Dissertation oindrila

AA E+E Environmental & Energy Studies Programme Architectural Association School of Architecture Graduate School MArch Sustainable Environmental Design Dissertation Project 2014-2016

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REVITALISING THE INFORMAL CITY Holistic slum redevelopment in Kolkata, India

Oindrila Ghosh February 2016

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Abstract: About 55% of the urban popula•on of India lives in slums. This disserta•on project endeavors to think beyond “housing” to provide a “comfortable, habitable and economically viable environment” in Kolkata. Lessons from vernacular helped generate a modular unit which can be replicated in different urban contexts. The unit provides good solar control and high permeability to air flow and uses of low cost local materials, such as mud bricks, bamboo and wa•le and daub for the allevia•on of slum condi•ons, media•ng community par•cipa•on and give spa•al form to the resident’s ambi•ons. This forms part of a holis•c approach to facilitate the transforma•on of slum typologies directly into 21st-century sustainable communi•es, with on-site energy genera•on to not only offset their energy demands but also provide them with another source of income.

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MArch Sustainable Environmental Design 2014-16 Authorship Declara•on Form

TITLE: REVITALISING THE INFORMAL CITY Holis•c slum redevelopment in Kolkata, India.

NUMBER OF WORDS: 12153 words in main text.

STUDENT NAME: Oindrila Ghosh

DECLARATION “I cer•fy that the contents of this document are en•rely my own work and that any quota•on or paraphrase from the published or unpublished work of others is duly acknowledged.”

Signature Date: February 5th, 2016

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Contents 1.Introduction

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1.1.Introduction: 1.2.Methodology:

12 13

2.Indian slums: Addressing the housing crisis.

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2.1.Slums in india 2.2.Slum housing issues in Kolkata and policies implemented.

2.3.Precedent Study 2.3.1.Yerwada slum redevelopment: 2.3.2.Quinta monroy, Iquique, Chile: 2.4.Social context of the slums in Kolkata: 2.5.Conclusion:

16 16 17 18 19 20 21

3.Climate and comfort

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3.1.Climate analysis: 24 3.1.1.Location: 24 3.1.2.General overview 25 3.1.3.Effect of humidity and wind: 26 3.1.4.Future scenario: 26 3.1.5.Comfort criteria for residents of Kolkata: 27 3.2.Adaptive behavior by the occupants (the first line of defense): 28 3.3.Adaptive features ingrained in vernacular buildings in hot and humid regions of india (the second line of defence): 29 3.4.Energy index for India and energy targets: 33 3.5.Conclusions: 34

4.Understanding occupant behavior and material performance.

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4.1.Slum survey 4.1.1.Overview of the slum settlement: 4.1.2.Urban conditions and access routes 4.1.3.Existing slum conditions: 4.1.4.Existing slum conditions (the environmental aspect) 4.2.The Material Survey: 4.2.1.Bamboo House: 4.2.2.Wattle and daub House: 4.2.3.Mud House: 4.2.4.Brick House: 4.3.Datalogger results: 4.4.Conclusions:

38 38 39 40 42 43 44 46 48 50 52 54

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5.Analytic work.

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5.1.Urban analysis of slum settlements: 5.2.Design of the dwelling unit: 5.3.Thermal analysis of base case: 5.4.Strategic improvements of the base case: 5.5.Annual percentage of discomfort hours: 5.6.Conclusions:

58 59 60 62 73 74

6.Design: Building Scale

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6.1.Design of the 3 flat cluster 6.2.Design of the 8 flat Cluster 6.3.Variations in design of the module 6.4.Plethora of uses for the stilted ground floor 6.5.Environmental performance of the module in the 8 flat cluster.

6.6.Wind analysis: 6.6.1. 3 flat cluster: 6.6.2.8 flat cluster: 6.7.Solar radiation analysis 6.8.Cluster analysis 6.9.Conclusions:

78 79 80 82 83 84 84 85 86 87 88

7.Design: Urban Scale

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7.1.Urban Design 7.2.Wind Analysis for urban design 7.3.Facade treatment 7.4.Daylighting studies 7.5.Renewables: 7.6.Conclusions:

90 92 94 96 98 102

8.Conclusions

103

8.1.Conclusion:

104

References

105

Appendix

109

List of figures

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Acknowledgments I would like to express my deepest gra•tude to my parents and my brother who gave me uncondi•onal moral and financial support. I would also like to thank Rajdeep and John for giving me my second home in London. Without all of them, this would not have been possible. I would also like to acknowledge the school for gran•ng me the AA school bursary to a•end the this course.

My sincere gra•tude goes to my advisor Paula Cadima and my course director Professor Simos Yannas who have great insights and perspec•ves for guidance and helpful assistance throughout the course and disserta•on project. I would like to thank all SED tutors especially Mariam Kapsali and Herman Calleja for providing me with construc•ve cri•cism and professional knowledge.

In addi•on, I would like to express special thanks to Ar. Sumalya Pramanick for his help during my fieldwork in Kolkata and also to Mr. Binod and his son with their invaluable knowledge about local materials and help with fieldwork in Silchar.

I also would like to thank all my SED friends especially Cindrella, Nimya, Jennifer, Ameer, Daniel, and Aly for their mo•va•on and valuable contribu•on, which made this academic experience memorable and complete.

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1.Introduction 1.1. Introduc•on 1.2. Methodology

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1.1.Introduction: Slums are gateway to the ci•es for the rural people of India.

They migrate with the hopes of a be•er lifestyle and find shelter in these informal se•lements. Half of the urban popula•on of India lives in slums and in response to this evergrowing problem, large-scale rese•lement colonies (fig1.1) get built by the government on the city edge as solu•ons. But these slum interven•ons, fail to address the issue of providing a “good environment” to the urban poor that make these megaci•es run. Therefore, this per•nent issue ini•ated the project – “Revitalising the Informal city”. The project is based in Kolkata which has the second highest slum popula•on a•er Mumbai in India.

The main objec•ve of this disserta•on project is to provide economically feasible, free-running comfortable buildings for the urban poor. The project will be fed by three important research ques•ons: 1. Understanding occupant behavior and aspira•ons 2. Analysis of the environmental performance of the local materials available that can be plugged into 21st century design.

3. Environmental design strategies relevant to the climate and context.

The two major constraint of the project is to provide for such a high popula•on density and a difficult, hot and humid climate.

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Fig 1.1: carelessly designed rese•lement colonies but which later get converted to ver•cal slums or dont get inhabited at all for various reasons.

Source: SRA,2016

1.2.Methodology: The method that was followed and the structure of the project are described below.

Chapter1: The main issue regarding slum rehabilita!on in India is iden!fied and then the objec!ves and limita!ons of the project are elaborated Chapter2: Urban social housing issues of Kolkata and the history of various interven!ons that were implemented were shortly analysed. Furthermore, successful redevelopment projects and the exis!ng social context of the slums were explored to gain a deeper understanding. Lastly rough criterias were laid down for successful slum upgrada!on.

Chapter 3: Detailed climate analysis was carried out. Comfort band for the locals were defined. Environmental adap!ve strategies on human and building scale were inves!gated.

Chapter 4: Occupant behavior, exis!ng living condi!ons and aspira!on of the slum residents were discussed as first part of the fieldwork. Second part of the fieldwork helped caliberate the environmental performance of the mud, wa#le &daub and bamboo along with brick paving the way for analy!c work.

Chapter 5: Informa!on from the previous chapters were assimilated to form a base case modular dwelling unit which was then improved with the help of step by step interven!ons into a free running unit.

Chapter 6: The final unit module is then replicated according to the urban context and therefore two scenarios for building design were created. The resul!ng 3 and 8-flat cluster buildings were tested for op!mum thermal performance Chapter 7: The design materialized to the final stage of urban design where again the final design was tested and adjusted to house the total exis!ng popula!on on site without compromising on the thermal performance. Lastly renewables were calculated to offset energy demand.

Chapter 8: Conclusion.

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2.Indian slums: Addressing the housing crisis.

2.1. Slums in india 2.2. Slum housing issues and policies in Kolkata 2.3.1. Yerwada slum redevelopment, Pune, India 2.3.2. Quinta Monroy, Iquique, Chile 2.4. Social context of the slums in Kolkata

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2.1.Slums in india The United Na•ons Human Se•lements Program (UN-Habitat) defines a slum as “a place of residence lacking one or more of the following: durable housing, sufficient living area, access to improved water, access to sanita•on, and secure tenure”.

Although India’s economy is the fastest growing with the GDP rate of 9.2% per annum and ranks third amongst na•on regarding PPP, it is s•ll a poor country. A large propor•on of India’s popula•on is s•ll poor and live in slums due to a number of factors including: 1. family poverty and a li•le educa•on 2. regional inequi•es and urbaniza•on 3. migra•on 4. a low-wage economy and unemployment 5. housing shortage Slums typically begin at the outskirts of a city, located on least desirable public lands or lands with no clear land •tle. Over •me, the city may expand past the original slums, enclosing the slums inside the urban perimeter. Figure 2.1 shows the gradual growth of the city and the simultaneous mushrooming of the slums in it. This makes the original slums valuable property, densely populated with many conveniences a•rac•ve to the urban poor. It is also a place where a lot of wealth is generated. Slum dwellers afford a lot of modern day equipment for their daily life and it is possible only because of their low cost living condi•ons in the slums (Bakshi, 2013).

18th century-some se•lement in indian town; dwellers mostly work for english

19th century-se•lements near factories, port and railway.

2.2.Slum housing issues in Kolkata and policies implemented.

Slums have generally been seen as a nuisance that should be eradicated from the urban fabric of the city. Urban management tended to address the slum problem as a barrier to urban development.

Over the years Kolkata Municipality corpora•on have come up with different policies to deal with this problem. The policies will be enumerated according to the different types of interven•on that was taken up: 1. Removal: In the 1950s, policies emphasized on clearance and removal of the poor and ugly housing structures from different parts of the city to keep the city clean. But that did not solve the root social causes which created and maintained a slum. Henceforth, was unsuccessful.

2. Reloca on: Borrowing ideas from the developed countries, a•empts were made to relocate the residents to single room tenements to be constructed in 4 storey walkup buildings, faraway from the exis•ng loca•on. And the newly emp•ed slum plot would compensate for the construc•on cost of the reloca•on project. This interven•on also didn’t work out because the residents didn’t want to move as they had become far away from their work places.

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first half of 20th century-rural migra•on, war refugees se•le on the edge of towns and industrial areas.

second half of 20th century-rural migra•on con•nues, old inner city se•lements pressured by growing city.

Fig 2.1: Timeline of the growth of the city and the simultaneous burgeoning of slums Source: A"er Herz,2008

3. Redevelopment: Following the failure of the previous programme, walk ups were built within the site. The slum dwellers agreed to move but the project faced constraints of li•ga•on concerning acquisi•on of lands and demoli•on of slums. The cost effec•veness of the project was hampered because the slum dwellers were not in a posi•on to pay. Extra cost in the name of environmental improvement. The redevelopment program lack par•cipatory approach and therefore the policy didn’t take into considera•on the aspira•ons of the slum residents. It was also a rapid process where demoli•on was supposed to be executed in one go which in•midated the residents.

4. Improvement: The experience of the previous endeavours led to a more limited slum improvement model approach which didn’t interfere with the rights and interests of the landowners and physically shi!ing of slum dwellers further from their places of employment. The programme was aimed at providing basic infrastructure facili•es like sanita•on, water supply and sewer systems. This was by far the cheapest interven•on. It also was designed to decongest the central area of the city which again meant forcibly removing the urban poor. How far this could be successful in addressing the problem in a correct manner is a debatable ques•on (Kundu, 2003).

2.3.Precedent Study It can be concluded that the third op•on of redevelopment is a viable solu•on. It had some major loopholes while execu•on but if they are taken care of in future. Redevelopment projects combined with slum improvement techniques can emerge as the most successful interven•on when carried out in stages over a period of •me. There have been successful redevelopment projects all over the world. In this chapter, two remarkable redevelopment projects will be discussed as precedents.

1.

Yerwada slum redevelopment project, pune, India 2.

Quinta monroy, Chile

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2.3.1.Yerwada slum redevelopment: Unit area = 24m2/family Unit cost = $6750/family It was ini•ated by Mahila Milan (NGO) in collabora•on with SPARC, JNNURM and BSUP. It was an “in-situ” upgrading scheme which has been done as a pilot project in Yerwada slum in Pune. This scheme was designed to keep the current structure of the 100 year old settlement and intended to allow districts to improve organically without uproo•ng the communi•es (Fairs, 2009).

Lessons learnt from the project: 1. Public par•cipa•on: Ac•ve par•cipa•on of the local body (in this case, the women’s group Mahila Milan) acts as a key player in almost every aspect of the project. Such local representa•ve body can offer with local knowledge and connec•ons as well as act as a collec•on point for advocacy on behalf of slum residents (fig 2.2a).

2. Mapping the exis•ng layout to have an informed master plan taking into account the uses of important elements like exis•ng streets and semi-open spaces, if any (fig 2.2c).

3. Retaining as much as possible of the exis•ng neighborhood by only removing substandard shelter and housing and replacing them with sturdier construc•on.

4. Redevelopment occurs ver•cally instead of expanding horizontally to provide more common open spaces and to accommodate larger densi•es (fig 2.2b).

5. Using slums residents who are already skilled in this industry as the major construc•on labour for the project.

This helped reduce overall project cost.

6. Encouraging the slum residents to invest a small por•on towards the construc•on of the project. Like the Yerwada residents along with the help of a number of beneficiaries had contributed about 10% of the construc•on costs while the rest 90% was sanc•oned by the government. This helps boost the pride and ownership of the residents and they are more dedicated towards making such slum upgrade projects a success.

public par•cipa•on

a.

going ver•cal

b.

mapping exis•ng layout

c.

