W07: Water Efficient Dishwashers – Above Green

Requirement Summary

This measure can be claimed if all the dishwashers installed in the building are water efficient (low consumption). This can be demonstrated when the purchased dishwasher(s) use less water than the base case. The base case dishwasher uses 5 liters per rack.

Intention

Minimize the water consumed by the dishwashers installed in the building.

Approach/Methodologies

The dishwasher consumption can be as low as 4 liters per load or greater than 21 liters per load. In a load two racks can be filled up. EDGE measures the water consumption per rack, which is calculated with the maximum total water consumption in liters divided by the number of racks in the dishwasher. The maximum total water consumption is taken from the manufactures datasheet on the cycle of the dishwasher that uses the most water. This measure can be claimed as long as the dishwasher uses 2 liters per rack or less.

Potential Technologies/Strategies

Dishwasher Overview

Key Features of Efficiency

About 60% of the energy used by a dishwasher goes towards water heating; therefore, models that use less water also use less energy.

An efficient dishwasher should:

Be the right size for the building
Have several wash cycles
Enable pre-rinse to be skipped
Have soil sensors, which test how dirty dishes are and adjust the cycle to reduce water and energy use
Have more efficient jets, which use less energy to spray detergent and water
Have ‘no-heat’ drying feature, which circulates room air through the dishwasher by fans, rather than using electric heating
Have improved water filtration

In terms of dishwashers, the way that occupant use them also influence the water performance. It is important to provide users with guidelines outlining the benefits of these appliances, and the best way to achieve maximum efficiency.

Relationship to Other Measures

Water reduction in the 'Kitchen' section of the water chart is expected by water efficient dishwashers. Moreover, it shows reductions in energy due to equipment and pumps which is part of 'Others.'

Assumptions

The base case assumes standard dishwashers with a water consumption of 5 liters per rack, while the improved case assumes 2 liters per rack, which is 60% more efficient.

Compliance Guidance

Design Stage

Post-Construction Stage

At the design stage, the one of the following must be used to demonstrate compliance:

Summary of the dishwasher(s) to be installed in the building, including quantity and proof of maximum water use; or
Specifications from manufacture detailing water use.

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

Updated summary of dishwasher(s) installed in the building including quantity, manufacturer and model; or
Proof of maximum water consumption from manufacture; or
Purchase receipts and delivery note for dishwashers