MUMBAI: Thousands of slumdwellers in Mumbai have been rehoused in the past few decades through various rehabilitation schemes. But how do these low-income homes fare in terms of livability? And if they fare poorly, what can be done to fix them? These are some of the questions that Ronita Bardhan and her team are trying to answer at the Centre for Urban Science and Engineering at the Indian Institute of Technology Bombay.
For the past few years, associate professor Bardhan and her colleagues have been conducting surveys, collecting data from sensors placed in homes, and modelling simulations in an effort to quantify how building design affects human health and well-being in low-income homes–and how this design can be optimised. The team contributed to an important new study by Doctors For Us linking high incidence of tuberculosis in low-income housing complexes in M/East Ward to poor ventilation and light in those buildings.
IIT
Slum rehabilitation projects have been important for meeting near-term demand for affordable housing stock, says Bardhan, who trained as an architect before doing her PhD in urban engineering at University of Tokyo. “But rehabilitation needs to be real,” she says. “Low-income families should be able to move into not just a new house but a healthier life.”
Bardhan’s lab has found issues of ventilation, inadequate light, and heat due to design shortcomings in several low-income buildings across the city. In newer blocks, lack of social and working spaces and privacy can be an additional problem, compared with say older chawl systems, says Bardhan.
Some findings are surprisingly complex. In one study comparing different kinds of low-income housing, the researchers found that while a low-rise stretch of slums had lower temperatures than multi-storied rehab buildings, the taller buildings cooled down faster— depending on their layout. In another study of BDD chawls published last year, Bardhan’s team found that a different layout of the same type of building in the same neighbourhood resulted in much better airflow.
The same study found that removing an obstruction on the windward side of one building could lead to a 50% reduction in stale air inside homes—a relatively simple fix. “We are looking for solutions within the existing policies of FSI and land space,” said Bardhan. “These include policy interventions on site layouts and orientation, as well as design retrofits to improve existing homes.”
Retrofit recommendations include installing high ventilators to improve air flow in lowincome homes—a typical feature of traditional Indian houses. Such solutions seem to reiterate architectural principles or conventional wisdom: Many homebuyers know to look for crossventilation and light, after all.
Yet those principles have been neglected in the rush to build affordable housing. And that neglect has been enabled by the fact that the benefits of good design have not been quantified, says Bardhwan. This lack of data—and the disconnect she found between architects, engineers, and social scientists—was partly what motivated her to pursue this research, she says. “If you can tell people you can save x rupees in energy consumption by designing for more sunlight, that’s more effective.”
One of her studies shows, for instance, that a middle-income building with a 17% window to wall ratio could save up to 26% on lighting bills if it increased that ratio by just 3% and reoriented to the south-east. Bardhan uses this saving to make a case for including daylight performance as a parameter in the city’s building byelaws. Even in some middle-income housing complexes, only the top floors have adequate daylight. (She notes that Hong Kong now has byelaws making one building pay if it blocks another’s light.) Evidence and data are especially important in social housing projects where builders seek to keep costs as low as possible. “But cheap construction is not really cheap,” points out Bardhan, “it doesn’t account for future costs of poor health or energy consumption.” And those costs will become only go up in a changing climate.
IIT team looks for ways to let light, air enter rehab colonies
