Performance evaluation of conventional and water saving taps.

The rapid pace of urbanisation comes with considerable environmental implications including pressures on already stressed limited water resources. In urban areas, most of the water use is associated with water consumption in buildings. The second largest use of water is via taps. It is often assumed that water taps with low flow rates can contribute to reduced per capita water consumption. However, this is based on very little evidence. This paper presents the synthesis of a 13,000 high resolution observations made to investigate the actual water consumption of innovative (water saving) electronic taps and conventional mixer taps. High resolution flow-meters and data loggers were fitted into two washrooms in two different buildings of a higher education institution to record the water use through the basin taps. The recorded data provided information on duration, frequency of use and volume of water consumption per use. The data was helpful in identifying trends in hot and cold water use and therefore can be useful in estimating energy for producing hot water and associated greenhouse gas emissions. Analysis of the observed data suggests that the low flow taps have greater mean water consumption per event than the conventional taps and water consumption is more influenced by user behaviour rather than the technology.

Environmental implications of water efficient microcomponents in residential buildings.

The Code for Sustainable Homes (CSH) in England sets out various water efficiency targets/levels, which form part of environmental performance criteria against which the sustainability of a building is measured. The code is performance based and requires reduction in per capita water consumption in households. The water efficiency related targets can be met using a range of water efficient microcomponents (WC, showers, kitchen taps, basin taps, dishwashers, washing machines, and baths). However, while the CSH aims at reducing the adverse environmental implications associated with the dwellings by promoting reduction in water consumption, little is known about the energy consumption and the environmental impacts (e. g. carbon emissions) resulting from water efficient end uses. This paper describes a methodology to evaluate the energy consumption and carbon emissions associated with the CSH's water efficiency levels. Key findings are that some 96% and 87% of energy use and carbon emissions, respectively associated with urban water provision are attributable to in-house consumption (principally related to hot water), and that achieving a defined water efficiency target does not automatically save energy or reduce carbon emissions.

A performance investigation of small-bore sewers.

This paper describes a full-scale physical model and its application to investigate the effectiveness/performance of small-bore sewers for a range of operational and design parameters. The implementation methodology involves observing the movement of synthetic gross solids in three small bore sewers (150, 100 and 75 mm diameter) for different volumes of simulated flush waves and gradients. The simulated flush waves were generated, using an automated wave sequencer, for three different flush volumes (3, 4.5 and 6 litres). To investigate the impact of solid shape factor, a number of tests were carried out using synthetic solids in combination with toilet tissue paper. In total, more than 1,000 tests were performed for different operational and design parameter combinations. Results obtained to date have confirmed earlier studies, particularly with respect to the role of flush volume in solids transport, and identified the impact of gradient variation and its significance particularly in small-bore sewers receiving low flush volume. Results from the physical model application exercise will be used to propose new design guidelines for wastewater collection systems with specific consideration to new developments and inform the decision support system, currently being developed as part of a research project on water cycle management for new developments (WaND).