Studying the demand-side vis-à-vis the supply-side of urban water systems – case study of Oslo, Norway

Abstract

The research focus of resource consumption and emissions from urban water services has, by and large, been restricted to what comes under the domain of the urban water utilities – the upstream sub-systems of water treatment and supply and the downstream sub-systems of wastewater collection, treatment and disposal. However, the material and energy flows necessitated by activities in the water demand sub-system (households, for instance) are by no means negligible. This paper studies the per-capita material and energy requirements, and the related emissions and life cycle environmental impacts, associated with water consumption in households of the city of Oslo for the year 2009. For example, the per-capita energy consumption in the household consumption phase, at 1.38 MWh per year, is eight times more than the corresponding consumption for the entire water-wastewater utility. All findings, taken together, clearly demonstrate the imperativeness of paying more attention to the demand-side management issues.

Keywords:

• Urban water services
• demand-side management
• energy
• materials
• chemicals
• emissions
• environmental impacts
• life cycle assessment

Acknowledgements

The authors would like to thank Ph.D. candidates at NTNU – Viggo Bjerkelund and Nina Sandberg – for their help with reports and journal papers (on water use and energy consumption in households) which were useful for this analysis. Thanks to Prof. Sveinung Sægrov and Prof Rita Ugarelli – both from NTNU – for their help with data and information on several occasions. Thanks also to Hilde Midsem and Bjørg Glesne, from Statistics Norway, Oslo (for links to reports on sales of household appliances in Oslo) and Dr Nicole Unger, Environmental Sustainability Scientist from Unilever, London, UK for discussion about environmental impact studies of the companies’ products. We also acknowledge personnel at Oslo VAV – Kari Aasebø, Ola Toftdahl, Per Kristiansen, Rashid Abdi Elmi and Chetan Hathi, among others. Thanks to the reviewers for their comments and help in improving this paper.