Behind a tall blue gate, a construction site in central Mumbai bustles with trucks and cranes, and workers wearing red and yellow hard-hats. Beyond the far fence stands a row of old barrack-like structures. And, beyond them still, new apartment towers rise into the clouds.
Here, in the heart of Mumbai, an ambitious project is underway to replace century-old tenements, across 37 hectares of land, with modern housing and commercial complexes. Known as chawls, the tenements were built by the Bombay Development Department, or BDD.
The question of what the redevelopment of these BDD chawls should look like has been a contentious one.
In Worli, the largest site, the government-sanctioned plan is putting up a forest of buildings of up to 40 and 60 storeys. An alternative proposal by local architects and planners would have had half the built-up area, balancing smaller blocks with a sports ground and other public facilities.
These divergent visions – and the brief battle between them in the courts – throw up important questions about the future of urban housing in an era of climate change.
In India, according to one estimate, urbanisation will create a demand for 25 million more affordable homes by 2030. Given the pressures on land, many of the new buildings will likely be dense high-rises. Clusters of towers can make for efficient urban design, especially when supported by good public transport, but they bring their own set of problems. They absorb and emit heat, raising local temperatures. And, if designed poorly, they can lead to unhealthy living conditions.
Climate change makes these problems more urgent. In Mumbai, authorities are paying attention to the threat of flooding from extreme rainfall and rising seas. But they have yet to grapple with how the city will cope with higher temperatures and more frequent heatwaves – or how new development might aggravate warming.
Meanwhile, the city is in a fever of post-pandemic construction. Hundreds of older buildings are being redeveloped; more derelict industrial land is up for grabs; and recently, the government cleared the redevelopment of one of the city’s largest slums. Mumbai’s built form is seeing its biggest transformation in decades – without, the story of the BDD chawls suggests, sufficient heed to consequences for health and environment in an era of global warming.
Walking into the BDD layout in Worli on a weekday afternoon feels a little like stepping out of time. The roofs are low, the trees are old, and the sky is wide.
Worli is the biggest of four BDD layouts in the city, with 121 buildings on 23 hectares of land. The blocks are laid out symmetrically on either side of the main street, interspersed with open grounds used for sports and other public functions. The colony has no boundary walls and the street-side buildings host small shops, a hospital, and schools. Hoardings of every political stripe plaster the walls and lampposts.
These buildings came up a hundred years ago, when colonial authorities, alarmed by general strikes in the city’s textile mills, as well as nationalist stirrings across the country, sought to assuage unrest by constructing new housing for workers. In 1920, they set up a new executive authority, the BDD, with a plan to build 50,000 one-room tenements.
It wasn’t the first such urban improvement effort in the city. In the late 1890s, after the bubonic plague arrived on a ship from Hong Kong and tore through Bombay, doubling mortality rates, authorities began to pay attention to the unsanitary and overcrowded conditions in the “native” part of town. They set up the Bombay Improvement Trust, with a broad mandate for urban planning, inspired by similar experiments in England.
The trust demolished buildings to create broad east-west avenues that would bring the sea breeze into the inner city, acquired land for suburban expansion, mandated light and ventilation norms for housing layouts, and built thousands of working-class tenements. These interventions are still visible today in areas such as Dadar-Matunga.
“The arrival of the plague profoundly changed the way in which they” – the British – “considered and understood these areas,” writes historian Vanessa Caru. The epidemic, she added, gave rise to “an intense production of knowledge about urban space.”
The experience came in handy twenty years later with the BDD, set up by a colonial government vying with an Indian-elected municipality to shape urban growth. The authority tested three designs, including cottage-style homes, Caru notes. The cheapest design was chosen, comprising identical four-storey structures, each of which had 20 rooms of 10 feet by 20 feet running on both sides of a central corridor, at the end of which were toilet blocks.
The BDD tenements were a milestone in some ways, suggest historians. They were among the earliest buildings in the country made of reinforced cement concrete, then a new technology. And their scale set a precedent for the provision of public housing in the city.
