alluded that introducing air velocity could increase the comfort zone by another 2°C, congruent with the study conducted by Ahmed (2003) as seen in figure 2.3.3.

Figures 2.3.1-2.3.2 show the psychromteric charts of Mumbai during the summer months and the rainy months. The comfort band is drawn using the equation above and strategies like sun-shading and night ventilation/reduction of thermal mass were applied to note the increase in the comfort.

Figure. 2.3.2. Rainy months psychrometric chart (source:after Climate consultant)

Figure. 2.3.3. Increase in outdoor comfort band in tropical countries (source: Ahmed, 2003)

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Chapter 2. Climate and Passive strategies

Figure. 2.3.4. Study on comfort in tropical countries (source: Ali et al, 1986)

Figure. 2.3.5. Adaptive opportunities used by locals to maintain comfort; left to right- low Clo values, sitting under a tree, sleeping outside under shade and using water for increasing comfort (source: Grime, 2012)

The equation can be enhanced using information of Tneutop = 0.57 Toutdm + 13.8 localised practices (figure 2.3.5 ) and surveys of locals.

The change in the comfort in tropical countries can be illustrated through Ali et al (1986) discussions, as it pointed how people experience comfort at warmer temperatures (figure 2.3.4) Nicol et al (2004) discus through a series of surveys how thermal comfort sensation is an adaptable and conditional process. In their comfort votes, it was noticed that if the indoor temperature was warm, the conditioning caused occupants to be comfortable at temperatures higher than neutral, while if the outdoor was high, then the comfort was voted at temperatures below neutral.

Another study along the same lines of Nicol’s comfort studies, was conducted by Toe and Kubota (2013). Their equation for naturally ventilated buildings in hot and humid climates provides a neutral temperature, which is a function of the outdoor mean temperature. Using the following equation,

Learning From The Chawl

where Tneutop is the neutral optimum temperature and Toutdm is the outdoor mean temperature, they arrived upon a comfort band ranging between 24.9- 31.2 °C This proposal uses Humphrey’s equation, which adopts the same concerns as the EN15251 and adapts it with the provision of wind velocity for localised comfort.

The effect of extention of the comfort zone due to air velocity, is illustrated by Givoni (1997) in figure above.

Using this equation, one can notice that Mumbai’s temperature lies mostly within comfort with the exception of the possibility of overheating during the summer months, when outdoor temperatures can soar to 35°C.

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2.4. Passive cooling strategies -I The term “passive” comes laden with many connotations and requires contextual appropriation.

In this paper, the term “passive cooling” will refer to a system that aims to lower the indoor temperature of a space by the use and manipulation of natural energy sources, through architectural means. It defines a “passive device” as an architectural element- the roof, certain spatial configurations, facade elements or the soil for instance- that collects, stores or facilitates cooling agents.

Passive cooling elements can be defined through many lenses, this paper aligns itself with the categories established by Balaras (1996) and refers to techniques that : • •

Prevent heat gains Modulate heat gains

Preventing heat gains entails : • • • • • •

Microclimate and Site design solar control Building form manipulation thermal mass manipulation occupancy behavioural pattern understanding internal gains control

while modulating heat gains is achieved through manipulation of the thermal mass of the building in order to generate ‘heat sinks’ that can be used to store heat during the day and release it into space during the night.

The above mentioned definition also calls for a clarification regarding the term ‘natural energy’ and what natural energy cooling refers to. Natural energy cooling, is referred to as the usage of : • •

•

•

ventilation ground cooling : cooling that is generated by using the earth as sink for absorbing heat evaporative cooling : cooling produced by evaporation of a liquid into the air radiative cooling : cooling produced due to loss of heat by radiation

By adopting a combination of various techniques at both design as well as post occupancy stages, it is then possible to reduce the cooling loads, enhance internal thermal conditions and maintain air quality

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Chapter 2. Climate and Passive strategies

Passive cooling in tropical hot and humid

Permeable elements like screens

Overhangs as solar shading

Meeting cooling demands is one of the salient concerns when tackling with the temperature ranges presented by tropical regions. In their seminal works, Santamouris(2007) and Hyde (2000) propose key guidelines for the design of buildings in the tropical region, which can be summarised as follows: • Solar shading to prevent excess solar gains • provision should be made for cross ventilation • usage of transitional or buffer spaces to

reduce solar gains • usage of permeable elements in building construction • thermal storage or lag should be minimal • usage of vegetation is highly recommended

(figure 2.4.1)

Transitional spaces

Thermal mass and porosity

Introducing vegetation for cooling and shade Figure. 2.4.1. summary of passive cooling features

Learning From The Chawl

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2.5. Passive cooling strategies -II Passive cooling strategies : cross ventilation A literature review was done to gain theoretical understanding of the best practices to induce natural ventilation into the scheme. Givoni states that natural ventilation can applied as a cooling strategy when the outdoor air temperature does not exceed 32°C, provided the diurnal difference is below 10°C. However, movement of air is necessary to provide occupants physiological comfort (figure 2.5.1). This when coupled with the fact that occupants can tolerate higher temperatures provided a minimal air movement of 0.4-0.6m/s is achieved (Toftum, 2000), it can be concluded that natural ventilation is an effective tool for passive cooling in Mumbai. The comfort studies in the previous section also establish a higher tolerance for temperatures if adequate air movement is provided.

Form and orientation

Figure. 2.5.1. Physiological cooling through movement of air (source: Chanasit, 2010)

Figure. 2.5.2. Irregular plan to induce more ventilation (source: after Givoni,1994)

To promote natural ventilation, key measures in the building form aid and abet the flow of air. Givoni (1994) suggests the irregularity of a form helps promote natural ventilation, by increasing the surfaces and openings to funnel the wind (figure 2.5.2) While it is optimum to place openings in the direction of the prevailing winds, Givoni (1994) suggests that oblique angles for wind flow are also efficient as long as the openings are towards the windward side (figure 2.5.5).

Anderson(2012) enlists numerous spatial reconfigurations for promoting cross ventilation through a space, where he suggests that a single room is more effective in cross ventilation than many small rooms (figure 2.5.3) He also reinforces the idea of internal walls running parallel to the flow of wind or usage of movable partitions, as does Hyde (2000) Thumb rules for cross ventilation can be obtained from Givoni’s treatise on climate suitable cooling, where he discourages deep plans and suggests a useful depth in proportion to the height of the building (figure 2.5.4)

Figure. 2.5.3. single room linearity promoting cross ventilation (source: after Anderson, 2012)

H

<4H Figure. 2.5.4. Useful depth of a space to promote and benefit from cross ventilation (source: after Givoni, 1994)

Figure. 2.5.4. Diagrams to indicate the flow of wind when parallel to opening versus oblique. (source: Chanasit, 2010) 19

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Chapter 2. Climate and Passive strategies

Opening design Givoni proposes that larger openings for more ventilation are suitable in hot and humid climates.

Figure 2.5.6 shows the diagrammatic proposal of window openings and positions, as put forth by KochNielsen (2002). Szokolay et al (2004), discuss various factors that affect wind flow through openings.

Smaller inlets as compared to outlets force air through a smaller area to build pressure and increases in speed as it passed through the larger outlet (figure 2.5.7). It is recommended to have lower inlet openings than outlets to ensure that air movement happens at body level.

Figure. 2.5.6. Wind flow with respect to position of inlet and outlet in section (source: Koch-Nielsen, 2002)

Szokolay (2004) also suggests that ventilation through an opening can be compromised in areas receiving high rainfall as opening of windows may also admit sprays inside the habitable space. The optimum suggestion for this is the provision of large overhangs or the placement of windows under corridors/verandas.

Solar protection

Figure. 2.5.7. Wind flow with changed inlet outlet proportions; where a is equal, b outlet greater than inlet and c is inlet (source: after Szokolay, 2004)

Gut (1993) deems solar protection and shading as an imperative in areas near the equator. The first measure to protect the building from solar gains is to adequately orient the building. The favourable orientation would be to place the long side against either the north or south. The east and west are avoidable as they receive most radiation (figure 2.5.8).

The next step in solar protection is to add shading devices. Basic shading (horizontal and vertical) would be adopted in different orientations. The east and west would be shaded with vertical elements while the north and south would be optimally shaded with horizontal shading devices. It is also necessary that screens and louvers that maybe used for shading should not impede natural ventilation.

Figure. 2.5.8. Shading as per orientations (source: Gut, 1993)

Koch-Nielsen (2002) discusses the effects of wind flow through horizontal shading elements (figure 2.5.9 ) and it can be observed that shading elements can be placed in tandem with the built to guide air into a space.

Thermal mass

Figure. 2.5.9. Wind flow through shading devices(source: after KochNielsen, 2002) Learning From The Chawl

Passive cooling through manipulation of thermal mass involves either decoupling the interior from the outside heat or disallowing heat storage within the material section. In warm climates, heat lag can be created using heavyweight construction like concrete to insulate the inside from the outdoor heat. However, Hyde (2000) discourages the storage of heat in the tropics and advocates porous structures with low thermal mass.

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2.6. Transitional spaces Transitional spaces can be classified as spaces that are neither outdoors or indoors, serving as a bridge from the outside environment to the inside. Through the course of history, transition spaces have found themselves existing in plurality, where their functions have been adaptable due to their ability to mediate between a relatively more controlled interior with a less controllable outdoor.

Be it the extensive use of jharokas (ornate balconies) in Mughal architecture (figure 2.6.1), the persistence of ‘otlas’ (courtyards) in traditional Guajarati architecture (figure 2.6.2), transition spaces have been tools to blur the boundaries between the urban from building domains, by varying the degree of permeability of the outside climate to the indoor. This section looks at the environmental functionality of transition spaces and how the passive cooling strategies discussed above are implemented in these spaces.

Figure. 2.6.1. Jharoka or gallery in Rajasthan mansion, India (source:wikipedia)

Transitional spaces referred to, will fall into either of the falling spatial configurations : •

•

•

Uncovered enclosed spaces;

Courtyards (figure 2.6.3) Covered enclosed spaces; Atria

(figure 2.6.4) Adjacent/attached spaces ;

Balconies, corridors and verandas (figure 2.6.5-2.6.6)

Figure. 2.6.2. Traditional gujrati courtyard house, Pol house (source: Loisos et al, 1988)

Figure. 2.6.3. Uncovered courtyard

Figure. 2.6.5. Balcony/ external corridor

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Figure. 2.6.4. Covered court/ atria

Figure. 2.6.6. enclosed corridor

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Chapter 2. Climate and Passive strategies

2.6a Courtyards A courtyard can be defined as a space open to sky, within a building, which is mostly enclosed on all four sides (Ching, 1943) Historically, courtyards were used as social spaces that served as a bridge between the indoor and the outdoor.

However, intrinsic to their design and spatial quality, courtyards also serve as key agents of inducing passive cooling.

Figure. 2.6.7. Day time courtyard mechanics (source: Gut, 1993)

Koch-Nielsen (2002) in his seminal work about passive cooling discusses the theory surrounding it. Courtyards reduce solar gains and promotes cooling breezes by creating a difference in temperature between the outside and the space within which the courtyard is contained.

In the day as shown in figure 2.6.7, the courtyard surface heats up faster than the air outside due to direct incident solar radiation. This causes the air around the court to heat up faster, which in turn rises up quickly setting up a breeze from the outside to the inside.

Figure. 2.6.8. Night time courtyard mechanics (source: Gut, 1993)

During the night, the reverse of the daytime mechanics occur, as shown in figure 2.6.8. The courtyard acts as a sink, collecting cooler air from the roof. This cold air then filters in through the openings and vents. If this inward bound air passes through vegetation or over a water body, it has a greater cooling effect, due to evaporative cooling, which schematically represented in figure 2.6.9 Courtyards provide greater protection against solar penetration as fewer surfaces are incident to direct solar radiation. If trees or water bodies are added within the courtyard, as demonstrated in figure 2.6.10, this enables the courtyard to create its own microclimate, which is cooler than the internal spaces.

This in turn, helps to cool the spaces inside.

Figure. 2.6.9. Schematic diagram showing cooling effect of courtyard (source: Gut, 1993)

Inward facing walls are often protected with awnings and shading devices atop of colonnades or verandas in order to prevent direct solar radiation on the fenestration opening into the courtyard.

Courtyards also create a difference in pressure causing the wind from the outside to flow inside. This phenomenon, when coupled with the stack effect, causes greater cooling.

Figure. 2.6.10. Schematic representation of the effect that presence of vegetation/ water can make to inbound breeze (source: Gut, 1993)

Learning From The Chawl

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2.6b Verandas and Corridors Chingâ&#x20AC;&#x2122;s (1943) exhaustive book on forms describes a veranda as a space like an open porch, that is partly enclosed, mostly roofed and flanks a house in the front and sides. Verandas act as shading devices (figure 2.6.11), preventing the glazed openings from receiving excessive solar heat gains, while promoting ventilation (figure 2.6.12). Hyde (2000) mentions how verandas allow for larger openings that can bring in adequate daylight to promote natural lighting without the adverse effect of added solar gains. Corridors, if placed on the outer edge of a building, serve similar functions as a veranda.

If placed in the direction of prevailing winds, corridors and verandas act as breezeways, funnelling wind into the internal spaces.

Figure. 2.6.11. Traditional Indian courtyard with colonaded corridors ( source: Raghu, 2012)

2.6c Balconies Making their presence felt across history, balconies have been a prominent feature in tropical and subtropical climates. Mughal architecture was characterised by jharokas, ornate overhanging enclosed balconies, often used by rulers to address the public. Balconies serve leisure functions, connecting the outdoor to the indoor in a conspicuous fashion, while mitigating the direct effects of weathering elements outside. In their most basic, balconies, as explained by Hyde (2000), act similarly to verandas by acting as shading devices which thereby reduce solar gains and promoting ventilation through the stack effect. However, due to their unique position, cantilevered balconies create thermal bridges, causing heat loss through radiation.

