W05: Water-Efficient Kitchen Faucets – Above Green

Requirement Summary

The actual flow rate of kitchen sink faucets must be entered in the software in all cases, irrespective of the value. Savings can be achieved if the flow rate of the faucets specified for the kitchen sinks is less than the base case specified in liters per minute.

In some cases, these savings are not applicable. For instance, in a building without a kitchen, there will be no kitchen water faucets and therefore no savings from this measure.

Intention

By specifying low-flow faucets for kitchen sinks, water use is reduced without adversely affecting the functionality. Hot water use is also reduced, reducing energy consumption for heating the water.

Approach/Methodologies

As the flow rate of a faucet is dependent on the water pressure, manufacturers often provide a chart that plots the flow rate at different pressures. To improve consistency, the flow rate used for the EDGE assessment must be that quoted for the operating pressure of 3 bar (43.5 psi). If this flow rate is not available, physical measurements can be made on site using a bucket of a known size and a timer to record the flow rate. If the flow rates of the faucets vary across a project, a weighted average must be used. Multiple measurements must be made across a variety of locations and floors to come up with a weighted average.

If the measure is claimed, the assumed improved flow rate defaults to 4 liters per minute. As long as the actual flow rate is lower than the base case in liters per minute, the measure can be claimed by specifying the actual flow rate. A lower flow rate contributes to greater water savings.

Potential Technologies/Strategies

Many different faucets are available that meet the flow rate required. 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. Flow restrictors or aerators can be added on to the specified faucets to reduce the flow rate, which may be a cheaper alternative to purchasing a low-flow faucet.

Relationship to Other Measures

Higher flow rate kitchen faucets use a significant quantity of hot water. Reducing the flow rate of the kitchen faucets reduces the energy required to produce hot water.

Assumptions

The base case assumption varies by location. Globally, the typical baseline assumption is a flow rate of 8 liters per minute and the improved case is a flow rate of 4 liters per minute at 3 bar.

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 kitchen faucet(s) or flow restrictor(s); or
Manufacturer’s data sheet for faucet(s)/flow restrictor(s) confirming the flow rate at 3 bar.

At the post-construction stage, the following must be used to demonstrate compliance:

On site test results by the auditor of the flow rate at the highest flow per minute, using a timer and a measurement container; and
Photographs of the installed faucet(s) or flow restrictor(s); or
Purchase receipts and delivery note for faucet(s) or flow restrictor(s).