How Energy Efficient Are Modern Dishwashers?

We present measurements of three recent vintage dishwashers of very different efficiencies showing that while they are substantially more efficient than older dishwashers, those tested will still use electric resistance elements for supplemental heat, even when supplied by solar water heating systems producing very hot water. We did find the DOE test results provide a reasonable guide to comparative performance, but suggest improvements that will make them more representative. We also identify a variety of influences on efficiency and performance to reduce dishwasher energy use