Fig 2.2: Various lessons learnt from yerwada slum, Pune.

Source: A#er Arc,2016; a#er Fairs, 2009

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2.3.2.Quinta monroy, Iquique, Chile: Unit area = 30m2 /family Unit cost = $7500/family The project se•led a hundred families on a 5000 m2 site where they had persisted as squa•ers for three decades. The residences designed by Elemental offered former squa•ers the rare opportunity to live in subsidized housing without being displaced from the land they had called their home, provided an apprecia•ng asset which can improve their family finances, and serves as a flexible infrastructure for the self-constructed expansion of the homes.

1. The decision to remain on the same site helped preserve and strengthen the social networks embedded in the community and the exis•ng links to jobs and other income-genera•ng ac•vi•es.

2. Public par!cipa!on: The incremental housing design relied on residents to take an ac•ve role in developing and adding to their homes, which can be a source of empowerment (fig 2.3a).

3. Future flexibility: Recent photos of the site reveals that most of the buildings have customized addi•ons, which reflect the investment of •me, money, and other resources that residents have made in their homes. Residents also benefit from the increased value of their house as a financial asset and helps accommoda•ng the growing family (fig 2.3b,c).

public par•cipa•on

a.

Therefore from both the precedents and the history of social housing policy of Kolkata it can be inferred that it is impera•ve to have a con•nuous dialogue between the government and the slum residents during the development of the project. And this should happen via a third party comprising of a government representa•ve, the architect, NGO officials who work in that slum community and slum representa•ves (fig 2.4). Work via third party help in a be•er workflow with lesser problems while dealing with legal ma•ers as well as aspira•on of the slum resident. This can make the project more viable for the slum residents and therefore more successful in the end.

future flexibility

b.

future flexibility

c.

Fig 2.3: Various lessons learnt from Quinta monroy,Chile.

Source: A"er MoMa,2016.

Fig 2.4: Summary of the lesson learnt for future implementa•on in the project

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2.4.Social context of the slums in Kolkata: One in every six person in India live in slums. Slums are considered as the entry points to the city. Migra!on of millions of villagers to the urban slum proves that they see slums as the way forward. And therefore they are the hubs of hope, progress and dignity in India.

In order to have a deeper understanding of how to provide these people with a “good environment”, it requires careful considera!on of various environmental, social and spa!al aspects (fig 2.7). Therefore, for a more holis!c approach, the social aspects of slums are enumerated as follows: 1. Strong social bonding: The basic resources necessary are provided in the slum. Since the resources are not adequate for all slum dwellers, they interact and share their resources. They harbor very strong social bonding (fig 2.5).

2. Security: No security issues as the residents are poor and have no valuable property. But slums generally do have very high crime rates, due to lack of educa!on and for access to easy money (fig 2.8).

3. Sense of belonging: They have a greater sense of belonging and are not ready to alter their space because it is important for their ability to con!nue their daily life and keep up the network they had built throughout the years (fig 2.6).

4.Privacy: It had never been an issue. It is almost looked at as a luxury and therefore is least of their priori!es.

Popula!on sta!s!cs

$ % &

Fig 2.5: Residents sharing water for washing clothes and utensils.

Source: Google images

$ % &

Fig 2.6: Strong social bonding and sense of belonging.

Source: Google images

!

"#

Fig 2.8: Frequent criminal cases emerging in slums.

Source: Herz, 2008

Fig 2.7: Frequent criminal cases emerging in slums.

Source: SED_Symposium1,2015

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"

2.5.Conclusion: This chapter helped with the analysis of the context in which the project will develop. The analysis of the slum housing issues and policies signifies the importance of redevelopment as an interven•on.

It also gave a deeper insight on how important it is to have the slum residents ac•vely par•cipa•ng throughout the whole process right from design •ll the construc•on phase. Problems in slums are localized and need careful a•en•on. Therefore the social characteris•cs learned about them will be very useful in shaping the design guideline of the project as a whole.

The next chapter will discuss the clima•c context in which the project is based. It will also henceforth point out the environmental strategies and the necessary vernacular features the project can learn from in order to achieve a comfortable habitat for the occupants.

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3.Climate and comfort 3.1. Climate Analysis 3.1.1. Loca•on 3.1.2. General overview 3.1.3. Effect of humidity and wind 3.1.4. Future scenario 3.1.5. Comfort criteria of residents in kolkata 3.2. Adap•ve behaviour by the occupants (the first line of defence) 3.3. Adap•ve features ingrained in vernacular buildings in hot and humid regions of India (the second line of defence) 3.4. Energy index for residen•al buildings in India and Energy targets.

3.5. Conclusions

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3.1.Climate analysis: 3.1.1. Location: Kolkata is located in the eastern part of india between la•tude 22°56’ N and longitude 88° 36’E. It is located just 0.7 degrees north of the tropic of cancer as shown in figure 3.1. It has a tropical savannah climate according to the Koppen climate classifica•on with hothumid condi•ons.

Kolkata has a tropical climate and is accompanied by a high level of rainfall, during ‘rainy periods’ (mid-june, july, august), and the climate of Kolkata is under the influence of seasonal monsoon winds.

So, the temperature and humidity are rela•vely high.

Aw- Tropical savannah (Koppen Geiger classifica•on)

Fig 3.1: Loca•on of kolkata

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solar radia•on (W/m2)

3.1.2. General overview

Fig 3.3: Solar radia•on Source: Meteonorm 7

Figure 3.2 shows the annual temperature, rela•ve humidity and solar radia•on variance (Meteonorm 7.0, average data from 20052009) in Kolkata. According to the chart, there are three dis•nc•ve periods over a year: a hot period from March and stretched up•l October, characterized by mean daily temperature of 25 - 28.6oC; a cool period from December to February, with mean daily temperature of 19.1-20oC. Rela•ve humidity remains above 60% throughout the year with the months from june to october experiencing highest humidity reaching up•l 100% which is generally the monsoon period. Therefore, the main focus months for design are from mid march to mid june.

Solar radia•on is almost similar throughout the year ranging between 0.35 – 0.5 KWh/m2. Since Kolkata is in the tropics, a high solar al•tude of 88 degrees is reached on summer sols•ce, while on winter sols•ce, the solar angle is 42 degrees (fig3.4). When looking at the solar radia•on on different facades it is obvious that the horizontal surface receives far more solar radia•on than ver•cal surfaces throughout the year, due to the high solar al•tude (fig 3.3).

This further implies that roo•op needs to be carefully dealt with to avoid overhea•ng in hot periods.

Fig 3.4: Solar al•tudes during summer and winter.

Source: Meteonorm 7

Fig 3.2: General overview of kolkata climate Source: Meteonorm 7

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3.1.3. Effect of humidity and wind: The weather data of Kolkata indicates that the high value of rela•ve humidity combined with high mean daily temperature causes great discomfort during hot periods (fig 3.5), therefore natural ven•la•on becomes one of the key strategies to increase the efficiency of evapora•ve cooling. The wind speed remains almost stable, at around 2m/s. There is a no•ceable change in wind direc•on in hot periods, which is primarily south, and in cold periods, it is from the north and northeast (fig 3.6). It could be a poten•al design guideline to promote natural ven•la•on in hot periods and prevent unwanted wind dra• in cold periods through the design of building shape, orienta•on and openings.

summer prevailing wind

3.1.4. Future scenario: The future scenario study indicates that the city of Kolkata will have a 4-5 K increase of average daily temperature and the rela•ve humidity decreases from 75% to 69% (fig 3.7). Therefore, it can be concluded that in the A2 scenario, the climate of Kolkata will be ho!er and drier. And therefore it might be neccesary to have a balanced propor•on of permeable walls as well as high thermal mass walls to achieve thermal stability. winter prevailing wind Fig 3.6: Illustrates wind direc•on and speeds through summer and winter.

Source: A•er Herman, 2015. absolute humidity

1.5m/s wind speed cooling effect: 5.1K

vapour pressure

1 m/s wind speed cooling effect: 3.8K

Rel. humidity(%)

temperature (oC)

0.5m/s wind speed cooling effect: 1.7K

Enthalpy(kJ/kg)

Hotter And Drier !

2015 2050 Fig 3.7: Climate comparison between year 2015 and 2050 (A2 scenario).

Fig 3.5: Effect of RH on temperature and wind of wind on the percep•on of temperature.

Source: A•er Szokolay,2013.

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3.1.5. Comfort criteria for residents of Kolkata: Extensive research was done in Term 1 (RP1) to deduce the comfort band equa•on most relevant to Kolkata (Ghosh, 2015). The final comfort equa•on chosen was taken from a research paper by Fergus Nicol in 2004, which is: Tc = 0.534 To + 12.9

And it can be seen that 13% of the •me of the year the external condi•ons are beyond comfort (fig 3.8). On closer inspec•on, it is found that the discomfort hours are spread across the months of may •ll September. Since, may - june are hot and dry months whereas july september are characterized by monsoons. This indicates that even though a light weight construc•on is generally preferable during monsoons, thermal mass will provide temperature stability during the hot and dry months as well as during winters (fig 3.9).

Fig 3.8: Percentage breakdown of uncomfortable hours per year

Fig 3.9: Seasonal breakdown of the year Soiurce: Meteonorm 7

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3.2.Adaptive behavior by the occupants (the first line of defense): The target occupants of the project are economically weak. Therefore when they experience discomfort they resort to various adap•ve behaviours for immediate relief (fig 3.10). For example use of hand fands, opening and closing of windows and cooling off under shaded spaces. Some adap•ve behaviours are ingrained in the culture because of the climate like wearing of very less clothing (around 0.3-0.5 clo) because of hot and humid condi•ons and taking a nap during to peak hours of the day to have a lower metabolic rate.

Figure 3.11 also provides informa•on as to which of these adap•ve behaviours are carried out the most by people in hot and humid region.

use of hand fans

Shaded spaces

Low clo values

Opening windows

Use of screens to avoid direct sunlight

Fig 3.11: Adap•ve behaviour

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Fig 3.10: Various adap•ve measures taken up by people Source: Google images

3.3.Adaptive features ingrained in vernacular buildings in hot and humid regions of india (the second line of defence):

Fig 3.12a: Overhangs source: Climate consultant 5.0

These adap•ve features are found in the vernacular buildings through out Kolkata and other hot and humid regions of india. It had been previously research by 3 students (Oindrila, Nimya and Jiaji) for their Term 3 symposium. These features are enumerated as follows: 1.

Verandahs and overhangs: Transi•onal spaces that help cut of the direct solar radia•on and keeps the envelope dry from torren•al rains. Also used for various social func•ons (fig 3.12a-c).

2.

Courtyards: Helps in natural ven•la•on as it promotes stack effect. They can have a microclimate of their own and can help create comfortable controlled outdoor spaces for various social uses (fig 3.13a,b).

Fig 3.12b: Pa•os or verandahs source: Climate consultant 5.0

Fig 3.12c: Verandahs are a common feature in old building of kolkata source: Herz,2008.

Fig 3.13a: Courtyard showing stack effect. source: Climate consultant 5.0

Fig 3.13b: Courtyard in an old residen•al house in kolkata source: Herz, 2008

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3.

Perforated screens: The climate of Kolkata receives a lot of diffuse solar radia•on. In addi•on, low angle sun from the east and west are also responsible for heat gains in the building Therefore perforated screens is a perfect solu•on for this problem. It can reduce the incoming wind speed and therefore requires judicious use.

However if the perforated skins are fine enough it can also act as an insect screen (fig 3.14a,b).

4.

Fenestra!on: Large windows help with ven•la•on. Hot and humid climate calls for the use of large fenestra•ons so that the building can act as a lightweight en•ty during the night to bring down room temperature to the comfortable outdoor temperature.

When these fenestra•ons have louvered shu!ers it helps block the diffuse rays while s•ll allowing breeze to flow in (fig 3.15a,b).

Fig 3.14a: perforated jali screens. source: Climate consultant 5.0

Fig 3.14b: Wooden thin louvered screens to block the a#ernoon sun in an old colonial office building in kolkata.

Source: Herz,2008

Fig 3.15a: Fenestra•on facilita•ng ven•la•on source: Climate consultant 5.0

Fig 3.15b: Various types of romanesque louvered windows prevalent in kolkata source: Herz, 2008

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Fig 3.16a: Elevated floor for windflow source: Climate consultant 5.0

5.

Raised floors: The region where the project is located have flooding issues because of prolonged monsoons and nearby marsh lands. Raised floors are an effec•ve method of comba•ng floods. If the floor is elevated, it op•mizes windflow which in turn cools the floor slab and creates ambient condi•ons underneath (fig 3.16a, 3.17). Whereas if it is s•ll a•ached to the ground, they act as “cool rocks” Such raised floors uses the ground as the heat sink because they are connected to the damp earth of that region (fig 3.16b). These surfaces have very low MRT. Therefore ac•ng as cool surfaces where locals enjoy taking their a•ernoon nap during the peak temperature hours (fig 3.18).

Fig 3.16b: Raised thick floor slab for coolth source: Climate consultant 5.0

Fig 3.17: house on s•lts in thailand Source: google images

Fig 3.18: Thick elevated floor slabs Source: google images

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6.

Materiality: High temperatures and humidity demands the local dwelling units to be able to block the direct and diffuse solar gain during the day with the help of high thermal mass walls. But at night, the walls should act as low thermal mass structures to allow night ven•la•on to help cool the indoor spaces (fig 3.20). Therefore local materials like bamboo, wa•le and daub can be used as lightweight materials and mud blocks can be used wherever high thermal mass is necessary (fig 3.21a-c).