From the beginning, however, the homes were criticised, historians say. People complained of the stink from the city’s main open drain, which ran through the area. The roofs leaked, and the windows had a concrete grill that limited light. There was no washing area inside the rooms – rather, residents had to use common facilities on each floor. The central corridor was always dark. The rooms were “not better than mere cells”, wrote architect Jameshedji P Mistri in a letter to the Bombay Chronicle in 1923.
“In India, a house or a chawl is not perfectly designed if there is no veranda,” he noted. “To remove a veranda from the dwelling place of a poor man is to remove all amenities of his dwelling. To throw that space into his room is to allure him to keep more boarders.”
Many British officials agreed. Well-known urban planner Patrick Geddes famously described the blocks as “warehousing”, and not housing.
But the place gained social significance. The Worli layout saw the formation of the city’s first worker-tenants’ union in the 1930s, Caru noted, and the setting up of recreational centres and educational societies. Its open ground was a rallying point for BR Ambedkar, champion of the rights of Dalits. “You do not get food to eat, clothes to wear, opportunities of educating your children, and medical help for want of money,” he told a crowd here in 1932, urging them to seek political power.
A British housing intervention intended to check worker unrest, Caru observed, had become a space for political mobilisation.
At the Worli layout, it wasn’t hard to see why. The buildings are shabby, but the ample space, as well as schools, hospitals and grounds, engender a sense of neighbourhood.
Yet the area also has a history of conflict, especially in the 1970s, a period of frequent clashes between Dalit and upper caste groups. As one paper notes, an inquiry commission into a riot in 1974 observed that between 15 and 20 people were crammed into each room, a level of crowding not seen today. The commission’s report suggested that living conditions were partly to blame for the violence. There was “dirt and filth everywhere”, it noted, adding, “the density of population coupled with the unhygienic conditions make the lives of these working class folk miserable”.
Building No. 42 of the Worli BDD tenement looks much like the others, with peeling walls and box-like window grills. Some tenants have extended their rooms with closed balconies, supported by external trusses. Up the stairway, garlanded portraits of Ambedkar greet you on each floor. The second-floor corridor is dark and the ceiling drips with clothes. At one end live Vijay Pratap and his wife with their son, daughter-in-law and granddaughter, six-year-old Naina.
The Prataps’ 160-square-foott home has been furnished to maximise space. A large bed with storage beneath occupies almost half the room, while a loft stretches across the far wall, big enough for a person to sleep in. The kitchen and washing area are curtained off. On one wall a table is folded up; next to it hangs a black guitar. The corner room has windows on two sides, but they are closed. The curtains are drawn and the air-conditioner and lights switched on. “Naina always wants the AC,” said her father Ashish.
Ashish’s father, Vijay Pratap, and his friend, Kiran Mane, both leaders with the tenement association, worked in a nearby factory and mill all their lives. So did their fathers, who were the first of their families to come to the city from their villages in rural Maharashtra. Today, most of the younger generation work in offices.
Pratap, 62, remembers each decade through amenities acquired: in the 1960s, they got electricity in their rooms, in the 1980s, they got cooking gas. The Prataps boast of the quality of the construction – “the walls are so thick you can’t knock a nail in” is part of BDD legend – and the absence of flooding thanks to good drains, but also complain of inconveniences.
Over the years, small families have expanded, outgrowing their homes and the number of shared toilets. Most households have four or five people, but some are larger, forcing the men to sleep in the corridor. The lack of private toilets means that women don’t want to marry men who live here (though some families have built a toilet inside their homes). Maintenance by the government public works department, which gets Rs 17 a month from each rent-controlled room, is inadequate.
The idea of redeveloping the BDD tenements was first mooted in 1999. But it was only in 2015, after Bharatiya Janata Party-led alliances came to power at both the national and state levels, that the project to redevelop all 207 tenement blocks moved forward. By the end of the next year, the process of transferring the land from the state urban development department, which owned it, to the housing board, which would redevelop it, was completed. The board called for architectural proposals. The architect Vivek Bole won the bid for Worli, and in 2018, Tata Constructions won the tender to execute the project.
