High above the city

The cities of the future are often imagined as blocks of high-rise towers, and with good reason. As populations grow and demand for urban space multiplies, it seems like — to borrow from the 1988 Pop single — “the only way is up”. Manhattan and Tokyo are often used as examples of successful high-rise urbanism that allow more people to live closer to their workplace, coupled with reliable public transport, and even some green spaces. Skyscrapers dominate the skyline in Shanghai, Singapore and Dubai, and India too. Walking around any tier I, II or III cities in India, one sees 7, 12, 20 or 40-storied structures rapidly filling up the skyline, whether they are luxury housing, commercial spaces, leisure activities, or government-supported affordable housing.

Not surprisingly the primary consideration in most, if not all planning decisions in India, is about maximising the floor space index (FSI). FSI, which is referred to as Floor Area Ratio (FAR) in the US context, determines the ratio of land to the built-up area. So, for instance, an FSI of 2 means you can build up to twice the land area once you account for setbacks, an FSI of 6 means you can build to a ratio of 1:6 and so on. Central New York, for instance, has a FAR of between 12 and 15, though structures there exceed this ratio. In contrast, the FSI for residential buildings in Bengaluru is between 1.75 and 3.35, and Mumbai is just 1.33 in many areas, though Nariman Point has an FSI of 3.5 and the Bandra Kurla Complex has an FSI of 5. It would seem that removing the cap on FSI would go a long way in increasing the supply of housing, opening up green spaces, and increasing density, which should allow more efficient service delivery for residents.

Is high-rise urbanism not just inevitable but also optimal for Indian cities? It turns out the answer is not straightforward. While high-rise structures allow you to maximise the short-term return on investment from land, they do not necessarily optimise land use, particularly when it comes to carbon emissions and liveability. In other words, there are hidden costs to high-rise urbanism which are not widely known or understood. Equally, an approach to cities that might work quite well in a developed country context with a temperate climate, may be less suitable in the context of tropical cities, with less than adequate infrastructure, where lifestyles and culture vary significantly.

In Indian cities, high-rise buildings at the high end promise modern amenities including enhanced security, gyms and swimming pools, which have high maintenance costs (50% higher than low and mid-rise constructions), as well as poor water and waste management. High-rise construction requires structures that ensure strength and stability, and focuses on advanced technologies to enhance building performance and to provide comfort to occupants and their well-being by providing indoor air quality, thermal comfort, sufficient daylighting, etc. All of these have implications for energy use, carbon emissions and overall sustainability. Research conducted at UCL’s Energy Institute in London, found that buildings of 20 storeys or more consume on average more than twice the amount of energy per square foot when compared with buildings of 6 storeys or fewer. Another study conducted by Edinburgh’s Napier University, using real-world data and computer modelling, established that low-rise dense cities like Paris are about 40% more sustainable in terms of whole life-cycle carbon emissions than high-rise dense cities like New York.

While high-rise buildings have their appeal and are often seen as the solution to urban density challenges in Indian cities, they come with significant hidden costs. The promise of modern amenities and maximised floor space must be weighed against the high maintenance costs, inefficient water and waste management, and substantial energy consumption. Moreover, the sustainability and liveability of such developments in India’s unique climate and infrastructural context remain questionable.

As research suggests, a low-rise, high-density urban model may offer a more sustainable and culturally appropriate solution, ensuring that the growth of Indian cities aligns with long-term environmental and social well-being. It is essential for urban planners and policymakers to consider these factors and strive for a balanced approach that optimises land use while minimising environmental impact.

Dhaval Monani is Associate Professor, Director, Affordable Housing, Anant Centre for Sustainability, Anant National University.

Nikhilesh Sinha is Professor of Economics, Finance, Hult International Business School, London.