Fig 3.21a: wood as a primary material for balconies and shades in kolkata source: Herz, 2008

Fig 3.21b: A vernacular house made of bamboo in Nagaland, India source: google images

Fig 3.20: High thermal mass walls with high fenestra•on to wall ra•o and transi•onal spaces surrounding the main house source: climate consultant 5.0

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Fig 3.21c: A vernacular house mud house in west bengal, India source: google images

3.4.Energy index for India and energy targets:

average EPI = 43kWh/m2.yr

% uncomfortable hours

EPI distribu•on of residen•al units in warm and humid clima•c region source: Survey in chennai. (Ganesan, K., Plea 2014)

A further study, carried out by the Swiss Agency for Development and Coopera•on, collected data from approximately 836 units on the energy consump•on of households in India as part of which, a detailed list of electrical appliances and their usage was collected from 30 households. The average resident energy performance index (EPI) was found to be in the range of 45- 50 kWh/m2/year (GBPN, 2014).

The study found that households with different orienta•ons yield reasonably iden•cal energy performances, indica•ng that EPI is largely governed by factors of lifestyle and occupancy and not orienta•on of unit (GBPN, 2014).

The ECBC also recommends the use of the materials with following u-values as shown in figure 3.23 to help reduce energy load of the building. The project would aim to have an EPI of 15KWh/m2 as its free running target (fig 3.22).

Fig 3.22: Energy trends in india source: GBPN, 2014

Fig 3.23: Building envelope proper•es comparison between tradi•onal materials and the ones recommended by energy conserva•on building code (ECBC), India source: GBPN, 2014

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3.5.Conclusions: Climate analysis: The climate of Kolkata, India is hot and humid with high solar radia•on both direct and diffuse. The main focus months of design are from mid-march to mid-june. The comfort band for Kolkata residents ranges from an average of 25.6 to 31.6 ºC. Environmental strategies call for the building envelope to work as high thermal mass during the day and low thermal mass at night.

Environmental strategies Human behavior: Using hand fans, wearing less clo, use of shaded spaces etc. can help ease thermal discomfort.

Adap!ve features: Building features commonly seen vernacular buildings in hot and humid climates of India have intrinsic environmental quality as follows 1.

Verandahs, overhangs and perforated screens to block the harsh solar radia•ons.

2.

Courtyards, raised floors and large fenestra•ons allowing varying level of porosity to the building and thus op•mizing ven•la•on and wind flow.

3.

Materiality: Various materials like bamboo, wa"le and daub and mud bricks allow the building to range from low to high thermal mass accordingly as per requirements.

Energy Index: It gives the project a guideline to adhere to while deciding the materials and environmental strategies.

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4.Understanding occupant behavior and material performance.

4.1. Slum survey 4.1.1. Overview of the slum se•lement 4.1.2. Urban condi•ons and access routes 4.1.3. Exis•ng slum condi•ons 4.1.4. Exis•ng slum condi•ons (the environmental aspect) 4.2. The material survey 4.2.1. Bamboo house 4.2.2. Wa•le and daub house 4.2.3. Mud house 4.2.4. Brick house 4.3 Datalogger results 4.4. Final comparison amongst materials 4.5. Conclusion

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4.1. Slum survey The first part of the fieldwork was undertaken to understand the exis•ng living condi•ons of the urban poor in Kolkata. And to understand their aspira•ons as to what they would consider as a “good environment”. So for the purpose of this study, two slum sites were visited (fig4.1):

4.1.1. Overview of the slum settlement: 1.

South City slum: Located in the heart of the city, this slum is 35 years old. The slum residents work as maids, drivers in the service industry for the high luxury apartments and gated communi•es that developed in that area. It is an illegal squa"er se"lement.

2.

Shahid Sri!: This slum is around 100-150 years old. This slum se"lement is legal. The residents also work in the service industry for the nearby general hospital and the upcoming high end living apartments in the neighborhood.

Both the slums are located near a water body, in a low lying marshy area. This indicated that such illegal development generally occur in unwanted spaces with a water connec•on. Spot measurements and occupant survey was conducted over a period of two days to understand the exis•ng scenario both socially as well as environmentally.

This part of the field work helped to create the base case for future analy•c work.

Fig. 4.1: Loca•on of the two slum sites in kolkata. Both located near luxury gated communi•es.

scale- 1:1000

Primary Access route (2 - 3 metres) Secondary Access route (1 - 1.2 metres) Ter•ary Access route (0.6 metres) Fig. 4.2: Urban plan is for the slum sites visted. South city slum (le•) and shahid sri• colony (right). with their highlighted access routes.

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4.1.2. Urban conditions and access routes It can be comprehended from the urban plans (fig 4.2) and the photographs (fig 4.3) that the dwelling units were haphazardly clustered together with no space between units which contributed to heat accumula!on in the area. This was also proved in the spot measurements taken along the access routes. The narrower the access route, the ho#er it became. The access routes were inadequately small. General building height was one floor.

Primary Access route (2-3m) Secondary Access route (1-1.2m) Ter!ary Access route (0.6m)

Fig. 4.3: Illustrates the various access routes in both the slum sites. And simlutaneous spot measurements taken in these routes.

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4.1.3. Existing slum conditions: An occupant survey was conducted in both the slums. 8 families had par•cipated in the survey describing their personal living condi•on in the slum as well as a few individuals who spoke for the slums condi•ons in general. This helped in gaining a deep insight as to needs and aspira•ons of the slum residents, who are the target occupants of the project. Average conclusions derived from the sta•s•cal data collected are shown in figure 4.5. And figure 4.4 illustrates the typical layout of the huts. The kitchen is basically stowed away under the bed. But if the family has more space and money the hut gets extended to accomodate a kitchen. When asked if they would like to share a common kitchen space with other families, they vehemently rejected the idea because of the exis•ng disparity in the financial condi•ons of each family. For more detailed informa•on regarding the slum survey and occupant behavior please see appendix.

Fig 4.4: Typical layout of an hut in the slum.

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AVERAGE STATISTICS OF SLUMS IN KOLKATA FAMILY SIZE

AVERAGE AREA

OF A HUT 4

5-6 sqm/FAMILY

WATER SOURCE

SANITATION

COMMUNITY TAP

1 TOILET SHARED BY 8-10 FAMILIES

APPLIANCES OWNED

ELECTRICITY

AS SHOWN

LEGAL AS WELL AS ILLEGAL ACCESS

WINDOWS

COOKING FUEL

1 SMALL OR NONE

LPG/KEROSENE

Fig 4.5: On the right, the figure represents the average sta•s•cs of the two slums that were surveyed (shahid sri• amd south city).

Source: google images

The photographs (fig 4.5a) depict the exis•ng poor living condi•ons of the residents. It was found during the survey that they have become habituated to such harsh condi•ons and are actually happy with the loca•on of their home. Their primary concern is to have a valid home address and avail proper water connec•on and sanita•on services. They also aspire to have more space but are not necessarily bothered.

water storage and washing done at the at the threshold

The pond is the major water source for the slum residents

one toilet shared by 8-10 families. crea•ng unhygienic condi•ons Building materials that are generally used are bamboo mat board, magalorean clay roof •les and if the family is financially more stable they afford to make their houses with brick

No storage space. Beds li•ed to create storage for kitchen materials and stove.

A typical interior of a hut. One hut has one room which is shared by 4 family members. 2-3 sleep on the bed. 1-2 sleep on the floor.

Fig 4.5a: photographs illustra•ng the poor living condi•ons of the slum inhabitants and how they try to ra•onalise space, material, comfort and hygiene to be able to work in the city.

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4.1.4. Existing slum conditions (the environmental aspect) It was also inferred from the survey that people were extremely uncomfortable during summers and resorted to various adap•ve behaviors as shown in figure 4.6. During the peak hours in the day they stay indoors and at night they try to cool themselves off in the nearby playground or open space before going to sleep. Mechanical ven•la•on is used throughout the whole •me. Absence of urban canyons, inability to lose kitchen heat gains and such high popula•on density were responsible for extreme discomfort in addi•on to the hot and humid summer temperatures. This trapped heat on the other hand helps during winter as the occupants reported to be satisfied during winters in the survey. It should also be kept in mind the winters are mild in Kolkata.

The occupant schedule (figure 4.6) also revealed an issue- The peak hours of the day (a#ernoon) clashes with the kitchen heat gains, because the wife and either of her children comeback home to prepare and eat lunch. This issue was taken into considera•on so that it can be solved in future through analy•c work.

use of hand fans

sun bathe

cool shade of trees

Si"ng at the threshold

sleep during peak hours

bon fires, warm clothing.

problem area Fig 4.6: Illustrates the various environmental aspects of the exis•ng slum condi•ons.

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4.2. The Material Survey: The second part of the fieldwork was carried out in Silchar, which is located east of Kolkata in the same clima•c belt. It is a small town where inhabitants s•ll use natural materials to build their vernacular houses. The main idea of this part of the fieldwork was to test the environmental performance of locally available materials like mud brick, bamboo and wa"le and daub as building envelope in hot and humid climate. Furthermore, verifying if it is viable for large scale use. For the purpose of the study, four huts were considered (fig 4.8). Each hut used one local material as its primary material which made it easier to compare their performance.

Fig 4.7: Loca•on of Silchar, India

Fig 4.8: Four different test huts and their respec•ve primary material used in envelope construc•on.

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4.2.1. Bamboo House: The bamboo house that was surveyed was a 2-roomed hut with a semi-detached kitchen. Spot measurements1 in the house revealed almost 3K higher temperature difference than external condi!ons (fig 4.9). This is because of the Galvanised Iron roof which was directly exposed to rooms (without false ceiling) making it unbearably hot (fig 4.10). The surface temperature of the roof was 43°C, around 10-12 degrees higher than the ambient air temperature. Since low clo induces higher thermal sensi!vity amongst occupants, the increased MRT was the determining factor in occupant discomfort (Szokolay, 2013).

The bamboo walls had two level composi!on with varying permeability as shown in figure 4.11. The walls have a perfora!on percentage of 1.6% (approx). They have a thickness of about 10mm and no thermal mass. This is why the bamboo house showed high day!me temperatures but by night the temperatures fell rapidly and closely followed external temperature.

Since the kitchen is decoupled from the main living spaces, the kitchen heat gains have no impact on the indoor room temperatures.

The par!!on walls are up!l 2 metres high which helps the incoming wind from the gable wall to sweep away the internal heat gains with it during the night. This also resulted in a uniform temperature throughout all corners of the living spaces (fig 4.12).

The house didn’t have any windows but it was s!ll ven!lated because of leaky contruc!on and the high permeability of the bamboo mat walls (fig 4.13). It had a 30cm elevated mud flooring which required plastering every month for maintenance purposes. Since it was a bamboo house, they had to rebuild it every 6 years.

Floor plastering: 1-2 !mes per month.

28.5OC, 83%RH

SUNNY,CLEAR SKY

33sqm

COMMUNITY TAP

DETACHED

7 MEMBERS

LEGAL CONNECTION

FIREWOOD

12 JUL, 12:27

N

OF A HUT

Fig 4.9: Illustrates the the general informa!on about the bamboo house and the spot measurements taken during that day.

0.3 clo, use of hand fans USe of tree shades

fig 4.10: Shows occupant comfort during summers and winters and their corresponding adatuve behaviour Sun bathe

Bonfires

1. Spot measurements were taken on various spots in all rooms of the house, but as all measurements had a minor temperature varia!on of 0-0.1K. Only one spot measurement is shown. For detailed info see appendix

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TWO LEVEL COMPOSITION OF WALLS

GI SHEET

1.6% - perfora"on percentage

fig 4.11: illustra"ng the 2-level composi"on of the unit envelope

fig 4.12: illustra"ng the environmental principles found in the bamboo house

BEDROOM Fig 4.13 : Photographs of the interiors of the house

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4.2.2.Wattle and daub House: This house was a two- bedroom house with a semi-detached kitchen and dining space. The walls of the house had a 3 level composi!on of mud bricks, wa"le and daub and bamboo. By wa"le and daub we mean a structure of reed or mostly bamboo which is then plastered with a thick layer of mud plaster (a mixture of cowdung, mud and water) as shown in fig 4.16. The house has two different roof construc!ons. One half is constructed with GI sheet roof and has a false ceiling to ward off the radiant heat gains whereas the older half of the house has a thatch roof construc!on (fig 4.14). This implied significant difference of temperatures between the spaces underneath. The bedroom with the thatch roof was reported to be cooler and more comfortable than the newly constructed GI sheet roof bedroom in the occupancy survey as well as from the datalogger measurements. Surface temperature of the walls were almost 2K lower than the ambient air temperature and much lesser heat gain through the roof also explains the reason for feeling cooler even though, the spot measurement1 as seen in figure 4.14 show no difference in temperature between the two spaces and the external condi!on. This was mainly because the thatch roof bedroom was almost in a dilapidated condi!on needing serious repairs and also because the occupants kept all the fenestra!on in the house open at all !mes.

The wa"le and daub wall is only 20 mm thick and it grows in thickness over the years through annual plastering work as maintenance which means the older the house gets, the more thermal mass it a"ains. If reed is used instead of bamboo, then the wall lasts longer and has the advantage of being insect resistant. They can be easily made into panels for mass produc!on and can last upto 30 years.

The decoupled kitchen, par!!on walls and the gable wall is like what was found in the bamboo house and they have the same environmental principle behind it as in the bamboo house (fig 4.17).

