Water Journal : Water Journal May 2011
technical features 78 MAY 2011 water demand management refereed paper a comparison of daily use from one week to the next and, finally, daily use over the last 28 days. The IHD devices also featured a leak alarm capability. If the unit detected continuous water use extending over a 24-hour period, it would display a 'possible water leak' message. This message cleared automatically once the leak had been rectified. Similarly, if a tap had been left on an alarm was sent, but once the tap was turned off, the leak alarm would disappear. Quantative Research Methods The quantitative research involved the analysis of consumption data collected from all 468 properties and 15-minute supply data from the bulk flow meter. In terms of leakage management, the water usage data obtained from the study allowed night usage in single residential dwellings to be characterised according to changes in seasons and weather conditions. The intention was to incorporate this information into a larger night usage model, which in turn would be used to refine system minimum night flow calculations and hence network leakage estimates. The continuous water consumption readings from the smart meters were totalled and used for simultaneous comparison with the bulk supply flowmeter readings. Differences between the readings would provide a direct measure of supply system leakage at any given point in time and would aid the development of information technology tools for leakage monitoring using smart meters. Lastly, and to the extent that the existing meters were able to measure very low flows, the data would allow leakage on residential water services downstream of the meter to be quantified. The IHD had the capability of tracking the user's screen touches. The number of touches was recorded half-hourly and sent to the Spider logger. This information is valuable in supporting the qualitative research to help understand how often the customers interacted with the device and how accepting they were of the technology. Qualitative Research Methods From a social behaviour perspective there were several elements to this research, which involved collecting information from customers through surveys and interviews. Figure 2 shows the social research stages. The participating households represented high, medium and low water users as well as a cross section of demographics and included households with and without IHDs. Twenty-four customers with an IHD also participated in a series of in-depth face-to-face interviews. The social research focused on gaining a better understanding of our customers, what their views and practices were in terms of water conservation, and what motivated or hindered their decisions about saving water. The emphasis of this part of the project was to determine if customers' behaviours can be changed -- and to what extent -- if they are given more detailed and timely information on their water usage. The extended duration of the trial would allow for the sustained acceptance of the smart metering technology to be gauged. Results: Water Savings and Behavioural Change One of the key findings of the project was an overall 7--10% reduction in water consumption in households with an IHD, or an average water saving of 16kL per property per year. This behavioural change was sustained throughout the study period, despite the use of the IHD starting to decline after two months. Figure 3 (overleaf) shows the mean daily AMR consumption of households with and without IHDs. The relevant climate data has been added to the graph to provide context for consumption patterns. The data demonstrates that the comparative consumption of the IHD group was lower than the AMR group from the beginning of the IHD installation process in May 2009. As a group, those with IHDs continued to consume comparatively less water through to the end of the project in June 2010, when the IHDs were removed. The IHD group appeared to be able to save more water in comparison to the AMR group in winter and spring (June 2009 to November 2009) than in summer and autumn (December 2009 to May 2010). These results could be interpreted as seasonal changes or initial enthusiasm in response to the IHDs. The majority of IHD participants liked having the IHD and their level of awareness was raised in terms of their water use. The behaviours that led to the reductions in water use were reported to be shorter showers, less garden watering, washing with full loads and installing water-efficient devices. For the IHD participants, a usage target was set that reflected the number of occupants in the household. These targets were met on an average daily basis of 61.5% of the time. While having a target was anticipated to be an incentive for participants, it proved to be a disincentive for those who were well above the target. Household Leakage Smart metering has proven to be an effective tool in detecting household leakage. About 80% of properties were identified as having a leak at some point in time during the project. Typically, on any given day, between 10% and 17% of properties had leaks. The average leakage rate at customer properties was in the order of about 3% of total usage, which is about 7kL per property per year. Over the study period, total leakage at individual properties ranged from 1.1L to 218kL and the duration of the leakage ranged from a single day to 468 days. Most of these properties (over 60%) had leakage that can be regarded as minor since the leaks detected were both relatively small and of less than 50 days duration. Leakage was much more significant at the remaining properties where the leaks were larger and/or extended over a considerable period. The 'top' 10% of properties in this category accounted for 62% of all leakage while the top 33% accounted for 92% of the volume of water suspected as lost due to leakage. Figure 1: IHD summary screen. Figure 2: Qualitative research stages.
Water Journal April 2011
Water Journal July 2011