Two methods of measuring and analyzing domestic hot water consumption are compared. The temperature-based event inference method relies on end-use temperature changes to characterize hot water consumption. This method requires extensive instrumentation and data acquisition system commissioning. Once the system is set up, simultaneous draw events of one, two, and even three end uses are automatically identified, offering unprecedented accuracy. Based on the pilot measurements described here, 97.1% of the hot water draw events were correctly allocated to different end uses.

The flow trace signature analysis method is well documented. This method employs flow measurements and a few supporting temperature measurements at the main branches of the piping network. This approach is less obtrusive and quick to install. However, it requires test runs to characterize flow rates and event durations, as well as significant analysis program customization. Due to overlap in the duration and rate of flows of all sinks and the shower, a differentiation between similar end uses (e.g., sinks) is not always possible. Furthermore, flow trace signature analyses make more errors with respect to failed end-use detections and wrong end-use allocations, providing an overall accuracy of 90.6%.

Units: SI