Wall plastering: 1-2 per month Floor plastering: 1-2 per month

12 JUL, 12:27

28.5OC, 83%RH

SUNNY,CLEAR SKY

N Thatch roof GI sheet roof

OF A HUT 41sqm

COMMUNITY TAP

DETACHED

6 MEMBERS

LEGAL CONNECFIREWOOD TION Fig 4.14: Illustrates the general informa!on about the wa"le and daub house and the spot measurements taken during that day.

fig 4.15: Shows occupant comfort during summers and winters 1. Spot measurements were taken on various spots in all rooms of the house, but as all measurements had a minor temperature varia!on of 0-0.1K. Only one spot measurement is shown. For detailed info see appendix

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GI SHEET ROOF

THATCH ROOF WATTLE AND DAUB (BAMBOO MAT BOARD WITH MUD PLASTER)

Fig 4.16 : 3 level composi•on of the unit envelope

KITCHEN (CLAY STOVE)

MASTER BEDROOM

Fig 4.17 : Illustrates the environmental design principles found in the wa!le and daub house.

BEDROOM WITH THATCH ROOF Fig 4.18 : shows the various spaces within the hut

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4.2.3.Mud House: This house was a one bedroom house with a store and a semi-detached kitchen. The walls of the house had a 2 level composi!on of mud bricks and bamboo. The house has a GI sheet roof construc!on with par!al false ceiling. This again implied hot indoors which is reflected in the spot measurements1 taken (fig 4.19). Surface spot measurements on the interior and exterior side of the wall revealed that there was a temperature difference of 2-3K (appendix) between the indoor air temperature and the interior surface of the wall. Similarly, a temperature difference of 1-1.5 K was registered between the outdoor air temperature and the exterior side of the wall. This clearly indicates a thermal lag happening through the cross sec!on of the wall which is not apparent because of the leaky construc!on of the house (fig 4.23) and high ven!la!on rate through the house.

But Since, the MRT of the walls were 2-3 K lower the occupants reported feeling comfortable even at 31°C. The mud walls were 300 mm thick and the villagers reported a general percep!on that mud houses were generally cooler than other type of construc!ons (fig 4.20). Datalogger results and previous research (Sindhu M.,2013) also indicate that it is a great dehumidifier. It reduces humidity by 10-20% when external rela!ve humidity cross 80% mark. It helps regulate humidity when the atmosphere is either too dry or too wet. This aspect gives mud brick construc!on a great advantage over tradi!onal and other vernacular construc!on materials. It has similar environmental principles like the other houses (fig 4.22).

Wall plastering: 1-2 !mes per year.

Floor plastering: 1-2 !mes per month.

12 JUL, 12:27

28.5OC, 83%RH

SUNNY,CLEAR SKY

N

OF A HUT 36 sqm

4 MEMBERS

COMMUNITY TAP

NONE

DETACHED

FIREWOOD

Fig 4.19: Illustrates the general informa!on about the wa"le and daub house and the spot measurements taken during that day.

fig 4.20: Shows occupant comfort during summers and winters 1. Spot measurements were taken on various spots in all rooms of the house, but as all measurements had a minor temperature varia!on of 0-0.1K. Only one spot measurement is shown. For detailed info see appendix

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GI SHEET ROOF

3 LEVEL COMPOSITE WALL SINGLE KNIT (MORE PERMEABLE) BAMBOO MAT BOARD

MUD BRICK WALL

Fig 4.21 : 2-level composi•on of the unit envelope

Fig 4.22 : Illustrates the environmental design principles found in the mud house.

BEDROOM

DETACHED KITCHEN

STORE

Fig 4.23: photographs illustra•ng the different spaces within the house

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4.2.4.Brick House: This house was a modern construc!on two storey house cum office of a contractor. The bedroom on the upper floor was tested for datalogger and spot measurements. The house was made of tradi!onal brick and mortar and had be"er construc!on than the previous houses with vernacular materials (fig 4.24). The indoor temperature was cooler as spot measurements (fig 4.26) recorded lower MRT than ambient air temperature because of high thermal mass of the bricks. The room had low occupancy and the house was well shaded by trees on all sides. The ground floor beneath was empty and had no internal heat gains and had huge openings which are always kept open during the summers. Since the bedroom is at a higher eleva!on than the neighboring buildings it is able to catch more breezes.

Although the house also had GI sheet roof, but because of the greater floor to floor height of 3.1m, a thick false ceiling and constant cross ven!la!on resulted in very comfortable condi!on indoors (fig 4.27). The occupants were happy living there (fig 4.25).

12 JUL, 12:27

28.5OC, 83%RH

SUNNY,CLEAR SKY

EXTERIOR VIEW OF THE BRICK

OF A HUT 100 sqm

PRIVATE

PRIVATE

6 MEMBERS

LEGAL

LPG

Fig 4.24: Illustrates the general informa!on about the wa"le and daub house and the spot measurements taken during that day.

fig 4.25: Shows occupant comfort during summers and winters

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Figure 4.26 : spot measurements taken

Figure 4.27 : Illustrates the environmental design principles found in the mud house.

BEDROOM

THICK FALSE CEILING, GREATER FLOOR TO FLOOR HEIGHT

Fig 4.28 : Photograph of the room that was tested.

1. Spot measurements were taken on various spots in all rooms of the house, but as all measurements had a minor temperature varia!on of 0-0.1K. Only one spot measurement is shown. For detailed info see appendix REVITALISING THE INFORMAL CITY

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4.3.Datalogger results: Dataloggers were placed on the test huts for over a period of two weeks. The inten•on was to simultaneously test the material performance of all 4 dwelling units. But because of lack of dataloggers, the wa•le and daub unit with two different roof types was tested on the first week and the other 3 units were tested all at a •me the following week.

The first week of the fieldwork, two datalogger were put in the wa•le and daub house. One in the bedroom with the thatch roof and the other with the GI sheet roof (fig 4.29). The datalogger results confirmed what was previously discussed in sec•on 4.2.2. On a closer look, it can be seen that the resultant temperature of the room with the thatch roof doesn’t dip with the peak low temperature (temperature difference 1K). It also barely exceeds the external temperature during the peak hours of the day. This behavior demonstrates the insula•ng property of the thatch roof.

The following week when the 3 units made of mud, bamboo and brick were compared, it was found that the brick unit performed the best followed by the mud house and the bamboo house. The temperature difference is basically visible during the day, as the temperature rises and the GI sheet roofs have a significant impact on the units. The bamboo house has slightly higher temperature (0.8K) than the mud house. The brick house has an indoor temperature lower by 1.5K from the mud house at peak hours (fig 4.30). Since the GI roofs have very low thermal mass, they cool down quickly a•er sunset and therefore it can be seen that all the units closely follow the outdoor temperature at night.

It had been already discussed in sec•on 4.2.2 that the test units had a leaky envelope. Therefore, the impact of the wall material wasn’t as pronounced as the roof. But the temperature difference shown by the datalogger gives a slight indica•on about the thermal mass of the walls. Further TAS simula•ons (See Appendix) reinforced the conclusions of the datalogger results.

Figure 4.3 shows the humidity levels measured in the mud house.

Unlike other huts, the mud house always maintained a 10% lower Rela•ve humidity (RH) whenever the external RH was more than 80%. But when the RH dropped around 80-55%, the indoor RH would follow the outdoor closely. This shows the immense poten•al mud envelope holds as a poten•al dehumidifier. Because, it is known from sec•on 3.5, that a combina•on of high temperature and rela•ve humidity can cause greater discomfort than just dry bulb temperature.

Along with this another test was also done on the mud walls In order to understand the thermal lag happening within the walls. Spot measurements were taken on the inner and outer surface of the wall and simultaneous indoor and outdoor temperature was measured at different intervals during the day over a period of 4-5 days.

But because the unit was so leaky and open the thermal lag was not no•ceable (See appendix for the graph).

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Fig 4.29 : graph depic•ng the thermal performance of the three test houses over the •me period of a week

Fig 4.30: graph illustra•ng the thermal performance of the two bedrooms in the wa•le and daub .

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4.4.Conclusions: The first part of the fieldwork revealed the poor living condi•ons of the slum residents. All basic resources are present but scarce and therefore they share everything. Environmentally, they are in great discomfort during summer season because of the following reasons: 1. Poor dilapidated hut envelope leading to high heat gains from the leaky roof.

2. High internal heat gains from kitchen trapped inside as they have no or only one window.

3. Dense urban scenario also trapping the anthropogenic heat because of the high popula•on density.

4. High humidity combined with temperature.

5. Flooding issues during the end of summer and monsoon period.

In winter they are comfortable as winters in Kolkata is mild and the above men•oned factors also help keep them warm. Therefore, the project will focus on mi•ga•ng the summer problems.

Fig 4.31: graph showed the datalogger results for RH inside the mud house.

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Second part of the field work was carried out for the purpose of understanding the material performance of the vernacular materials.

The study revealed that, the generic brick construc•on performed the best thermally. Figure 4.32 is a summarized comparison of all the materials that were tested. The average temperature difference between the external and the indoor temperature was the least (-0.1K) for brick, followed by (-0.6K) for mud. Although the brick building had a be•er construc•on as men•oned in sec•on 4.2.4, mud nonetheless has great poten•al. It performed as good as brick (because of its high thermal mass) even without a false ceiling and a mechanical fan and with a leaky construc•on. Therefore, mud and brick can be used in places with higher solar exposure. Wa•le and daub with the thatch roof performs third best (-0.9K) followed by bamboo in the last (-1K). This indicates that they are low thermal mass materials and requires judicious use in the project. They need to be used in places with lesser solar exposure. It also gave an idea about the durability and workability of these materials.

The next chapter will deal with mi•ga•ng all the issues that was encountered during the fieldwork and try to come up with a free running comfortable unit that can be poten•ally replicated throughout the design project.

external temperature-indoor temperature

Fig 4.32: final comparison of the different materials in the respec•ve huts.

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5.Analytic work.

5.1. Urban analysis of slum se•lement 5.2. Design of the dwelling unit 5.3. Thermal analysis of base case 5.4. Strategic improvements of the base case 5.4.1. Case 1 - Improved roof 5.4.2. Case 2 - Case1+ raised floor 5.4.3. Case 3 - Case2+ wider streets & overhang analysis 5.4.4. Case 4 - Case3+ fenestra•on change 5.4.5. Case 5 - Case4+ all materials change 5.4.6. Case 6 - Case5+ sun shading 5.4.7. Case 7 - Case6+ orienta•on 5.4.8. Thermal analysis on all floors 5.5. Annual percentage of discomfort hours 5.6. Conclusions

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5.1.Urban analysis of slum settlements: A•er gaining insight on the occupant behavior, aspira•ons and general spa•al layout of their houses, the next logical step was to carry out an analysis on an urban scale. A study was carried out by selecting 3 different exis•ng slums in Kolkata. The purpose of this study was to understand the spa•al pa•erns of the slum and factors affec•ng them (fig 5.1). It was also meant to infer any design principle from the study of the organic growth of these se•lements that can be further implemented during the design stage.

The three slums that were considered for the analysis were: 1.

Slum near south city (age 35 years) 2.

Shahid sri• colony (age 60-75 years) 3.

Kasai bustee (age 150+ years) Its study revealed that as all the se•lements had different morphology for the dwelling units. As the slums grew older, the urban spa•al pa•ern improved. The south city slum which is the youngest (fig 5.1a) has no streets alignments, square housing and minimal access routes, whereas in Shahid sri• (fig 5.1b), street alignment gets be•er and spa•al pa•ern is more or less like row houses with be•er access routes. The kasai bustee slum (fig5.1c) seems to be the best in terms of spa•al arrangement as each cluster of houses have a court yard with op•mized street widths and alignments.

Most houses in all three slums were north-south oriented which in principle is the be•er orienta•on for Kolkata’s climate.

An urban survey in kolkata’s slum reveals that the slums residents spend 7.2% of their income on electricity which is way much higher than the na•onal average of 4.4%. This is because of the hot and humid climate of Kolkata. Therefore, being able to reduce the energy consump•on for mechanical cooling is a priority (PRIA,2014).

N Slum near south city, kolkata (35 years old)

N Shahid sri• colony, kolkata (60-75 years old)

N Kasai bustee slum, kolkata (150+ years old) Fig 5.1: Three different types of slums seen in kolkata and their street alignments highlighted in red.

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5.2.Design of the dwelling unit:

5000

5000

Fig 5.2: Dwelling unit layout

Fig 5.3: illustrates the process of replacement of the exis•ng test site with the base case unit of 25m2.

To begin with the analy•c work, it is important to define the spa•al arrangement and area of the dwelling unit that will be used as a prototype for the project (fig 5.2). An area of 25m2 was allo•ed for each unit based on minimal anthropological requirements and regula•ons from the Na•onal Building Code of India (NBC,2005).

Each person was ensured a habitable space of 6.25m2/ person. The dwelling unit is designed to have 2 bedrooms and a kitchen. Toilet will be a shared facility amongst the residents.

In con•nua•on to this, it is also necessary to deduce the different configura•ons with which these units might cluster up together.

Therefore, Shahid sri• colony is taken up as the test slum se•lement. For ease of work and clarity, only half the area of the slum is considered. A grid of 5 by 5 metres is placed over the exis•ng urban plan and then the base case unit of 25m2 is over lapped over the urban plan to deduce the various scenarios for clustering of the modular unit (fig 5.3). During this process, the street widths were op•mized, open spaces and street alignments were also improved and became more defined. In the end, this exercise revealed three most common scenarios (fig 5.4): a. one unit b.

3-4 unit cluster c.

