Abstract
Energy consumed for hot-water supply is to account for about one third of household energy consumption. For energy conservation, reducing the energy consumption for hot-water supply plays a big part. As basic research towards reducing hot water consumption in daily life, we determined the minimum required water temperature for dishware washing by subjective experiments and by survey and calculated the energy-saving effect of not using hot water for dishware washing. The results showed that the water temperature needs to be 20℃ or higher for dishware washing. If water at 20℃ is supplied only for dishware washing in winter, hot-water supply energy consumption will not be reduced by more than about 13%. The total energy consumed for hot-water supply, however, will be reduced by about 35% because the water temperature itself is high.
