Measuring Household Metabolism in the City of Cape Town: A first step to a Differential Urban Metabolism

Informal settlement upgrading is an important consideration for cities of the global South, many of which are facing rapid urbanization in the context of limited city-wide resource availability or access. These already... [ view full abstract ]

Informal settlement upgrading is an important consideration for cities of the global South, many of which are facing rapid urbanization in the context of limited city-wide resource availability or access. These already overburdened cities are under pressure to develop urban plans which can maximize economic opportunity and social welfare for its residents, many of whom live in improvised homes, while limiting negative environmental externalities. Stated political agendas aim either to undo legacies of differential resource provision - via colonial, capitalist or apartheid mechanisms - or to increase standards of living and associated economic participation in under-developed areas through improved resource availability and utilisation. Urban metabolism is cited as a tool to encourage development of such plans. However, many studies of urban metabolism remain at aggregate city-level and do not provide information about the differential stocks and resource consumption patterns throughout the city. Moreover, the methods used to estimate and assess urban metabolism tend to focus on arbitrarily bounded systems, which excludes many processes which shape resource flows and limits the ability to extrapolate information beyond these boundaries. To address this, a differential exploration of urban metabolism, making use of smaller units of resource consumption which can be extrapolated to city-level, presents a useful approach to assessing the current resource patterns of the city. This is a particularly important consideration for examining informal systems and upgraded settlements, as future resource impact will rest on how informal settlements are upgraded or relocated.   

This study presents a first step in towards estimating a differential urban metabolism for Cape Town. It follows a methodological inquiry and examines in detail the concentration of resource stocks and consumption patterns for three representative households types  in Cape Town. These households were chosen using building typology as a proxy for income and resultant resource consumption, and are located in: (i) an informal settlement; (ii) a newly upgraded government settlement; and (iii) a lower-middle income neighborhood, with market-driven housing. The explicit aim was to understand the efficacy and outputs of various data collection methods used to identify and quantify household metabolism. This includes a broad, but detailed investigation of energy, water, food, consumer goods and wastes. The methods included observation and recording, interviews, surveys, household activity diaries and accessing municipal records. These methods were undertaken for each household so as to compare results and ascertain the benefits and limitations of each. The specific tension underlying the choice of method is between the time and funds necessary and the detail of information acquired.  

The preliminary investigation of this study demonstrates that data scarce environments would benefit from the use of household metabolism to estimate city-wide metabolism. This has more direct implications for policy makers as household activities are a key driver of energy and resource consumption. A number of more focused estimations of household metabolism are underway, which will increase the sample size and be used to generate types of household resource consumption to enable extrapolation to city-level metabolism.