6- 8 unit cluster Since the project will be built by the families themselves with some professional assistance, it is impera•ve to maintain the simple layout of the prototype unit for ease of construc•on. Therefore, only the overall envelope and walls dividing the different spaces will be played with during the course of thermal and daylight simula•ons in the project.

Fig 5.4: Show the different scenarios that had emerged from the replacement exercise.

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5.3.Thermal analysis of base case: 5.3.1.Base case: It was developed to incorporate all the exis•ng problems that were registered in the slum se!lement during the process of fieldwork.

The dwelling unit has very small windows (fenestra•on to floor ra•o- 9.9%). Poor envelope materials like clay roof •les and exposed brick walls were used (fig5.7). The fenestra•ons are open throughout the day and the unit is then placed in a single-storeyed, densely packed urban context (fig 5.6). The height to width ra•o of the urban context is 2.5:1. An es•mated occupancy pa!ern has been defined according to resident ac•vity and survey sta•s•cs. The slum residents had only a few basic appliances like light bulb, TV and a mechanical fan. Main heat gains were due to the gas stove used for cooking and high popula•on density (fig 5.8). However, as we have already provided a be!er habitable space of 6.25m2/person. Heat gains due to occupant density will be less pronounced in the base case than in real life slum dwelling unit.

It is already known from chapter 3 that Kolkata has harsh hot and humid summers and mild winters. The slum survey also revealed that people were highly in discomfort during the summer •me and quite happy during the winters. Therefore, the analy•c work would focus on reducing summer discomfort and all corresponding simula•ons will be shown for 3 typical summer days (figX).

The comfort band that is used in the project uses Nicol’s equa•on for adap•ve comfort (Nicol,2004).

Tc = 0.534 To + 12.9

window to floor ra•o 9.9%

Fig 5.6: The TAS model for the base case

Fig 5.7: u-values of the envelope

Fig 5.8: illustrates the occupancy schedule, internal condi•ons in the base case scenario. The aperture schedule was used in later stages in the base case improvements.

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The results show an average difference of 6K between the bedroom and the outdoor resultant temperature. The peak indoor temperature reaches upto 38oC and simultaneous outdoor rela•ve humidity of 80% during the occupancy hours of lunch •me demonstrates the high level of discomfort a slum resident has to go through. Annually, the base case is out of comfort for 43.3% •me of the year which is quite high in comparison to the external temperature which is out of comfort only for 16.1% •mes of the year.

It is essen•al to keep in mind what Szokolay had said in his book (Introduc•on to Architectural Science, 2014) for designing for hot and humid climate: “The best the designer can do is to ensure that the interior does not become (much) warmer than the outside (it cannot be any cooler), which can be achieved by adequate ven•la•on removing any excess heat input.”

Therefore, further analysis would focus on different strategies to bring down temperatures to the outdoor condi•ons in its upcoming simula•ons.

Fig 5.9: Resultant temperature of base case for 3 typical days of summer.

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5.4.Strategic improvements of the base case: 5.4.1.Case 1-Improved roof: The first and most important improvement that was done was to improve the roof. As it has been discussed in the chapter of climate and context, the site is around the tropics where the sunpath is near the zenith (fig 5.10). Therefore the roof receives very strong irradia•on (fig 5.11). Preliminary heat loss calcula•on (fig 5.12) also show that 38% of cumula•ve heat loss happens through the roof. Therefore it is essen•al to improve the fabric of the roof as the first step towards providing thermal comfort. The ini•al clay roof •les (u-value4.7 W/m2.K) have been replaced with the tradi•onal construc•on of concrete slab with a layer of damp-proofing. Since solar panels will be installed on the roof to offset the residual energy demands of the building. It would also shade the roof and thereby reducing the overall u-value of the building (fig 5.14). The new improved u-value for concrete roof with solar panel installa•ons is around 0.2W/m2.K. TAS simula•on for the typical summer days, show a significant drop in the resultant temperature of the bedroom. It has become more consistent throughout the day. Case 1 registered 5K lower resultant temperature than the base case during the peak hours of the day and 2K higher temperature during the minimum temperatures at night.

fig 5.10: Sun angles in kolkata

fig 5.11: Solar radia•on (annual) for kolkata

fig 5.12: Percentage heat loss for different materials

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fig 5.13: Resultant temperature of test unit a•er improvement of the roof

U-value - 4.7 W/m2K

U-value - 0.24 W/m2K fig 5.14: Change in roof material Source: google images

fig 5.15: Highlights the improvement in design in (pink strategy) on the final output

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fig 5.16: Resultant temperature of test unit a•er improvement of the floor

5.4.2.Case 2- C1+elevated floor: The next step was to mi•gate the major issue of flooding which was one of the primary concerns of the residents because the slum sites are generally in low lying areas with a water body nearby. Therefore, the unit is elevated to first floor. The ground floor is kept empty which can be used for other auxillary purposes (fig 5.19).

Eleva•ng the floor had both a posi•ve and a nega•ve impact. Firstly the posi•ve impact is on an urban scale, as lower site coverage improves urban ven•la•on (fig 5.18). The nega•ve impact is that the eleva•on causes the unit to lose the ground as the heat sink. This is reflected in the graph (fig 5.16). It can be seen that the resultant temperature has increased by 1K.

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fig 5.18: Effec•veway of improving city ven•la•on Source: Ng, 2006

fig 5.19: Highlights the improvement in design in (pink strategy) on the final output

5.4.3.Case 3- C2+wider streets & overhang analysis:

fig 5.20: Urban street widths

The third step was to slowly improve the urban canyon. A preliminary study of solar angles was done (fig 5.21) to decide the average road width to op•mize solar access throughout the year. The streets were widened on all sides as shown in figure 5.20. This resulted in higher solar exposure of the envelope which slightly increased the overall indoor air temperature.

The next step was to work with the horizontal overhangs. A parametric study was conducted (fig 5.22) to develop an op•mized overhang depth of 800mm. This depth shades the walls completely during summer and only up•l sill level during mid-seasons. The purpose of doing it that way was to allow heat gains through the mud walls throughout the day and during the night when the temperature drops the walls would radiate the heat indoors. The effect of this strategy counteracted the effect by the urban canyon.

2160

fig 5.22a: op•mised overhang depth

5400

Summer sols•ce

Spring equinox 5000

Autumn equinox

Winter sols•ce fig 5.22: preliminary study for op•mised overhang depth

8500

fig 5.21: study of op•mal street width according to solar access

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5.4.4.Case 4- C3+fenestration change: Up!l now all strategies focused on reducing the effect of direct solar radia!on on the test unit. But from our precedent study and fieldwork we have no!ced that the building should perform as a high thermal mass during the day and low thermal mass at night. For this purpose, fenestra!on sizes were increased. An op!mized window to floor ra!o was selected by carrying out test box studies which is elaborated in the (appendix). The final window to floor ra!o selected was 43.4% which showed a huge drop in the temperature.

The bedroom is in comfort throughout the day (fig 5.24). The resultant temperature in case 4 has dropped by 1K during peak hours during day!me because of higher u-values and area of the window wooden panels. And by night !me it drops by 4K. As the large fenestra!ons are open allowing night ven!la!on. Since the prevailing winds are from the south, the bedroom inlet was kept smaller than the kitchen window for increased wind speeds during cross-ven!la!on. When the kitchen is decoupled during cooking !me to avoid heat gains and smell into the bedroom can have single sided ven!la!on through the two different apertures. Thus, closing the window during peak hours maintain the high thermal mass of the unit and when the windows are open, it follows the outdoor temperature to maintain comfort condi!ons (low thermal mass). This step was one of the most important interven!ons.

Since, there is a lot of diffuse solar radia!on in the atmosphere. The windows are louvered to block that and allow only ven!la!on during day!me.

Increased wind speed when outlet is larger than the inlet

fig 5.23: illustrates principles behind fenestra!on design in the test unit

fig 5.24: Resultant temperature of test unit a&er improvement of the fenestra!on

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fig 5.25: single sided ven•la•on

fig 5.26: cross ven•la•on

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5.4.5.Case 5- C4+all material change: The next important step was to see the effect of replacing the generic brick construc•on with all the vernacular materials we had tested during our fieldwork. A series of tests were done to deduce the size and height of each material panel that will be implemented on the unit (fig 5.27). See appendix for all the detailed study in this regard. The final configura•on of the materials to be used as the envelope had a similar performance as the exis•ng brick one (fig 5.28).

But it is s•ll worthwhile to take up this interven•on because of the following reasons: 1. Energy consump•on in a cubic meter can be 5 to 20 •mes less (auroville,2015), (BMTPC,2015).

2. The pollu•on emission will also be 2.4 to 7.8 •mes less than fire bricks (auroville,2015).

3. Produced locally with natural resourceand semi-skilled labour (in this case te residents themselves, who are somewhat familiar to these materials), almost without transport.

4. Bill of quan••es of just the wall envelope proves that it can be 46% cheaper than tradi•onal brick construc•on. (See appendix for the breakdown)

fig 5.27: Vernacular materials replacing brick construc•on

fig 5.29: illustrates how each panel size and posi•on help the test unit to achieve similar performance like the brick and the envirionmental principle behind them. It is also noteworthy that this configua•on was also the best configura•on. Any other op•on was not performing be•er than the brick envelope.

fig 5.28: Tas results showing similar resultant temperature for case 4 and case 5.

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source: auroville,2015

a.

b. source: auroville,2015

c.

source: auroville,2015

Fig 5.29: Illustrates how each material contributes towards the thermal performance of the unit

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5.4.6.Case 6- C5+Sun shading: As discussed in sec•on 3.1.2, it is necessary to protect the east and west façade from the harsh sun (fig 5.30). As the test unit faces a wide street on the east, sun penetrates the urban fabric to heat up the unit (fig 5.31). Therefore, the next logical interven•on was to provide sun shades on the east corridor.

Thus having the circula•on core on the west and extra shading on the east corridor help reduce the temperature marginally (fig 5.32).

fig 5.30: solar radia•on analysis

fig 5.31: N-S orienta•on of the streets align with the summer prevailing winds

fig 5.32: Design strategies highlighted in pink

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5.4.7.Case 7- C6+orientation: Since Kolkata is in the tropics the sun is mostly overhead. And therefore, change in orienta•on in theory should not have affected the temperatures as such. But s•ll TAS was done in different orienta•on only to confirm the hypothesis (see appendix). The final orienta•on kept was N-S orienta•on as it was aligned with the exis•ng streets (fig 5.34, 5.35) and the prevailing wind direc•on. Fig 5.36 shows the slight drop that was registered in the resultant temperature of case 7.

fig 5.34:Summer prevailing wind

fig 5.35:street parallelto prevailing wind direc•on. This ensures penetra•on of wind suc•on pressure on the facade of the building fig 5.37: Resultant temperature of test unit a•er change in orienta•on

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5.4.8.Thermal analysis on all floors: A TAS analysis was carried out to comprehend the thermal performance of the final improved unit. 3 cases were considered as shown in fig 5.38. The resultant graph fig 5.39 shows the all the units perform very similar to each other and all the cases are s•ll within the comfort band throughout the test period.

Temperature (oC)

flat at the bo•om

flat in the middle

topmost flat fig 5.39: Comparison of the resultant temperature of the three cases

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fig 5.38: The 3 condi•ons that were analysed

5.5.Annual percentage of discomfort hours: While tes•ng the different cases, the percentage of hours when the indoor resultant temperature was beyond 31.6oC (upper limit of comfort band for the extreme month of summer) was also checked for the whole year. Figure 5.40 shows how the percentage discomfort hours have been reduced from 43.3% (base case) to 10.6% (final case) which is also well below 16.1% (external temperature). This indicates success as per discussion in sec•on 5.3.1 which quotes Givoni. Furthermore, if percentage discomfort hours is considered only during occupancy hours, it reduces to 3.25% (11 days approx.) which can be easily mi•gated by using mechanical fans (fig 5.42) at a speed of 0.5m/s.

Percentage of discomfort hours

fig 5.42: Physiological cooling using mechanical fans 25%

19.32%

20% 15% 10% 5%

4.79%

3.78%

3.25%

0% external base case final case temperature

case in between flats

Percentage of discomfort hours

fig 5.41: Percentage discomfort during occupancy hours (T > 31.6oC)

fig 5.40: Comparison of the percentage discomfort hours of all the interven•ons for the whole year (T > 31.6oC)

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5.6.Conclusions: To begin with the analy•c work, a base case was formulated which was incorporated with all the issues that were registered during the slum survey. Only excep•on was the area, which was 25m2 (5 •mes the original hut size). Interven•ons were priori•zed on the basic of thermal impact. The most important interven•ons were roof improvement followed by increasing the fenestra•on to floor ra•o to 43.4%. Each of them were governed by the principle of solar protec•on and ven•la•on respec•vely.

Then the most significant interven•on was that of replacing brick construc•on with the vernacular materials of mud, wa•le and daub and bamboo. Even though it did not change the thermal performance but it had a huge economic and environmental impact. Since these materials were familiar to slum residents. Therefore, using these materials allowing the project finances to be used on people rather than the industry (which would have been the case had they been using brick and concrete.

This chapter resulted to the final design of a free-running unique modular unit, which can be replicated in all direc•ons to create a mul•story building. The percentage discomfort hours was reduced to 3.25% per year which can be easily mi•gated with the use mechanical fans.

Therefore the following chapter will see the development of the design on a building scale.

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6.Design: Building Scale 6.1. Design of the 3-flat cluster 6.2. Design of the 8-flat cluster 6.3. Varia•ons in design of the typical unit 6.4. Plethora of uses for the s•lted ground floor 6.5. Environmental performance of the module in the 8 flat cluster 6.6. Wind analysis: 6.6.1. 3-flat cluster 6.6.2. 8-flat cluster 6.7. Solar radia•on analysis: 6.8. Urban cluster analysis 6.9. Conclusions

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6.1.Design of the 3 flat cluster The next scenario for building design was the 3-flat cluster. The units were arranged to cause least sharing of walls amongst each other.