This is referred to as the cooling fin effect and is illustrated in figure 2.6.13. This contributes further to the cooling of the internal spaces. hgjg

Figure. 2.6.12. Schematic representation of the verandah promoting ventilation (source : Gut et al, 1993)

Figure. 2.6.13. Diagram showing heat loss through formation of thermal bridges in cases of balconies (source : Gut et al, 1993)

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Chapter 2. Climate and Passive strategies

Theoretical studies suggest that transitional spaces not only serve as spatial devices but are also intrinsic to cooling as they deploy multiple strategies at once. In a study by Karol et al (2014) on the changing social needs in the tropics and how that impacts climatic design, it is remarked how growing population densities and urbanization in Sarawak, a tropical city in Malaysia, have resulted in rapid building technology, that is devoid of climatic features.

It is also suggested that the shift from less to more urban landscapes that foster the growth of private families and built spaces, have led to the decline in semi-private spaces like the veranda, the corridor and the court.

This premise serves as introductory point for the next chapter, which explains the chawl as a precedent in detail. It aims to highlight the plural use of transitional spaces by the occupants, thereby justifying their use in buildings not only for enhancing environmental performance of the building but also as a proponent of the urban communal lifestyle.

Learning From The Chawl

24

03 3.1 3.2.

3.3.

3.4.

3.5 3.6.

Learning From The Chawl

Precedent study What is a chawl History of the chawl Evolution of the chawl About the typology Materiality & typology Universal applicability of the chawl type

26

3.Precedent study 3.1 What is a chawl As alluded to in an earlier section, chawls (fig 3.1.1) can be classified as social housing of the colonial times, consisting of buildings with long corridors, flanked by one room tenements and an enclosed courtyard. They were constructed to house migrant mill workers(Adarakar, 2012).

Largely concentrated in the south of Mumbai, these housing blocks gained their name from the Marathi word ‘chaal’ which meant ‘to walk’ (Deshpande,1958).

Chawls boasted of a very high density, almost 500 people per acre, thus becoming synonymous with high density social housing (Edwards, 1909).

While this typology is no longer built in Mumbai as it is plagued with issues of neglect and policy driven challenges, they

“...stand even today as the most viable form of social housing in the city” (Rao, J, personal communication, 2016) In order to delineate the learning from a chawl, it becomes essential to study it both, qualitatively and quantitatively.

In the following sections, an architectural qualitative understanding of the chawl will be illustrated.

Figure. 3.1.1. Mumbai’s heritage chawl, Jer Mahal (source: Raj, 2008)

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Chapter 3 Precedent study

3.2. History of the chawl The chawl’s history is a fluid one, with no clear consensus on its first appearance in the city fabric.

Geddes (1930) remarked that chawls were not housing but rather meant to warehouse people. Thus making it possible that the earliest appearance of the progenitor of the chawl that exists today was in the early 1930s, as a barrack-esque housing quarters, cramped to the hilt with people.

Mumbai’s mass housing took two major routes : western apartment art deco blocks (figure 3.2.3) and the chawls. The Indian elite soon found home in the former, which was characterised by four storeys of simple brick, concrete and steel elegance. They ushered in a new age of transition from the Victorian city to a modern metropolis; chawls were a product of this transitional phase (Urban, 2013) Initially, chawls were seen as an Indian response to Berlin’s backyard building (figure 3.2.1), in lieu of the maddening levels of urbanization brought due to the textile mills.

Figure. 3.2.1. Hinterhaus or backyard house in Berlin(source: Nicolai, 1999)

Serving as mill workers quarters, they were first built as ground storey buildings with thatched roofs and timber construction (Gupte, 2011) The ground storey structures were demolished as they were low density and were not aiding in housing migrant workers, to give rise to the 3-4 storey chawls that were built with brick masonry, thatched roofs and timber framework as seen in figure 3.2.2. (Urban, 2013) Soon the demand of this typology increased and they started being inhabited by families instead of just single male migrant workers.

Figure. 3.2.2. Picture of a chawl in Old Bombay(source: Fernandes, 2008)

Initially only private developers built chawls, later two institutes adopted the use of chawls to provide housing quarters for their employees; the Bombay Improvement Trust and the Bombay development department. While they were heavily criticised for the quality of life provided by these chawls, the trust continued to participate in Mumbai’s urban development through the housing market well through the twentieth century. (Urban, 2013) The poor quality, the depreciating profit in construction of chawls and the rent and land policies pushed the commissioning of chawls to its death. The existing ones today are dilapidated but continue to thrive as popular housing choice for low-income groups. Figure summarises the growth of building development of the chawl.

The summary of this evolution can be found in the next page

Figure. 3.2.3. Art deco apartments in Mumbai (source: Talalay, 2013) Learning From The Chawl

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3.3. Evolution of the chawl Chawl evolution summary 1. 1900s - 1930 Baithi chawl (figures 3.3.6 & 3.3.5) Ground structures built by migrant workers mimicking the village house type. Being just about ground storied or ground plus one, they maintained a close relationship with the ground and many activities spilled over onto the ground plane. They were largely destroyed and replaced with higher density housing (Gupte, 2011)

Figure. 3.3.1. Drawings of the baithi chawl (source: Gupte, 2011)

2. Early 1930s 2-3 storey high privately built chawls. (figures 3.3.2 & 3.3.6) These were privately commissioned 3-4 storey high chawls built with timber framework and brick masonry.

Figure. 3.3.2. Drawings of the 2-3 storey chawl (source: Gupte, 2011)

3. 1930-1960s Government commissioned chawls (figures 3.3.3 & 3.3.7) Soon government agencies started building chawls as a solution for mass housing problems and as housing quarters for their employees. The open spaces became sparse in them and they were made with concrete and brick for speed of construction.

Figure. 3.3.3. Drawings of the government chawl (source: Gupte, 2011)

4. late 70s to current (figures 3.3.4 & 3.3.8) No new chawls are being constructed. Old chawls are being inhabited.

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Figure. 3.3.4. schematic drawing of current chawl

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Chapter 3 Precedent study

Figure. 3.3.5. Baithi chawl (source: http://www.oldindianphotos.in)

Figure. 3.3.6. 2-3 storey chawl (source: Shetty et al, 2007)

Figure. 3.3.7. BDD chawl (source: Shetty et al, 2007)

Figure. 3.3.8. government chawl Learning From The Chawl

30

3.4. About the typology A chawl could be characterised by some of its distinct architectural features, namely: The Room (kholi) : A kholi or a unit, consisted of living quarters and a kitchen, measuring around 10â&#x20AC;? by 12â&#x20AC;?, housing anything between 1 and 8 people. (figure 3.4.1 and 3.4.4) Figure. 3.4.1. diagram of the unit

The courtyard (maidan) : Most chawls were known for their ample proportioned enclosed courtyards.

These courtyards became extremely important social enablers, where festivals, religious functions as well as day-to-day activities like playing cricket, spontaneous discussions and ancillary kitchen activities occur.

Courtyard are found in many scales and sizes and become a subject of interest in environmental performance due to their position. (figure 3.4.2 and 3.4.5)

Figure. 3.4.2. diagram of the courtyard

Corridors: The characterising feature of a chawl could easily be its long, entwining corridors that serve as key access points for the room inhabitants. Marked at the end of these corridors is an opening, where the main stairwell occurs. This opening is also where common sanitary facilities are located. (figures 3.4.3 and 3.4.6)

Figure. 3.4.3. diagram of the corridor

Due to the compact size of the housing units, corridors serve an unique function of becoming an extension to the living space. It is often found that people begin to inhabit the corridors, store furniture, thereby making this transitional space as responsible as the courtyard in promoting a social landscape.

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Figure. 3.4.4. Unit interiors (source: Adarkar, 2000)

Figure. 3.4.5. children playing in the courtyard(source: Adarkar, 2000)

Figure. 3.4.6. corridor being used for socialising and thoroughfare (source: Adarkar, 2000)

Learning From The Chawl

32

When the question of chawls is brought up, a reference to Adarkar’s (2012) book is inevitable. Adarkar views the chawl in plurality as she speaks about context, structure and social fabric. She explains how the chawl makes an interesting study as they existed as a sustainable settlement consisting of mixed use development, amenities and infrastructure attuned to the inhabitants’ needs.

The chawl typology was heralded as a ‘vertical village’ in the city. Its courtyards, series of semi-open spaces, each blurring the lines between private and public, resulted in the creation of a heterogeneous community within a highly urban city. (figures 3.4.7 and 3.4.8) Karandikar (2010) in her study on two chawls in Mumbai, refers to chawls as a model for affordable housing. She alludes to the prevalent social diversity, economic and environmental sustainability and the ability to house large densities as important learning from the chawl typology. However, it is important to note that while she states that the socially rich spatial configuration and the rent of these chawls, still make them lucrative places to stay, she concludes her paper by stating that due to their dilapidated state, refurbishing chawls is not prudent, but imbibing qualities present in chawls into new affordable housing is important.

Figure. 3.4.7. Children playing human pyramid during a festival in a courtyard (source: Adarkar, 2000)

Figure. 3.4.8.The corridor is uniformly lit up during a festival giving a communal common aesthetic (source: Adarkar, 2000)

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Chapter 3 Precedent study

Another extensive research carried out by Rane et al (2012) reveals key insights about how spaces are used by inhabitants in chawls.

In their research, they mapped the elements of a chawl neighbourhood in which they identified connecting roads and squares as urban components of the chawl network. as depicted in figure 3.4.9. Other than the previously mentioned courtyards and corridors, Rane et al identify : Gully : a narrow street between two chawls which may be flanked with small shops run by the occupants of the chawls Nukkad : the junction between gullies which is adorned with small newspaper stands and more intimately scaled public functions. The nukkad is however, much less important in terms of function and scale than the court.

Chowk: the junction where the gullies meet the main road.

Figure 3.4.10 is the culmination of their survey across ten chawls in Mumbai, which studied the occupancy periods of various elements of a chawl through the course of a day. It is noteworthy how the occupancy of the courtyard is quite significant, almost reaching 90% during the evening, closely followed by the corridor. Both spaces are heavily used in the mornings.

Figure. 3.4.9. The diagrammatic scheme of surrounding spaces near a chawl (source: Rane et al, 2000)

Figure. 3.4.10. Space usage study summary (source: Rane et al, 2000)

Thus the existing predisposition of the occupants to maximise their comfort through the adaptive opportunities presented by the typology generates a broad scope for research. It also exalts the study of this typology as a precedent to inform the design of low-cost social housing.

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3.5 Materiality & typology As alluded to in the previous section, chawls experienced a progression in construction technology due to their increasing demand as a low-cost solution.

They were initially constructed using brick masonry, load bearing wooden framework and were finished with sloping thatched roofs that were laid with Mangalore tiles as seen in figure 3.5.1 (Urban, 2013).

Later when the construction of chawls moved from private to governmental sector, they were built with a concrete framework, concrete partitions and brick masonry due to reduced cost of material and labour (figure 3.5.2). The thatched roof too was replaced with a slab and terrace which was seldom accessed (Shetty et al, 2007) A quick Mean indoor temperature test of the two fabrics revealed that the better performing fabric was the one with timber framework, the detailed analysis of materiality will follow in the analytic section.

The variation in building body from private to government also lead to development of formal typologies. While the older chawls retained the typical U-shape, the ones built later began to squeeze out the large courtyards and began to develop parallel bars and C-shaped built forms.

Brick-timber construction U value_timber walls : 2.6 W/m² People/sq.m : 0.4 Mean indoor temp : 34.5°C Figure. 3.5.1. Timber and brick construction chawl

Figure 3.5.3 illustrates the various typologies of chawls that developed.

Figure. 3.5.3. Typologies of chawls over time (source: source: after Vosburgh, 2014)

Concrete section U value : 1.9 W/m² People/sq.m : 0.4 Mean indoor temp : 35.7°C Figure. 3.5.2. Concrete construction chawl

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3.6. Universal applicability of the chawl type The chawl typology though unique to the city of Mumbai in its presence, has congruence in similar typologies around the world. While some demonstrate a similar social ethos, other demonstrates the similar usage of semi open spaces.

The Bouca housing by Alvaro Siza (figure 3.6.1) connects each household with their own staircase to the courtyard, to generate a sense of community, much as the Aranya low-cost housing in Indore, India by B.V Doshi, uses courtyards at unit and cluster levels to induce cooling, ventilation and create a space for the housing occupants to use together as illustrated in figure 3.6.2 Figure. 3.6.1. Bouca housing by Alvaro Siza (source: Hyde, 2004)

The Pedregulho housing in Rio (figure 3.6.3), resembles the chawl greatly with its winding corridors that aim to provide workers with a communal space. Built by Affonso Reidy, the complex was to serve as a home for government workers, whose salaries could have afforded them expensive housing, thus creating a congruence in their program to the chawls as well.

The massive modernist giant of exposed concrete is characterised by its wooden brise soliels (sun-shading).

The next step to understanding the performance of the space was to conduct fieldwork. Fieldwork was conducted over two weeks in April and July, to understand the environmental performance and how social parameters play a role in enhancing or impacting the performance of the space. The fieldwork and the inferences and design hypothesis generated from the study will be illustrated in the next chapter.

