Influence of water pressure in the evaluation of energy savings achieved through the use of low flow shower heads

The use of low flow shower heads is presently considered as one of the solutions that can contribute to the global effort towards the optimisation of energy consumption. In the leisure (hotels, gymnasiums) and residential sectors, the use of low flow shower heads can lead to significant energy savings. In South Africa, Eskom has recently launched a mass roll out programme intended to save energy through the use of this technology. Given the recentness of this programme in the country, the evaluation of energy savings achieved by using of low flow shower heads remains a challenge. One of the major steps in the evaluation of energy savings achieved through the use of low flow shower heads is the evaluation of the difference between the flow rate of the old shower heads (before retrofitting) and that of the new shower heads (after retrofitting). As a result, the correct measurement of the flow rates is an important requirement for accurate determination of the savings achieved. For this reason, parameters and conditions that affect the flow rate value have to be taken into consideration during the measurement process. Current measurement and verification (M&V) literature provides very few details about the measurement methodology to use in order to ensure that results are accurate and relevant to the context of the project. This paper provides an overview of parameters that have to be considered when measuring the flow rate. Using laboratory measurements, the influence of context parameters on the flow rate measurement is demonstrated. Furthermore, a measurement approach that ensures relevance of results is suggested.