Efficient Shower Nozzle

Low-Flow Shower Head Energy Saving Test

The intention of this test was to check the energy saving claims made by aerated or energy saving shower nozzle suppliers.  These devices reduce the flow of water through the shower nozzle quite substantially, but at the same time introduce turbulence and/or air bubbles to make the user feel that the water flow is still adequate to shower under.  Suppliers claim water savings of up to 65%.  If that translates into an equivalent saving in hot water used, then the energy savings could be significant!

Methodology

The energy saving nozzle installed was a RST Profilence shower head.  The electricity used by the geyser supplying water to the shower was measured over a period of 4 weeks – two weeks before the nozzle was changed and then two weeks after.  Two normal showers were taken on most days during the test period. The test results were analysed and all shower events isolated on the data log.  The total energy consumed heating water after showers for each two week period was divided by the number of showers to establish an average amount of energy consumed per shower.

The old nozzle that was replaced can best be describes as “nothing special”.  Its about the same physical size as the RST nozzle (ie quite small).

Results

The two graphs below show electricity consumed heating water in the geyser during two of the showers taken, before the new nozzle was installed:

 

Summary figures for the normal shower nozzle:

• Total number of showers included in the test                     – 26
• Total energy consumed heating water for those showers    – 63.65 kWh
• Average energy consumed per shower                              – 2.45 kWh

The two graphs below show electricity consumed heating water in the geyser during two of the showers taken with the new nozzle installed:

Summary figures for the RST shower nozzle:

• Total number of showers included in the test                     – 24
• Total energy consumed heating water for those showers    – 39.19 kWh
• Average energy consumed per shower                              – 1.63 kWh

Observations

Some personal observations:

• The RST shower nozzle definitely uses far less water.  This was immediately evident in the time taken for hot water to reach the shower from the geyser.
• The reduced water flow is noticeable and does take some getting used to.  The water is confined to quite a narrow spray cone, far less than before.
• The feel of the water jet is actually quite pleasant once you are used to the narrower cone of water.  The water velocity is higher but the drops are smaller.

 Conclusions

The summary figures for the test are:

Reduction in energy used to heat water	0.82 kWh per shower
Average daily energy saving (2 showers per day)	1.64 kWh
Energy saving achieved	33%

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