Bole’s plan for the Worli site aims to convert the low-rise area into a high-rise one to accommodate every current tenant – almost 10,000 families, over 200 commercial establishments, and six religious structures – as well as to create space for buildings to be sold to finance the project. As mandated by the authorities, each family will get a 500-square-foot home with two bedrooms and two bathrooms. These tenants will be accommodated in twenty 40-storey buildings, while ten buildings for sale will hold larger apartments, and rise to 60 storeys. Shanties that have occupied a part of the plot are to be rehoused in a separate building of 225-square-foot homes.
MHADA officials said that the Worli plan retains most of the existing open grounds, and adds new green spaces in the form of gardens and playgrounds situated above several floors of parking. Existing hospitals and schools will get new premises. The complex will have its own waste-treatment plant, the plan says. In the past, low-income rehousing projects sometimes failed because families couldn’t afford the costs of living in a high-rise, such as of maintaining a lift. But here, the housing board will take care of the maintenance costs for 12 years. “The people are happy,” said Mane.
There are benefits for the government, too. The commercial part of the project will add 5,000 residential apartments and 1,500,000 square feet of office space for sale. Authorities expect revenue of between Rs 7,000 and Rs 8,000 crore from the project, to be shared 70:30 between the state government and the housing board. The new housing, commercial, and parking will be a boon for the locality, an official told me, as will the “enhanced skyline”.
But not everyone was sold.
In August 2019, two veterans of urban policy filed a public interest litigation in the Bombay High Court, alleging that the government’s redevelopment plan for the BDD tenements violated future residents’ constitutional right to life.
The project was designed, the petitioners charged, to help government authorities make “enormous profits”. The rehabilitation buildings would be built on a smaller slice of the land, and so close together that residents would “be denied proper light and air and run a serious risk of infection from TB and other pulmonary diseases”. Constructing hundreds of new flats in an already congested locality, they added, would also result in densities that “necessarily put the existing civic infrastructure under even more pressure”.
The petitioners were veteran urban planners Shirish Patel and Sulakshana Mahajan. Patel had been the chief planner of Navi Mumbai, a planned town across the harbour, in the 1970s. Mahajan is a former planner with the now-defunct Mumbai Transformation Support Unit, a government body that produced a survey on the BDD chawls and a report on their potential redevelopment in 2009.
The petition in the court was delayed by the pandemic. But in July 2022, they held a press conference to present an alternate vision for the BDD as part of a group of more than 100 city architects, environmentalists and others, called “Consensus of Concerned Professionals”.
For the Worli site, Patel and Mahajan envisioned a lower-rise layout of buildings no higher than 36 storeys, with central atriums to improve light and ventilation, and a commercial sale component just enough to finance the project, not generate a profit. Only shops and other commercial establishments on the lower floors would be sold under this plan, so that more residents would not be added to the area. The extra land, they suggested, could be used for a full-size cricket and football ground. While the official plan provides “scattered formal recreation areas”, new sports grounds would add amenities to a city starved of them, they argued in a July 18 letter to the state chief minister.
Densities in the area “are already among the highest in the world because people are living in very small apartments of 160 square feet,” Patel said over an online interview. The official plan, he argued, would increase the density even further, potentially affecting the buildings’ light and ventilation, while adding nothing to the area’s amenities.
“Housing is not just the provision of a roof over your head,” he said. Further, they said, any free parking would encourage cars and lead to more traffic congestion and air pollution.
The data he and Mahajan produced was compelling. The existing BDD layout in Worli hosts 415 dwelling units per hectare. The government plan would raise this to 642 units per hectare, they calculated, while their alternative plan would keep it to no higher than 546 units a hectare. India’s National Building Code recommends a maximum of 500 units per hectare in low-income housing, and an ideal of between 125 and 150 units.
On environmental metrics, too, the official plan does not fare well. Paved ground currently covers 59% of the colony in Worli; the official plan will increase this to 89%, while the alternative plan would lower it to 35%. Unpaved ground soaks up water – thus in a tropical monsoon city like Mumbai, a higher proportion of paved ground means more potential flooding. The extent of built-up area will also affect local temperatures – the official plan will increase built-up area nine-fold, while the alternative plan only four-fold.
