W01: Low Flow Shower heads

Requirement Summary

The actual flow rate of shower heads should be entered into the software in all cases, irrespective of whether the value is low or high. Savings can be achieved if the average flow rate of the shower heads is less than the base case flow rate.

Intention

By specifying low-flow shower heads, water use is reduced without adversely affecting the functionality.

Approach/Methodologies

The flow rate of a shower can be as low as 6 liters per minute or greater than 20 liters per minute. As the flow rate of a shower head is dependent on the water pressure, manufacturers often provide a chart which plots the flow rate at different pressures. For consistency, the flow rate used for the EDGE assessment in the design/pre-construction phase must be that quoted for the operating pressure of 3 bar (43.5 psi). At the post-construction stage, actual flow rates must be used. If the pressure and flow rates of the shower heads vary across a project after construction, a weighted average at full flow must be used. Multiple measurements must be made across a variety of locations and floors to come up with a weighted average.

This measure can be claimed if the actual flow rate is entered and is lower than the Base Case. A flow rate that is lower than the default value for the design case contributes to even greater water savings.

Potential Technologies/Strategies

Many different shower heads are available that meet the flow rate required. In order to maintain user satisfaction at the lower flow rates, some manufacturers mix water with air to cause turbulence in the flow; this in turn gives an increased sense of pressure without increasing the flow rate.

Relationship to Other Measures

Higher flow rate showers use a significant quantity of hot water. Reducing the flow rate of the shower reduces the energy required to produce hot water. Therefore, both water consumption from showers, and energy consumption due to hot water, are reduced.

Assumptions

Assumptions for the base case and improved case vary by building type and location. The relevant improved case automatically gets displayed in the software. The base case flow rate can be deduced by changing the improved case values to get the same water consumption as the base case. Typically, it is either 8 or 9 liters per minute at 3 bar (43.5 psi).

Compliance Guidance

Design Stage	Post-Construction Stage
At the design stage, the following must be used to demonstrate compliance:  Plumbing drawings/specifications including make, model, and flow rate of the shower head(s); and Manufacturer’s data sheet for the shower head(s) confirming the flow rate at 3 bar.	At the design stage, the following must be used to demonstrate compliance:  Plumbing drawings/specifications including make, model, and flow rate of the shower head(s); and  Manufacturer’s data sheet for the shower head(s) confirming the flow rate at 3 bar.

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