Density, Energy and Metabolism of a proposed smart city

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This paper reports on a detailed analysis of the metabolism of the Island City of Mumbai should the Indian Government’s proposal for ‘smart’ cities be implemented. It focuses on the environmental impact of increased population density achieved by demolishing existing medium-rise (3-5 storey) housing and replacing it with the proposed high-rise (40-60 storey) towers. The resulting increase in density places a burden on the demand on such things as electricity and water and simultaneously increases the output flows of drainage, solid waste and greenhouse gas production. An extended urban metabolism analysis is carried out on a proposed development in Mumbai (Bhendi Bazaar) that has been put forward as an exemplar case study by the Government. The flows of energy, water and wastes are calculated based on precedents and from first principles. The results of the case study are then extrapolated across the City in order to identify the magnitude of increased demands and wastes should the ‘smart’ city proposals be fully realised. Mumbai is the densest city in the world. It already suffers from repeated blackouts, water rationing and inadequate waste and sewage treatment. The results of the study indicate, on a per capita basis, increasing density will have a significant further detrimental effect on the environment.

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Density, Energy and Metabolism of a proposed smart city Dr.Anindita Mandal1and*Dr.Hugh Byrd2 Luleå Tekniska Universitet, Sweden1 School of Architecture & Design,University of Lincoln, UK2 1E mail: aninditamandal@yahoo.com, 2E mail:hbyrd@lincoln.ac.uk A B S T R A C T This paper reports on a detailed analysis of the metabolism of the Island City of Mumbai should the Indian Government’s proposal for ‘smart’ cities be implemented. It focuses on the environmental impact of increased population density achieved by demolishing existing medium-rise (3-5 storey) housing and replacing it with the proposed high-rise (40-60 storey) towers. The resulting increase in density places a burden on the demand on such things as electricity and water and simultaneously increases the output flows of drainage, solid waste and greenhouse gas production. An extended urban metabolism analysis is carried out on a proposed development in Mumbai (Bhendi Bazaar) that has been put forward as an exemplar case study by the Government. The flows of energy, water and wastes are calculated based on precedents and from first principles. The results of the case study are then extrapolated across the City in order to identify the magnitude of increased demands and wastes should the ‘smart’ city proposals be fully realised. Mumbai is the densest city in the world. It already suffers from repeated blackouts, water rationing and inadequate waste and sewage treatment. The results of the study indicate, on a per capita basis, increasing density will have a significant further detrimental effect on the environment. CONTEMPORARY URBAN AFFAIRS (2017) 1(2), 57-68. https://doi.org/10.25034/ijcua.2017.3648 www.ijcua.com Copyright © 2017 Contemporary Urban Affairs. All rights reserved 1. Introduction In the study of the relationship between urban form and resource consumption, there are differing conclusions concerning the impact of dense urban form. For example, reduced transport energy consumption has been shown to correlate with increased urban density (Newman & Kenworthy, 1989), household space heating energy consumption reduces with compact house forms (Rode et al, 2014) and more general unsupported claims are also made (Leung, 2016; Albino et al, 2015;Nia, 2017). However, other studies have indicated that CO2 emissions from transport and electricity consumption per capita show little correlation with the density of urban areas (Hammer et al, 2011) and there is evidence that dispersed urban forms are more energy efficient when disruptive technologies such as photovoltaics to charge electric vehicles (the more likely technologies of the future) (Byrd et al 2013) are widespread and there is empirical evidence demonstrating that compact residential building forms are less energy efficient (Myers et al, 2005; Byrd et al 2012). However, policies on urban form tend to favour compaction but there is little evidence of what densities urban form should target to optimise resource consumption (Steadman, 2015). While some studies have indicated an optimum density of about 18 dwellings per Ha (Gosh et al, 2006) most policies advocating increased density (Sridhar, 2010) stay clear of a density target which can result in the impression that the denser; the more efficient. If that is the case, the consequences of urban forms of very high-density need to be understood and the implications back-casted to inform cities with policies of increased compaction. This research concerns the densest city in the world, Mumbai, and the environmental impact of the proposed redevelopment proposals that are likely to increase densities from about 3,500persons per hectare to about 5,000, achieved by demolition of existing 3-5 storey height buildings and replacing them with towers averaging 40 floors. What has become known in Mumbai as ‘vertical with a vengeance’ (Rathod, 2012). The study investigates the environmental impact of a proposed redevelopment of a 16.5-acre site. Of the many redevelopment proposals in Mumbai, this is in the most advanced stage and is an exemplar for both Mumbai in its ambition to become a ‘global city’ and the Indian Government who have identified it as a key development in their proposal to achieve 100 ‘smart’ cities (Government of India, 2015). The study firstly compares the existing urban form with the proposed form. For example, numbers and heights of buildings, density of dwelling and population, parking provision, open space, landscaping and street frontages. It uses the extended urban metabolism model (Newman et al, 1996) as a basis of analysis and predicts the flows of water supply (reticulated and rainwater harvesting), drainage, solid waste, electricity supply, potential for solar energy, fuel for transport, carbon dioxide production and sequestration. From the results of the 16.5-acre site, the analysis is then extrapolated to the overall impact if similar developments were to be carried out, as is proposed, across all of the Island city of Mumbai. The results indicate that metabolism does not increase linearly (on a per capita basis) with density but accelerates instead. The results also indicate that the compact urban form increases dependence on infrastructure security and that the increased demand of water and electricity is unlikely to be supplied in a reasonably reliable and secure manner. Furthermore, the outputs (waste water, solid wastes, and carbon dioxide production) would increase disproportionately resulting in both health and accelerated climate change issues. The Indian Government (2015) has claimed this type of development to be sustainable, environmentally friendly and ‘smart’. This research indicates the opposite may be more likely. 2. Background to the development Proposals The Island City of Mumbai trebled in population over a period of about 50 years (1931-1981) mainly due to rural-to-urban migration (Census of India, 2011). The population peaked and has subsequently experienced a marginal decline as the suburbs have grown. The migrants into the City were protected by the Mumbai Rent Restriction Act (1939) limiting returns on landlord’s investments and resulting in disrepair of the housing stock. As a result, in 1969, the “cess” tax was introduced and a levy placed on landlords by the municipal authorities who took over property repairs. Regulated rent levels combined with the ‘cess’ tax made redevelopment financially unattractive. Added to this were limitations on the ratio of site area to floor area of developments (FSI). In the first Development Plan of Bombay (1964), FSI was limited to 1.66. But with few new developments and, in order to try and encourage developers, this was eased to 2 in 1984 and then 3 in 1991 and 4 in 2009. These inducements had little impact and relatively few high-rise housing was built. The ‘cessed’ property (generally 3-5 storeys) predominated (Bertaud, 2013). The cessed properties did not conform with the image that the municipal authorities wanted to see of the City that was the financial capital of India. In 2011, Mumbai hosted the Tall Building conference and announced its proposals to redevelop the city by demolition of cessed property and replacing it with towers with the intention of being perceived as a “global” city (CBTUH, 2010). Further FSI incentives were again introduced in 2009 by Development Control Rules (DCR 33(9)) provided developments were of a significant scale. This triggered new development proposals and one of the first and largest developments was proposed at Behndi Bazaar, Ward C in the Island City. A 16.5 acre site containing 247 buildings (typically 3-5 storey) are due to be demolished and replaced by 30 towers of between 40 to 60 floors (a built-up area of almost 11 times greater than the site area).

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