Meanwhile, though the official plan suggests that the buildings will have adequate light and ventilation, Patel and Mahajan say that the “sky view factor”, a measure of how much sky you can see from the ground, which can affect light and air flow, will worsen with the official plan.
When the BDD chawls were built in the 1920s, the city had adopted a “63.5 degree light angle rule” as part of measures taken after the plague to optimise light and air around buildings – according to the rule, the line connecting the top of one building to the bottom of the nearest building had to make no more than a 63.5-degree angle with the flat ground. That rule was replaced in 1964 by setback norms based on building height and plot area. Over the decades, these norms were diluted, especially in affordable housing projects, to accommodate more units in a given plot.
“We now have a stipulation which says that buildings can be nine metres apart, regardless of height,” observed Patel. This number is not determined by health considerations but by the minimum space needed to get a fire truck into the plot.
In a high-rise complex, argued Patel, such small distances would mean “the lowest floors will never see daylight.”
Patel and Mahajan had a cautionary tale to cite. A 2018 study by doctors and scientists had found a high prevalence of tuberculosis in a slum rehousing project in the eastern suburb of Govandi. The buildings were built just three metres apart and the density of units was as high as 1,000 units a hectare in one complex. The researchers found that between 8% and 10% of residents in the less well-ventilated buildings had tuberculosis, while only 1% did in better ventilated ones. Even within a building, the risk of contracting the disease declined on higher floors. The report blamed poor design and “compromises” in building norms, such as the exemptions on setbacks.
One of the study’s authors was Ronita Bardhan, an architect then with the Indian Institute of Technology Bombay and now with Cambridge University, United Kingdom. For many years now, Bardhan has been using a combination of sensors, models, and ground surveys to understand how built forms shape living and social conditions in low-income housing.
An early study of Bardhan’s looked at the Worli BDD tenements and found that their room designs too had inadequate airflow. Low-income housing designs often don’t consider how people use space, Bardhan said. In the Govandi project, for instance, people replaced window shutters with sliding windows that reduced the size of the opening by half. Lack of privacy in design meant women often kept these opaque windows closed. And box-like window grills installed for safety were used as shelf space, further blocking air.
Homes in low-income housing can sometimes feel hotter than outside in summer, Bardhan’s work suggests, leading to greater use of cooling devices. That increases energy bills and, if air-conditioners are used, can also generate heat in the locality – spurring even more use of cooling devices. A vicious microclimate cycle is created, one that could worsen with global warming.
Authorities tend to view public housing purely as shelter, said Bardhan, but “not just housing, the entire built environment is an upstream determinant of health.” Patel asked Bardhan to run her analysis on the government BDD plans. Her study, which is currently under review with a scientific journal, found that there were some good aspects to the design – especially the large central space between clusters of buildings – but that the lower floor apartments could have problems with daylight and ventilation.
In much of India, traditional structures were built to maximise ventilation in hot weather – but the popularity of these designs faded with the advent of fans and air-conditioners in the late twentieth century. As the problem of climate change has become more pressing, however, the need to cope with rising temperatures while also reducing energy use has brought new attention to natural ventilation techniques, called passive cooling.
As more homes are built in the country and gain access to regular power, and as more families begin to be able to afford heating and cooling devices, energy consumption will rise. Gross electricity consumption in homes rose four times between 1996 and 2016, and is projected to increase further from 260 terawatt-hour in 2016 to between 630 and 940 terawatt-hour by 2032. The building sector consumes around 30% of electricity in India, and thus has a role to play in any effort to limit greenhouse gas emissions.
With this in mind, over the last decade, the Central government has introduced new construction codes for the country. They include two new guidelines for energy efficiency and climate resilience: the Energy Conservation Building Code for commercial buildings and the Eco Niwas Samhita for residential ones.
The latter recommends designing buildings according to the climatic zone – Mumbai falls into the warm and humid zone – to minimise heat gains and losses. For instance, it gives formulas for the size of windows in relation to room areas to improve natural lighting and ventilation. It also recommends materials and designs for roofs to reduce heat absorption.
The codes integrate some traditional principles of cooling, said Prima Madan, who leads work on energy efficiency at the Natural Resources Defence Council. But they also assume that air conditioning will be necessary with rising temperatures and heatwaves.