Figure. 3.6.2. Aranya low-cost housing complex by BV Doshi (source: Silva,2016 )

Figure. 3.6.3. The winding corridor of the Pedrogulho housing with the brise soliels visible at the back (source: Hartmann,2013 )

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04

Fieldwork

4.1 Fieldwork site 4.2 Interviews 4.3 Occupancy pattern 4.4 Gains charts 4.5 Outdoor study 4.6 Indoor Studies 4.6b. Data logger (april_summer week) 4.6c. Data logger (July_rainy week) 4.7 Key inferences from fieldwork

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4.fieldwork

Figure. 4.1.1. Site of fieldwork, Government colony chawl

4.1 Fieldwork site In order to understand the performance and quality of the various space types in the chawl, a typical chawl was chosen for fieldwork. The fieldwork was carried out in two weeks, one in the summer period and one during the rainy season, in order to gain an comprehensive idea of the nature of the chawlâ&#x20AC;&#x2122;s performance.

Chosen building : Government colony, Bandra East, Mumbai (Figure 4.1.1) Total plot area : 120 acres, with built up area of 9290 sq.m Total units : 4932 tenements,

Figure. 4.1.2. Figure ground of site complex

Built between : 1958-68 Located in the populated suburb of Bandra, the government colony is a community of seven buildings flanked around spacious courtyards(figure 4.1.2). The colony is enclosed by four arterial roads and is located opposite the community temple on the other side of the northern road. Dotted around the colony are numerous amenities, such as Cardinal Gracias high school, Indian education society, a community centre, a bank, a healthcare centre and a police station.

COURTYARD

COURTYARD

Built form description The complex consists of U-shaped buildings, which are 4 storeys high. Wrapping itself around the building are the corridors, which serve as primary circulation. Enclosed within the built are large courtyards (Figure 4.1.3). The ends of the corridors culminate into shared sanitary facilities. Each unit contains a living space and a kitchen.

For the study, a single building with its courtyard was chosen.

Figure. 4.1.3. schematic plan diagram of the fieldwork building to demarcate the various spaces

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4.2 Interviews The first part of the fieldwork was conducted through a series of interviews with the occupants with the aim of understanding occupant behaviour and their interaction with the built. This helped in gaining an insight of their adaptive opportunities, their aspirations, socially driven preferences, grievances and advantages.

Method: The method of occupant feedback was conducted via informal interviews with the occupants and enhanced by an occupant survey, details of which can be found in the appendix.

The summary of the percentage of satisfaction versus dissatisfied occupants with respect to the thermal comfort inside their unit is represented in the pie chart :

satisfied, 31%

not satified , 69%

Figure. 4.2.1. percentage of satisfied versus unsatisfied occupants

The basic demographics of the studied chawl are illustrated in figure

Figure. 4.2.2. Key demographics of the occupants and snippets of the interviews

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Interviews with the occupants revealed some key behavioural aspects that have direct impacts on comfort: â&#x20AC;˘ Families tend to stay together due to social construct, thereby resulting in large number of people occupying a small space. High density is also a function of economic viability. â&#x20AC;˘ On being asked if they prefer communal kitchens, the women folk vehemently opposed it. In the Indian social setup, the kitchen is a space where the women of the household assert their dominance, thus a common kitchen can only serve as an ancillary space and not a primary space to cook daily meals. The prevalence of the caste system also deems it socially unacceptable for certain foods to be cooked with others (for instance, non vegetarian food would not be cooked near a Brahmin[] household)

corridor used as a social space (source: Paul, 2012)

â&#x20AC;˘ Due to this increased discomfort caused by the gains due to the kitchen appliances and high occupant density, occupants tend to use the corridor in plurality.

Women use the corridor to meet and cut vegetables in the early noon, children use the corridor to study in the late noon and it used as a communal space during the evenings. The courtyards are also used in the mornings and evenings, when it is relatively more comfortable.

Figure 4.2.3 is a compilation of pictures of aspects of living in a chawl and quotes from the occupants who were interviewed.

serving food in the court (source: mythologies of mumbai, 2009)

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Using the corridor (source : mythologies of Mumbai, 2009) AA School: Susatainable Environmental Design

Chapter 4 .Fieldwork

• The corridor is also used for sleeping purposes in the night if the unit gets uncomfortable. Thus the lines of privacy are blurred as the corridor becomes a semi-open, semi-private living annexe

• The communal nature of the space is encouraging for most occupants. It is one of the key features of why people prefer to continue living in chawls. The older occupants revealed how the community takes care of each other, even if their own children have moved out.

• Younger families demonstrated a need for improved and private sanitation facilities • the courtyard is used not just by children for playing, but also by the adults for communal functions and festivities through the year. source : Sinha, 2015

•

courtyard as a gathering space (source: Nair, 2016)

Figure. 4.2.3. a)-f)Collection of pictures depicting chawl life and some quotes to illustrate occupants’ views Festiviities (source: Vijapurkar, 2014) Learning From The Chawl

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4.3 Occupancy pattern Through the interviews, occupancy patterns were constructed to understand the negotiation and usage of space, which is illustrated in Figure 4.3.1 It can be observed through the chart that occupancy is highest in the night between 8pm to around 6am in the morning, that is between dinner and sleeping.

It then reduces when the corridor is used for activities such as reading the news, morning tea and is further reduced by 9am when children depart for school and the male members leave for work.

The unit is at its lowest occupancy between 9 - 11am, when women keep the door open and use the corridor and courtyard for drying and cutting vegetables and talking. As the solar angle gets steep around noon, the unit is occupied by the women of the house and windows are shut.

Children return from school and the unit is used for lunch and repose, and the corridor for studies between 12 pm and 4 pm. Children then use the courtyard extensively in the evening for playing and are joined by the men who are returning from work and use the courtyard to socialise.

The courtyard and corridor become seamless communal spaces in the evening between 5 and 8 pm.

Thus it can be observed that the continuous flow of space between the corridor, unit and the courtyard and the multiplicity of their use lies at the centre of the adaptive opportunities of the occupants.

9pm-6am

3pm-5pm

5pm-8pm

Figure. 4.3.1. Occupancy patterns as informed by observation, literature and interviews images source: Adarkar, 2000

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4.4 Gains charts Using the occupancy chart and the interviews with the occupants, an internal gains chart was arrived upon (figure 4.4.1). It can be observed that the number of appliances are quite sparse and with adequate ventilation, the gains accrued by the kitchen can be dissipated. It can therefore by concluded that the maximum gains are accumulated due to people gains.

A quick study of heat loss and heat gains co-efficient illustrates the same, as it can noted that solar and internal gains due to occupancy are largely responsible for heat gains. The insufficient heat loss due to ventilation and increased thermal mass are also indicative of discomfort parameters.

Figure. 4.4.1. Equipment gains, usage pattern of appliances and heat gains due to activity and occupancy

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4.5 Outdoor study Spot measurements were taken on 16/4/16 thrice in a summer day, 9 am when most male occupants leave for work and the courtyard is therefore used by women for cooking and socialising, 1 pm when it is sparsely used and 5 pm when the court is most occupied by children and adults.

They were taken in courtyard (C), in the corridor (B) and inside the room (A) in order to calculate the mPET of the outdoor spaces and compare them to the indoor temperature to establish which of the spaces is more comfortable. The location of the measures is indicated in Figures 4.5.1 and 4.5.2. The same process was repeated for on the 11/7/2016, a day in the rainy season, the results of which are tabulated in tables 4.0 and 4.1

Figure 4.5.1 location of spot measures schematic section

Table. 4.0. Summary of spot measures taken through the day in court and corridor_ April Air temp. (ยบC) Wind speed (m/s) Relative mPET humidity (%) B (at 9am)

28.5

1.5

67

26.4

B (at 1pm)

29.9

0.2

70

28.4

B (at 5pm)

29.1

1.2

68

26.6

C (at 9am)

30.1

2.1

59

27.7

C (at 1 pm)

31.8

1.4

60

28.3

C (at 5 pm)

31

0.8

58

29.1

Table. 4.1. Summary of spot measures taken through the day in court and corridor_ July Air temp. (ยบC)

Wind speed (m/s) Relative humidity (%)

mPET

B (at 9am)

28.5

3

79

25.8

B (at 1pm)

29.9

1.9

81

26.8

B (at 5pm)

29.1

3.2

83

25.1

C (at 9am)

27

4.2

90

22.3

C (at 1 pm)

29.8

3.6

87

26.8

C (at 5 pm)

28

5.1

89

24.7

C

D

Figure 4.5.2 location of spot measures - C- courtyard , B-Corridor

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Results from spot measures: It can be observed that both the corridor and the courtyard are more comfortable than the unit.

Upon further investigation with the aid of thermal pictures (figures 4.5.3-4.5.5), it can also be seen that the corridors contribute to heat losses due to their structural position (cantilevered structure causing a thermal bridge, aiding in heat loss) and due to the admission of natural ventilation into these spaces.

Thus making them thermally comfortable spaces, where sometimes, occupants even choose to study and sleep.

Figure 4.5.3 Thermal imaging of the facade showing heat loss through corridor

Figure 4.5.4 Thermal imaging of the facade showing heat loss through corridor

Figure 4.5.5 Thermal imaging of the corridor Learning From The Chawl

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4.6 Indoor Studies The unit chosen was occupied by two families, Kapse, totalling to a maximum of 8 occupants. It is occupied by all members largely during dinner time and in the night to sleep. The anterior portion is the living area that contains the bed, a study table, one ceiling fan and a TV (figure 4.6.4). The posterior portion of the unit is the kitchen area that is often used for dinning as well. Figure 4.6.1 shows the high thermal gains in the kitchen area.

Figures 4.6.2 and 4.6.3 show the interiors of the studied unit.

The preliminary set of measures pointed to high indoor temperatures as compared to the corridor and the courtyard (Figures 4.6.6-4.6.7). This when coupled with occupants stating discomfort they experience in the unit, prompted further investigation. A data logger was placed to study the nature of the space and the insight that could be culled from the same.

The spot measures for daylight levels indicated poor day light levels in the unit as illustrated in Figure 4.6.5

Thermal performance analysis

Figure 4.6.1 Thermal imaging of the kitchen

General characteristics : Living unit area : 26 sq.m Volume :91 cu.m Window to floor ratio : 0.19 Fenestration percentage: 10.8% No. of occupants (max) : 8

Building materials : Walls : brick with plaster/paint (U value : 2.0 W/m²K) Roof : concrete slab , 150 mm ( U value : 1.7 W/m²K Window : single glazing ( u value : 5.9 W/m²K) 3.0M 6.0M

Figure 4.6.3. View of the unit

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Figure 4.6.2 Living space unit interiors

Figure 4.6.3. Living space unit interiors AA School: Susatainable Environmental Design

Chapter 4 .Fieldwork

75000 Lux

191 Lux

90 Lux

121 Lux

Figure 4.6.5. Section indicating spot measures of day light levels in Lux 31.4°C 9.00am

air temp : 33.1°C RH : 64% air velo : 0.1m/s

air temp : 32.6°C RH : 58% air velo : 0.1m/s

Figure 4.6.6. Plan indicating spot measures taken at 9am 32.6°C 1.00pm

air temp : 34.6°C RH : 74% air velo : 0.2m/s

air temp : 34.9°C RH : 60% air velo : 0.3m/s

Figure 4.6.7. Plan indicating spot measures taken at 1pm Learning From The Chawl

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4.6b. Data logger (april_summer week) Figure 4.6.8 illustrates the thermal performance of the unit during a week in april, recorded by the data logger.

• The indoor operative temperature was largely stable and not affected by the outdoor temperature. Peaks can be observed at points marked ‘A’ and ‘B’, which can be attributed to the increase in occupant density.

• Although there is a sharp rise in outdoor temperature around noon, the indoor temperature remains stable. This can be attributed to the occupants closing the windows and using mechanical fans to increase comfort. However, due to the lack of adequate ventilation, the unit is unable to remain in comfort despite the reduced occupant density around noon.

solar radiation (w/sq.m)

Temperature (°C)

• There is a gradual decline in indoor temperature from midnight, which then drops to its lowest around 6:30 am. Low solar gains and ventilation through windows at night account for the gradual decline, while the lowest can be a cumulative of occupant adaptive behaviour (usage of the corridor), reduced solar gains and increased ventilation.

Solar radiation (w/sq.m

Comfort band

outdoor temp (°C)

indoor temperature (°C)

Figure 4.6.7. Data logger reading _summer week Living unit area : 26 sq.m People/sq.m : 0.3 Volume :91 cu.m Window to floor ratio : 0.19 Fenestration percentage: 10.8%

Walls : brick with plaster/paint (U value : 2.0 W/m²K) Roof : concrete slab , 150 mm ( U value : 1.7 W/m²K Window : single glazing ( u value : 5.9 W/m²K)

X8

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Chapter 4 .Fieldwork

Data logger (july_rainy week) • The outdoor temperature is largely within the comfort band, however the unit remains mostly outside of comfort.

• The unit experiences its lowest when solar radiation is the least, with the exceptions of periods marked as ‘C’ and ‘D’, which could have been caused due to increased occupant density on the particular day.

Temperature (°C)

solar radiation (w/sq.m)

• It can noted that the peaks in outdoor do not cause a sharp difference in the performance of the unit. The occupants’ tendency to shut the windows during the noon and use the mechanical fan are reflected in the stability of the unit performance.