They are strategically placed in such a way that parts of the unit act as wing walls and redirect the prevailing winds into the kitchen spaces to take away the heat gains. The floor plans repeat a!er every third level (fig 6.1). The core consis#ng of the staircase and the toilet facility are con#nuous ver#cally on all floors for easy plumbing purposes. There is 1 bathroom per 2 families in this typology as per Indian byelaws (NBC,2005). In order to stop future encroachment; cut outs have been made on the floor slab in the common area. These cutouts would not only prevent these typologies from becoming a ver#cal slum in future but also help in op#mising ver#cal wind circula#on within the building (fig 6.2). The average area of each floor plate is around 144m2.

Fig 6.1: preliminary massing model of the 3-flat cluster

dwelling units

future extension

washroom

slab cut-outs

Fig 6.2: Typical floor plans of the 3-flat cluster model.

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6.2.Design of the 8 flat Cluster

Fig 6.3: preliminary massing model of the 8-flat cluster

dwelling units

future extension

The 8 flat cluster was designed in a similar fashion as the 3 flat cluster. The main idea was to maintain the porosity which is intrinsic for buildings in hot and humid climate. Similar to the previous design for the 3 flat scenario, it shares minimum wall surface area with the neighboring unit. It also has units star!ng from the mid landing level.

Therefore the staggered feature is not only pronounced horizontally but also ver!cally (fig 6.3). The core services are again located at one end. All bathroom facili!es are concentrated there. If the building is more than 5 floors, li#s get added to that core as it can be seen marked in blue (fig 6.4). As it can be seen, a clear defined boundary (module) has been provided for each family. Adaptability in terms of movable walls or any such feature to manoeuvre their kitchen or bedroom space with the immediate outdoors hasn’t been provided.

This is because if the slum residents are provided with such ambiguous boundaries, they would see it as an opportunity to encroach more space for themselves and ul!mately conver!ng the building into a ver!cal slum. The entry to each flat and cutouts on the floor slab has been provided in such a way that if any resident tries to build more than the designated space for future expansion, they might end up blocking somebody else’s entrance. 18% of the flat space has been set aside of the floor slab for future expansion when the family size increases. These extra spaces are also strategically placed so that they do not hamper the air movement throughout the building. average floor plate area is 302m2.

washroom

slab cut-outs

Fig 6.4: Typical floor plans of the 8-flat cluster model.

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6.3.Variations in design of the module As seen in figure 6.6, the units slightly vary in their design, so as to allow be•er air penetra•on in the building or to optmise heat loss through the kitchen to the exterior .

A percentage breakdown is also shown in figure 6.5. It’s worthwhile to men•on that the circula•on space takes up around 25% of the total floor plate area which is a bit more than generic building standards (NBC,2005), but it’s acceptable, as the idea was to have more wind penetra•on in the circula•on area and the units. It is no•ceable that the units don’t touch each other. They are exposed on all sides but s•ll well shaded which is an op•mum condi•on to provide comfort in hot and humid climates.

Duplex units have been put on the topmost floor (fig 6.7). The area of each floor of the duplex is half the original module, thereby allowing twice the number of apartments to be accommodated without needing to provide another extra floor. This is especially helpful when the building blocks are only 5 floor walk-ups to avoid installa•on of li"s.

Fig 6.5: Percentage breakdown of the different zones in each floor plate

a.

b.

c.

kitchen

bedroom

kitchen

bedroom

bedroom

kitchen

bedroom

Fig 6.6: Varia•on in the design layout of the dwelling unit for be•er cluster design.

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bedroom

bedroom

bedroom

bedroom

kitchen

kitchen

duplex: lower floor

3D sec•on

bedroom

bedroom

duplex: upper floor

Fig 6.7: Plans and sec•on of the duplex unit

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6.4.Plethora of uses for the stilted ground floor All building will have a s•lted ground floor (fig 6.9) to prevent damages from future flooding which is incessant in this low lying area.

Strategically, depending upon the urban plan some buildings can have the excep•on of providing units on the ground floor.

In general these s•lted empty floor spaces can provide the following uses (Fig 6.8 a-f): 1. Parking spaces for cycles and rickshaws at night 2. Can serve as temporary vending stalls for the resident vendors who had been doing their business since the previous •mes.

3. Some units can also have permanent shops. Depending upon the loca•on of the building and if the building had replaced some shop used by the slum residents.

4. Temporary communal spaces for various gatherings 5. Temporary classrooms set up by NGOs to educate children by day and eager parents by night.

6. These s•lted ground floors also help environmentally op•mise urban ven•la•on (as discussed in sec•on 5.4.2).

fig 6.9: S•lted ground floor

fig 6.10: Strategy for construc•on

fig 6.8a: Parking for two wheelers Source: google images

fig 6.8c: more permanent exis•ng ones

fig 6.8b: Temporary markets on the s•lted ground floor

fig 6.8d: congrega•onal spaces Source: Kere architects,2016

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fig 6.8e: allocated spaces as classrooms for children Source: Anna heringer,2016

6.5.Environmental performance of the module in the 8 flat cluster.

test unit placement in the building

Tas simula•ons were run to check the environmental performance of the module when placed in the new 8 flat cluster forma•on (fig 6.13). The 8 flat unit was also put in the relevant urban design scenario surrounded by other 3 and 8 flat buildings and wider streets.

Figure 6.12 shows the typical summer days that had been considered for other cases previously and it was inferred that it performed well and was well within the comfort limit. Therefore this proved that a comfortable microclimate is maintained around these buildings therefore allowing each module to perform well.

fig 6.13: Showing the loca•on of the test unit

fig 6.12: TAS results depict the resultant temperature of the unit when placed in the proposed 8-flat unit and the urban scenario

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6.6.Wind analysis: 6.6.1. 3 flat cluster: The idea of maintaining porosity in the building scale by staggered placements of modules in each floor plate was tested by a quick wind analysis using WinAir from Ecotect. The wind direc•on was chosen was from the south like the prevailing winds in Kolkata.

Large openings were created in the kitchen spaces for simplicity in the model. The analysis revealed that a steady wind speed of 1 to 1.5 m/s was maintained through the kitchen and the circula•on spaces (fig 6.11) which was enough to take away the kitchen internal heat gains and maintain a cool breezy environment in the inters••al spaces(fig 6.12).

Ground floor

Second floor

Third floor Fig 6.11: Plans of building showing air flow rate Sec•on A’ through slab cutout

Sec•on through midpoint Fig 6.12: Sec•on B’ through building showing the airflow vector

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6.6.2. 8 flat cluster: Wind analysis for the 8-flat cluster showed similar posi•ve results.

Even though it had a greater con•nuous floor slab area, the stair wells and cutouts help maintain good wind movement ver•cally (Fig 6.14). The varying gaps between the units act like inlets and outlets to the circula•on spaces and kitchen walls act as wing walls. Thereby enhancing wind speeds within the building. A wind speed of 0.5 to 1 m/s can be noted in the kitchen spaces and 1.25m/s wind speed in circula•on spaces.

Ground floor

Third floor

Sec•on B through the width of the building Sixth floor Fig 6.13: Plans of building showing air flow rate

Sec•on A through the length of the building Fig 6.14: Sec•on through building showing the airflow vector

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6.7.Solar radiation analysis The solar radia•on analysis shows how the interspersed floor plan facilitates self-shading in alternate floors. The radia•on analysis was a preliminary study and was done without the use of overhangs.

The east facade receives an average of 500-700KWh/m2/yr. and the south and the west facade receives more or less similar amount of radia•on of around 1050 KWh/m2/yr. the semi-open circula•on spaces and walls of the modules facing the circula•on space have an incident radia•on ranging from 0- 175 KWh/m2/yr. It can be well noted that the staggered shape exposes only a frac•on of each facade to direct solar radia•on average as men•oned above

Northeast view

Southwest view Fig 6.15: Solar radia•on analysis of 3-flat unit

Northeast view

Southwest view

Fig 6.16: Solar radia•on analysis of 8-flat unit

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Cluster analysis

Northeast view

A preliminary study of a cluster consis•ng of a courtyard was formed with the typical 3 and 8 flat buildings. Similar wind and solar radia•on analysis was carried out. In terms of solar radia•on analysis, the units partly shaded each other thereby the overall radia•on falling on each facade of the buildings had reduced by 100-200KWh/m2/yr in all orienta•ons (fig 6.17).

Ini•al wind analysis was done in WinAir and it was found that the group of buildings had caused reduc•on in wind speed. Then for a more detailed analysis further it was tested on Autodesk flow design. The figure 6.18 depicts the wind pressure co-efficient on each wall surfaces of the modules and the unit as a whole. A pressure difference of almost 10Pa was noted between any two opposing walls of a module, which further meant that on the event of very low wind there will be enough pressure difference for cross-ven•la•on.

Thereby removing excess humidity from the living spaces and making them more comfortable.

Southwest view Fig 6.17: Solar radia•on analysis of the cluster

Northeast view

Southwest view

Fig 6.18: Wind pressure co-efficient analysis for the group of buildings

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6.8.Conclusions: This chapter dealt with design and analysis on building scale and the idea was to maintain porosity at all scales as it is intrinsic for hot and humid climate. The 3 and 8 unit clusters had similar design principles. Each unit within the floor plan tried to maintain minimum contact, therefore allowing maximum exposure. Overhangs provided helped in minimising direct solar exposure.

Wind analysis revealed a wind velocity of 0.5 to 1.5m/s in the kitchen and circula•on spaces of these building which is enough to remove kitchen internal heat gains and maintain a cool breezy environment throughout the spaces.

Solar radia•on analysis show low solar exposure (0- 175 KWh/m2/ yr) in majority of the unit facades because of the staggered design.

And a TAS simula•on was done in the proposed design environment which revealed that each of these typical units performed well and were in comfort.

The next chapter will take the design to the last stage- the urban scale. Similar process of design and analysis will be carried out while trying to accommodate the high popula•on density.

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7.Design: Urban Scale 7.1. Urban Design 7.2. Wind analysis 7.3. Facade treatment 7.4. Dayligh•ng analysis 7.5. Renewables 7.6. Conclusion

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7.1.Urban Design The step by step design from the simple module to mul•storeyed 3/8module cluster unit and its analysis was followed by urban design.

The exis•ng layout was carefully mapped out on a 5x5 grid and strategically upgraded to accommodate wider access routes, apartment blocks and green open spaces. All this while keeping in mind that when the construc•on begins, it happens piecemeal without disrup•ng the whole slum area at a go.

Now to explain how this development process will happen on site, it will be worthwhile to men•on that; an addi•onal empty plot was also taken into considera•on along with the test plot of 15000sqm for the urban design. This addi•onal plot which is just 75m away from the site would help lower the popula•on density of the test plot and contribute towards the smooth transi•on of the urban design of the slum (Fig 7.1).

Henceforth, the first prototype units get built in the adjacent plot.

Then a sec•on of the residents from the test site relocates to the newly built prototype. Therefore the empty plot formed because of the shi" becomes the site for the first set of improved buildings on the test site. Consequently another sec•on of the slum residents relocate there and again the newly formed empty plot becomes the site for the next set of building. This whole process keeps repea•ng un•l and unless the whole site gradually converts to the final urban design (figure 7.2).

Fig 7.1: Depicts test site for slum redevelopment (shahid sri• colony) as well as the adjacent plot that was used to accommodate the exis•ng popula•on.

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1.

2.

3.

4.

6.

7.

8.

9.

10.

Fig 7.2: Depic•ng the gradual process of redevelopment occuring in the test site.

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temporary markets on weekends

probable site for an elementary school and a healthcare unit.

playground for children or congrega•on space on occasions.

fig 7.14: Final urban layout

building more than 5 storeys

7.2.Wind Analysis for urban design Even though it was known that the improved streets and urban canyons would have an overall be!er urban ven•la•on and wind speed but a further detailed analysis was required to confirm the hypothesis. Subsequently wind analysis was carried out again on an urban scale. The study revealed that at street level of 1.1m there was an average wind speed of 0-0.6m/s on all access routes, which is comfortable as it feels like a gentle breeze (fig 7.5). As we start moving higher the wind speed increases. At 5 storey high level the wind speed surrounding the buildings is on an average 1.2m/s (fig 7.5&7.6). Since building taller than 5 storey (requiring li#s) are only a few and sporadically placed throughout the site (fig 7.4). It helps in op•mising the windflow throughout the site. This was also supported by previous research (Ghosh.O,2014) which suggest that interspersed arrangement of blocks and varia•on in height amongst the building blocks facilitate be!er urban ven•la•on in hot and humid regions (fig 7.3).

N.B- The whole site would require only 9 li#s (Kone, 2015).With each li# cos•ng around 800 pounds (Eco,2012).

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Fig 7.4: Sporadic placement of buildings more than 5 storeys in height. they are basically in the periphery

Fig 7.3: Previous research on op•mised urban design on the basis of urban ven•la•on.

Fig 7.5: Plan view showing urban windflow rate

Fig 7.6: Sec•on through the urban plan show urban windflow vector.

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7.3.Facade treatment A sun hours analysis was done on the site and as shown in figure 7.8a, b. Each side of the facade facing different orienta#on (for majority of the buildings) receive different amount of sunlight. Therefore, this also calls for different treatment of each facade for each orienta#on. Figure 7.7 depicts the north and the east facade. Since the north facade receives far less solar radia#on; it has wa$le and daub walls. It also houses the toilet block. Since it is provided by the government and deals with more complicated aspects of plumbing, it uses brick construc#on. The east facade on the other hand has higher thick mud walls to block the low angle strong east radia#on.