“The idea is to design to reduce the demand for cooling, and then, for whatever demand remains, recommend the most efficient equipment in the market,” she said. These two codes are in line with global best practices, added Madan.
But their adoption is voluntary. Currently, around 20 states and two union territories have notified and mandated the code for commercial buildings. No state has notified the code for residential buildings yet, though a few are considering it, according to NRDC, which is working with some of those states. Maharashtra has not mandated either code yet. “It really depends on the political leadership,” said Madan.
Introducing climate-resilient measures is particularly tough in the residential sector, Madan noted. In commercial buildings, clients may commission a builder to implement an energy efficient design. For housing projects, developers build and then sell units – thus, they have little incentive to implement such measures, which could push up prices and put off home buyers. The incentive to choose energy efficient designs is almost non-existent in low-income or slum rehousing projects.
Guidelines similar to the national codes were proposed in the Mumbai Climate Action Plan, or MCAP, a blueprint produced by the World Resources Institute (WRI) India in collaboration with city authorities. The plan recommended developing climate-resilient affordable housing models “with mitigation and adaptation solutions, such as passive cooling, rainwater harvesting, and solar energy, to improve livelihoods and overall well-being.” The plan was released early last year but, with the government change in June 2022, it is unclear whether it will be implemented.
Meanwhile, thousands of low-income homes are being built that don’t follow the new guidelines. The Mumbai region will need four million more homes by 2036, according to official estimates – proposed slum rehabilitation and other redevelopment projects will provide 1.5 million of those units. “From a climate point of view, there is a risk that many of these homes will eventually be uninhabitable,” said WRI’s Lubaina Rangwala. She added, “For example, the higher floors might be too hot, and the lower floors may not get enough light.” (Rangwala said that officials from the slum rehabilitation authority and the state housing board did not show up to the climate action plan meetings.)
For the BDD redevelopment, authorities had to carry out an environment impact assessment and also obtain clearance from the ministry of environment. But as Patel noted, the assessment report for Worli covers only the impact of the construction work in terms of waste, air and noise pollution, and not the potential impact of the development on the area or residents.
Officials also said the project is certified under GRIHA, a green rating system developed in the early 2000s that scores projects from one to five stars. The system focuses largely on efficient use of energy and water, though thermal comfort and daylight are also among the factors it evaluates. Officials did not disclose the rating of the Worli proposal. “Whatever guidelines are there have been complied with,” said Anil Diggikar, vice president of the state housing board.
Not far from Pratap’s tenement in Worli is Tulsi Pipe Road, the main avenue that runs through the former mill district. Most of the 600 acres of land in central Mumbai once occupied by textile mills has been converted over the past decade into offices, malls, and luxury housing – a gentrification that has brought new jobs and people into a once fading area. But the large-scale redevelopment was not accompanied by a comparative expansion in civic infrastructure. Tulsi Pipe Road is an urban nightmare, especially at rush hour.
Underneath canopies of elevated roads, the street is thick with dust, pollution, and noise. Commuters rushing to the train station spill over narrow pavements. There are few trees or parks. The new developments remain behind high walls, havens of air-conditioned space. Some mill owners have provided 225 square-foot homes for their former workers – in response to court orders – and these tightly-packed buildings of between ten and twenty storeys sit next to luxury towers.
Architects and planners anticipated such a scenario. In the 1980s, architect Charles Correa, a contemporary of Patel, served on a state government committee tasked with creating a plan for the area – he envisioned redevelopment that would bring in affordable housing, parks and amenities alongside new commercial projects. This was conceivable under a regulation according to which a mill owner who wanted to redevelop land had to give a third to the city for open space and public amenities, and another third to the housing authority for public housing, retaining a third for commercial development.
But in 2001, the state government amended this rule so that the mill owner would only have to divide open land in this way. Since plots were largely covered by the industrial units, this left little land for the public. In 2005, an unprecedented alliance of mill workers, environmentalists, and civil society groups challenged the rule change all the way to the Supreme Court, but lost the case.
That defeat aided the shift away from town planning, the discipline born of the epidemics of the nineteenth century. The redevelopment of Mumbai today is happening plot by plot, project by project. “It’s all piecemeal,” said Patel.
