Urban metabolism of an ecosensitive subdivision in Brisbane, Australia

Abstract

We report on the initial results from a 22 lot water sensitive subdivision in Brisbane and show that the rainwater (individual and communal tanks) and greywater reuse systems are providing potable water savings well in excess of 50% compared with a traditional subdivision. However water self sufficiency measures come at the cost of increased energy use due to the intrinsic and operational inefficiencies of small electric pumps and UV disinfection units compared with large centralised systems. Whilst the energy penalties (kWh/hh/day) are not large compared with power use from household pool pumps and air conditioners, a number of suggestions are made to offset the disbenefits. Resident behaviour during regional water restrictions showed a "disconnect" between their rainwater tanks and the supplementary water source (Council mains) highlighting the importance of education for people moving into less traditional subdivisions. Future monitoring will focus on collecting longer term and a larger water end use dataset as house construction proceeds, documenting emerging social attitudes of residents and their water/energy use behaviour, identifying causes of variation in greywater quality (sodicity is a concern), and formulating metrics that compare net sustainability gains with traditional urban development at a "whole of system" level.