The windows are jali windows made from the same mud blocks which not only makes it cheaper but also helps prevent the low angle sun from directly entering the bedrooms. The Kitchen windows facing the east facade are large and have wa$le and daub walls as it is not generally in use during the morning hours.

Fig 7.7a: North facade

Fig 7.7b: East facade

Fig 7.8a: Sunhours analysis of the test site. Northeast view

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Similarly, the south facade looks very different from the other facades. As it has mud bricks up•l sill level and above that it gets treated with wa•le and daub. This is because the sun is mostly overhead by noon •me and the overhang par•ally covers the wall during midseason (which is why the thermal mass) and then it is completely shaded during summer (fig 7.9a).

Again the west facade also looks different with majorly mud walls with few or no windows. The sizes of the windows are also smaller to avoid harsh solar radia•on gains from the low angle west sun. There are also a lot of addi•onal sun louvres at the periphery of the building beyond the mud walls to prevent solar incidence on the mud walls and thereby crea•ng a sort of transi•onal space in between (fig 7.9b).

Fig 7.9a: South facade

Fig 7.9b: West facade

Fig 7.8b: Sunhours analysis of the test site. Southwest view

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7.4.Daylighting studies Even though the urban scale was designed keeping in mind op•mised urban canyons which meant op•mised dayligh•ng. It was necessary to analyse the worst case scenario flats surrounded by taller buildings and compara•vely narrower access routes and test if there was enough daylight to perform any ac•vi•es in the kitchen area. Therefore, three flats were chosen as shown in figure 7.107.11 which was predicted to may have some dayligh•ng issues. Only the work planes in the kitchen were considered for the analysis. A con•nuous daylight autonomy test was carried out on all the three cases. And it was found that even the worst case scenario had more than 300lux on the work plane for more than 66.09% •mes of the occupied hours which is acceptable.

fig 7.10: illustrates the loca•on of the units in 3D

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fig 7.11: the test units highlighted in red in plan

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Fig 7.12a illustrates the worst case scenario with a con!nuous daylight autonomy of 300 lux for 66.09% !mes of the occupied hours.

The next unit shown in fig 7.12c is be"er with a CDA of 300lux for 74.09% and the best amongst all the test cases (which will be the average sceanario throughout the urban site) has 87.59% (fig 7.12b).

fig 7.12a: Kitchen 1 (CDA- 66.09%)

fig 7.12b: Kitchen 3 (CDA- 87.59%)

fig 7.12c: Kitchen 3 (CDA- 74.09%)

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7.5.Renewables: Solar radia•on is high in india and in recent years, the use of solar panels have become increasingly popular and cheap. Therefore, use of PV solar panels were considered (fig 7.13). Accoun•ng for the circula•on and overshadowing of the panels, roughly 66% of the total roo•op area was considered to be covered by solar panels. The detailed calcula•on is shown below:

Fig 7.13: Roo•ops highlighted in yellow have been considered for solar panel installa•on 1. The subsidy of 30% is provided by the indian government on purchase of 100KW PV panel system or more (MNRE,2015)

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Fig 7.15: Shot of the final proposal across the lake. The use of different material gives it a very vernacular feel. Each material follows its func•on. The exposed brick signifying the toilet block and circula•on facili•es that are provided by the government and other local materials deno•ng public par•cipa•on. Folk art on the circula•on cores would landmark each block. No two building look the same because changing orienta•on changes facade treatment.

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Fig 7.16: The mul•level inters••al voids in the buildings not only helps with porosity of the building but also doubles up as a social space. Cool, Shaded and breezy- These spaces would be a place of respite for the residents during the harsh summer months. The dwelling unit walls can also be decorated with folk art that a re na•ve to each resident. The dwelling unit walls can also be decorated with folk art that are na•ve from the residents village. The whole idea is to provide home away from home. The cut-out in the slabs can be fi•ed with ne•ed hammocks that can be used for lounging and taking an a•ernoon nap. Such spaces should be popular with the residents as they like spending •me socialising in semi-outdoor spaces.

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Fig 7.17: Wider streets and op•msed urban canyons. The s•lted ground floor can get converted to a temporary market with local vendors selling their wares.

7.6.Conclusions: The Chapter begins with a detailed descrip•on of how the construc•on of these units will occur piecemeal without disrup•ng the whole slum site at one go. In the end, a final urban layout was achieved which had wider road widths. The main access routes had a width of 5meters and the smallest access routes had a width of 2.5m (fig 7.14). The buiding heights varied throughout the site. Few building had to be higher than 5 storeys in order to accommodate the existing popula•on in the same loca•on.

The new empty plots that had emerged because of the new urban design can be used for various purposes. For example as playgrounds, weekend markets, site for small healthcare unit etc. to make the slum self sufficient in terms of all basic needs.

Wind analysis confirmed a wind speed of .5m/s at ground level which gradual increased as the height increased. Sun hours analysis revealed the necessity of each building to have dis•nc•ve façade in each orienta•on even though the building were seemingly designed to be close to each other.

A dayligh•ng analysis was also done to find out if there was enough daylight in the kitchen work spaces. On analysing the worst case scenario it was found to have a con•nuous daylight autonomy of 300 lux on the kitchen work plane even for 66.09% of the occupied hours.

And lastly all the roof tops were considered for installa•on of PV panels in order to offset the energy demand. It was found that the amount of energy produced will not only offset the energy needs of the slums residents but will also provide each of them with an extra 40-60 pounds annually if they sell it back to the grid.

temporary markets on weekends

probable site for an elementary school and a healthcare unit.

playground for children or congrega•on space on occasions.

fig 7.14: Final urban layout

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8.Conclusions

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1.1.Conclusion: Slums in India house the people who help run the megaci•es every day. But they are looked down with a nega•ve connota•on in the society. They have no basic infrastructure to live in and therefore have a poor quality of life as well as suffer from thermal discomfort. Moreover current housing policies also don’t priori•ze comfort and are o•en lop-sided when providing solu•ons resul•ng in failure of such interven•ons.

Therefore this disserta•on focuses on providing a comfortable environment using passive design principles and reinvents the use of locally available materials into 21st century design.

Extensive research, fieldwork and analy•c work and design process helped in achieving a passive low energy modular unit which acted as a high thermal mass unit during the day to block off the high incident solar radia•on and as low thermal mass during the night by allowing the cool breeze to flow indoors through the large fenestra•ons taking away internal heat gains.

Therefore, maintaining comfortable indoor temperatures at all •mes. The use of local vernacular materials also made it much more sustainable and environment friendly. And this also meant lesser project cost.

The resul•ng modular unit was then replicated in the building scale and finally took the form of urban scale. All this while trying to maintain the same comfortable environment at all scales.

At urban scale, some buildings had to go beyond 5 storeys in order to accommodate the exis•ng popula•on. Going large scale raised ques•ons on the choice of materials. But that didn’t necessarily jus•fy the use of tradi•onal contruc•on materials which causes high CO2 emissions. Natural materials can be s•ll used but with more refined cra•smanship. Therefore, the project would end up inves•ng money on the people and not the industry which in this case is a much more promising approach.

Another ques•on arises on future livability in the building that go beyond 5 floors. As per indian social context and gauging the influx of people migra•ng to the ci•es, these buildings will be in constant use. And their unique look which speaks of the local narra•ves of the residents roots back in the villages would facilitate posi•ve connota•ons not only among the residents but in the city as a whole.

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References

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REFERENCES Bakshi, S. (2003). The Slums of Kolkata: a Truth We Know and a Truth We Don’t See. Unpublished report, Kolkata.

Building Materials and Technology Promo!on Council. Bamboo: a Material for Cost Effec"ve and Disaster Resistant Housing.

Available on: h"p://www.tn.gov.in/tsunami/digitallibrary/ebooksweb/36%20Bamboo_%20A_%20Material_%20For_%20Cost_%20 eff.pdf (Retrieved 10th October 2015) Compressed Stabilised Earth Block. Auroville Earth Ins!tute, UNESCO Earthen Architecture Website. Available on: h"p://www. earth-auroville.com/compressed_stabilised_earth_block_en.php (Retrieved 1st October 2015) Design with the Other 90%: CITIES Opening October 15 at the United Na"ons. Archinects News Website. Available on: h"p:// archinect.com/news/gallery/22642717/0/design-with-the-other90-ci!es-opening-october-15-at-the-united-na!ons (Retrieved 28th September 2015) Elevator Traffic Calcula"on. KONE Quick Traffic Website. Available on: https://toolbox.kone.com/media/mpb/frontpage_mpb/ Quick%20Traffic.html (Retrieved 11th November 2015) Fairs, M. (2009). Incremental Housing Strategy by Filipe Balestra and Sara Goransson. Available on: h"p://www.dezeen. com/2009/05/05/incremental-housing-strategy-by-filipe-balestraand-sara-goransson/ (retrieved 12th April 2015).

Fyhr, K. (2012). Par"cipa"ng in Upgrading of Informal Se$lements: a Case Study of the Project “City In-Situ Rehabilita"on Scheme for Urban Poor Staying in Slums in City of Pune under BSUP JNNURM”. Master’s Thesis in Urban and Regional Planning from the Department of Human Geography of Universitet Stockholms, Sweden.

Ganesan, K., B. Prashant, C. Kira, C. Saswa!, J. Pierre, M. Sameer (2014). Baseline Scenario of Energy Consump•on of Urban Mul•Storey Residen•al Buildings in India. In Proceedings PLEA 2014.

Ahmedabad, India.

Ghosh. O., Comfort band in hot and humid climates, Research paper 1 (2015), AA E+E Environment & Energy Studies Programme Architectural Associa!on School of Architecture Graduate School.

Ghosh. O., Slums in india: Addressing the housing crisis, Research paper 2 (2015), AA E+E Environment & Energy Studies Programme Architectural Associa!on School of Architecture Graduate School.

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Givoni, B. (1998). Climate considera•ons in building and urban design. Wiley, New york.

Global Buildings Performance Network and Centre for Environmental Planning and Technology University (2014). Residen•al Buildings in India: Energy Use Projec•ons and Saving Poten•als. Available on: h!p://www.gbpn.org/newsroom/report-residen"al-buildingsindia-energy-use-projec"ons-and-savings-poten"als (Retrieved 20th October 2015) Global Buildings Performance Network (2014). Residen•al Buildings in India: Energy Use Projec•ons and Savings Poten•als. Available on: h!p://www.gbpn.org/sites/default/files/08.%20INDIA%20 Baseline_TR_low.pdf (Retrieved 1st November 2015) Herz, M., S. Rahbaran and Y. Zhou (2008). Images of Tiljala. ETH Studio-Basel. Zurich, Switzerland.

Heywood, H. (2013), 101 Rules of thumb for low energy architecture. RIBA, London Kundu, N. (2003). The Case of Kolkata, India. Understanding Slums: Case Studies for the Global Report on Human Se!lements 2003.

Available on: h!p://www.ucl.ac.uk/dpu-projects/Global_Report/ pdfs/Kolkata.pdf (Retrieved 23rd September 2015) NBC (2005). Na•onal building code of India. Bureau of Indian Standards, New delhi.

Paramita, B. and H. Fukuda (2013). Building Groups Design Strategies in Hot and Humid Climate: a Dense Residen!al Planning in Bandung, Indonesia. In Proceedings PLEA 2013. Munich, Germany.

PRIA (2014). Kolkata Study Report 2014: Government Led Exclusion of the Urban Poor – A Greater Contributor through a Lesser Recipient. Available on: h!ps://terraurban.files.wordpress. com/2014/01/kolkata-study_april-2014.pdf (Retrieved 20th August 2015) Quinta Monroy Housing. Small Scale Big Change: New Architectures of Social Engagement Website. Available on: h!p://www. moma.org/interac"ves/exhibi"ons/2010/smallscalebigchange/projects/quinta_monroy_housing (Retrieved 1st October 2015) Sindhu M. (2013). Design of a Clima"c Adap"ve Façade System using bamboo for Urban India. TU Del$ Graduate report.

Singh, S. K. (2012). Construc•on Boom Li"s Ghaziabad’s Elevator

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Industry. The Economic Times Website. Available on: h•p://ar•cles. economic•mes.india•mes.com/2012-12-24/news/35991851_1_elevator-industry-ghaziabad-floors (Retrieved 15th November 2015) Solar Roo!op-Grid Connected. Government of India Ministry of New and Renewable Energy Website. Available on: h•p://mnre.gov. in/schemes/decentralized-systems/solar-roo!op-grid-connected/ (Retrieved 20th December 2015) Swiss Agency for Development and Coopera•on (2011). A Report on the Baseline Scenario of Energy Performance of Residen"al Buildings in Hot Humid Coastal Climate.

Szokolay, S. V. (2013). Introduc"on to Architectural Science: the Basis of Sustainable Design. Abingdon: Routledge.

The World Bank (2008). Residen"al Consump"on of Electricity in India. Available on h•p://www.moef.nic.in/downloads/public-informa•on/Residen•alpowerconsump•on.pdf (retrieved 12th August 2015) Turner, J. F. C. and R. Fichter (1972). Freedom to Build. Collier-Macmillan, London.

UN/DESA (2014). Economic Situa"on and Prospects. United Na•ons, New York.

UN-Habitat (2006). The State of the World’s Ci"es Report 2006/2007: the Millenium Development Goals and Urban Sustainability: 30 Years of Shaping the Habitat Agenda. Earthscan, London.

