抄録
Energy consumption of 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 daily use by subjective experiments, and we calculated the energy-saving effect of not using hot-water by supplying the preheated water. The results showed that 50% of subjects accept the water temperature of 24 degC for usually use. And the water temperature of 28 degC is necessary for 90% of subjects to accept. If preheated water is supplied to kitchen and bathroom vanity, 30% or less of heat requirement for hot-water supply will be reduced, and if preheated water is supplied to all of household water use, there is possibility of reduction in about 75% heat requirement for hot-water supply.