Solar radiation (w/sq.m

Comfort band

outdoor temp (°C)

indoor temperature (°C)

Figure 4.6.8. Data logger reading _rainy week Living unit area : 26 sq.m People/sq.m : 0.3 Volume :91 cu.m Window to floor ratio : 0.19 Fenestration percentage: 10.8%

Walls : brick with plaster/paint (U value : 2.0 W/m²K) Roof : concrete slab , 150 mm ( U value : 1.7 W/m²K Window : single glazing ( u value : 5.9 W/m²K)

X8

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4.7 Key inferences from fieldwork Inferences from data logger readings • The unit is almost insulated from the outdoor and while this helps not raise the temperatures in the summer, it prevents cooling down of the unit in the rainy period when the outdoor temperature is favourable.

• The thermal mass and inadequate ventilation causes heat caused by excessive internal gains remains trapped inside.

• occupants optimize comfort through the usage of transitional spaces.

• occupants tend to keep windows shut during the afternoon when air movement through the space does not lower air temperature.

• Increased night ventilation when occupancy density is maximum could alleviate discomfort.

• addition of screens or shading devices would reduce discomfort caused due to solar gains both in the unit as well as the corridor, thereby allowing extended usage of the corridor for sleeping and other activities through the day.

• Inadequate window to wall ratio reduces rate of air changes. Optimization of fenestration percentage to improve daylight as well thermal quality is required Inferences from spot measures and outdoor studies • Though the outdoor spaces are comparatively more comfortable than the outdoors, they are not optimized for performance by themselves.

• The courtyard lacks seating, outdoor infrastructure, adequate vegetation to increase comfort.

• The corridor is used for multiple purposes, but the depth is not suitable to provide adequate shading and facilitate different uses as adapted by the occupants.

• There are no shading elements in the corridor to prevent excess solar gains, thereby making the inhabitation of the transitional space less comfortable.

As the occupants tend to use the space actively, it is necessary to take into account their pattern and design the court and corridor in tandem with that.

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Summary table : inferences and design guidelines

Table 4.3. Key inferences and design guidelines

Features

Concept diagram

Current condition

Development/change

Form

Compact form with Addition of toilet facilities increased height, containing kitchen and living

Material

Concrete structure with Reduce thermal mass and increase brick, no additive insulation porosity

-Inclusion of Jaalis (screens) to induce ventilation without compromising protection from rain.

Windows

window to wall ratio : 0.19 Increased window to wall percentage to optimize daylight and increase ventilation potential Glazing percentage : 7.8%

Transitional spaces

Extension to living space, communal spaces.

Enhance existing adaptive potential by spilling over living space further into corridor and making courtyard more comfortable

Shading devices

Corridor and eaves shade and protect from excess solar gains

Inadequate solar protection.

Introduction of shading devices to reduce solar gains. increasing depth of corridor to allow passage and living space, thereby increasing shading

Occupant behaviour induced consideration

High internal gains due to Extend living/sleeping space to corridor occupancy and inclusion of to reduce internal gains kitchen

Research agenda : Understanding the relationship of the corridor, the courtyard and the unit, to identify their role in bettering environmental and social performance.

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05

Analytic work

5.1 Courtyard 5.1a. Shape optimization 5.1b. Aspect ratio 5.1c. Material study 5.1d. Activity pattern and courtyard usage 5.1e. Effect of trees, vegetation and water bodies 5.2. Unit studies _base case description 5.2a. Unit strategies 5.2b Unit studies_top floor analysis 5.2c Orientation studies 5.2d Unit peformance conclusion 5.3 Corridor analysis 5.3a. Case study summary 5.3b. Depth and shading analysis 5.3c. Daylight analysis 5.4 Conclusions

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5.Pre-design studies The analytical work was divided into three sections, namely, the courtyard, the corridor and the unit. Each element of the chawl was analysed for various aspects with the primary intent being that of optimizing them for comfort.

The first section consists of analysis of the courtyard and aspects that affect outdoor comfort. Not only does this create favourable outdoor microclimates, but also increases the opportunity to reduce outdoor air temperature during extremely hot months such as may, thereby, aiding in creating favourable environments in the corridor as well as the unit.

The following section consists of unit performance analysis and strategies to improve unit thermal performance.

The last section analysis the corridor as a bridging element between the unit and the courtyard. Factors such as shading, comfort, depth and activity were analysed.

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Chapter 5 .Analytic work

5.1 Courtyard Juneja (2015) states the following factors that influence comfort in a courtyard : Activity level, clothing, air temperatures, mean radiant temperature, air velocity and relative humidity Table 5.0 further enlists factors that may or be impacted by the above mentioned parameters.

The branches then further form parameters that were tested and analyzed for comfort.

Table 5.0. Factors impacting comfort in a courtyard

Activity level Affected by

Clothing

Air temp MRT

Occupant Occupant -Material -incident solar radiation

Air velocity

-Air temp -height -openings on ground level

Humidity -vegetation -presence of water body

-orientation

-material

(Berkovic et al, 2012)

(Yannas and Chatzidimitriou, 2016)

Affected by

shape of the courtyard/shading

Affected by

Neighbouring buildings/FSI norms/ Aspect ratio

Thus the parameters that would be studied are : Shape optimization, effect of aspect ratio, surface material, activity and current usage patterns and the effect of vegetation and water bodies.

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5.1a. shape optimization As discussed in the earlier section, chawls developed formal variations, depending on the agency that was responsible for building it.

Currently, three typological variations of the chawl type exist, the U shaped court, a L shaped built enclosing a court on two sides and a courtyard enclosed between two parallel blocks. (figure 5.1.1 ) Almhafdy et al (2015) discuss factors affecting comfort in a courtyard in hot and humid climatic conditions. Simulations and CFD tools were used to analyse the same and it can be inferred that incident radiation and wind velocity form key factors to manipulating a comfortable microclimate in a courtyard.

Therefore to analyse which shape of a courtyard is most suitable in to achieve a comfortable atmosphere, each shape was analysed for its efficacy in reducing incident radiation. Sensitivity studies were conducted and the average incident radiation over a period of one day in summer was calculated.

Figure 5.1.2 illustrates the radiation testing for the three forms of the court, in different orientations, for 21st march

It can be concluded that the form that helps in the reduction is the U shaped built form. This type will be used in further analysis.

Figure 5.1.1. Chawl typologies and court types (source: after Vosburgh, 2014)

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N O R T H

AVERAGE RADIATION : 1.5 kwh/sq.m

AVERAGE RADIATION : 1.65 kwh/sq.m AVERAGE RADIATION : 2.7 kwh/sq.m

AVERAGE RADIATION : 2.4 kwh/sq.m

AVERAGE RADIATION : 2.6 kwh/sq.m AVERAGE RADIATION : 3.1 kwh/sq.m

AVERAGE RADIATION : 2.3 kwh/sq.m

AVERAGE RADIATION : 1.9 kwh/sq.m AVERAGE RADIATION : 3.9 kwh/sq.m

AVERAGE RADIATION : 2.5 kwh/sq.m

AVERAGE RADIATION : 2.7 kwh/sq.m AVERAGE RADIATION : 4.2 kwh/sq.m

E A S T

S O U T H

W E S T

Figure 5.1.2. Radiation testing for different forms of the courtyard for 21st march

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5.1b. Aspect ratio Aspect ratio is defined as the ratio between the width and the height of a space.

The impact of this factor is well discussed in literature.

Yannas and Chatzidimitriou (2016) highlight the impact of aspect ratio in producing comfort, through a series of measurements and simulations.

Their extensive research concludes noting that the aspect ratio has a strong effect on PET values, and is more significant in the courtyard than in a public square.

A study on two vernacular courtyard houses in Kolkata, India, illustrates the relationship between the aspect ratio of a court and ventilation (Das et al, 2005) Das notes that the key factors in determining comfort in a court are incident radiation and induced wind velocity. It can also be noted that these two factors are essential in the calculation of the PET. The study concludes that a smaller aspect ratio induces more ventilation. (figure 5.1.3)

Figure 5.1.3. Summary of the analytic work by Das regarding impact of aspect ratio on wind velocity (source: Das, 2005)

In order to arrive at a optimum aspect ratio for the courtyard, several existing chawl courts in Mumbai were mapped and the aspect ratios of their courts were calculated (figure 5.1.4).

These were then analysed for average incident radiation and induced wind velocity due to form, over a period of one summer day. The day chosen was 21st march when the average wind velocity was 2.5 m/s The results of the analysis were then compiled to form a graph in order to generate a tendency line. Two graphs (figures 5.1.5 and 5.1.6) were generated, one for average incident radiation and one for induced wind velocity.

It can be seen that greater the aspect ratio, larger the average incident, ergo higher the PET values. The exact converse is observed with the wind velocity, where smaller aspect ratios yield stronger winds, thereby increasing comfort. In order to optimize for both, a smaller aspect ratio must be chosen to increase comfort.

Using these graphs a point of optimization was arrived at, beyond which the results yield diminishing returns. This optimum ratio was then used in further analysis.

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Chapter 5 .Analytic work

average incident radiation (kwh/sq.m)

Figure 5.1.4. Some of the chawls that were included in the analysis

aspect ratio

average wind velocity (m/s)

Figure 5.1.5. Graph plotting average incident radiation against aspect ratio to generate a tendency curve

aspect ratio Figure 5.1.6. Graph plotting average wind velocity against aspect ratio to generate a tendency curve Learning From The Chawl

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5.1c. Material study A conceptual courtyard was generated using an aspect ratio and shape derived from the previous section to analyse the impact of surface material.

Various ground cover materials were analysed using ENVIMET and the surface temperature generated was compared.

The simulation was conducted over a span of one day in the summer.

In order to account for corrections, the view factor and incident solar radiation of each patch of material was calculated as well, to prevent a possible effect overshadowing of the form may cause (figure 5.1.8).

Commonly occurring material for ground cover that are found in Mumbai were observed and used for the process of analyses, namely, grass, concrete paving, mud/earth, paver block and terracotta tiles (figure 5.1.7) The results are tabulated in table 5.1. To gain a clear perspective of the effect on comfort, the PET values were calculated for three instances of the day (refer to appendix), one of which is illustrated in the table. The conditions used to calculate the PET are as follows :

Figure 5.1.7. Ground materials that were tested; left to right- grass, mud, concrete paving, paver block and terracotta tiles

a)

a) concrete paving

b)

b) terracotta tiles c) paver block d) grass e) mud

e)

c) d)

Figure 5.1.8. courtyard with patches of ground materials

21st march, 2pm Air temp : 32.3°C Air velocity : 0.12 m/s Relative humidity : 67.7% Table 5.1. Compiled data for material analysis for 2pm

Concrete paving

mud/ earth Paver block

Grass

terracotta tiles

Surface temp (°C)

35.2

37.3

36.2

33.3

37.6

Solar radiation (W/sq.m)

892.1

892.1

892.1

892.1

892.1

Sky view factor

0.39

0.47

0.54

0.54

0.47

PET (°C)

29.1

30.9

30.7

28.6

30.6

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Figure 5.1.9 shows the resultant surface temperatures for the material study at 9am, while figures 5.1.10 and 5.1.11 are for 2pm and 6pm times respectively

<20°C 21.0-23.7°C 23.7-25.6°C 25.6-27.6°C 27.6-29.5°C 29.5-31.4°C 31.4-33.5°C 33.5-35.3°C 35.3-37.2°C

The results show that grass is a preferred material in lowering ambient temperature thereby helping in reducing the PET. However, the difference in surface temperatures between grass and concrete is 2.0 K, which makes it suitable for use with additional vegetation and adequate overshadowing, the effects of both of which will be tested in the following sections.

>37.2°C

Figure 5.1.9. Surface temperature_9am

<21.7°C 21.8-23.7°C 23.7-25.6°C 25.6-27.6°C 27.6-29.5°C 29.5-31.4°C 31.4-33.5°C 33.5-35.3°C 35.3-37.2°C >37.2°C

Figure 5.1.10. Surface temperature_2pm

<21.7°C 21.8-23.7°C 23.7-25.6°C 25.6-27.6°C 27.6-29.5°C 29.5-31.4°C 31.4-33.5°C 33.5-35.3°C 35.3-37.2°C >37.2°C

Figure 5.1.11. Surface temperature_6pm

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5.1d. Activity pattern and courtyard usage The courtyard is the centre of many communal activities. It also serves as a spill-over space for many daily activities. It becomes imperative to understand the usage pattern of the courtyard so as to gain insight on factors that influence design of the court.

To understand the plethora of programs that the court generates, the activity pattern of the court was documented over a day. Interviews revealed the more occasional and festive uses of the court. Thus, the materiality and comfort would also have to take into account the usage of the space.

Figure 5.1.12 illustrates the usage of court space through the day.

Figure 5.1.12. courtyard activity usage and pattern

The court is not actively used before 9am, after which it sees a series of activities. Women who supply lunch boxes to single migrant men, assemble in the court to do so. Hawkers bring in their wares, women dry vegetables capitalizing on the approaching overhead sun and some wash their clothes and leave them out to dry.

Due to overhead sun and resulting discomfort, the court is sparsely used between 11am and 4pm. Thereafter, the court sees a lot of activity as children use it for playing purposes, men returning home from work socialise, play cards and deliberate on the dayâ&#x20AC;&#x2122;s work.

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5.1e. Effect of trees, vegetation and water bodies Theoretical studies were used to understand the effect of vegetation and water in increasing comfort in a court. Yannas and Chatzidimitriou (2016) conclude through a series of fieldwork and analysis that vegetation and foliage cover have a significant impact on reducing PET values.

Trees and grass covers reduce PET and increase comfort in courtyards.

While tree covers increase comfort, the effect of canopies is reduced if the courtyard is shaded by other buildings around it. In such a case, the canopy may cause an increase in air temperature and PET. Smaller water bodies are more effective than larger in lowering ambient temperature.

