Use of home food digesters to reduce household waste Available to Purchase

As a first step to understanding household material flows and waste arisings, a detailed picture of household consumption is required. This task is particularly problematic for local areas such as deprived inner-city housing estates that are under-represented in national surveys. This paper describes two methodologies for assessing household expenditure as a consumption proxy and applies them to such an area. The first is a top-down approach using national datasets to model household expenditure at high levels of socio-economic and geographical disaggregation. The second method is a bottom-up approach in which a sample of household expenditure diaries was collected, augmented by a variety of qualitative techniques to gain a detailed picture of household practices. The results from the two methodologies showed marked discrepancies: locally collected data demonstrate a higher degree of variability than modelled results based on aggregate data. It is suggested that neither approach is ‘right’ or ‘wrong’, but that the two methodologies serve different purposes. Use of top-down modelled data is pragmatic and affordable for use by administrative or commercial bodies. However, without recognition of the localised volatility revealed by the bottom-up method, it is unlikely that realistic and efficient collection strategies can be devised.