UN-Habitat (2014). World Habitat Day. Available on: h•p://unhabitat.org/whd-2014/ (retrieved 11th April 2015)

So!wares Used: Ecotect Tas EDSL Autodesk flow design Rhino Grasshopper: Ladybug, Galapagos, Honeybee.

Revit Autocad DIVA-rhino.

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Appendix

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Slum survey results in detail.

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Vernacular houses survey results in detail.

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Surface spot measurements taken over different intervals of time to understand thermal inertia within materials.

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spot measurements relative humidity

bamboo brick temperature

bamboo brick

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spot measurements relative humidity

temperature

temperature

116

relative humidity

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Comparison of the veracular materials with modern construction materials.

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Detailed breakdown of the TAS analysis for the base case to the final case.

base case- slum CASE 1- slum - IMPROVED ROOF WITH FALSE CEILING CASE 2- slum - CASE 1+ELEVATED FLOOR CASE 3- slum - CASE 2+ UNEXPOSED CASE 4- slum - CASE 3+ ORIENTATION CHANGED TO NORTH-SOUTH CASE 5- slum - CASE 4+ WIDER STREETS+OVERHANG MODIFIED CASE 6- slum - CASE 5+ APERTURE FOR WINDOWS CASE 7- slum - CASE 6+ WINDOW SIZE CASE 8- slum - CASE 7+ WINDOW SIZE 20% (W TO F) CASE 9- slum - CASE 8+ EXTRA WINDOW ON EAST WALL (BDRM2 5% - WINDOW TO WALL) CASE 10- slum - CASE9+CONCRETE ROOF+LOUVERED VENTILATORS (UPTIL HERE ALL BRICK) CASE 11- slum - CASE10+EXTERNAL COMPOSITE WALLS (mud+bamboo+wa•le and daub) CASE 12- slum - CASE11+COMPOSITE WALLS- (only mud + wa•le and daub) CASE 13- slum - CASE12+MUD UPTIL LINTEL (east wall+kitchen_ bedroom2 par••on wall) CASE 14- slum - CASE13+louvers (acts as transi•onal space) CASE 15- slum - CASE14+ east window removed CASE 16- slum - CASE15+ east ven•lator removed (final case) CASE 17- slum - CASE16+ wider streets

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floor plans of 8-flat unit

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A A

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floor plans of 8-flat unit

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4TH FLOOR 4th

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1900

floor plans of 8-flat unit

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6TH FLOOR

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floor plans of 8-flat unit

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7TH FLOOR (DUPLEX - SECOND LEVEL) 7th (duplex level)

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Bill of quan••es comparison between tradi•onal construc•on VS vernacular construc•on.

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List of Figures

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1.1.List of figures: Fig 1.1: Carelessly designed rese•lement colonies but which later get converted to ver•cal slums or don’t get inhabited at all for various reasons.

Fig 2.1: Timeline of the growth of the city and the simultaneous burgeoning of slums.

Fig 2.2: Various lessons learnt from Yerwada slum, Pune.

Fig 2.3: Various lessons learnt from Quinta monroy, Chile.

Fig 2.4: Summary of the lesson learnt for future implementa•on in the project.

Fig 2.5: Residents sharing water for washing clothes and utensils.

Fig 2.6: Strong social bonding and sense of belonging.

Fig 2.7: Frequent criminal cases emerging in slums.

Fig 3.1: Loca•on of Kolkata.

Fig 3.2: General overview of kolkata climate.

Fig 3.3: Solar radia•on.

Fig 3.4: Solar al•tudes during summer and winter.

Fig 3.5: Effect of RH on temperature and wind of wind on the percep•on of temperature.

Fig 3.6: Illustrates wind direc•on and speeds through summer and winter.

Fig 3.7: Climate comparison between year 2015 and 2050 (A2 scenario).

Fig 3.8: Percentage breakdown of uncomfortable hours per year.

Fig 3.9: Seasonal breakdown of the year.

Fig 3.10: Various adap•ve measures taken up by people Fig 3.11: Adap•ve behaviour Fig 3.12a: Overhangs Fig 3.12b: Pa•os or verandahs Fig 3.12c: Verandahs are a common feature in old building of kolkata Fig 3.13a: Courtyard showing stack effect.

Fig 3.13b: Courtyard in an old residen•al house in Kolkata.

Fig 3.14a: Perforated jali screens.

Fig 3.14b: Wooden thin louvered screens to block the a•ernoon sun in an old colonial office building in kolkata.

Fig 3.15a: Fenestra•on facilita•ng ven•la•on.

Fig 3.15b: Various types of Romanesque louvered windows prevalent in Kolkata.

Fig 3.16a: Elevated floor for windflow.

Fig 3.16b: Raised thick floor slab for coolth.

Fig 3.17: house on s•lts in Thailand.

Fig 3.18: Thick elevated floor slabs.

Fig 3.20: High thermal mass walls with high fenestra•on to wall ra•o and transi•onal spaces surrounding the main house Fig 3.21a: wood as a primary material for balconies and shades in kolkata Fig 3.21b: A vernacular house made of bamboo in Nagaland, India Fig 3.21c: A vernacular house mud house in west bengal, India Fig 3.22: Energy trends in india Fig 3.23: Building envelope proper•es comparison between tradi•onal materials and the ones recommended by energy conserva•on building code (ECBC), India.

Fig. 4.1: Loca•on of the two slum sites in kolkata. Both located near luxury gated communi•es.

Fig. 4.2: Urban plan is for the slum sites visted. South city slum (le•) and shahid sri• colony (right) with their highlighted access routes.

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Fig. 4.3: Illustrates the various access routes in both the slum sites. And simlutaneous spot measurements taken in these routes.

Fig 4.4: Typical layout of an hut in the slum.

Fig 4.5: On the right, the figure represents the average sta•s•cs of the two slums that were surveyed (Shahid Sri• and south city).

Fig 4.5a: photographs illustra•ng the poor living condi•ons of the slum inhabitants and how they try to ra•onalise space, material, comfort and hygiene to be able to work in the city.

Fig 4.6: Illustrates the various environmental aspects of the exis•ng slum condi•ons.

Fig 4.7: Loca•on of Silchar, India Fig 4.8: Four different test huts and their respec•ve primary material used in envelope construc•on.

Fig 4.9: Illustrates the general informa•on about the bamboo house and the spot measurements taken during that day.

Fig 4.10: Shows occupant comfort during summers and winters and their corresponding adap•ve behaviour.

Fig 4.11: illustra•ng the 2-level composi•on of the unit envelope Fig 4.12: illustra•ng the environmental principles found in the bamboo house Fig 4.13: photographs of the interiors of the house Fig 4.14: Illustrates the general informa•on about the wa•le and daub house and the spot measurements taken during that day.

Fig 4.15: Shows occupant comfort during summers and winters.

Fig 4.16: 3-level composi•on of the unit envelope.

Fig 4.17: Illustrates the environmental design principles found in the wa•le and daub house.

Fig 4.18: shows the various spaces within the hut.

Fig 4.19: Illustrates the general informa•on about the wa•le and daub house and the spot measurements taken during that day.

Fig 4.20: Shows occupant comfort during summers and winters Fig 4.21: 2-level composi•on of the unit envelope Fig 4.22: Illustrates the environmental design principles found in the mud house.

Fig 4.23: Photographs illustra•ng the different spaces within the house.

Fig 4.24: Illustrates the general informa•on about the wa•le and daub house and the spot measurements taken during that day.

Fig 4.25: Shows occupant comfort during summers and winters Fig 4.26: spot measurements taken Fig 4.27: Illustrates the environmental design principles found in the mud house.

Fig 4.28: Photograph of the room that was tested.

Fig 4.29: Graph depic•ng the thermal performance of the three test houses over the •me period of a week Fig 4.30: Graph illustra•ng the thermal performance of the two bedrooms in the wa•le and daub.

Fig 4.31: Graph showed the datalogger results for RH inside the mud house.

Fig 4.32: final comparison of the different materials in the respec•ve huts.

Fig 5.1: Three different types of slums seen in kolkata and their street alignments highlighted in red.

Fig 5.2: Dwelling unit layout Fig 5.3: illustrates the process of replacement of the exis•ng test site with the base case unit of 25m2.

Fig 5.4: Show the different scenarios that had emerged from the replacement exercise.

Fig 5.6: The TAS model for the base case Fig 5.7: u-values of the envelope Fig 5.8: illustrates the occupancy schedule, internal condi•ons in the base case scenario. The aperture schedule was used in later stages in the base case improvements.

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Fig 5.9: Resultant temperature of base case for 3 typical days of summer.

Fig 5.10: Sun angles in Kolkata Fig 5.11: Solar radia•on (annual) for kolkata Fig 5.12: Percentage heat loss for different materials Fig 5.13: Resultant temperature of test unit a•er improvement of the roof Fig 5.14: Change in roof material Fig 5.15: Highlights the improvement in design in (pink strategy) on the final output Fig 5.16: Resultant temperature of test unit a•er improvement of the floor Fig 5.18: Effec•ve way of improving city ven•la•on Fig 5.19: Highlights the improvement in design in (pink strategy) on the final output Fig 5.20: Urban street widths Fig 5.21: study of op•mal street width according to solar access Fig 5.22a: op•mised overhang depth Fig 5.22: preliminary study for op•mised overhang depth.

Fig 5.23: illustrates principles behind fenestra•on design in the test unit Fig 5.24: resultant temperature of test unit a•er improvement of the fenestra•on Fig 5.25: single sided ven•la•on Fig 5.26: cross ven•la•on Fig 5.27: vernacular materials replacing brick construc•on Fig 5.28: tas results showing similar resultant temperature for case 4 and case 5.

Fig 5.29: illustrates how each panel size and posi•on help the test unit to achieve similar performance like the brick and the envirionmental principle behind them. It is also noteworthy that this configua•on was also the best configura•on. Any other op•on was not performing be•er than the brick envelope.

Fig 5.29: Illustrates how each material contributes towards the thermal performance of the unit Fig 5.30: solar radia•on analysis Fig 5.31: N-S orienta•on of the streets align with the summer prevailing winds Fig 5.32: Design strategies highlighted in pink Fig 5.34:Summer prevailing wind Fig 5.35: street paralle lto prevailing wind direc•on. This ensures penetra•on of wind suc•on pressure on the facade of the building.

Fig 5.37: Resultant temperature of test unit a•er change in orienta•on.

Fig 5.38: The 3 condi•ons that were analysed Fig 5.39: Comparison of the resultant temperature of the three cases.

Fig 5.40: Comparison of the percentage discomfort hours of all the interven•ons for the whole year (T > 31.6oc).

Fig 5.41: Percentage discomfort during occupancy hours (T > 31.6oc).

Fig 5.42: Physiological cooling using mechanical fans.

Fig 6.1: preliminary massing model of the 3-flat cluster.

Fig 6.2: Typical floor plans of the 3-flat cluster model.

Fig 6.3: preliminary massing model of the 8-flat cluster Fig 6.4: Typical floor plans of the 8-flat cluster model.

Fig 6.5: Percentage breakdown of the different zones in each floor plate.

Fig 6.6: Varia•on in the design layout of the dwelling unit for be•er cluster design.

Fig 6.7: Plans and sec•on of the duplex unit.

Fig 6.8a: Parking for two wheelers Fig 6.8b: Temporary markets on the s•lted ground floor.

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Fig 6.8c: more permanent exis•ng ones.

Fig 6.8d: congrega•onal spaces.

Fig 6.8e: allocated spaces as classrooms for children. fig 6.9: S•lted ground floor. fig 6.10: Strategy for construc•on.

Fig 6.11: Plans of building showing air flow rate.

Fig 6.12: Sec•on through building showing the airflow vector.

Fig 6.13: Plans of building showing air flow rate.

Fig 6.14: Sec•on through building showing the airflow vector.

Fig 6.15: Solar radia•on analysis of 3-flat unit Fig 6.16: Solar radia•on analysis of 8-flat unit Fig 6.17: Solar radia•on analysis of the cluster Fig 6.18: Wind pressure co-efficient analysis for the group of buildings Fig 7.1: Depicts test site for slum redevelopment (shahid sri• colony) as well as the adjacent plot that was used to accommodate the exis•ng popula•on.

Fig 7.2: Depic•ng the gradual process of redevelopment occuring in the test site.

Fig 7.14: Final urban layout.

Fig 7.3: Previous research on op•mised urban design on the basis of urban ven•la•on.

Fig 7.4: Sporadic placement of buildings more than 5 storeys in height. they are basically in the periphery Fig 7.5: Plan view showing urban windflow rate Fig 7.6: Sec•on through the urban plan show urban wind flow vector.

Fig 7.7a: North facade Fig 7.7b: East facade Fig 7.8a: Sunhours analysis of the test site. Northeast view Fig 7.8b: Sunhours analysis of the test site. Southwest view Fig 7.9a: South facade Fig 7.9b: West façade Fig 7.10: illustrates the loca•on of the units in 3D Fig 7.11: the test units highlighted in red in plan Fig 7.12a: Kitchen 1 (CDA- 66.09%) Fig 7.12b: Kitchen 3 (CDA- 87.59%) Fig 7.12c: Kitchen 3 (CDA- 74.09%) Fig 7.13: Roo•ops highlighted in yellow have been considered for solar panel installa•on Fig 7.15: Shot of the final proposal across the lake.

Fig 7.16: The mul•level inters••al voids in the building not only helps with porosity of the building but also doubles up as a social space.

Fig 7.17: Wider streets and op•msed urban canyons. The s•lted ground floor can get converted to a temporary market with local vendors selling their wares.

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