A quick sensitivity test using ladybug was conducted to gain a numeric understanding of the impact of trees. The conceptual court (U shaped with an aspect ratio of 1.9) used for analysis in the previous section was further tested for the effect of trees. The ground material chosen was concrete paving, the day used for simulation was 21st march and an instance in the day was selected, 2pm.

Figure 5.1.13 shows the microclimate immediately under the tree as compared to the rest of the court. It can be observed that the presence of trees helps reducing the UTCI by 2.0 K.

>32.6 32.4 32.2 32.0 31.8 31.6 31.4 31.2 31.0 30.8 <30.6

Figure 5.1.13. Microclimate analysis to test the effect of trees (source: after Grasshopperladybug)

The efficacy of water bodies in reducing ambient temperature is dependent on the wet bulb temperature. It is recommended for the wet bulb temperature to be in the range of 22 - 24 °C, with a relative humidity of 40-50% (Arandara et al, 2012) Weather data analysis as discussed in section 2.2. of Mumbai reveals that evaporative cooling would prove to be ineffective during the rainy months when the humidity and wet bulb temperature indicate a highly saturated air quality. However, during the drier and hotter months between march through to may and October, evaporative cooling would be effective in lowering outdoor air temperature.

Thus smaller tanks which can be used as rain water percolators may be effective as evaporative cooler during the dry months. This would be drained into underground tanks during the rainy season to prevent additional discomfort due to humidity.

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5.2. Unit studies _base case description The fieldwork indicated a thermally poor environment in the unit caused by high internal gains, inadequate ventilation and insufficient solar shading. The simulations for improving thermal performance were guided by the inferences generated through the fieldwork.

The base case was generated using data from fieldwork and literature review of the climatic context. The dimensions and characteristics of the base case are illustrated in figure 5.2.1 base case dimensions : WxDxH _ 4.0 x 6.0 x 3.0m maximum no. of occupants: 8 internal gains (equipment) : 1.7 w/sq.m lighting loads : 1.35 w/sq.m Living unit area : 26 sq.m Volume :91 cu.m Window to floor ratio : 0.19 Fenestration percentage: 7.8% ach : 10

0.9m m

1.2

Figure 5.2.1. Base case description Walls : brick with plaster/paint (U value : 2.0 W/m²K) Roof : concrete slab , 150 mm ( U value : 1.7 W/m²K Window : single glazing ( u value : 5.9 W/m²K)

Each unit contains a living space, a kitchen with an overhang of 1.2 M. The default orientation assumed is the same as the unit in which fieldwork was conducted, that is west facing. The shoe box was then simulated for various orientations. Schedules and internal gains were informed by the current usage pattern. A typical summer week was chosen for the analysis.

The question of density remains a pressing issue and in order to acknowledge the high demand on land and property in Mumbai, the base case uses a high occupant density of 8 people per unit, as seen in the fieldwork.

46°

68 ° 78 °

The unit tested is located on the first floor of the building, however, as the tropics experience high solar angles (figure 5.2.2), the top floor unit will also be tested.

21ST JUNE

21ST DEC

21ST MARCH

Figure 5.2.2. Location of the base case and solar angles

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5.2a. Unit strategies Climate context and passive cooling theory suggests that the main strategies to improve thermal comfort in the tropics are increase in ventilation and solar protection. The strategies tested further are centred around the same.

Each strategy is tested against the base case individually first and the cumulative of the most effective strategies is tested further.

WINDOW TO WALL RATIO

Through the fieldwork, it was identified that the window to wall ratio was insufficient for both, ventilation and daylight. The first strategies used were to increase the glazing percentage from 7.8% in the base case to 20% and subsequently to 30% and 40%.

The U value of the glazing was maintained at single glazing 5.9 W/m²K.

Temperature (°C)

solar radiation (w/sq.m)

The base case is mostly out of the comfort band and increasing the glazing to 20% caused most of the peaks to fall by 1.5K. However, further increasing the glazing percent to 30 and 40 percents, caused the indoor temperature to rise again by 0.2 K and 0.7 K respectively.

Solar radiation (w/sq.m Case C indoor temp (°C)

Comfort band

Case B indoor temp (°C)

outdoor temp (°C) Case A indoor temp (°C)

Figure 5.2.3. Graph of typical summer week to test window to wall ratio strategy

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5.2a

Temperature (°C)

solar radiation (w/sq.m)

NIGHT VENTILATION

The next improvement was through the addition of night ventilation. Between 9 pm and 6 am, additional natural ventilation was simulated to account for increased occupancy during this period. It can be noted that the peaks in indoor temperature fall by 1.3K from the base case and a more stable indoor temperature is generated (figure 5.2.4)

Solar radiation (w/sq.m

Comfort band

Base case indoor temp (°C)

outdoor temp (°C)

Base case+night ventilation (°C)

Figure 5.2.4. Graph of typical summer week to test night ventilation strategy

The next strategy tested was addition of a screen. The thickness of the screen is assumed to be 30 mm and the dimensions of the spacing and hole is illustrated in figure 5.2.5 The addition of the screen proved very effective as it can observed that the peak temperatures reduce by 2.4 K and bringing the indoor operative temperature nearly into comfort. Through this measure, the percentage of hours above comfort is 25%

Temperature (°C)

solar radiation (w/sq.m)

SCREEN

Solar radiation (w/sq.m Base case indoor temp (°C)

Comfort band

outdoor temp (°C)

Base case+screen (°C)

Figure 5.2.5. Graph of typical summer week to test addition of screens

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5.2a

Temperature (°C)

solar radiation (w/sq.m)

LOW THERMAL MASS (CHANGED MATERIAL)

Fieldwork indicated that the thermal mass of the unit was also contributing to the accumulation of heat. Thus the in the next strategy, the thermal mass was reduced by changing the material. The material considered was timber with a U-value of to 2.6 W/m²K. changing the thermal mass caused a reduction in indoor temperature from the base case by nearly 2.4 K, reducing the percentage of hours of discomfort to 13% (figure 5.2.6)

Solar radiation (w/sq.m Base case indoor temp (°C)

Comfort band

outdoor temp (°C)

Base case+changed material (°C)

Figure 5.2.6. Graph of typical summer week to test changing material

A summary of the strategies tested can be summarised in figure 5.2.7. The cumulative effect of 20% glazing, addition of a screen, night ventilation and changed materiality are studied further.

Figure 5.2.7. Summary of cooling strategies measured with annual cooling loads

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5.2a This also generates design possibilities and enhancement of adaptive opportunity. by replacing the material to lightweight timber, foldable doors can be installed, which result in the unit opening out into the corridor and including the corridor as an extended living space, which can be used for reading, sleeping and light dining.

While this creates an opportunity for reducing internal gains due to occupancy and increasing ventilation, it also creates a possible scenario where over ventilation could cause increase in operative temperature.

This was simulated as three cases. a) Case A- the foldable doors are opened and the unit is ventilated only when the temperature is higher 31°C (upper limit of the comfort band) b) Case B- the foldable doors are scheduled to be opened only during periods of maximum discomfort. c) Case B + addition of screens

Temperature (°C)

solar radiation (w/sq.m)

The learning from the previous analyses was taken into account. The unit was modelled with 20% glazing and night ventilation (Figure 5.2.8).

Solar radiation (w/sq.m Case C indoor temp (°C)

Comfort band

Case B indoor temp (°C)

outdoor temp (°C)

Case A indoor temp (°C)

Figure 5.2.8. Graph testing combined strategies of thermal mass, screen and ventilation_summer week

Door used as an opening.

And open whenever indoor temperature exceeds 31°C

Door opened only when ventilation is needed to maintain comfort

Case B +screen

The improvement from Case A, B to C brings in the indoor operative temperature nearly within the comfort zone, with only 7% out of comfort. The indoor operative temperature peaks are reduced by 5-6 K from the base case. The foldable doors increase porosity and promote cross ventilation through the unit.

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5.2b Unit studies_top floor analysis

Temperature (°C)

solar radiation (w/sq.m)

The same strategies were applied to a unit on the top floor to understand the impact of solar radiation on the roof on comfort within the unit (Figure 5.2.9).

Solar radiation (w/sq.m base case top floor (°C)

Comfort band

Clay roof temp (°C)

outdoor temp (°C)

Clay roof+insulation temp (°C)

Green roof (°C)

Figure 5.2.9. Graph of roof system performances

It can be noted that the indoor temperature peaks are raised by 3.2 K from the first floor unit when simulated as a roof unit. Various roof systems were simulated to reduce the indoor temperature of the unit. The existing roof system is a concrete slab (U value:1.7 W/m²K) which was then changed to a clay tiled roofing (U value 1.4 W/m²K). This reduced the indoor temperature peaks by 1 K, however, the unit was still outside of comfort for 20% hours. Rock wool insulation was added to the clay roof system, which further reduced the indoor temperature by 0.9 K. The installation of a green roof, created the most effective performance, resulting in an overall reduction of 2.4-3 K in temperature peaks, nearly mimicking the performance of the first floor unit.

The cost benefit and maintenance of the green roof system is explored in a later section.

Plant Clay tile (20mm)

Clay tile (20mm)

Soil (150mm)

Mosaic tile (20mm)

Mortar (20 mm)

Mortar (20 mm)

Drainage (45mm)

Brickbat (100mm)

Weathering

Rock wool

Damp proof

course (150mm)

insulation 40mm)

layer (10 mm)

Bitumen (20mm)

CONCRETE SLAB

CLAY TILE ROOF

CLAY TILE +INSULATION

GREEN ROOF SYSTEM

Figure 5.2.10. Sections of roofing system

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5.2c Orientation studies

temperature (°C)

solar radiation (w/sq.m)

The combination of unit strategies was then tested for each orientation. It can be observed that there is a marginal difference in the performance of the unit in various orientations. The orientation with the highest indoor temperature is the west facing unit, followed by the east and south, with marginal variations and the north having the lowest. The west and north peaks are seperated by 0.34K difference (figure 5.2.11) The graph (figure 5.2.12) shows the solar gains through the windows in each orientation, where the west and east have spikes in the gains during the noon and mornings respectively, thereby mandating a shading for these two orientations.

It can be concluded that the effect of orientation on the performance of the unit is minimal and differences can be mitigated with adequate shading.

Solar radiation (w/sq.m

Comfort band

outdoor temp (°C)

solar radiation (w/sq.m)

indoor temp_west (°C) indoor temp_north (°C) indoor temp_east (°C) indoor temp_south (°C) Figure 5.2.11. Graph showing the thermal performance of the unit in different orientations

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Incident rad_west (w/sq.m)

Incident rad_south (w/sq.m) Incident rad_east (w/sq.m) Incident rad_north (w/sq.m) Figure 5.2.12. Solar gains through the windows for different orientations AA School: Susatainable Environmental Design

Chapter 5 .Analytic work

5.2d Unit peformance conclusion It can be summarised that the strategies most effective in creating a well-performing unit were increasing and optimizing glazing percent, extending the unit into the corridor thereby increasing cross ventilation and adaptive opportunity, change of material to light weight construction and addition of shading devices to reduce solar gains.

The design of the unit aims to combine the performance strategies with the aspiration and flexibility of the occupantâ&#x20AC;&#x2122;s usage of the space, to generate a thermally comfortable space that also creates a suitable architectural environment.

The next section extrapolates the learning from this section to analyse and optimize the corridor to serve as both, an effective shading device and as an extension to living space.

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5.3 Corridor analysis 5.3a. Case study summary The previous section introduces the idea of using the corridor as an extension to the living space, which could also be used for sleeping purposes in the night. To enable both functions of being used as a living space and for thoroughfare, analysis were conducted to arrive upon a suitable depth to allow both. The corridor also serves as a horizontal shading device.

A literature review consisting of a case study of Bedok housing in Singapore (Bay, 2004) deliberated on the optimal depth of a veranda/corridor for social and environmental benefits.

Figure 5.3.1. Effect of wind and solar radiation on thermal sensation (source:Bay, 2004)

.

Bay records the effect of wind and solar radiation on thermal sensation in the forecourts of the housing complex. He states that solar radiation should be > 700 w/ sq.m for corridors where wind speed of 0.5-1 m/s can give thermal comfort. Larger semi-open spaces should have > 100 w/sq.m of incident solar radiation where even minimal 0.3-0.6 m/s wind speed provides thermal comfort (figure 5.3.1).

Thereby concluding that solar radiation has a greater impact on comfort in the tropics than wind (Bay, 2004)

Figure 5.3.2. Summary of diagrammatic inferences of effect of depth of forecourt (source:Bay, 2004)

Bayâ&#x20AC;&#x2122;s studies concluded with the following findings (figure 5.3.2): - optimization can be reached at 2m depth.

- larger than that can provide sufficient shade and facilitate social activities.

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Using the case studiesâ&#x20AC;&#x2122; method and inference as a starting point, radiation analyses were conducted to arrive upon an optimum corridor depth, in which maximum radiation is reduced while allowing for functional use and maintaining structural integrity.

Average incident radiation on the vertical surface that is shaded by the corridor (figure 5.3.3) was calculated using Ladybug over one summer day.

The length was gradually increased from the existing a minimum of 1.5m to 3.0m, for all orientations. The results are summarised through a graph in figure 5.3.4. It can be noted that beyond 2.6m the returns are not significant enough for the extra load on structure and cost it would incur.

Hence, a depth of 2.6m was chosen for the corridor.

