The application of heat pumps for hot water supply and heating systems is expected. Through
this, the energy consumption of hot water supply and heating, which account for a substantial
proportion of the total energy consumption in a building, will be reduced. The level of reduction
can be dramatically increased by use of "sewage heat," which is part of waste heat in an urban
area. So far, however, it has been difficult to determine whether sufficient technical or basic data
available to widely use sewage heat exists. Therefore, demonstrations on the evaluation method for
the potential of sewage heat in an urban area and the actual- equipment scale of verification using
untreated sewage were conducted to understand the characteristics of sewage heat, and major
technologies for use of sewage heat were developed. The technologies were applied to the system
using sewage heat, and the system achieved a 29% reduction in the annual energy consumption
and a 69% reduction in the running cost in the hot water system in lodging facilities compared to
the conventional system using a boiler. The depreciation timespan of the difference in the initial
cost between the conventional system and the heat pump system is about four years, and this system
has an economically large advantage. In this report, the results obtained through the development
and the demonstrations are systematically organized and the technical information needed for
introduction of use of sewage heat is provided.