For much of the twentieth century, urban authorities managed growth through the planned locality or “scheme”, to ensure that areas had adequate roads and other facilities. But since the 1990s, Patel said, that approach has been replaced by one centred on floor space index, a measure that determines how much can be built on a given plot. (In general, a higher FSI means buildings can go taller.)
Since the 1960s, Mumbai’s FSI was kept relatively low, compared to cities such as New York City, to prevent further densification. But since the 1990s, after industries began moving out of Mumbai, authorities have sought to increase FSI to encourage development. Many of those increases have been in the form of amendments or exemptions, said Patel, and “each specific change helps the developer in some way”.
In earlier years, authorities would grant a builder extra FSI only if other conditions were met, added VK Phatak, former chief planner of the Mumbai Metropolitan Region Development Authority. “Now FSI has become the superior entitlement for which other conditions can be compromised, including light and ventilation,” he said.
Phatak is one of the “Concerned Professionals” who supported the alternative BDD plan. He was also commissioned to draft an early version of a development plan for the city for the years 2012-’34. (A different version was adopted eventually.) His plan envisioned an overall higher FSI for the city but, he said, only subject to other considerations.
“If you wanted to rebuild a small plot with very tall towers, that would not have been possible because the requirements for light and ventilation would be compromised,” he said.
Phatak had also recommended that local area plans be drawn up for neighbourhoods undergoing reconstruction, to ensure holistic development and also allow the participation of local citizens and groups. “That recommendation was discarded right away,” he said.
From a climate perspective, even the new green building codes focus only on individual structures, not the larger area. And they don’t address urban geometry – that is, the size, number and placement of buildings – which plays an important role in local temperature. For instance, several tall buildings standing close together will store more heat, as a result of which more trees, parks or ponds will be needed to mitigate the warming.
When asked to address Patel and Mahajan’s critique of the BDD redevelopment, state housing board officials said that the distance between the window of one rehabilitation building and the window of an adjacent building would not be less than 29 metres. (In the buildings for sale, they said, the distance will be 108 metres, allowing for even better ventilation.)
As for extra infrastructure required to support the new development, they pointed out that there would be roads, gardens and schools inside the complexes. The housing board is the planning authority only for what lies inside the layout, they emphasised, while the roads and environment outside were the municipality’s responsibility. “It has given all the clearances,” said the board’s Diggikar.
Phatak and others pointed out that parks on a private podium above the street are not the same as public spaces at the street level. But the former is becoming the norm in Mumbai. “People see these new high rises with pools and private parks, and that becomes the aspiration,” Phatak said.
On January 13, the Bombay High Court rejected Patel and Mahajan’s petition. The judges observed that they were not experts on planning, and could only look at whether the project was “in consonance” with the rules. Since the BDD project had the requisite permissions and environmental clearances, the court said, “no interference is called for”.
At the tenements in Worli, Mane and Pratap told me they were satisfied with the distance between buildings. “This is not like the slum rehabilitation buildings,” Mane said.
Residents were happy with the models of the new apartments they had seen, said Mane, as well as the community hall and parks. As for Patel’s alternative plan, he added, “Why do we need a big football ground?”
At the Prataps’ home, I asked Vijay Pratap’s son, 31-year-old Ashish, what he thought. Ashish is an event planner who has travelled for work to other countries, most frequently to Dubai.
“From 160 square feet, we are getting a 500-square-foot two-bedroom, and that too in Worli,” he said. “Can’t complain.”
Neera Adarkar, an architect who worked with a mill union for decades, explained the residents’ attitude in historical terms. By the time the BDD battle came around, the workers had lost much of their political power. After a failed fight against mill closures in the 1990s and early 2000s, they had struggled to get retirement and housing benefits that were their due. “They were reduced to such insecurity, they were only concerned with getting a home, forget about how it is situated or planned,” said Adarkar.
The civil society alliance that had battled for the mill lands 15 years earlier had fragmented. “We were not able to convince the people that it didn’t have to be either-or,” she said. “That they could get a home in their name and also demand a better quality of environment.”