Figure 5.3.3. Average incident radiation on vertical surface on obstruction by overhang 1.6

average incident radiation (kwh/sq.m)

1.4 1.2 1

0.8 0.6 0.4 0.2 0

1.5m

2.0 m north

2.5m

2.6m

2.7m

south east depth of corridor (m)

2.8m

3.0m

west

Figure 5.3.4. Graph showing the relationship between radiation and increasing depth of corridor

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5.3b. Depth and shading analysis Upon arriving at an optimum depth, it could be noted that there was still a scope for reduction in radiation and to make the corridor thermally comfortable to become more usable, shading elements were tested.

Referencing from the discussion in the previous section regarding shading, each orientation would require a different kind of shading element, owing to solar angles, therefore, to gain a holistic analysis of shading requirements, the shading elements were analysed keeping four parameters in mind : a) reduction in radiation b) orientation c) implications on daylight within the unit d) occupancy patterns The corridor is envisaged to home various daily activities (figure 5.3.5) and it therefore becomes necessary to provide adaptability of the shading to ensure that the connect between the courtyard and the corridor is maintained, privacy and solar protection is offered during sleeping or eating and daylight is uncompromised for reading and studying.

Figure 5.3.5. Different activities as imagined in the corridor

Thus a combination of fixed and movable shading devices would be used to increase adaptive opportunity. All shading devices used would be fashioned with bamboo to decrease cost of construction. Movable shading and fixed screens made with woven bamboo could be produced within the complex by the women folk, while a framework of bamboo sticks, could form the base on which light vegetative shading could be generated (figure 5.3.6).

Figure 5.3.6. Shading devices used; left to right- bamboo trellises for vegetation, movable bamboo shutters, bamboo woven screens.

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The combination of these were then tested for radiation analysis, results of which are represented in figure 5.3.7. Each case was compared with a base case, which is an un-shaded corridor of a depth of 2.6m, as arrived upon in section.

Avg incident radiation 1275 w/sq.m

base case: only overhang Avg incident radiation 1056 w/sq.m

base case+ vegetation+ movable shutters

Avg incident radiation 1155 w/sq.m

2.6M overhang + vegetative shading Avg incident radiation 961 w/sq.m

base case+ vegetation+ movable shutters+screen

Figure 5.3.7. Radiation analysis of the impact of shading in reducing solar gains (source: ladybug)

The lightest shading was applied to the north orientation, where vegetation and movable panels were used.

For the south, a combination of movable shutters, movable screens and vegetation was applied.

The west and east, receiving the most radiation, were treated with fixed screens and movable shutters.

The vegetation does not contribute greatly in the east and west directions.

It can be seen that application of the shading devices in the north reduces the average incident radiation from the base case by 9.4%, 17.1% in the south and by 24.6% in the east and west respectively. The shading systems were further validated by generating shading masks (figure 5.3.8).

Figure 5.3.8. Shading masks of various shading devices (source: ladybug)

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5.3c. Daylight analysis The presence of a deep overhang and numerous shading elements can adversely impact daylight within a space. Therefore the next step of the analysis was to measure daylight levels in each of the shading systems. To avoid compromised daylight due to the overhang, corridors would be placed in alternating positions on each floor and a smaller more private extension on the rear end of the unit would provide shading, extra space to sleep, without hampering daylight needs (figure 5.3.9).

private extension

M A I N CORRIDOR 2600

1550.00

M A I N CORRIDOR

private extension

2600

1550.00

private extension

M A I N CORRIDOR 2600

1550.00

M A I N CORRIDOR

private extension

2600

1550.00

Figure 5.3.9.Diagram showing alternating corridor strategy to maximize daylighting

This concept was put to test when the module as depicted in figure 5.3.10 was tested for daylight. It was concluded that the operable nature of the shading, the increased glazing and the alternating overhang, produced desired results for daylight. A minimum of 200 lux is desirable for residential buildings (CIBSE) and this target is achieved by nearly 76-82% of the area. The opening and closing of shading schedules was designed based on occupancy patterns of the corridor (refer to appendix) Daylight autonomy [DA-150 lux50%] - 12%

Daylight autonomy [DA-150 lux50%] - 87%

M e a n daylight factor - 1.5%

M e a n daylight factor - 1.5%

BASE CASE

VEGETATIVE SHADE + MOVABLE SHUTTER

Daylight autonomy [DA-150 lux50%] - 84%

Daylight autonomy [DA-150 lux50%] - 75%

M e a n daylight factor - 1.5%

M e a n daylight factor - 1.5%

MOVABLE SHUTTERS

FIXED SCREEN + MOVABLE SHUTTERS

Figure 5.3.10.Daylight analysis of unit through various shading (source:DIVA)

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5.4 Conclusions The analysis of the three elements was done delineating their parts and identifying the role and function of the same.

It was however, essential to keep the comfort of the occupants in focus of the analysis, thus all elements were studied for their performance along with the envisaged activity in them to assure that space will be used to generate vibrant spaces.

The learnings from the analysis would then be applied to solve the problems that were culled out from literature and fieldwork.

The design methodology followed the following steps : 1) Design of the unit and the corridor 2) Application of the unit into a conceptual courtyard block 3) Site selection and mapping of site 4) massing strategies and design 5) placing the unit block into the massing scheme to generate a master plan 6) design of master plan The design section would then be concluded with a set of performance assessments of the unit, the corridor and the courtyard for their comfort.

The unit will be assessed through thermal simulation and the corridor and courtyard through outdoor comfort factors.

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06

Design application

6.1. Unit design 6.2. Building Block design 6.3. Elevation design 6.4. Views 6.5 Site Analysis 6.5a Site selection 6.5b. Site mapping 6.6. Massing strategies 6.7. Master plan 6.8 Views_outdoor 6.8a. Design assessment 6.8b. Courtyard assessment 6.9. Summary of performance

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6. Design Strategies

The design strategies for chawls are formulated and guided by learning from fieldwork, literature review and analysis.

At the epicentre of the design principles lie occupant adaptability and comfort. The design aims to respect the social ethos of the inhabitants, at the same time, introduce more challenging concepts of space and comfort to provide a better environmental and spatial quality of life.

The passive design concepts are enlisted as follows: Encourage cross ventilation: promoting ventilation through the space to rid the unit of unavoidable excess internal gains Permeable and operable facade: Solar protection through shading which is operable to allow wind and daylight when desired.

Flexibility of space usage through transitional spaces: creating multiple thermal zones and microclimates (the unit/the corridor/ the courtyard) , in order to provide greater options for comfort, thereby negotiating and distributing internal gains.

Light weight materials : materials that reduce thermal mass and increase porosity Insulating roof with green roof system : reduction of heat transmission through the roof to lessen thermal discomfort, while also providing a substrate on which wall vegetative shading could grow; from roof to ground.

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6.1. Unit design The first step in designing the unit was to take forward the analysis from section .

The basic dimensions of the unit are illustrated in figure 6.1.1 2.6m 6.0m 1.5m

4.0m

Figure 6.1.1.Dimensions and plan of the unit

The next step was to design the outer fabric of the unit. A light weight material glass fibre reinforced gypsum (GFRG) was used for the walls between two units (figure 6.1.3).GFRG is a prefabricated panel, consisting of gypsum plaster reinforced with glass fibres. It consists of modular cavities that could either be filled with concrete or left as it is.

The physical characteristics and the advantages of the GRFG walls are summarised in figure 6.1.2 Further details of construction can be found in the appendix

The density is 1.14g/cm (10% of the weight of concrete) U value : 2.85W/M2K Benefits of using GRFG : Low embodied carbon Low energy comsumption during production stage light weight Can be installed within a concrete shell struction

manufactured using industrial waste Good sound insulation prperties easy installation low cost of manufacturing and installing

Figure 6.1.2.Section and summary of GFRG panel features (source:Chowdhary, 2015)

Figure 6.1.3. Unit design_locating the GFRG panels

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Next, the materiality and design of the exposed walls was chosen. Coconut timber panels were used for the exposed walls. The design of the windows was guided by literature review which recommended a larger outlet than inlet to promote cross ventilation (figure 6.1.4).

timber jaali door (source: https://elementsilove.com)

Coconut timber facade and opening (source : http://www.fao.org) Figure 6.1.4. Unit design, windows, front facade material and design

For better wind flow and daylight, the inlet window was shifted to the top of the facade. Foldable operable doors made of timber jaalis[3] were used to create a seamlessness between the living area of the unit and the corridor, while aiding in solar protection in the day and wind flow during the night.

Figure 6.1.5 shows the wind flow through the unit through partly opened front door and the back window. The movement of air cools the occupants at standing level and aids in allowing the internal gains accumulated due to the kitchen to exit out of the unit. Thus preventing thermal saturation within the space.

Figure 6.1.5. Wind flow through the unit section (source: after Flow design and Butterfly)

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6.1

The plan of the unit is flexible and spaces are cordoned off with movable partitions. The kitchen is located at the rear end to facilitate the egress of gains due to appliances. (figure 6.1.6) All furniture is foldable and flexible to account for varying sizes of families, accommodate various functions through the day and promote wind flow.

Figure 6.1.6. Unit design showing location of spaces and foldable flexible furniture

The design of the corridor is as per the analysis done in the previous section, where alternating floors have a corridor of a larger depth, providing space for both sleeping as well as passageway. (figure 6.1.7)The final step in unit and corridor design was the addition of shading. Detailed analysis of the type and form of shading is described in the previous section.

Figure 6.1.7. Unit design showing location of main corridor, private extension space and shading devices

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6.2. Building Block design

The unit and corridor design were then incorporated into a conceptual building block. The design development of the block was conducted in the following stages

Figure 6.2.1. Diagram showing position of corridor, private communal space, with respect to the courtyard

First the units were flanked around the courtyard with the corridor looking inward and the more private extension looking outward. Areas demarcated in purple serve as extensionterraces or are used for communal functions like day-care and laundry (figure 6.2.1).

The plan is inverted on the next floor with the corridor on the external edge (figure 6.2.2).

The alternating sequence is repeated for the subsequent floors (figure 6.2.3).

The core staircases are then located to provide easy access in case of emergencies (figure 6.2.4).

Figure 6.2.2. Diagram indicating inversion of the corridor location

An additional set of staircases that open from the court, wrap around the building, connecting the communal spaces to each other, complementing the vibrant nature of the corridor (figure 6.2.5).

Figure 6.2.3. Diagram indicating replication of alternating scheme

Figure 6.2.4. Diagram indicating location of core staircases and additional staircases that wrap around the building

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Figure 6.2.5. overall building spaces diagram

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6.3. Elevation design

The elevations were a consequence of the building block design and the shading analysis. In contrast to the rationality of the plan and organisation, the design of the elevation was aimed at being more organic with the usage of bamboo elements and the wall vegetation growing in an irregular pattern.

Figure 6.3.1 is the elevations for the east and west facades. As the analysis showed, the vertical facades recieving highest radiation is the east and west, therefore these facades have been designed with movable shutters, bamboo screens and vegetation.

Figure 6.3.1. East and west elevation design

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Figure 6.3.2 is the elevations for the south facade. The south recieves moderate to high radiation, generating the necessity for medium shading. Therefore this facade has been designed using movable shutter, bamboo trellises on which vegetative shading could grow and movable screens.

Figure 6.3.2. South elevation design

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The north facade (Figure 6.3.3) by the virtue of receiving the lowest radiation is treated more organically than the rest. It is largely shaded with bamboo trellises on which vegetation could grow, thus providing light to medium shading whilst generating an organic language for the aesthetic of the building.

Thus each of the elevations are punctuated with different combinations of the same elements, to make construction cheaper at the same time, account for varied radiation needs and impart a different language to each facade.

Figure 6.3.3. North elevation design

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Figure 6.3.4. Sectional view of building block

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6.4. Views Following are internal views of the designed unit and corridor spaces. Each view is marked with environmental performance markers to indicate the nature of space usage while highlighting the comfort in the same.

Figure shows how the corridor starts gaining a plural function as the man sleeps near the unit and the other occupants use it for passage.

air temp: 31.1 °C

Rela. humidity: 66% Wind speed : 2.1m/s Rela. humidity:66% Wind speed : 2.1m/s

Figure 6.4.1. Corridor view

Corridor view_ man sleeping

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Figure shows how the variety of uses the corridor adorns as people use it for sitting and reading, talking and chatting. The movable shutters allow for occupants to view the happenings in the court below and participate and when required, they can shut the shutter to increase comfort. air temp: 32.1 °C

Rela. humidity: 45% Wind speed : 1.8m/s

Figure 6.4.2. Corridor view

Corridor view_ man reading

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6.4

Figures 6.4.3 and 6.4.4 are the day and night views of the unit, respectively. In the day it can be observed that the furniture is pulled up, the partitions are drawn for shade and the kitchen is being used. The door is open and the unit is extending into the corridor.

Outdoor temp: 31.6 °C

Indoor operative temp: 28.3°C

Figure 6.4.3. Interior view : day time view

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The night view highlights how the furniture is pulled down for sleeping, the floor is used too, people are using the outdoor extensions for sleeping as well. The unit is closed however the jaali door allows for ventilation even at night.

outdoor temp: 28.4 °C

Indoor operative temp: 29.1°C

Figure 6.4.4. Interior view : night time view

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6.5 Site Analysis 6.5a Site selection Site information : The site that was chosen (figures 6.5.1 and 6.5.3) for fieldwork is touted to undergo a massive redevelopment process, the master-plan for which has been partly showcased.

The redevelopment (figure 6.5.2) has come to a standstill at the very conceptual phase as occupants are reluctant to move into stylised towers (Malpakwari,2015) that disregard the nature of the bonds they have formed due to the chawl type.

This makes the site a contextually charged location to place the thesisâ&#x20AC;&#x2122; proposed intervention, which could provide a scope for comparison between the present, the proposal and the governmentâ&#x20AC;&#x2122;s master plan (Nair, 2009).

However, due to the lack of data about the governmentâ&#x20AC;&#x2122;s redevelopment plan, the thesis proposal will be compared numerically to the existing chawl and visually to the redevelopment plan.

Figure 6.5.1. Aerial view of the site (source: Dinodia photo, 2015)

Figure 6.5.2. Views and imaginations of the redevelopment of the chosen site (source: Times of India, Nair, 2009)

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Plot area : 26047 sq.m Existing built up : 28232 sq.m Current FSI : 1.1 Total available FSI if redeveloped : 4.0 No. of tenements : 670 Floors per building: 4

Figure 6.5.3. Chosen site and details of site

Site microclimate : Figure 6.5.4 summarises the microclimate of the site.

The prevailing winds blow from the south west and the radiation comes from the south west and south east.

Figure 6.5.4. Microclimate analysis of the site (source: after ladybug)

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6.5b. Site mapping The site was then mapped (Figure 6.5.5) to understand its urban morphological nature. The site is located in the heart of the city in the suburban area of Bandra.

Due to the vibrant nature of the chawl, amenities like schools, hospitals and religious centres grew around the chawl.

There are open spaces around the site serving as playgrounds for the religious community centre.

green spaces & amenities

The site lacks green spaces and only has trees parsimoniously dotted around. The study of built form reveals a that most of the surrounding built is mid rise, causing the chosen site to be largely free of overshadowing.

This is confirmed through a series of overshadowing analysis of the site (Figure 6.5.6).

Key inferences from site mapping:

courtyards

â&#x20AC;˘ addition of green spaces is required to create more ambient microclimates â&#x20AC;˘ the surrounding buildings are mid rise and do not overshadow the site, therefore any massing generated on site would have to shade itself â&#x20AC;˘ the density of built-up on site is low owing to the open spaces

open spaces

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Figure 6.5.5. site mapping

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Figure 6.5.6. Overshadow analysis of the site (source: after sketchup2015)

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6.6. Massing strategies The massing steps were informed by the courtyard comfort studies carried out in section. The aim of the massing was to create comfortable microclimates in the form of enclosed courts, which would in turn shape the built around it.

Massing : Establishing the grids The process of massing was started by laying grids on site.

The grids were informed by two factors, a limiting height and the aspect ratio of the court due to the height. The height was influenced by the socially quality of interaction and connection.

The chawl promoted a feeling of a dense community and it was necessary to maintain that connectivity in the proposal.

Brazilian architect, Jan Gehl (2010) discusses how the connection with the ground diminishes as the height of buildings grow. Therefore to maintain a relationship between an occupant on the highest floor and the court, he recommends through a series of documentation and analysis, that the height must be restricted at five floors.

(Figure 6.6.1) Using this idiom and restriction, the height for the proposal massing was capped at five floors.

National building code (2005) also state that lifts are mandatory for residences above 15m in height1. Thus the cap on height helps maintain a social connectivity and reduces cost for lift installation and maintenance Using this height, a suitable aspect ratio was chosen from the previous studies and a resulting width for the courtyard was arrived upon. This is illustrated in figure 6.6.2 Figure 6.6.1. Studies of trying to establish the height beyond which the relationship with the ground is lost (Gehl, 2010)

Figure 6.6.2.Applying the aspect ratio to the site as grids 1) The reconstituted National building code of India, 2005, states in section 5 of building services that a provision for lifts shall be made for buildings for 15m and above.

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Chapter 6 .Design application

Massing : extruding the built Using the grid, the width of the courtyard was generated.

The previous studies suggested a width for the built form, which was 10m, 6m for the length of the unit, 2.6 m of the front corridor and 1.4 m for the rear extension.

The built form generated from laying grids was then extruded to a maximum height of five floors (figure 6.6.3 ) Massing: cutting pedestrian axes Two pedestrian axes of widths 4.5m were cut across the massing to promote easy access to the roads flanking the site and allowing access to the multiple blocks within the site. (figure 6.6.4 ) Figure 6.6.3.Extruding the built form

Massing : opening courts to axes The resultant courts that were generated due to the above massing steps were then opened out into the pedestrian axes (figure 6.6.5).

Figure 6.6.4. Cutting pedestrian axes through the extruded grids.

Figure 6.6.5. opening the courts to the axes

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6.6 Massing : wind analysis The next step was to test and modify the form for wind flow.

Analysis was conducted on a prototype unit to identify the most optimal locations to create cut-outs to promote wind flow (figure 6.6.6 ) The learning from this was then replicated through the massing and the overall form was optimized for wind flow (figure 6.6.7)

Figure 6.6.6. Analysis to test the optimum location for cutouts (source: after flow design)

Figure 6.6.7. Optimizing massing for windflow

Massing : Overshadow analysis As gathered from the mapping inferences, the massing form must overshadow itself to provide comfort in the courts. The prototype module was studied to manipulate heights (figure 6.6.8) within one U-shaped block to increase and optimize overshadowing of the form. The variations were then replicated through the massing and figure 6.6.9 illustrates the overall overshadow analysis

Figure 6.6.9. Optimizing massing for overshadowing

Figure 6.6.8. Overshadow tests (source: after ladybug)

Massing : overlaying program Programs that are complementary to the housing complex and were a part of the aspirations of the occupants were mapped out. Figure 6.6.10 is a relationship diagram of these functions.

Physical and spatial relationships were mapped for functions like informal markets, commercial spaces, day care facilities and small workshop spaces.

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Figure 6.6.10 .Relationship diagram showing the proportional relationship of the functions imagined in the courts

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Chapter 6 .Design application

Massing : final form The massing that emerged through the series of steps above generated courtyards which can be used for playing, gathering, celebrations and leisure. Spaces are also allocated for small shops, a communal day-care, laundries, public kitchen for women who wish to use it for commercial purposes and market stalls. (figure 6.6.11 ) The resultant massing generates 65% more built up than the existing chawl and has significant area of green open spaces. While the built up is not comparable to the density generated by SRA buildings, it is noteworthy that the open space to built up ratio in a SRA scheme is 1.5% while in the proposal, it is nearly 15%, which can be noted in figure 6.6.11. Thus, the chawl provides a solution for density which does not neglect the needs of an urban community and puts forth a new face for low-cost housing.

Figure 6.6.10 . Final massing form showing the built form, the open spaces and the zoning of spaces

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Figure 6.6.11 .comparative built up of existing chawl, proposal and SRA

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6.7. Master plan The master plan was generated by placing the building block design within the massing. The courtyards were further optimized by the change of materiality of the ground, inclusion of trees and smaller urban furniture to create animated microclimates that can support a variety of functions, the diagrammatic progression of which is shown in figure 6.7.1. The master plan was realised to demonstrate the strong relationship that the three elements, the courtyard, the corridor and the unit share. (figure 6.7.2) Areas marked in blue are small shops, market stalls and commercial spaces and areas marked in red are common facilities. Small stepped tanks for rain water collection are also provided, which can also be used for leisure purposes.

Within the scope of this thesis, the design of the commercial and communal facilities are developed to a conceptual spatial level. They are not studied and detailed for environmental performance.

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Figure 6.7.1 .analysing and combining massing, ENVIMET simulations and single block design to arrive upon masterplan

0m

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Figure 6.7.2 .Master plan of the housing complex Learning From The Chawl

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6.8 Views_outdoor The following views are outdoor views of different courtyards with different functions being carried out.

Air temp :30.4°C Rela. humidity: 63.2% Wind speed : 2.9m/s mPET: 27.7°C Air temp : 30.6°C Rela. humidity: 75.3% Wind speed : 2.9 m/s mPET: 25.9°C

Figure 6.8.1 . View of market plaza courtyard

Air temp : 31.6°C Rela. humidity: 64.5% Wind speed : 1.3m/s mPET: 28.7 °C

Figure 6.8.3 . View of a wedding taking place in one of paved courts

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The materiality was chosen based on surface temperature generated in a given court, the plethora of functions that the occupants could put it to use in and its role in generating a vibrant masterplan

Air temp : 30.3째C Rela. humidity: 62.3% Wind speed : 2.3m/s mPET: 28.7째C

Figure 6.8.2 . View of garden courtyard

Air temp : 31.5째C Rela. humidity:54.9% Wind speed : 1.4 m/s mPET: 28.6째C

Figure 6.8.4 . View from the corridor, watching people play in a playground courtyard

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6.8a. Design assessment Summary of thermal performance Design assessment_Summer week The design assessment of the thermal performance of the unit was done for two weeks, typical summer and a typical rainy week. The simulation revealed that the culmalative effect of increasing window to wall ratio, increasing ventilation, lowering thermal mass, extension of the living space and addition of shading resulted in the unit being largely within comfort, with the percentage of hours in discomfort being just about 6.5 % during the summer week and 4% during the rainy week (figures 6.8.4 and 6.8.5) The corridor’s operative temperature was also simulated, however, the comfort in the space will be calcuated through the mPET measures, which are demonstrated in the next section of the assessments.

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Figure 6.8.6 shows the cooling loads through the year.

TYPICAL SUMMER WEEK Solar radiation (w/sq.m)

infiltration (ach)

outdoor temp (°C)

corridor temp (°C)

Comfort band

indoor operative temp (°C)

Figure 6.8.4 . thermal assessment graph for summer week (source: after energyplus + Openstudio)

maximum no. of occupants: 8 internal gains (equipment) : 1.7 w/sq.m lighting loads : 1.35 w/sq.m

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Timber walls : 2.65 w/sq.m GFRG walls : 2.8 w/sq.m Single glazing : 5.7 w/sq.m Bamboo shading device : 3.7 w/sq.m

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opera�ve temperature (°C)

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Chapter 6 .Design application

TYPICAL RAINY WEEK Solar radiation (w/sq.m)

infiltration (ach)

outdoor temp (°C)

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Figure 6.8.5 . thermal assessment graph for rainy week (source: after energyplus + Openstudio)

Timber walls : 2.65 w/sq.m GFRG walls : 2.8 w/sq.m Single glazing : 5.7 w/sq.m Bamboo shading device : 3.7 w/sq.m

maximum no. of occupants: 8 internal gains (equipment) : 1.7 w/sq.m lighting loads : 1.35 w/sq.m

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Figure 6.8.6 . annual cooling load moth wise for unit performance (source: after energyplus + Openstudio)

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6.8b. courtyard assessment Assessment of the courtyards was done using ENVIMET simulations. The day tested was the 21st of March (summer day) and it was simulated for a period of 24 hours.

The simulation results revealed that the courts produced favourable PET values as shown in figures 6.8.7 and 6.8.8.

Certain portions were slightly out of comfort, which was largely in the walkway connecting the courts (central spine) to which more shade through trees was added to maximise comfort and prevent discomfort through radiation.

<25.8°C 25.8-26.9°C 26.9-27.8°C 27.8-28.8°C 28.8-29.7°C 29.7-30.6°C 30.6-31.6°C 31.6-32.5°C 32.5-33.5°C

Figure 6.8.7 . Assessment of courtyards, 21st march, 6pm (source: ENVIMET)

33.5-34.4°C

<25.8°C 25.8-28.7°C 28.7-31.7°C 31.7-33.6°C 33.6-34.6°C 34.6-35.6°C 35.6-36.4°C 36.4-37.3°C 37.3-38.4°C 38.4-39.4°C

Figure 6.8.8. Assessment of courtyards, 21st march, 9am (source: ENVIMET)

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6.8c. Sectional stratification of air temperature Sections through the courtyard were cut to understand and extent of the impact the microclimate is having in alternating air temperature, which in turn affects the comfort and performance of the space.

Figure 6.8.9 shows the vertical stratification of air temperature at 4pm on 21st april. It can be noted that the greatest impact of the microclimate can be experienced in the lower levels at elevation +2.0m. Thereafter, the temperature increases again and then begins to reduce further beyond +15m elevation. It can however, be noted that the temperature variation experienced creates a difference of 1.45k between the lowest and the highest temperatures experienced.

<31.4°C 31.4-31.6°C 31.6-31.7°C 31.7-31.9°C 31.9-32.0°C 32.0-32.1°C 32.1-32.3°C 32.3-32.4°C 32.4-32.6°C >32.6°C

Figure 6.8.9. Vertical stratifcation of air temperature in courtyard (source: ENVIMET)

While the air temperature stratification is not varying greatly, figure 6.8.10 shows the wind velocities generated at various sections. It can be noted that due to the configuration of the courtyard microclimate, wind speeds ranging from 0.7-6.2m/s are generated, thereby increasing the potential of creating comfort in both the courtyard and the corridor.

<1.3m/s 1.3 - 1.8m/s 1.8 - 2.3m/s 2.3 - 3.0m/s 3.0 - 3.4m/s 3.4 - 4.0m/s 4.0 - 4.5m/s 4.5 - 5.1m/s 5.1 - 5.6m/s >5.6m/s

Figure 6.8.10. Wind flow and wind velocity in courtyard (source: ENVIMET)

The summary of the environmental performances of each of the three spaces, namely, the courtyard, the corridor and the unit is illustrated in the combined sectional drawings in the next section.

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6.9. Summary of performance Summary of design features and performance.

The following sections are a summary of the design performance of the three elements, the unit, the courtyard and the corridor.

The indoor operative temperature of the unit is compared to the mPET values generated in the corridor and court, in order to see all the thermal spaces that are created to increase the comfort of the occupant.

Figure 6.9.1 is a section cut at 9am, where most occupants are either inhabiting the unit or the corridor. Maximum occupancy is reached at this time. It can be observed that temperature inside the unit and the corridor remain comfortable.

Figure 6.9.1. Summary section of environmental performance of the spaces, 9am

Figure 6.9.2 is cut at at 11am, when occupancy is low. The radiation is laregly over head. It can be noted that the temperature inside the unit and the corridor remain towards the higher, but within the comfort zone.

Figure 6.9.2. Summary section of environmental performance of the spaces, 11am

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Summary of design features and performance.

Figure 6.9.3 is a section at 3pm, when the occupancy is nearly 75%. Due to the high radiation the outside temperature is high. Though the indoor temperature is marginally out of the comfort zone, it is noteworthy to see that there is a difference of almost 3.0 K between the indoor and the outdoor temperature.

Figure 6.9.3. Summary section of environmental performance of the spaces, 3pm

Figure 6.9.4 is cut at at 5pm, when the courtyard is actively used. People in the court are in comfort and the disturbuted internal gains creates favourable temperatures in the unit and the corridor.

Figure 6.9.4. Summary section of environmental performance of the spaces, 5pm

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7. Conclusions Mumbai is a city of diversity, a home to the richest and the poorest and within this barcode existence lies the migrant worker, who comes in search of a job and in search of way to assimilate himself into the cityâ&#x20AC;&#x2122;s fabric. He hopes to find housing within this overwhelming city only to find a lack of adequate low-cost housing, thus resorting to find home within illegal settlements.

To rid the city of slums, the government planned a rehabilitative scheme, relocating slum dwellers into towers. These towers however, are inadequate in multiple ways.

Not only is the environmental performance lacking, but there is also a lack of ventilation, daylight, open spaces and community fostering spaces, thus making them a systemic failure.

It is within this context that the chawl becomes a precedent worth pursuing. Historically built to house migrant workers, the chawl typology boasts of courts, socially rich corridors and bare minimal living spaces. While chawls do provide a rich framework, they are not optimised for providing thermal comfort in the living unit, adequate shading through the corridor, encouraging the existing vibrancy of the extended living space in the corridor and benefitting from the almost rare presence of open space.

This thesis focuses on learning from the chawl and improving its shortcomings to enhance adaptive opportunities for the occupants while proposing a new approach to low-cost social housing. The strategies for improving the unit include increasing window to wall ratio, reducing thermal mass, addition of

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shading devices, increasing flexibility and porosity of the space and encouraging the use of transitional spaces.

Chapter 7. Conclusions

The existing social fabric promotes the usage of the corridor as an annexe to the living space. This thesis centres the design scheme around that concept to reduce gains, increase shading and maintain the more subjective quality of an urban community. Aspects like the shading devices and the green roof are installed with not just environmental performance in mind, but also to supplement the communal aspect of the chawl type.

The courtyards are optimized in materiality, shape, vegetation and form to encourage an array of uses within them, such as weddings, festivals, playing and other communal functions.

Being one of the densest cities in the world, in terms of population, the question of density becomes a looming theme over most current housing projects. This has developed a tendency for most proposals favouring vertical growth. The thesis chooses to align itself towards a mid-rise, high density approach, to propose a housing type that seeks to balance community life with density requirements.

The proposal produces nearly 65% more built up than the existing chawl and has more than 10 times the open space as provided in an rehabilitative scheme.

This thesis aims to encourage a new outlook on low-cost social housing within the city of Mumbai, in attempting to create a freerunning housing at whose heart lies the occupant and their cultural ethos, thus hoping to create a low energy asset that the occupants and the city cherish. ÂŹ

Figure 7.0.0. Aerial view of the proposal Learning From The Chawl

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08 8.1 8.2 8.3

Learning From The Chawl

Post Design studies Green roof system Bamboo shading making Cost benefit analysis

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8. Post Design 8.1 Green Roof system The inclusion of a green roof for bettering thermal performance of the top floors was deemed suitable through analysis. However, as the proposal is a lowcost housing proposal, the cost viability of the scheme also becomes a factor in the decision of materiality.

The green roof system has been gaining great momentum in the city and one such venture founded in 2008 by Preeti Patil, called Maharashtra Nature Park (MNP). The MNP has been promoting the growth of urban community farms, by holding workshops on urban farming, conduct seminars, provide the knowledge and collaborate with many groups and individuals to encourage the growth of urban farms (Urbanleaves, 2014).

The initiative is called Urban leaves. Urban leaves have started a workshop to teach urban occupants how to make roof gardens through the creation of what is colloquially called â&#x20AC;&#x2DC;amrit mittiâ&#x20AC;&#x2122;.

Amrit mitti is formed through the compaction of cow dung, cow urine, kitchen waste, jaggery which is then combined with any biomass available, like old leaves and garden waste. This mixture is then combined with mud/earth/soil and laid over any substrate (figure 8.1.1). MNP uses this technique on terraces for home terrace gardens (urbanleaves, 2014). The soil thus created is inexpensive, compacted to create a density equal to regular soil thereby providing the needed insulating equality and providing a platform for the occupants to engage with the building.

Another initiative called Anubal Agro, Kurukshetra, India, provides farmers and low-income group people with free seeds and consultancy on how to grow produce in small spaces (Choudhary, 2016).

Thus a module can be proposed in the proposal, where a piece of terrace is allotted to each family, they are supplied soil and seeds through the aforementioned schemes and whatever is grown can be sold in the market places provided in the master-plan or consumed.

This ensures the maintenance of the roof system as it is now an asset to the occupants, thereby ensuring its thermal and communal properties to be cherished.

Figure 8.1.1. Process of producing Amrit mitti (source: Urbanleaves, 2014)

Few plants that can be grown in the weather and on the roof :

Passionfruit

Okra

bitter gourd/ cucumber

railway creeper

-grows well in monsoon -yields produce that is profitable/ consumable -grows in region of sunlight and water abundance

-grows well in monsoon -yields produce that is profitable/consumable

-grows well in monsoon -yields produce that is profitable/consumable - grows trellises that can be used for shading

-creeper grown commonly in india to provide shading over trellises -has medicinal quality and helps purify air quality

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Chapter 8. Post design studies

8.2 Bamboo shading making Bamboo is a material found in abundance in India and has often found a plethora of uses in the subcontinent.

In this proposal, all the shading devices are made with bamboo to ensure a low cost of material.

India is also home to some illustrious bamboo weaving art. Bamboo wood and cane are used to create an array of furniture, wall panels and screens. Screens and panels are created by thinly split bamboo pasted or framed around a plywood framework. Bamboo lathe is woven to create fabric-like shading (Figure 8.2.2).

Agencies like â&#x20AC;&#x2DC;Gaathaâ&#x20AC;&#x2122;, promote and encourage the preservation of bamboo art by conducting workshops and providing lessons to local women (Figure 8.2.1), selling their craft with no profit margins.

This proposal tries to encapsulate the ethos of traditional weaving art by involving the female occupants to weave the shading devices used in the design. Any replacement of the bamboo shading will thus be produced by the women folk themselves, thereby promoting the growth of cultural ethos and reducing cost to construction.

Figure 8.2.1. Women weaving with bamboo (source: Gaatha, 2012)

Figure 8.2.2. Bamboo woven shading (source: Gaatha, 2012)

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8.3 Cost benefit Analysis A basic cost benefit analysis of the material and labour cost was conducted to understand the comparative cost of building an SRA building, versus that of the proposal.

Initiatives as described in the previous heading, regarding cost of manufacturing of the shading, cost of the green roofing, were taken as measures to reduce the cost to construction, while promoting local ethos.

The calculated rates for material cost have been arrived upon using present market rates.

Figure 8.3.1 is summary of the comparative analysis of the material costs.

It can be concluded that while the cost to construction per sq. ft of an SRA building is Rs. 1375, the proposalâ&#x20AC;&#x2122;s cost to construction is 7.4% lower at Rs. 1274 per sq.ft Note: this estimation includes labour cost at 0.2% of cost to construction. (source of costs: http://cpwd.gov.in/Publication/DSR14.pdf)

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Figure 8.3.1. Cost comparison chart of proposal and SRA.

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Bibliography

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List of references

Adarkar, N. (2006) life day chawl. Available at: http://el.doccentre.info/website/DOCPOST/sep-06-rdc/sep-06-rdcformated/HA03-TS1-H-J10-life-day-chawl.pdf (Accessed: 24 April 2016).

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Appendix

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1) age: 35

Appendix 1 : chawl Survey, some results

1) age: 45

2) occupation: housewife

2) occupation: driver

3) gender: female

3) gender: male

4) how many people live in your house? 6, husband, me two children and his parents

4) how many people live in your house? 6

5) how long have you lived here? 10 years now with both children 6) do you like it here? if yes why? I like it here because there are many people to keep you company

5) how long have you lived here? 12 years 6) do you like it here? if yes why? I like it, it is like a family house now. My parents lived here, they were government employees, and now I live here also.

7) is it hot in the summer? it is hot

7) is it hot in the summer? I’m not at home when it is hot, so when I come back from work, it is pleasant

8) what do you prefer, indoor or outdoor? outdoor, but I cannot step out without a saree so I stay indoors

8) what do you prefer, indoor or outdoor? both are fine, though we prefer sitting out and chatting and relaxing

9) what do you want changed about this chawl? bathroom inside the house and bigger room

9) what do you want changed about this chawl? more space and toilet facilities

10) if you are asked to move, would you do it? depends on where I have to go

10) if you are asked to move, would you do it? no I will not.

This house is an asset now, but if I get a bigger house for this rent, then maybe yes (laughs)

1) age: 25 2) occupation: housewife who runs a tailoring business from home

1) age: 75 2) occupation: retired

3) gender: female

3) gender: male

4) how many people live in your house? 8

4) how many people live in your house? 3, my children moved away, so only me, my wife and our servant stay

5) how long have you lived here? we just got married so I’ve lived only for 3 years 6) do you like it here? if yes why? I do not like it very much there are too many people 7) is it hot in the summer? it is hot but we keep the windows and doors open so it is fine 8) what do you prefer, indoor or outdoor? I prefer indoor because it is private 9) what do you want changed about this chawl? a little more privacy 10) if you are asked to move, would you do it? only if the house is much bigger, otherwise no

5) how long have you lived here? almost 30 years 6) do you like it here? if yes why? yes very much, with my children abroad, the neighbours take care of us. nowhere else will you get that.

7) is it hot in the summer? yes it gets hot, but some fan and open windows solve the problem 8) what do you prefer, indoor or outdoor? I’m too old to sit out for long, but I enjoy sitting in the corridor and talking to people passing by.

9) what do you want changed about this chawl? toilet in each house 10) if you are asked to move, would you do it? as a youngster, yes I would have moved. Not now, now this is family.

1) age: 8 2) occupation: student

1) age: 63

3) gender: male

2) occupation: retired

4) how many people live in your house? 4

3) gender: female

5) how long have you lived here? daddy moved from the village here and then we came 3 years ago

4) how many people live in your house? 3

6) do you like it here? if yes why? I like it a lot, I can play a lot, I stay with many people. We all enjoy together 7) is it hot in the summer? I don’t think it is hot only in the afternoon it is so we stay indoors and play cards 8) what do you prefer, indoor or outdoor? outdoors 9) what do you want changed about this chawl? nothing. It is very nice.

10) if you are asked to move, would you do it? no, my other friends in schools dont have playgrounds where they live. We have, so I dont want to move

5) how long have you lived here? my whole married life that is almost 32 years 6) do you like it here? if yes why? I used to hate it because of the nosy neighbours and stuffy space, but now I very much love it because I dont feel lonely 7) is it hot in the summer? yes yes. We sprinkle water on the courtyard to make it cooler 8) what do you prefer, indoor or outdoor? I like to sit out, more comfortable 9) what do you want changed about this chawl? toilets, more room and better construction

Appendix 2 : Bedok Case study summary

Appendix 3 : Quinta Da Malagueira summary

Appendix 4 : existing chawl courtyard analysis

Appendix 5 : corriodr shading, screens, louvers and depth analysis

Appendix 6 : single building ground floor plan

Appendix 7 : plan of communal space on ground floor

Appendix 7 : GRFG panel construction details (source: Saini, 2014)

Appendix 8: surface material courtyard analysis table

2pm 6pm 10am 2pm 6pm 10am

2pm 6pm 10am 2pm 6pm 10am 2pm 6pm 10am

conc. Pav brick bats paving grass 35.3 38.2 37.2 26.2 27.4 28.0 32.1 31.8 32.1 solar radiation 892.1 892.1 892.1 45.1 45.1 45.1 839.7 839.7 839.7 sky view factor 0.39 0.47 0.54 air temp 32.3 30.8 30.9 wind velocity 0.12 0.09 0.13 relative humidity 67.7 69.6 73.1

33.3 26.1 29.3 743.4 45.1 793.1 0.54

Appendix 9: U value table Mumbai RCC construction plaster int S Plaster int 12 mm concrete blocks Plaster ext. 20 mm Plaster ext.

Mumbai Brick and timber plaster int S Plaster int 12 mm Brick Plaster ext. 20 mm Plaster ext. floor timber int resis floor board tiling

0.18 0.7 0.18

0.18 0.8 0.18

0.14 1.3

0.012 0.225 0.012

0.012 0.15 0.012

0.05 0.02

ext resis

RCC floor int resis Tiling RCC slab ext resis

glass window

0.125 0.07 0.32 0.07 0.580

1.7

0.125 0.07 0.19 0.07 0.446

2.2

0.17 0.36 0.02 0.04

1.3 0.7

0.02 0.15

0.583

1.7

0.17 0.02 0.21 0.04 0.440

2.3 0.96

Appendix 10:Schedules for thermal modelling (source: openstudio)